Identification Of Wheat M₃ Grains Induced By EMS And Screening Of Mutants With High Resistant Starch Content

Wheat is the second largest food crop in the world, which cultivated widely in China and has been become main food source for people in most areas of northern China. Resistant starch is the starch which can escape to be digested in small intestinal while can be absorbed as short-chain fatty acids after digestion by microorganisms in the large intestine. And it can prevent effectively from some metabolic diseases, such as obesity, diabetes in human. Resistant starch own good processing characteristics compared with the ordinary dietary fiber. However, wheat is hexaploid that consists of three homologous chromosomes and with a large number of repetitive sequences and gene redundancy, natural mutation rate is very low, genetic base is narrow and resistant starch content is very low. EMS (ethyl methane sulphonate) is efficient chemical mutagen which can cause point mutation easily, in particularly, mutation density is high extremely in polyploid wheat. In this study, physicochemical properties and resistant starch content were researched in M3 seeds per plant in mutation group of Jimai20 and Jimai22 induced by 1.2% EMS. Meanwhile screening of materials with high resistant starch preliminary and several major amylase gene were conducted to detection with PCR amplification to elucidate the possible molecular mechanism of mutation. The study results will provide theoretical and material basis for breeding in quality improvement of wheat flour and wheat varieties with high content of resistant starch. The main results were as follows:1 Variability of pasting viscosity parameters of EMS mutagenesis population was very high with the coefficient of variation of Jimai22 between 30.92-40.61%, and Jimai20 was lower slightly, between 12.25-25.48%. 2 Total starch content of most of the mutagenic materials (>90%) of two cultivars was lower than the materials that was not mutagenic. variation of amylose content was large with the coefficient of variation mutagenic materials of Jimai2017.82%, Jimai22 16.26%. but the trend of variation was different, the average amylose content of mutagenic materials of Jimai22 was lower significantly than the material that was not mutagenic, and the average amylose content of mutagenic materials of Jimai20 was little difference with the material that was not mutagenic.3 Resistant starch content of mutagenic materials of Jimai22 ranged from 0.97% to 2.64%, average was 1.84%, Jimai20 was from 0.95% to 1.48%, average was 1.12%. Jimai22 was more suitable for mutation material with high resistant starch content compared with Jimai20.4 Among 41 mutagenic materials which were specific in pasting properties of Jimai22, sample of percent 60% had deletion mutants in the major starch synthase gene loci in varying degrees, and M08412-5 which was the material with highest content of resistant starch carrying 4 loci mutated in Wx and SBEIla gene simultaneously.