Grain-filling Characteristics Of Cultivar Shumai 969 Derived From Synthetic Hexaploid Wheat

The evolutionary bottleneck, narrowed the genetic basis of common wheat(Triticum aestivum L.,2n=6x=42, AABBDD), which restricts the wheat genetic improvement on high yield. As a "bridge", synthetic hexaploid wheat can effectively used to transfer desirable genes from tetraploid wheat and Aegilops tauschii into common wheat, which can increases the genetic diversity of cultivated wheat and provide important application value on further genetic improvement on yield, quality and other important agronomic traits.This research analyzed the grain-filling characteristics of Shumai 969 and its sister line number 25,and their synthetic hexaploid wheat parent SHW-L1 (including SHW-L1'parents tetraploid wheat AS2255 and Aegilops tauschii subspecies tauschii accession AS60), common wheat parents Chuanmai 32, Chuanyu 18,and Chuanmai 42 (a derivative of another synthetic hexaploid wheat), and Ae. tauschii subspecies strangulata accessions AS2388 and AS2404. The main results are as follows:1. Shumai 969 and line number 25 are consistent with their common wheats parents in heading and flowering time, experienced about 5-6 days from heading to flowering.Synthetic hexaploid wheat SHW-L1 bloomed later 5 days than heading, while tetraploid wheat AS2255 bloomed later 7 days than heading, showing SHW-L1 is quicker than its parent tetraploid wheat AS2255 from ear to flower. For the Ae. tauschii, the heading and flowering period had no obvious boundaries and ears had blossom before heading. Ae. tauschii AS2404 and AS2388 showed later flowering than AS60.2. Shumai 969 showed similar grain-filling duration and finished grain-filling at 35 days after flowering as its parents synthetic hexaploid wheat SHW-L1,Chuanmai 42, and Chuanmai 32. However, its sister line number 25 had longer duration of grain filling and continued grain-filling after 35 days after flowering, similar to the wheat parent Chuanyu 18. The mean grain-filling rates of Shumai 969 and Chuanmai 42 were consistent in different stages, suggesting that Shumai 969 inherited grain-filling rate of Chuanmai 42; The mean grain-filling rates in each stage of its sister line number 25 were more similar to Chuanmai 32 with relatively slow grain-filling speed. Shumai 969 and its sister line may not inherit the grain-filling trait of synthetic hexaploid wheat SHW-L1.3. We divided the materials into two types (>45g and <45g), basing on the thousand-grain-weight (TGW) at 35 days after flowering. We found the grain-filling rates of the higher TGW type are significantly higher than the lower type, showing that the grain-filling rates had important contribution to TGW. In addition, the mean TGW of Shumai 969 and its sister line had no significant difference in the 25 days after flowering, while the TGW of Shumai 969 was significantly higher its sister line in the 30 days after flowering. The grain-filling rates of Shumai 969 is slighter faster than its sister line in each stage although there had no significant difference, suggesting the accumulation of marginal effects may have strong positive effect on TGW.4. By comparing the contribution rates of dry matter accumulation, we found that dry matter of synthetic hexaploid wheat SHW-L1 and its parents tetraploid wheat AS2255 and Ae. tauschii AS60 accumulated more in the early stage of grain-filling. Again, the contribution rates of dry matter of derivatives of synthetic hexaploid wheat were significantly higher than non-derivatives in 10-20 days and 10-25 days, showing the higher accumulation at early stages of derivatives of synthetic hexaploid may relate to synthetic hexaploid wheat parents. However, it was unclear wether the higher accumulation of Shumai 969 and its sister line were from synthetic hexaploid wheat SHW-L1 or the derivative Chuanmai 42 of synthetic hexaploid. We further analyzed the correlation of TGW between SHW-Ll and its parents AS2255 and AS60 and showed that AS2255 had stronger effects than AS60 on TGW.