Genetic and environmental effects on puroindoline-a and puroindoline-b content and their relationship to technological properties in french bread wheats

Grain hardness (GHa) in hexaploid wheat (Triticum aestivum L.) is a major factor of end use quality. The variation of texture has been related to the Hardness locus, closely linked with the puroindoline-a (PIN-a) and puroindoline-b (PIN-b) genes. In order to study the role of puroindoline content in texture variation, the quantity of puroindolines was determined. Puroindoline-a (PIN-a) and puroindoline-b (PIN-b) content was determined and a total of 11 bread making parameters were obtained from 40 bread wheat cultivars grown in four experimental locations. The 11 parameters were significantly influenced by the genotype whereas location did not significantly affect PIN-a or PIN-b content and loaf volume. PIN-b and grain hardness displayed the highest heritability coefficients (both 0.88). PIN-a and PIN-b content were not correlated with grain protein content (Prot) and grain hardness in hard and soft wheat types. In soft samples PIN-(a+b) content was negatively correlated, with loaf volume in two locations. Multiple regression analyses, carried separately for soft and hard types, revealed that PIN-b content explained variation of dough strength (W) and loaf volume, however their influence was mostly significant in soft types. For each location, from 22 to 91% of the phenotypic variation of strength and loaf volume was explained by combining up to three flour traits. Protein content, PIN-b and the average score of high molecular weight glutenin subunits (HMW-GS) were frequently introduced by multiple regression (without GHa) as explanatory variables of strength and loaf volume. These results strengthened the significant role of PIN-b in breadmaking (loaf volume), and indicated that biochemical factors other than puroindolines are involved in the grain hardness variation.