GrainGenes

ITEMS FROM ARGENTINA

CÓRDOBA NATIONAL UNIVERSITY

College of Agriculture, P.O. Box 509, 5000 Córdoba, Argentina.

Flag leaf morphology changes after six cycles of recurrent selection in bread wheat. [p. 17]

S.P. Gil, L.I. Mas, A. Semino, R.H. Maich, and M.M. Cerana.

The flag leaf is well-known as one of the main organs related to grain filling in bread wheat, and its morphology was modified after three cycles of recurrent selection (see Cerrana et al. Ann Wheat Newslet 48:23). Today, we are working with six cycles (C0 to C6,) of recurrent selection in order to evaluate the effects of plant breeding on three morphological, flag-leaf characteristics: length, width, and area.

Plants were grown at the Experimental Farm of the College of Agriculture (31^o^29'S and 64^o^00' W), Córdoba, Argentina, during 2002 under rainfed and semiarid conditions. Five flag leaves from each of the 12 S-derived families/population were studied. Data were processed with ANOVA and Duncan's Multiple Range Test. We observed that the C6-derived families had shorter leaves than those of the C0.

Publications.

• Cerana MM, Gil SP, and Maich RH. 2002. Plant breeding scheme effects on the flower number and grain yield components in bread wheat. Cereal Res Commun 30(3-4):307-313.
• Maich RH, Ordóñez, AV, and Manero de Zumelzú D. 2002. Multiple characters selection and genetic progress in triticale and bread wheat. In: Proc 5th Internat Triticale Symp (Arseniuk E ed). Pp. 37-40.

'Genotype x environment' interactions - response to negative recurrent selection. [p. 17-18]

R. Maich, G. Manera, and M.E. Dubois.

For wheat cultivars of intermediate biological cycle grown under rainfed conditions in central Argentina, choosing an accurate sowing date is recommended so that the end of the heading stage is in late September, when better environmental conditions will assure the highest seed set. During 2002, a drought occurred during the heading and ripening stages in the Córdoba province in central Argentina. In these conditions, the shorter cycle, commercial cultivars yielded more than the long cycle cultivars (89 %). Simultaneously, we evaluated 84 S-derived families; 12 from each cycle of recurrent selection (C0 to C6) and 12 bread wheat cultivars provided and suggested by National Institute of Agricultural Technology (INTA) Marcos Juárez. Plot data were recorded on grain yield, seed number/spikelet, spikelets/spike, spike and grain number/m2, 1,000-kernel weight, and sowing/heading interval. Samples of the S-derived families or cultivars were grouped according their biological cycle, heading before or after 30 September. The first group (before 30 September) included the C0, C1, C2, and C3 samples, whereas C4, C5, and C6, and the commercial cultivars were in the second group (after 30 September). The mean value for grain yield of the shorter-cycle material (238.3 g/m^2^) was higher than those of the longer cycle (184.1 g/m^2^). A similar tendency was observed for the remaining characters measured except 1,000-kernel weight. Contrasting the number of cycles of recurrent selection (C0-C3 versus C4-C5), a difference of 16.3 % was observed for the physical grain yield component grain number/spikelet. Comparing these results with those previously reported (see Maich et al. Ann Wheat Newslet 48:22), we conclude that the G X E interaction is of the crossover type.

Reference.

• Cantarero M, Dardanelli J, and Badiali O. 1998. Factores ambientales que determinan el rendimiento potencial en trigo. In: Riego y Agricultura de Presición, 16­26. EEA INTA Manfredi, Córdoba, Argentina (in Spanish).

Bread-making quality of lines after six cycles of recurrent selection versus that of 12 commercial wheat cultivars. [p. 18]

M.E. Dubois, R. Maich, and Z. Gaido.

The bread-making quality in wheat lines of six cycles (C0­C6) of recurrent selection for grain yield was evaluated together with 10 bread wheat cultivars for the first time. The cultivars, provided and suggested by the INTA Marcos Juárez (ACA 223; Buck Farol and Sureño; Cooperación Nanihue; Desimone Caudillo; Klein Escorpión and Estrella; and PROINTA Puntal, Bonaerense Alazán, and Redomón), were all released commercially in 2001. The highly promoted Baguette 10 and Las Rosas INTA, the best parental line for recurrent selection, also were evaluated.

No significant differences were observed in the bread-making quality of the C0, the C6-derived lines, Baguette 10, and Las Rosas INTA. Among the commercial cultivars, one line was low (Klein Estrella), no differences were observed in four, and five were higher when compared to the checks (Table 1).

INSTITUTO DE BIOTECHNOLOGIA, INTA CASTELAR

CC 25 (1712), Castelar, Pcia. de Buenos Aires, Argentina.

Cloning and characterization of a novel fructosyl transferase gene in wheat. [p. 18-19]

F. del Viso, A.F. Puebla, R.A. Heinz, and H.E. Hopp.

During low-temperature acclimation, several physiological changes are induced, including increased levels of sugars, soluble proteins, prolines, and organic acids; the appearance of new isoforms of proteins; and an alteration in lipid membrane composition (Hughes and Dunn 1990). Several studies report that grasses from temperate and cool climate zones respond to chilling and drought by accumulating fructans (fructose polysaccharides) (Levitt 1980). Fructans not only are considered to be reserve polysaccharides but also to play a role as protective agents against chilling and freezing.

Characterization of Argentinian wheat cultivars shows a high correlation between low-temperature tolerant cultivars and high levels of fructans in the shoots of stressed plants (Tognetti et al. 1990). Two cDNAs were recently cloned and characterized in T. aestivum that encode the 1-SST (1-sucrose-sucrose fructosyl transferase) and 6-SFT (6-sucrose-fructan fructosyl transferase) fructan enzymes (Kawakami and Yoshida 2002). The levels of 6-SFT mRNA increased through autumn into winter and high levels of fructans were shown in snow mold-resistant cultivars.

To study low-temperature tolerance and fructan-gene expression, we cloned the fructosyl-transferase genes related to fructan metabolism in wheat. A BAC genomic library from T. monococcum (Lijavetsky et al. 1999) was used. High-density filters were hybridized using a 6-SFT cDNA probe. Sixteen positive clones were found and analyzed through restriction analysis and hybridization. A 4.2-kb NotI fragment of one of the positive clones was subcloned and sequenced by chromosome walking. The nucleotide sequence showed a high similarity with the Graminean fructan genes and a 63 % and 70 % similarity with the 1-SST and 6-SFT wheat cDNAs, respectively. Our results confirmed that the isolated genomic clones share homology but are definitely different than any previously reported cDNA sequences (Kawakami and Yoshida 2002) and most likely represent another fructosyl transferase gene type. Functional analysis using transient transformation of heterologous tissues will confirm the enzyme activity of the encoded protein and its involvement in stress tolerance.

References.

• Hughes MA and Dunn MA. 1990. The effect of temperature on plant growth and development. Biotech Genet Eng Rev 8:161-188.
• Kawakami A and Yoshida M. 2002. Molecular characterization of 6-SFT and 1-SST associated with fructan accumulation in winter wheat during cold hardening. Biosci Biotech Biochem 66:2297-2305.
• Levitt J. 1980. Responses of plants to environmental stresses, Vol I and II. Academic Press, New York, NY.
  Lijavetzky D, Muzzi T, Keller B, Wing R, and Dubcovsky J. 1999. Construction and characterization of a bacterial artificial chromosome (BAC) library for the A genome of wheat. Genome 42:1176-1182.
• Tognetti JA, Salerno GL, Crespi MD, and Pontis HG. 1990. Sucrose and fructan metabolism of different wheat cultivars at chilling temperatures. Physiol Plant 78:554-559.