ITEMS FROM INDIA

BHABHA ATOMIC RESEARCH CENTRE

Nuclear Agriculture and Biotechnology Division, Mumbai-400085, India.

Genetic improvement of wheat quality and rust resistance in Indian wheat. [p. 31]

B.K. Das and S.G. Bhagwat (Nuclear Agriculture & Biotechnology Division) and A. Saini and N. Jawali (Molecular Biology Division).

We are using HMW-glutenin subunits as a selection criterion for the genetic improvement of wheat for quality in Indian wheat background. Rust-resistance genes such as Sr31/Lr26/Yr9, Sr26, and Sr24/Lr24 are being combined with high-yielding ability and protein subunits for quality traits. A number of intervarietal crosses were made and selections are being carried out. Marker-assisted selection with SCAR markers is being used to select for rust resistance genes Sr31 and Sr24 and HMW-glutenin subunits 5+10 (coded by Glu-D1d).

Genetic diversity among Indian wheat cultivars as revealed by AP-PCR markers. [p. 31]

B.K. Das and S.G. Bhagwat (Nuclear Agriculture & Biotechnology Division) and A. Saini and N. Jawali (Molecular Biology Division).

Genetic diversity among 44 Indian wheat genotypes was assessed using arbitrary primed polymerase chain reaction (AP-PCR). Long primers (16-24 bases) were used, and the PCR conditions standardized. At an annealing temperature of 55°C, the primers worked well. Of the 20 long primers, eight gave consistent results. Using those eight primers, 61 amplified bands were obtained. Twenty-five of the bands were polymorphic, with an average of 3.3 polymorphic bands/primer. Similarity coefficient values were in the range of 0.14 to 1.0. Based on these values, a cluster analysis was done using the UPGAM method, and a dendrogram with three clusters was drawn. One of the clusters consisted of wheat cultivars with the T1BL·1RS translocation. Based upon the pedigrees, similar cultivars were grouped together in the clusters. With the exception of four cultivar pairs, the cultivars could be distinguished from each other. Although only a few primers were studied, our results show that AP-PCR markers can be used to identify cultivars or make DNA fingerprints of wheat genotypes. Based on the similarity coefficient values, we observed that the genotypes have narrow genetic diversity.

Identification of two DNA markers linked to stem rust-resistance gene Sr26 in bread wheat. [p. 32]

Ruchi Rai, B.K. Das, and S.G. Bhagwat (Nuclear Agriculture and Biotechnology Division).

Sr26 is an effective gene not yet used in Indian wheat-breeding programs. Marker-assisted selection and pyramiding with other Sr genes will help to achieve durable resistance. A population consisting of 140 individual plants was developed from cross between Kalyansona and Kite (+Sr26). The population segregated for a single rust-resistance gene and fit a 3:1 ratio. A total of 100, random decamer primers and 24 AP-PCR primers were analyzed. Two markers were polymorphic in both parents and the resistant and susceptible bulks. Linkage analysis using MAPMAKER detected two markers SS30R_480bp and OPAE-07_620bp linked to Sr26. One AP-PCR and one RAPD-based marker linked to Sr26 were cloned and sequenced, and SCAR primers have been designed. Two of the three SCAR markers amplified monomorphic fragments, whereas a third primer detected polymorphism associated with Sr26 and will be used for screening and validation.

Genetic linkage map of bread wheat and a QTL map for spike-related traits. [p. 32]

Nalini Eswaran and Narendra Jawali (Molecular Biology Division) and S.G. Bhagwat (Nuclear Agriculture & Biotechnology Division).

A genetic linkage map was constructed using an F₂ population derived from a cross between two Indian bread wheats Sonalika and Kalyansona. The map consisted of 236 markers and spanned a distance of 3,639 cM with 1,211.2 cM for the A genome, 1,669.2 cM for the B genome, 192.4 cM for the D genome, and 566.2 cM for unassigned groups. The average density was one marker/15.4 cM. The map included 37 linkage groups of which 24 were assigned to 17 chromosomes by making use of anchor markers such as STMS and AFLP markers that were physically mapped using nullitetrasomic lines.

The two spike-related quantitative traits, spike length (SL) and number of spikelets/spike (NSS), are related to yield. The spike of Sonalika is thinner, longer, and has fewer spikelets compared to that of Kalyansona, which has a thicker, shorter spike with more spikelets. The data for SL and NSS were collected on an F₂ population grown in Trombay. QTL were detected by CIM and MCIM with an LOD threshold >2.0. Two QTL were detected for NSS. The QTL on chromosome 5B showed higher phenotypic variation (21.7%) than that on chromosome 1B (6.9%). One marker, ITS-HaeIII, likely to be from the Nor-B1 locus of chromosome 1BS, was found to be closest to a QTL for NSS. Four QTL for SL, with phenotypic variation ranging from 8.6 to 36.6 %, were on chromosomes 1B, 2B, 5A, and 6B. The QTL for SL on chromosome 1B was same as that for NSS with the closest marker being ITS-HaeIII.

Analysis of the data from the F₂ population showed that SL and NSS are significantly correlated (correlation coefficient (r) = 0.58). Seven QTL were detected by joint MCIM for the two traits in combination and of these, two also were detected by CIM, three were detected by individual MCIM, and the remaining two were detected by CIM and individual MCIM. The two QTL on chromosomes 2B and 6B, which were detected by CIM and MCIM, can be considered as QTL that influence both NSS and SL.

Allelic variation at the Rht8 locus in Indian wheat cultivars. [p. 32-33]

Suman Sud and S.G. Bhagwat (Nuclear Agricultural and Biotechnology Division).

Reduced height in wheat has been used as yield-enhancing option in wheat-growing regions of India. The Norin 10 dwarfing genes were used widely and resulted in a significant yield advantage. The search for an alternative source of dwarfing genes identified another reduced height gene Rht8 in the Japanese cultivar Akakomughi. The Rht8 gene also is reported to provide an advantage in warm environments. A wheat microsatellite marker, GWM-261, on the short arm of chromosome 2D cosegregated with the Rht8 gene in hexaploid wheat. This microsatellite primer is known to give different allelic variants at Rht8 locus, and an 192-bp allele is associated with the presence of Rht8. Therefore, we wanted to find allelic variants at the Rht8 locus and study the adaptive advantage of this locus in Indian wheats. Ninety-five cultivars were screened for polymorphism at the Xwms-261 locus. Allelic variants of 165 bp and 192 bp were more common compared to 174 bp among the analyzed cultivars. Ten cultivars had bands greater than 200 bp, which need to be sequenced and further studied for their advantage over the 192-bp allele.

Characterization of a GA3-insensitive, reduced height mutant of emmer wheat NP200 (T. turgidum subsp. dicoccum). [p. 33]

Suman Sud, K.A. Nayeem, and S.G. Bhagwat (Nuclear Agricultural and Biotechnology Division).

A ammag-ray-induced, reduced height mutant was obtained in the emmer wheat NP200. The mutant was insensitive to externally applied gibberellic acid. An allele-specific marker for the major dwarfing gene RhtB1b was used to check the status of the dwarfing gene in the mutant, semidwarf, and tall emmer and semidwarf durum wheat cultivars. The primer showed amplification of the RhtB1b gene in the semidwarf durum and emmer cultivars. The NP200 parent had the wild-type allele (RhtB1a) with the primer pair BF-WR1. All semidwarf emmer cultivars had a band of 237 bp with primer pair BF-MR1. However, the mutant (HW1095) lacked amplification for both RhtB1a and RhtB1b alleles with the respective primer pairs. The results indicated that the reduced-height mutant carried a mutation different than from the existing allele RhtB1b.

Computer-based image analysis for class and cultivar identification in wheat.[p. 33]

S.P. Shouche (Computer Division), S.G. Bhagwat (Nuclear Agriculture & Biotechnology Division), and J.K. Sainis (Molecular Biology Division).

Computer-based image analysis is being applied for wheat class identification and cultivar identification. Fifteen wheat samples belonging to bread wheat, durum wheat, and emmer wheat were used. Images were taken in transparency or reflectance mode. Shape, size, and color parameters were derived from the images. Correct class identification was indicated for 13 of the 15 samples. Four samples were reused as unknown but could be correctly identified on the basis of minimum Euclidean Distance.

Studies on the sphaerococcum locus in bread wheat. [p. 33]

A.Saini and N. Jawali (Molecular Biology Division) and S.G. Bhagwat (Nuclear Agriculture & Biotechnology Division).

The sphaerococcum locus is an unused/unexplained locus in breeding that has a pleiotropic effect on many morphological characters, such as reduced height, erect leaves, and round grain. The locus was introduced into T. aestivum subsp. aestivum from T. aestivum subsp. sphaerococcum, and NILs were generated after several backcrosses and selection (for the trait) using the cultivar Kalyansona as the recurrent parent.

An F₂ population of 91 NILs and the parentals were scored for several morphological traits such as plant height, spike length, culm length, and seed morphology. Spike and culm length are traits are governed by single, recessive loci. Leaf material from individual plants was collected and DNA isolated. Two bulks, for carrier and noncarrier of sphaerococcum traits, were prepared. The analysis of the bulks and NILs by AP-PCR, RAPD, and AFLP is in progress to identify markers linked or associated with the trait.

Publications. [p. 33-34]

• Das BK, Saini A, Bhagwat SG, and Jawali N. 2006. Development of SCAR markers for identification of stem rust resistance gene Sr31 in the homozygous or heterozygous condition in bread wheat. Plant Breed 125(6):544-549.
  
• Das BK, Saini A, Bhagwat SG, and Jawali N. 2006. AP-PCR analysis of Indian wheat genotypes: genetic relationship and association analysis. In: BARC Golden Jubilee and DAE-BRNS Life Sciences Symposium on Trends in Research and Technologies in Agriculture and Food Sciences, BARC, Mumbai, India. 18-20 December 2006. Book of Abstracts, p. 136.
  
• Dubey BP, Bhagwat SG, Shouche SP and Sainis JK. 2006. Potential of artificial neural networks in varietal identification using morphometry of wheat grains. Biosystems Eng 95(1):61-67.
  
• Nalini E, Bhagwat SG, and Jawali N. 2006. Analysis of QTLs for earliness components in bread wheat (Triticum aestivum L.). In: BARC Golden Jubilee and DAE-BRNS Life Sciences Symposium on Trends in Research and Technologies in Agriculture and Food Sciences, BARC, Mumbai, India. Book of Abstracts, p. 53.
  
• Nayeem KA, Bhagwat SG, Das BK, Kulkarni PG and Ismail M. 2004. Replacement of 2+12 subunits with 5+10 for improving bread quality performance in newly evolved wheats (Triticum aestivum L.). In: Wheat for Tropical Areas (Nayeem KA, Sivasamy M, and Nagrajan S, Eds). IARI Regional Station, Wellington, Tamil Nadu, India. Pp. 253-259.
  
• Ruchi R, Das BK, and Bhagwat SG. 2006. Identification of two DNA markers for stem rust resistance gene Sr26 in bread wheat (Triticum aestivum L.). In: BARC Golden Jubilee and DAE-BRNS Life Science Symposium on Trends in Research and Technologies in Agriculture and Food Sciences, BARC, Mumbai, India. 18-20 December 2006. Book of Abstracts, p. 66.
  
• Sainis JK, Shouche SP, and Bhagwat SG. 2006. Image analysis of wheat grains developed in different environments and its implications for identification. J Agric Sci 144:221-227.
  
• Suman S, Das BK, and Bhagwat SG. 2004. Identification heat stress tolerant varieties of bread wheat using seedling assays. In: Wheat for Tropical Areas (Nayeem KA, Sivasamy M, and Nagrajan S, Eds). IARI Regional Station, Wellington, Tamil Nadu, India. Pp. 169-175.
  
• Suman S, Nayeem KA, and Bhagwat SG. 2006. Characterization of reduced height mutant of emmer wheat variety NP200 (Triticum aestivum L.). In: BARC Golden Jubilee and DAE-BRNS Life Science Symposium on Trends in Research and Technologies in Agriculture and Food Sciences, BARC, Mumbai, India. 18-20 December 2006. Book of Abstracts, p. 63-64.

BHARATHIAR UNIVERSITY

Cytogenetics Laboratory, Department of Botany, Coimbatore-641 046, India.

Hybrid chlorosis in some Indian varieties of Triticum turgidum subsp. dicoccum. [p. 34-36]

S. Premalatha and V.R.K. Reddy.

Introduction. Inter- and intraspecific hybrids of wheat often show various types of hybrid weakness, among which chlorosis is the most frequent. Chlorosis starts at the same time in nearly all leaves and in all parts, and the whole plant becomes greenish-yellow (Tsunewaki 1966). The hybrids in these cases are lethal or semilethal and often unproductive. The likely occurrence of chlorosis not only interferes with the choice of parental material but also restricts the productivity of the cross. Chlorosis is caused by two complementary genes, Ch1 and Ch2. Ch1 is located on 2A (Tsunewaki 1960; Hermsen and Waninge 1972) and Ch2 is located on chromosome 3D (Tsunewaki and Kihara 1961). The distribution of Ch1 and Ch2 was studied extensively in polyploid wheat and Ae. tauschii, the D-genome donor to common wheat (Sachs 1954; Tsunewaki and Kihara 1962; Tsunewaki and Hori 1967). The gene Ch2 is widely distributed in all hexaploid wheats except T. aestivum subsp. macha, which unlike other 6x wheats has the Ch1 gene. The Ch1 gene is commonly found in the tetraploid wheats T. turgidum subsps. dicoccum and dicoccoides (Tsunewaki and Nakai 1973; Kochumadhavan et al. 1984). The present study seeks to identify genotypes with respect to hybrid chlorosis in 18 varieties of T. turgidum subsp. dicoccum by crossing them with the appropriate testers. The tested Thatcher is a noncarrier of necrosis.

Materials and methods. Eighteen lines of T. turgidum subsp. dicoccum were crossed to a Thatcher tester line (ne1ne2ch1Ch2). The F₁ hybrids and plants were raised in the greenhouse under optimum conditions. The F₁ hybrids were observed for the occurrence of hybrid chlorosis and genotype of the parents with respect to the gene for chlorosis, which was determined form the phenotype of the F₁ hybrids.

Results and discussion. The results obtained are presented in Table 1. All the T. turgidum subsp. dicoccum lines produced strong chlorotic F₁ hybrids when crossed to Thatcher (ne1ne2ch1Ch2 carrier), indicating that they carry the ch1 gene. Because hybrid chlorosis results from the complementation of the ch1 and ch2, the T. turgidum subsp. dicoccum accessions have the Ch1 gene. The Ch1 gene is located on chromosome 2A (Hermson and Waninge 1972), whereas Ch2 is on chromosome 3D (Tsunewaki and Kihara 1961). Nisikawa (1967) reported that the Indian, T. turgidum subsp. dicoccum cultivar Khapli has the Ch1 gene. Tsunewaki and Nakai (1973) have reported on a Ch1-carrier in T. turgidum subsps. dicoccum, dicoccoides, and durum of Ethiopian origin. The Ch2 gene is extremely widespread in hexaploid species (97%) except in subsp. macha (Tsunewaki 1971). Tsunewaki and Nakai (1973) reported a high frequency (85%) of Ch1-carriers in T. aestivum subsp. macha. A wide prevalence of the Ch1 gene in T. turgidum subsp. dicoccum from India has been reported (Kochumadhavan et al. 1984).

A high level of chlorosis was observed in all F₁ hybrids from crosses between all T. turgidum subsp. dicoccum lines and Thatcher. The F₁ hybrid plants did not survive beyond the one-leaf stage (severe chlorosis), indicating a very strong interaction between the alleles of Ch1 and Ch2. McIntosh (1973) reported allelic variation at the Ch2 locus. Lines of T. turgidum subsp. dicoccum, like other tetrraploid species of wheat, are either Ne1-carriers or noncarriers (Nishikawa 1967; Tsunewaki 1969). Because hybrid chlorosis results from complementation of the Ch1 and Ch2 genes, the Thatcher tester used in this study has Ch2. Ch2 is distributed widely among the hexaploid wheats, except in T. aestivum subsp. macha, which has the Ch1 gene.

The Ch1 gene also is widely prevalent in T. turgidum subsp. dicoccum (Table 1), and it is presumed that a Ch1-carrying T. turgidum subsp. dicoccum was involved in the origin of T. aestivum subsp. macha. Our results show a high frequency of Ch1-carriers in T. turgidum subsp. dicoccum lines of Indian origin, because the Ch1 gene was present in all T. turgidum subsp. dicoccum lines tested.

Acknowledgment. Our sincere thanks to Mr. Menon for helpful discussion and comments. Thanks are due to The Head, IARI, Wellington, Nilgiris.

References.

• Hermsen JGTh and Waninge J. 1972. Attempts to localize the gene Ch1 for hybrid chlorosis in wheat. Euphytica 21:204-208.
  
• Kochumadhavan M, Tomar SMS, Nambisan PNN, and Ramanujam S. 1984. Hybrid necrosis and chlorosis in Indian varieties of Triticum dicoccum Schubl. Euphytica 33:853-858.
  
• McIntosh RA. 1973. A catalogue of gene symbols for wheat. In: Proc Fourth Internat Wheat Genet Symp (Sears LMS and Sears ER, Eds). MO Agric Exp Sta, Columbia. Pp. 905.
  
• Nishikawa K. 1967. Identification and distribution of necrosis and chlorosis genes in tetraploid wheat. Selken-Ziho 19:37-42.
  
• Sachs L. 1954. Reproductive isolation in Triticum. In: Proc IX Internat Congr Genet 2:1145-1146.
  
• Tsunewaki K. 1960. Monosomic and conventional gene analysis in common wheat. III. Lethality. Jap J Genet 35:71-75.
  
• Tsunewaki K. 1966. Gene analysis on chlorosis of the hybrid, Triticum aestivum var. Chinese Spring X T. macha var. subletschchumicum, and its bearing on the genetic basis of necrosis and chlorosis. Jap J Genet 41:413-426.
  
• Tsunewaki K. 1969. Origin and phylogenetic differentiation of common wheat revealed by comparative gene analysis. In: Proc Third Internat Wheat Genet Symp (Shepherd KW, Ed), University of Adelaide, Australia. Pp. 71-85.
  
• Tsunewaki K. 1971. Distribution of necrosis genes in wheat. V. Triticum macha, T. spelta and T. vavilovi. Jap J Genet 46:93-101.
  
• Tsunewaki K and Hori T. 1967. Distribution of necrosis genes in wheat. IV. Common wheat from Australia, Tibet and Northern Europe. Jap J Genet 42:245-250.
  
• Tsunewaki K and Kihara H. 1961. F1 monosomic analysis of Triticum macha. Wheat Inf Serv 12:1-3.
  
• Tsunewaki K and Kihara H. 1962. Comparative gene analysis of common wheat and its ancestral species. I. Necrosis. Jap J Genet 37:474-484.
  
• Tsunewaki K and Nakai Y. 1973. Considerations on the origin and speciation of four groups of wheat from the distribution of necrosis and chlorosis gene. In: Proc Fourth Internat Wheat Genet Symp (Sears LMS and Sears ER Eds). MO Agric Exp Sta, Columbia. Pp. 123-129.

A biochemical investigation of rust-resistant, near-isogenic wheat lines. [p. 36]

S. Premalatha, V.R.K. Reddy, K. Gajalakshimi, K. Thamayanthi, R. Kannan, and Biju John.

Through a backcross breeding program, 28 NILs in the BC₂F₅ and BC₅F₅ involving four Indian wheat cultivars (HW 517, HD 2135, HD 2204, and UP 301) and seven donor wheat stocks with four leaf rust-resistance genes (Lr19, Lr28, Lr32, and Lr37), six stem rust resistance genes (Sr25, Sr26, Sr27, Sr34, Sr36, and Sr38), and two stripe rust resistance gene (Yr8 and Yr17) present either singly or in combination (linked condition) were produced. Immune to moderately resistant reaction at the seedling stage and highly resistant reaction at adult-plant stage from the aforementioned genes strongly advocate the use of specific rust-resistance genes for durable resistance. Specific rust-resistance genes such as Lr19, Lr28, Lr32, Lr37, Sr25, Sr26, Sr27, Sr34, Sr36, and Sr38 provided single-gene resistance, whereas the stripe rust-resistance genes Yr8 and Yr17 provide their resistance in combination with other resistance genes already present in the genetic background of recurrent parents. The benefit from well-characterized traits or resistance based on resistance genes will come only from a detailed investigation of the biochemical pathways involved in host-plant resistance. The NILs were evaluated for various biochemical parameters including peroxidase, polyphenol oxidase, catalase, chitinase, lipoxygenase, ribonuclease, lipid, soluble protein, free amino acids, proline, phenols, and tannin content. In addition, chlorophyll content, nuclear DNA, and respiration rate also was studied to differentiate susceptible wheat parents and their rust-resistant NILs. Changes in biochemical parameters often are used indirectly to confirm gene transfers.

Peroxidase and polyphenol oxidase activity increased in all NILs 2 to 7 days after inoculation but declined in susceptible wheat plants. Catalase and lipoxygenase activity increased more in susceptible wheat parents than resistant NILs. The specific activity of soluble protein, proline, total free amino acids, and chitinase increased more rapidly in the resistant plants than in the susceptible wheat parents. The total lipid content of the leaves showed an increase in both susceptible and rust resistant NILs 2 days after inoculation but subsequently decreased with an increase in postinoculation time.

The specific activity of both ribonuclease-I and combined ribonuclease-II and nuclease-I was high at the 15-day stage as compared to the 10-day stage in both susceptible parents and the NILs. The increase was more pronounced in the resistant lines than in the susceptible parents. Resistant NILs retained a relatively steady level of chlorophyll content, which reduced at a faster rate in the susceptible wheat parents. Respiration rate had a greater increase in the resistant NILs compared to susceptible wheat parents the third day after inoculation. The reduction in respiration rate was drastic in susceptible parents, whereas it was more or less constant in the resistant NILs. A significant increase in total free phenols, tannins, and nuclear DNA content was observed in the NILs over the recurrent parents.

The effect of sodium stearoyl-2-lactylate on rheological properties, baking, and pasting quality in three Indian bread wheats. [p. 36-37]

K. Gajalakshimi, V.R.K. Reddy, S. Premalatha, R. Kannan, K. Thamayanthi, and Biju John.

Three hexaploid bread wheat cultivars, HS 240, HUW 549, and VL 852, were used to study the effect of the additive sodium stearoyl-2-lactylate (SSL) on rheological characteristics and baking (bread and biscuit quality) and pasting (chapatti quality) characteristics. Cleaned grain samples (10 kg) from each cultivar were milled in a Naga Research Institute Laboratory Mill, Dindigul, Tamil Nadu, India. The additive SSL is a surfactant that is light tan and does not effect the quality of bread and other products. We studied the effect of SSL in wheat dough at different concentrations (0.1, 0.2, 0.3, 0.4, 0.5, and 0.6%). Rheologic characteristics used farinographs and extensographs according to the procedures of the American Association of Cereal Chemists.

The addition of SSL up to 0.4 % improved the strength and quality of the dough in all the three wheat cultivars (Table 2). The addition of SSL to the dough increased water absorption, dough stability, and the area of the extensograph curve. On the other hand, the mixing tolerance index value of the dough decreased considerably. The effect of SSL on baking and pasting quality increased the overall quality and softness of the baking (bread and biscuit) and pasta (chapatti) products. Bread score, crispness of the biscuits, and hand feel of chapattis also increased with the addition of SSL.

Publications. [p. 37-38]

• Kannan R, Reddy VRK, and Thamayanthi K. 2007. Changes in enzymatic activities in near-isogenic wheat lines carrying various rust resistance genes. Res Crops 8(1):In press.
• Kannan R and Reddy VRK. 2007. Performance of near-isogenic wheat lines carrying various leaf rust resistance genes against leaf rust. Res Crops 8(1):In press.
  
• Kannan R, Thamayanthi K, Biju John, and Reddy VRK. 2007. Studies on changes in peroxidase enzyme activity in near-isogenic wheat lines carrying rust resistance genes. In: Proc Natl Seminar 'Current Developments in Chemistry' (NSCDC-07). 18-19 January, 2007, Department of Chemistry, Bharathiar University, Coimbatore. No. PP5, p. 20.
  
• Kannan R, Thamayanthi K, Biju John, and Reddy VRK. 2007. Physical and chemical properties of 15 Indian hexaploid wheat varieties. In: Proc 5th National Seminar 'Emerging Trends in Biotechnology'. 16-17 February, 2007. Department of Biotechnology, Vivekanandha Colelge of Engineering for Women Elayampalayam, Tiruchengode, Tamil Nadu. No. LS 8, p. 104.
  
• Kannan R, Thamayanthi K, Biju John, and Reddy VRK. 2007. Triticale and soya addition to wheat flour dough and their effect on rheological properties. In: Proc Internat Conf 'Opportunities and Challenges in Biotechnology and Environmental Sciences'. 22-23 February, 2007. Department of Botany, Vellalar College for Women, Erode. No. BC-21 pp.102.
  
• Premalatha S and Reddy VRK. 2006. Identification of HMW glutenin subunit composition in Indian hexaploid wheat cultivars. In: Proc 3rd Natl Symp Modern Biological Sciences, Symbios. 15-16 February, 2006, Department of Microbiology, Biochemistry and Biotechnology, Sri Nehru Maha Viyalaya College of Arts and Science, Malumachampatti, Coimbatore. No. B-2, p. 27.
  
• Premalatha S and ReddyVRK. 2006. Confirmation of specific rust resistance gene through molecular marker. In: Proc Natl Sem 'Bio Xplore-06'. 17-18 February, 2006, Department of Industrial Biotechnology, Elayampalayam, Tiruchengode, Tamilnadu. No. BT/O/-10, p. 9.
  
• Premalatha S and ReddyVRK. 2006. Biochemical changes associated with rust resistance in hexaploid wheat. In: Proc Natl Seminar 'Advances in Enzymology'. 9-10 March, 2006, Department of Plant Science, Bharathidasan University, Tiruchirappalli. No. 31, p. 19.
  
• Premalatha S and Reddy VRK. 2007. Allelic variation of high molecular weight glutenin subunits in some Indian hexaploid wheat cultivars. Res Crops 8(1):In press.
  
• Premalatha S and Reddy VRK. 2007. Evaluation of resistance to rust in some wheat varieties (Triticum aestivum) and distribution of genes for hybrid necrosis. Res Crops 8(1):In press.
  
• Thamayanthi K and ReddyVRK. 2006. Rheological and baking performance of composite flours. In: Proc Natl Sem 'Bio Xplore-06'. 17-18 February, 2006, Department of Industrial Biotechnology, Elayampalayam, Tiruchengode, Tamilnadu. BS/O/13, p. 97.
  
• Thamayanthi K, Kannan R, and Reddy VRK. 2007. Biochemical characterization of rust resistance in wheat (Triticum aestivum L.). Adv Plant Sci 20(2):In press.
  
• Thamayanthi K, Kannan R, Biju John, and Reddy VRK. 2007. Rust resistance breeding in hexaploid wheat. In: Proc Internat Conf 'Opportunities and Challenges in Biotechnology and Environmental Sciences'. 22-23 February, 2007. Department of Botany, Vellalar College for Women, Erode. No. BC-18, pp. 100-101.
  
• Thamayanthi K, Kannan R, Biju John, and Reddy VRK. 2007. Enhancement of genetic diversity through transfer of rust resistance genes into Indian wheat cultivars. In: Proc Natl Conf 'Environmental Challenges and Management' (ECM-2007). 8-9 March, 2007. Department of Environmental Science, Bharathiar University, Coimbatore. Pp. 21-23.
  

DIRECTORATE OF WHEAT RESEARCH
Post Box 158, Agrasain Marg, Karnal 132001, India.

Improvised and effective technology os wheat seed storage in farmers' fields in eastern India. [p. 38-40]

B.S. Tyagi, Gyanendra Singh, and Jag Shoran.

Introduction. Wheat is an excellent cereal crop for India that serves as a staple food for more than 65 percent of the population of India. The current level of wheat production in India is around 72 x 10⁶ tons, whereas the demand for wheat is expected to be around 109 x 10⁶ tons by 2020. To achieve this target yield, raising productivity per unit area by adopting modern technologies such as high yielding cultivars, improved cultural practices, and proper management of seed production and storage is needed. The seed of wheat cultivars is stored for both short (from harvest until sowing) and long (1-2 years) periods in storage houses. The inaccessibility of an organized market and imperfect pricing in local and rural markets have made it necessity for growers to store agricultural produce, giving rise to innovative indigenous and low-cost methods of seed storage. Being a cereal crop, the maintenance of wheat seed vigor and viability during storage poses several problems, especially in eastern India and warmer areas, where more than 10 x 10⁶ ha of wheat have inadequate or uncontrolled environmental storage facilities.

Aspects of seed storage. The storage life of seed varies with species and cultivar. During storage, viability also is affected by various factors such as the preharvest climatic conditions, temperature, relative humidity, seed moisture content, and packing material. During storage, biotic (insects, fungi, and rodents) and abiotic (temperature, humidity, and light) factors affect the quality and viability of the seed. Roughly 10% of total food grains produced in the country is lost due to improper storage alone, whereas waste by insects is as much as 3% higher than losses inflicted by other debilitating agents. Storage pests that cause significant loss include Trogoderma granarium, Rhyzopertha dominica, Tribolium castaneum, Sitotroga cerealella, and Sitophilus oryzae.

Methodology and approach. The study was part of a study on seed production and storage conducted in eastern India under the National Agricultural Technology Project. Five different sites were selected, with consideration of their typical, highly humid conditions with respect to seed storage and source of seeds. The respondents comprising 170 farmers were taken randomly from previously selected sites. A comprehensive questionnaire, schedule was prepared incorporating all related variables to be studied. The respondents were contacted personally for collecting the relevant data.

Results and trends. The survey conducted on 170 farmers in eastern India has shown that only 35 percent of the farmers use their own seed, 15 percent purchase seed from neighbors, 30 percent purchase from nongovernmental agencies, and nearly 20 percent purchase seed from governmental seed agencies (Table 1). The results indicated the need for popularizing obtaining quality seed through state agricultural universities (SAUs), government organizations, and NGOs in this large wheat-growing area.

Methods of seed storage.Our survey, conducted on wheat seed production and storage by the farmers in eastern India, revealed that one percent of the farmers use polybags and five percent farmers use metal bins (Table 2). The survey also highlighted the need for more scientific methods of seed storage at the farmer's own field, which also will help in providing high quality seed for wheat crop cultivation at an affordable cost. The highest percentage (88%) of the farmers packed the seed in gunny bags after drying and kept them in wheat straw, the traditional method of seed storage.

In eastern India, preharvest sprouting is forcing farmers to purchase the fresh seed every year, which they can not afford due to lack of resources. Grain deterioration in storage can be minimized or prevented by keeping the grain dry (less than 12.5% moisture), cool (less than 10°C), and free from insects. A small number of resident insects in the bin or introduced with the grain when it is warm or if the grain remains in storage for a long time are some possible sources of insect infestation in stored wheat seed. A brief, high-temperature treatment of grain was found to disinfest all stages of Sitophilus granaries in wheat (20 minutes at 70°C) and other storage insects (2 minutes at 55°C). In eastern India, the big problem in stored wheat grain is high humidity, which causes a loss of viability. Therefore, the storage pits, bins, or go downs should be moisture proof and fumigated.

On-farm seed storage and quality. The traditional method of seed storage has certain problems and, as a result, the quality of seed produced and utilized by the farmers is very poor. The Participatory Varietal Selection (PVS) program in this region of India was initiated to emphasize the issue of quality seed production and storage. An on-farm seed production and storage system will not only enhance production, but also will help to make this vast wheat-growing region self-sufficient.

Under this program, freshly harvested seed of five wheat cultivars, NW 1014, HD 2643, K 9107, HW 2045, and HD 2733, were stored at selected locations in poly-lined gunny bags to demonstrate a low cost and safe storage system. At the time of next sowing the bags were opened up and germination percent was tested. In all five cultivars at all sites, germination percentage was very good, ranging between 90 and 98 %, even after storing the seed for one year (Table 3).

The above described and demonstrated system of wheat seed storage is much better and more cost effective than the traditional system, being an improved version of the local seed-storage system that still has good scope and potential for quality seed production. This method will help to improve the local availability of quality seed and also the horizontal spread of new technology.

References.

• Agrawal PK and Dadlani M. 1984. Seed quality, storability and yield of wheat as influenced by sprouting and spoilage due to rain. Seed Res 12(2):11-19.
  
• Harris D, Raghuvanshi BS, Gangwar JS, Singh SC, Joshi KD, Rashid A, and Hollington PA. 2001. Participatory evaluation by farmers of on-farm seed priming in India, Nepal and Pakistan. Exp Agric 37: 403-415.
  
• Sharma SP and Sankaran V. 2002. Wheat seed production and storage. In: Compendium of Training Lectures on 'Seed production technology and quality control'. BAU Ranchi, India.
  
• Singh G, Tripathi SC, Tyagi BS, Shoran J, and Nagarajan S. 2004. Promising wheat varieties for eastern and warmer regions of India. Directorate of Wheat Research, Karnal, India. Technical Bulletin No 3, 28 pp.
  
• Singh G, Shoran J, Tyagi BS, Chatrath R, Tripathi SC, and Nagarajan S. 2004. Participatory varietal selection in wheat-an approach to increase the adoption of new technologies. Directorate of Wheat Research, Karnal, India. Research Bulletin No 17, 28 pp.
  

 

 

INDIAN AGRICULTURAL RESEARCH INSTITUTE REGIONAL STATION

Wellington - 643 231, the Nilgiris, Tamilnadu, India.

Diversifying the genetic base for resistance in Indian bread wheat cultivars through introgression and pyramiding of newer, effective stem rust-resistance genes to combat the threat from the Ug99 pathotype virulent on Sr31. [p. 40-43]

M. Sivasamy and R.N. Brahma (Indian Agricultural Research Institute, Regional Station, Wellington), S.M.S. Tomar and Vinod (Division of Genetics, Indian Agricultural Research Institute, New Delhi -12), Rattan Tiwari (Directorate of Wheat Research, Karnal), and M. Prashar (Directorate of Wheat Research, Regional Station, Flowerdale, Shimla).

Introduction. In India, wheat is cultivated on approximately 26 x 10⁶ ha with a present day production level of 72 x 10⁶ tons. Wheat production has stagnated at around 72 x 10⁶ tons for the past 5 years, and we are resorting to imports to meet the requirement of a targeted, public distribution system. To meet the ever increasing demand for wheat grain resulting from population growth, a reduction in area under wheat due to crop diversification, and other biotic and abiotic stresses, we need to reorient our research priorities. The wheat crop in India is grown under various micro- and macroclimatic zones and varied production conditions. The entire region is under the constant threat from stem and leaf rust epidemics. Because of limited use, diverse gene sources for rust resistance are needed for the release of cultivars for commercial cultivation.

The need to diversify the genetic base. Most of our present day cultivars have the gene complex Sr31, Lr26 (not effective in India), Yr9 (a new virulent pathotype reported), and Pm8, because of the significant yield advantage associated with it in addition to resistance to rust diseases in spring wheat. With the occurrence of the new, virulent stem rust pathotype Ug99, a threat to wheat production worldwide is possible. Ironically, in a Ug99 epidemic, no wheat-producing country in the world is safe, although each zone is protected by micro- and macroenvironmental conditions and the dispersal mechanism of rust pathogens. In India, avoiding such a rust epidemic will be by deploying new cultivars with new, diverse gene sources in a mosaic pattern to curtail evolution and spread of new rust pathotypes.

Nagaranjan and Singh (1990) reported that the Indian subcontinent, though at a less risk, needs to diversify gene sources to tackle such threats. As the global environmental changes, frequent human travel across the globe can incidentally cause damage, although it could be insignificant. A certain level of genetic diversity in currently grown wheat cultivars in India may not offer a high level of protection against the Ug99 or the likely emergence of future races of all three rusts. Incidentally, a few genes, such as Sr24 (a virulent pathotype 40-1 for Sr24 has been reported from India) and Sr25 have been effective against Ug99 and fully exploited. The gene sources evaluated at Kenya (Njoro) indicated that a number of stem rust-resistance genes, Sr14, Sr24, sr25, Sr26, Sr27, Sr29, Sr32, Sr33, Sr35, Sr36, Sr39, Sr40, and Sr44, conferred resistance against the race Ug99 (Singh et al. 2006).

Work already done in India. A number of NILs carrying Sr24, Sr25, Sr27 (Ag. elongatum), and Sr26 (S. cereale cv. Imperial) have been developed in India in the background of the popular Indian wheats C 306, Kalyansona, Lok-1, WH147, and HUW 234 (Tomar and Menon 2000, 2001). The transfer these genes has been confirmed by molecular studies (Kumar et al. 2006). However, considering any stem rust epidemic due to pathotype Ug99, which can spell doom for wheat production in India, front now we need to formulate our new strategy to combat this threat. Although some Indian commercial wheat cultivars do confer resistance against Ug99, we should not remain complacent on this very serious issue. Thus, a well-planned, scientific and systematic crop improvement approach to tackle this issue is needed.

Scientists worldwide are advocating a durable resistance mechanism by exploiting vertical resistance sources. The targeted of effective stem rust genes in a cultivar background already carrying specific leaf and stripe rust genes can effectively combat this new stem rust pathotype.

Strategies and approaches. The present situation demands strategic preparedness to tackle the perceived threat from stem rust epidemics, particularly from one like Ug99 that is virulent on Sr31. Our first priority is to utilize resistance sources already available in the background of popular Indian bread wheat cultivars. The long-term strategy is to diversify gene sources for resistance to stem rust with newer genes such as Sr24, Sr26, Sr27, Sr29, Sr32, Sr33, Sr35, Sr36, Sr39, Sr40, and Sr44, which confer effective resistance against Ug99 (Singh et al. 2006). These genes should be pyramided in the background of a targeted cultivar(s) already carrying resistance genes for leaf and stripe rusts to combat stem rust in more scientific and efficient way. Many popular Indian bread wheat cultivars developed at the IARI Regional Station in Wellington carry Lr19+Sr25, Lr24+Sr24, Lr28, Lr32, and Lr37 and can effectively be utilized for further incorporating effective new stem rust genes.

Marker-assisted backcross selection offers a more efficient way of selecting material carrying the targeted genes, although there is an inherent risk of producing a low-yielding phenotype. We need to slightly modify our approach, effectively using backcross selection to introgress targeted genes in a particular cultivar background. The simultaneous validation of markers and seedling evaluation for host-pathogen interaction to confirm the presence of these genes in more than one elite, high-yielding phenotype in each cultivar background will offer useful material, and these lines will be used for for multilocation testing and further selection.

Work already initiated at IARI, RS, Wellington to develop rust resistant wheat lines with effective genes against the Ug99 stem rust pathotype. Newer genes for stem rust resistance and their source, chromosomal location, which were used for the backcross program, are in Table 1.

Popular Indian bread wheat cultivars used in this program. C 306, HD 2285, HD2402, HD2687, HS240, HUW234, K9107, Lok1, Lok bold, Lok-45, PBW226, PBW 343, PBW 502, HD2733, NIAW34, UP262, HI 977, RAJ3077, KRL99, HD 2833, and WH147.

Backcross selection at IARI, Regional Station, in Wellington, which is a hot spot for wheat rust, can take three generations of wheat in a single year. Simultaneous selection using MAS is at IARI, New Delhi, and the Directorate for Wheat Research (DWR), Karnal, for the targeted genes. The entire lot will be shuttled between the centers for selection of best yielding phenotype with specific genes with wider adaptability. Segregating material will be regularly screened at DWR, Regional Station, Shimla, for host-pathogen interaction and confirmation of the resistance offered by each targeted gene(s).

Our objectives are to

1. develop elite diverse genetic base for resistance to stem rust in select popular India wheat cultivars using modified simultaneous/ stepwise transfer of genes,
2. effectively combat stem rust disease resulting due to emergence of new rust pathotypes,
3. pyramid the effective genes in the elite wheat lines constituted through modified background selection and molecular-assisted selection,
4. develop newer isogenic lines of popular Indian bread wheat cultivars for use as donors in breeding program and use in gene tagging and if need be as new cultivars,
5. evaluate the constituted stem rust resistant lines under field conditions for yield parameters,
6. study the effect of newer genes on quantitative and qualitative traits in the popular Indian wheat background,
7. validate molecular markers for the targeted genes, and
8. study the host-pathogen interaction for the lines carrying newer rust resistance genes.

Expected outcomes of our approach will be to

1. effectively combat rust diseases including the present threat from Ug99 pathotype for stem rust and avoid frequent evolution of new virulent pathotypes,
2. develop elite wheat lines carrying specific stem rust resistance genes (NILs),
3. develop high-yielding and rust resistant wheat lines carrying confirmed pyramided genes for durable resistance,
4. make available diverse, genetic base material for stem rust resistance for use in the national wheat improvement program,
5. produce mapping populations for effectively targeting gene tagging, and
6. validate molecular markers linked to each targeted gene.

References.

• Kumar Y, Kumar S, Priyamvada, Siha P, Kumar Mall A, Chhokar V, Sivasamy M, and Tiwari R. 2006. Detection of specific rust resistance genes in near isogeneic lines (NILs) and segregating populations using molecular markers. In: Biohorizon 2006, 8th Natl Symp on Biochemical Engineering and Bio Technology, 10-11 March, 2006, New Delhi-16 (Poster presentation).
  
• Nagarajan S and Singh DV. 1990. Long-distance dispersion of rust pathogens. Ann Rev Phytopathol 28:39-53.
  
• Singh R. 2006. Effective stem rust genes against Ug99 race. CIMMYT report and personal communication. (Evaluation of gene sources by the authors Sivasamy M and Prashar M along with the global team of scientists during their visit to Kenya, September 2006, under a GRI program sponsored by CGIAR/CIMMYT, Mexico, and ICAR, India)
  
• Tomar SMS and Menon MK, 2000. Evaluation of stem rust resistance genes in bread wheat and introgression of Sr26 into adapted cultivars. In: Proc Internat Conf on Integrated Plant Disease Management for Sustainable Agriculture. Ind Phytopath Soc, New Delhi. Pp. 650-653.
  
• Tomar SMS and Menon MK. 2001. Genes for resistance to rusts and powdery mildew. Ind Agric Res Inst, New Delhi-12, pp. 152.