Starch Physicochemistry Properties,Genetic Backgrounding,and Physiological Mechanism For The Superior Palatability Of Longjing18

Rice grain quality is affected by both genetic factors and environmental conditions.The rice breeded in Heilongjiang is famous for its high quality,but there is still a gap between with the famous foreign high-quality varieties.Longjing 18 is a high-quality japonica rice variety explored by Heilongjiang Academy of Agricultural Sciences.it is also the only new variety in Heilongjiang Province that can achievethe national first-grade rice standard with good appearance quality and excellent taste.In order to clarify the genetic basis of high quality species and the physiological mechanism of high quality formation of Longjing 18,In this paper we take Longjing 18 and its male parent(Longdao 3),the female parent(Dongnong 423)and Dongnong 415 underlying relatively poor taste of rice as materials to determine the physical and chemical characteristics of starch formed by Longjing 18 in the quality of traits in HaErbin,Heilongjiang Province and Hangzhou,Zhejiang.Furthrmore,we analyzed the key enzymes involving in starch anabolism and their isoforms in the grain filling process of the tested varieties,and the polymorphisms of some important functional gene-specific genetic loci were detected.The main results are as follows:1.There was no signicant difference in between in Longjing 18 and the male parent(Longdao 3)and the female parent(Dongnong 423)and Dongnong 415 in amylose.Mainly manifested in the higher value of expansion potential and lower level of gelatinization temperature(GT)of Longjing 18 rice starch.correspondly,Longjing 18 and its parents also had significant differences in the fine structure of rice amylopectin,Longjing 18 had the higher ratio of short A chain(6?DP? 12)than that of male parent Longdao 3,and the ratio of B1 chain(13?DP?24)was higher than that of female Dongnong 423,which was the responsible for its gelatinization temperature was better than that of the two parents.2.There was no difference between Longjing 18 and its male parent(Longdao 3)and female parent(Dongnong 423)in the single nucleotide polymorphism of SS?a gene,However,the difference between Dongnong 415 and Longjing 18 in SS?a polymorphism(SNP3 and SNP41oci)may result in the high starch gelatinization temperature and the deviation of cooking and eating quality of Dongnong 415 rice.Further studies found that Longjing 18 and its male parent(Longdao 3)and female parent(Dongnong 423)had the same base sequence of the 12 single nucleotide mutation sites of the SS?a gene,indicating that the difference in the physical and chemical characteristics of starch between Longjing18 and its parents in the amylopectin fine structure and gelatinization temperature was not caused by the difference in the structure of SS?a gene.3.The SSS activity of Longjing 18 filling grains was significantly higher than that of its parents(Longdao 3 and Dongnong 423).However,for SBE and DBE activities,Longjing 18 and Longdao 3 had lower SBE and DBE filling grains than Dongnong 423.The results of isozyme electrophoresis showed that the relatively higher SSS activity and higher SSI,and ISA1 isoenzyme protein expression,and relatively lower SBE?b SS?a activity in filling grains may be an important factor in the formation of good quality of Longjing 18 physioloigcal characteristics.