GrainGenes

Bharathiar University

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

Variation in biochemistry and nuclear DNA content in susceptible and constituted rust-resistant lines of Indian wheats.

V.R.K. Reddy, Aloka Saikia, S. Dhamodaran, R. Asir, P. Viswanathan, and S. Arumugam.

The popular, high-yielding, Indian, hexaploid, wheat varieties HD2329, NI5439, WH147, and WL711 have become highly susceptible to three rusts in a few years from their introduction. These varieties were improved for resistance to stem, leaf, and stripe rusts by a simple backcross method with the successive incorporation of an alien gene/gene complex, i.e., Sr24/Lr24, Lr9, Lrl9, Lr28, Yr9, and Sr31/Lr26/Yr9, Lr25, and Sr27 from rye addition lines and Lrl9/Sr25 and Sr26 from Agropyron addition lines, by manipulating the 5B system using ph mutant. On the basis of resistance to the respective rusts, 20 lines were constituted at the BC₅S₄ generation. The breeding work was carried out at the Indian Agricultural Research Institute's Regional Station, Wellington, Nilgiris, Tamil Nadu, which is a hotspot for all three rusts.

Total free phenols and tannins were estimated in the susceptible recurrent parent and the constituted lines following the methods of Bray and Thorne (1954) for phenols and Burns (1971) for tannins. Nuclear DNA content was estimated with the help of a Vicher's M85 Scanning Micro-densitometer. Biochemical analysis was carried out at the seed physiology laboratory, Botany Department, Bharathiar University, Coimbatore, and the DNA content was estimated at the Department of Botany, Meerut University, Meerut, India.

Biochemical estimation in the recurrent and constituted rust resistant lines revealed that the total free phenols and tannin content were relatively high in the respective constituted rust-resistant lines compared with their recurrent susceptible parents. Tannins were completely absent in the recurrent parents HD2329 and WL711 and in lines derived from `WL711 x Dwarf Kite'. Similarly, the DNA content of the constituted lines derived from the `wheat x addition line' crosses had significantly higher DNA content compared with their respective recurrent parents.

Publications.

Reddy VRK and Saikia A. 1994. Transfer of rust resistant genes into Indian wheat cultivars. In: Proc Natl Sem, Biodiversity: Strategies for Conservation and Future Challenges, Coimbatore, India. Pp. 53-57.

Saikia A and Reddy VRK. 1994. Development of rust resistance through induced mutations. In: Proc Natl Sem, Biodiversity: Strategies for Conservation and Future Challenges, Coimbatore, India. Pp. 46-48.

Saikia A and Reddy VRK. 1994. New resistant wheat lines. Ann Wheat Newslet 40:208-209.

Performance of newly constituted wheat lines carrying stripe rust resistance genes.

V.R.K. Reddy, R. Asir, S. Dhamodaran, P. Viswanathan, and S.Arumugam.

The popular, dwarf, high-yielding, Indian, wheat varieties HD2285, HW741, Kalyansona, and Sonalika, which revolutionized Indian agriculture, have become highly susceptible to three rusts after a few years of cultivation. By concerted efforts, these varieties were successfully improved for resistance to stem and leaf rusts with the incorporation of Sr24/Lr24, Sr26/Lr24, Sr26, Sr27, and Lrl9. However, these improved (Unnath) varieties remained highly susceptible to stripe rust. Their susceptibility to yellow rust also rose by 10-20 % over the original varieties. In order to improve these unnath varieties for yellow rust, genes conferring yellow rust resistance, i.e., Yrll, Yr12, Yrl3, Yrl4, Yrl6, Sr31/Lr26/Yr9. and Sr38/Lr37/Yr17, were successfully incorporated by a simple backcross method and by manipulating the 5B system of wheat, followed by vigorous plant selection in the BC₂ and BC₅ generations. The breeding work was undertaken at the Indian Agricultural Research Institute Regional Station, Wellington, which is a hotspot for all three rusts. Resistant genotypes with desirable agronomic attributes were then constituted at the BC₂F₅ and BC₅F₅ generation. The rust reactions of the constituted lines are given in Table 1.

Significant increases in plant yield and 1,000-grain weight were observed in the newly constituted lines compared to the original and unnath varieties. We also noticed that the yield was greater in the BC₂F₅ than in the BC₅F₅ generation in the backcross progenies carrying the linked gene complexes of Sr31/Lr26/Yr9 and Sr38/Lr37/Yrl7. However, in the constituted lines carrying Yrll, Yrl2, Yrl3, Yrl4, and Yrl6, the plant yield and 1000-grain weight were improved considerably in the BC₅ generation. Incorporation of Yrl5 from Triticum dicoccoides, line G-25, into the above Indian wheat varieties is also in progress.

Publications.

Asir R and Reddy VRK. 1994. Transfer of yellow rust resistance genes into Indian wheat cultivars. In: Proc Natl Sem, Biodiversity: Strategies for Conversation and Future Challenges, Coimbatore, India. Pp. 49-52.

Asir R, Reddy VRK, and Viswanathan P. 1994. Incorporation of stripe rust resistant specific genes into Unnath Kalyansona carrying different gene complexes. Wheat Inf Serv 78:24-27.

Asir R, Reddy VRK, and Viswanathan P. 1994. Introduction of Aegilops ventricosa derived gene complex Sr38+Lr37+Yrl7 into popular Indian bread wheat cultivars. Ann Wheat Newslet 40:207-208.

Reddy VRK, Asir R, and Viswanathan P. 1994. Development of rust resistance in wheat variety HW 741. Cereal Res Comm (In press).

Reddy VRK, Asir R, and Brahma RN. 1994. Transfer of Secale cereale derived Sr27 into Indian wheat cultivar Unnath Kalyansona. Crop Res 7(2):305-307.

Reddy VRK, Asir R, Viswanathan P, and Arumugam S. 1994. Development of disease rust resistance in hexaploid wheat - An overview. In: Plant Breeding Advances and In vitro Culture (Siddiqui BA and Samiullah K eds). (In press).

Table 1. Stem (Sr), leaf (Lr), and yellow (Yr) rust reactions of parents and newly constituted lines.

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Rust Reactions

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Parents/Crosses HD 2285 HW 741 Kalyansona Sonalika

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Progenies/Genes Sr Lr Yr Sr Lr Yr Sr Lr Yr Sr Lr Yr

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HD 2285 40MS 60S 60S

Unnath HD 2285 F F 90S

(Sr26+Lr24)

HW 741 40MS 80S 60S

Unnath HW 741 F F 80S

(Sr26+Lr24)

Kalyansona 60S 80S 60S

Unnath Kalyansona F F 80S

(Sr26+Lr24)

Sonalilka 20MS 80S 70S

Unnath Sonalika F F 90S

(Sr24+Lr24)

Crossed with Unnath Parents

/Veery'S' F F F F F F F F F F F F

(Sr31+Lr26+Yr9+Pm8)

donor: S. cereale

/Josschambier (Yr11) F F F F F F F F F F F F

donor: Joschambier

/Pride (Yr12) F F F F F F F F F F F F

donor: Pride

/Virtue (Yr13) F F F F F F F F F F F F

donor: Virtue

/Moulin (Yr14) F F F F F F F F F F F F

donor: Moulin

/Capelle-Desprez 5BL-7BL

(Yr16) F F F F F F F F F F F F

donor: Capelle-Desprez

/RL 8061 F F TMR F F TMR F F TMR F F 5MR

(Sr38+Lr37+Yr17)

donor: T. ventricosum

Rye (Secale cereale) addition lines in Chinese Spring (CS, 2n=6x=44) crossed with original parents.

/CS+1R TMS F F TMS F F TMS F F TMS F F

(Sr31+Lr26+Yr9+Pm8)

/CS+3R (Sr37) F 60S 80S F 80S 60S F 80S 60S F 80S 70S

Agropyron intermedium addition lines in CS (2n=6x=44) crossed with original parents.

/Argus (Lr19) 40MS F 80S 40MS F 60S 60S F 60S 20MS F 70S

/PW327/8*Thatcher F 60S 80S F 80S 60S F 80S 60S F 80S 70S

(Sr26)

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Himachal Pradesh Krishi Vishvavidyalaya

Department of Plant Breeding and Genetics, Palampur, 176 602, Himachal Pradesh, India.