No abstract

No abstract

No abstract

No abstract

Puroindoline proteins were purified from selected UK‐grown hexaploid wheats. Their identities were confirmed on the basis of capillary electrophoresis mobilities, relative molecular mass and N‐terminal amino acid sequencing. Only one form of puroindoline‐a protein was found in those varieties, regardless of endosperm texture. Three allelic forms of puroindoline‐b protein were identified. Nucleotide sequencing of cDNA produced by RT‐PCR of isolated mRNA indicated that these were the ‘wild‐type’, found in soft wheats, puroindoline‐b containing a Gly→Ser amino acid substitution (position 46) and puroindoline‐b containing a Trp→Arg substitution (position 44). The latter two were found in hard wheats. Microheterogeneity, due to short extensions and/or truncations at the N‐terminus and C‐terminus, was detected for both puroindoline‐a and puroindoline‐b. The type of microheterogeneity observed was more consistent for puroindoline‐a than for puroindoline‐b, and may arise through slightly different post‐translational processing pathways. A puroindoline‐b allele corresponding to a Leu→Pro substitution (position 60) was identified from the cDNA sequence of the hard variety Chablis, but no mature puroindoline‐b protein was found in this or two other European varieties known to possess this puroindoline‐b allele. Wheats possessing the puroindoline‐b proteins with point mutations appeared to contain lower amounts of puroindoline protein. Such wheats have a hard endosperm texture, as do wheats from which puroindoline‐a or puroindoline‐b are absent. Our results suggest that point mutations in puroindoline‐b genes may confer hard endosperm texture through accumulation of allelic forms of puroindoline‐b proteins with altered functional properties and/or through lower amounts of puroindoline proteins.