| Pre-harvest sprouting is a potential problem in wheat production of the world. Seed dormancy is known as a major genetic component for pre-harvest sprouting resistance. In this paper, the mechanism of ABA-regulated seed dormancy by using proteomic method and QTL for seed dormancy using SSR marker in two RILs populations were investigated, the results were as follows:(1) Dormant embryos were treated with 10μmol·L-1 ABA (sterilized distilled water as control) and a total of 18 ABA-responsive proteins were identified in embryos of wheat landrace Wanxianbaimaizi with high dormant level by using two-dimensional gel and MALDI-TOF-MS. These proteins are involved in different physiological reaction pathway. For instance, cold regulated protein, heat shock protein HSP26, aldehyde dehydrogenase and dehydrin are involved in stress reaction; auxin-responsive-like protein, ethylene receptor, calcium dependent protein kinase CP4, putative ethylene-responsive protein suggest signal cross talk; LEA B19.1, LEA 1, Em protein, bZIP transcription factor, zinc finger protein, myb family transcription factor, starch synthase, and putative cellulase belong to regulating and storage proteins involved in seed development. These results reflect the complexity of ABA action to dormancy. ABA not only induces dormancy, but also triggers other cross-linked reaction.(2) The characteristics of above 18 ABA-responsive proteins were analyzed by using 2-D gel. A dehydrin [Triticum turgidum subsp. durum] among these proteins increased obviously following the onset of dormancy and decreased during the release of dormancy. The expression level of dehydrin correlated positively with change of endogenous ABA level during seed maturation as well as during seed germination. Furthermore, the expression of dehydrin was more sensitive correspondingly to the exdogenous ABA in dormant embryos than in non-dormant embryos. The results suggest that the dehydrin is involved in ABA-regulated dormancy in embryos.(3) The dehydrin gene was isolated from Wanxianbaimaizi based on partial polypeptide sequence obtained using Q-TOF2 tandem mass spectrometry. The coding sequence and 3'and 5' sequence of dehydrin from Wanxianbaimaizi contained abundant base pair mismatch with dehydrin from Triticum turgidum subsp. Durum. It is concluded that dehydrin is a protein closely related to the expression of dormancy induced by ABA in wheat.(4) The expression of dehydrin was studied in transcriptional level in Wanxianbaimaizi embryos. The results show that expression profiles of dehydrin in transcriptional level is identical to that of it in translational level.(5) QTL mapping for seed dormancy were conducted in two RILs populations, Wanxianbaimaizi/Jing411 and Wanxianbaimaizi/Zhongyou9507, using SSR markers. The results show that two major QTLs were commonly mapped on chromosome 3AS and 2DS. The percentage of phenotypic variance explained by QTL located on 3AS and 2DS was 35.1%—43.7% and 17.5%—23.4%, respectively. (6) A total of 113 wheat varieties containing 87 wheat cultivars and 26 landraces from different wheat region were analyzed to detect the effects of SSR markers closely linked to dormancy gene. The results of jointly detecting by BARC294, BARC310, BARC321 and BARG57 on 3AS indicated that 23 wheat landraces were identified to have the same fragment of PCR product with Wanxianbaimaizi and a significant correlation was observed between germination behavior of 20 wheat landraces, accounting for 86.9% in a total of 23 wheat landraces, and the fragment of PCR products of 4 SSR markers. However, a few wheat cultivars were found to have the same fragment of PCR products with Wanxianbaimaizi. The 4 SSR markers on 3AS can be used for MAS for wheat varieties with high dormant level. As to SSR markers on 2DS, the effects of CFD53, WMC112 and GWM210 were not significant and need to be identified in different growth environments. |
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