| As one of the three major grain crops in China, wheat plays an important role in our food security. Nowadays, the loss of grain during storage has become an increasingly severe problem in China. The nutritional quality, processing quality and marketability of wheat has been seriously destroyed by aging deterioration, mildew and pests during storage. The storability of wheat is influenced by many factors including different origins, strains and storage conditions but the fundamental one is genetic factor. In this study,60 wheat accessions from CIMMYT core pool were used for germplasm screaming for good storability through artificial aging test and the traits related to wheat storability; including PHS resistance and the insect resistance to Sitophilus zeamais Motschulsky were also evaluated. The effects of aging time on the seed vigor of the materials with different storability and the relationships between storability and lipoxygenase gene polymorphism were also studied. The goal of this study is to provide basis for breeding of high storability varieties.The main results are as following:(1) Highly significant differences among 60 varieties were showed in all the four indicators, including relative germination potential, relative germination rate, relative SVI and relative EC after the 3 days’artificial aging treatment under 43±0.5℃. All the samples were clustered into 3 categories depending on the different storability by cluster analysis. In an order from cluster 1 to cluster 3, the wheat storability was increased. The varieties number of each cluster was 21,31 and 9, the mean relative germination rate was 0.97±0.03, 0.82±0.10 and 0.55±0.09, and the mean relative SVI was 0.84±0.08,0.63±0.11 and 0.38±0.08, respectively.(2) The relative germination rate of the 3 types of materials with the storability from strong to weak decreased less than 0.25 after the artificial aging treatment of 11d,7d and 5d under 43±0.5℃, respectively. The relative germination rate, relative germination potential and seedling vigor index of the tested wheat materials were reduced with the increase of aging time, on the contrary, the relative EC was increased. The better the storability was, the more smoothly the trend of the relative germination rate, relative germination potential and seedling vigor index declined, also the more smoothly the trend of the relative EC increased. The wheat materials excellent for storage could tolerate the storage environment with high temperature and humidity for a longer time, and the reducing rate of the seed vigor was smaller. Furthermore, cell repair and activation of the cell membrane at the beginning of the germination, material and energy supply during the seedling growth period as well as the cell membrane permeability of the higher storability varieties were less influenced by aging treatment.(3) 57 out of the 60 samples (95%) belonged to TaLOX-B1b allele at the TaLOX-B1 locus. Besides, there are respectively 4 and 3 types of alleles at the two LOX active sites QLpx.caas-4B and QLpx.caas-lAL, the haplotypes of which had 60% materials in Xgwm251-117/Xwmc312-235 (21.67%), Xgwm251-117/Xwmc312-247 (20.00%) and Xgwm251-113/Xwmc312-247(18.33%). Combination of the haplotypes of these two sites can affect the storability in a synergistic way and has a relative coefficient of 0.312 with relative germination rate and 0.298 with relative seedling vigor index, implying that there are other important LOX active sites that had a joint impact on wheat storability.(4) 10 wheat varieties with high PHS resistance were selected in the study, among which NO.8, NO.21 and NO.46 were white-grained ones and had better PHS resistance than the white-grained resistance resources such as Fulingxuxumai, Zitongnvermai and Yongchuanbaimaizi. All the selected germplasm resources could be valuable for application in the wheat breeding for PHS resistance.(5) 60 samples could be clustered into 4 categories by cluster analysis depending on their different insect resistance to the stored-grain insects Sitophilus zeamais Motschulsky. The differences of the resistance were reflected in the inhibition of the wheat materials to the growth and reproduction of the insects. With the prolong of the storage, the curves of both the insect-eaten rate and the live insects number which were weekly recorded in all the clusters had the tendency of ascending first and descending in succession. NO.3, NO. 16, NO.23 and NO.31 wheat variety were selected to provide good anti-source for the wheat anti Sitophilus zeamais Motschulsky breeding. |
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