EFFECTS OF PROLAMINS ENCODED BY CHROMOSOMES IB AND 1D ON THE RHEOLOGICAL PROPERTIES OF DOUGH IN NEAR-ISOGENIC LINES OF BREAD WHEAT

Fourteen bread wheat near-isogenic lines (NILs) with different alleles at 1B- and 1D-chromosome loci Glu-1, Glu-3 and Gli-1 coding for high molecular weight glutenin subunits (HMW-GS), low molecular weight-GS, and gliadins, respectively, were grown in replicated plots to investig ate the individual and combined effects of glutenin and gliadin compon ents on the rheological properties of dough as determined by the Chopi n alveograph. NILs did not reveal significant differences in seed yiel d, protein content, kernel weight, test weight, flour yield, and starc h damage. On the contrary, they had a large variation in alveograph do ugh tenacity P (55-93 mm), swelling G (17-26 mt) and strength W (140-2 52 J x 10(-4)). The null alleles at the Gli-D1/Glu-D3 loci, and allele Glu-D1d (HMW-GS 5+10) were found to have a strong positive influence on dough tenacity and a remarkable negative influence on dough swellin g (extensibility) when compared to alleles Gli-D1/Glu-D3b and Glu-Dla (HMW-GS 2+12), respectively. On the other hand, alleles Glu-B1c (HMW-G S 7+9) and Gli-B1/Glu-B3k gave greater G values than alleles Glu-B1u ( HMW-GS 7+8) and Gli-B1/Glu-B3b. The effects of individual Glu-1, Gli- 1, or Glu-3 alleles on P and G values were largely additive. The impac t of the null allele at Gli-D1/Glu-D3 on gluten strength was highly po sitive in NILs possessing HMW-GS 2+12, and negligible or negative in N ILs containing HMW-GS 5+10, suggesting that there is scope for improvi ng dough quality by utilizing this allele in combination with HMW-GS 2 +12. Gli-D1/Glu-D3-encoded prolamins were shown to play a major role i n conferring extensibility to dough, and could account for the superio r breadmaking characteristics of bread wheat as compared to durum whea t.