Kernel texture (grain hardness) in common wheat (Triticum aestivum L.) is of primary technological importance and is largely determined by puroindoline gene sequence and expression. We investigated the puroindoline haplotypes of 246 Asian common wheat varieties. All but three were conclusively characterized for puroindoline a and b haplotypes. Of the total, 174 possessed the soft Pina-D1a/Pinb-D1a ‘wild-type’ gene sequences with SKCS hardness indexes (HI) ranging from 13.5 to 61.8. Among the remaining 72 varieties with HIs of 56.1–97.8, nearly half (30) were Pina-D1a/Pinb-D1b, 4 were Pina-D1a/Pinb-D1c, 19 were Pina-D1a/Pinb-D1p, 10 were Pina-D1b/Pinb-D1a (‘a-null’), 3 were Pina-D1l/Pinb-D1a, 2 possessed a new C-to-T SNP mutation at position 382, which is tentatively designated Pinb-D1ab, 1 was a ‘double null’ with neither puroindoline a nor b expressed and no PCR-detectable gene sequence, and 3 had undetermined/ambiguous puroindoline a sequence but possessed Pinb-D1a. The double null was the hardest of all varieties tested with an HI of 97.8. The frequency of soft and hard varieties and puroindoline hardness haplotype varied depending on the origin of the varieties. The lowest frequency of hard varieties occurred in Korea and south-western Japan. Tibet and Pakistan also had low frequencies of hard varieties. The highest frequency of hard varieties appeared in north-east China followed by north-west China and Nepal. Within Asia, the Pinb-D1p allele appears in a region extending from north-eastern China through Inner Mongolia, north-western China, Xinjiang and Tibet, with the greatest frequency in north-western China. This allele was also present in Pakistan and Afghanistan, but not found in Japan, and may have been dispersed along the ‘Silk Road’. All three Pina-D1l varieties came from China. The newly discovered SNP originated in Afghanistan and the ‘double null’ in Xinjiang.

The endosperm of dormant wild oat (Avena fatua L.) grains contains a number of mRNAs, including low levels of transcripts encoding avenin (AV10), puroindoline-like (AV1) and serine proteinase inhibitor-like (Z1) proteins. During dry afterripening, a period of warm dry storage that relieves dormancy, the abundance of these intact transcripts gradually declined to undetectable levels in pooled grain samples. In contrast, the three mRNAs did not decline in grains stored for the same period at −20°C, and levels of mRNA decay products derived from these transcripts did not change during afterripening. Disappearance of the three intact mRNAs was not a general phenomenon, since abundance of more than 5000 other seed mRNAs did not change during this period. Additional experiments were conducted to test the idea that the presence of these transcripts was positively correlated with seed dormancy status. First, the rate of intact Z1 mRNA decline was similar to the rate of dormancy relief during 9 months of afterripening. Second, cultivated oat (A. sativa) grains (which are not dormant at maturity) contained much lower levels of these mRNAs than did highly dormant wild oat grains. Third, levels of full-length AV1 and Z1 mRNAs remained constant in dormant grains during 6 d of imbibition. However, Northern analyses of individual grains from a partially afterripened seed lot showed that amounts of intact AV1 or Z1 mRNAs were highly variable in germinating and dormant grains and were not correlated with dormancy status. Even though loss of these transcripts occurred under the same environmental conditions that promote afterripening, a causal relationship between the two processes seems unlikely. The apparently specific mechanism(s) by which these mRNAs are degraded in endosperm tissue may represent a novel post-transcriptional process for regulating levels of certain transcripts in dry grains.