| Rice(Oryza sativa L.) is one of the three major food crops in the world.More than 50% of the world’s population live on rice as the staple food.Rice planting area accounts for about 1/3 of the grain planting area in China,and the total rice production accounts for more than 40% of the total grain production.Therefore,rice production plays an extremely important role in national economy.Nowadays,with the continuous growth of the world population and the continuous improvement of people’s living standards,people have higher and higher requirements for rice quality.Scientists also pay more and more attention to the research of rice quality.In recent years,many researches have been made by scientists on genetic analysis and improvement of rice quality,especially on starch quality in rice.However,the genetic mechanism for the protein content of the second largest storage material in rice remains unknown.Protein in rice is not only of high nutritional value,but also another important factor affecting the cooking and eating quality of rice.Therefore,it is of great theoretical and practical significance to analyze the genetic mechanism of protein content in rice for further improvement of rice quality.Based on the previous studies,QTLs associated with grain protein contents were identified based on two populations,one is from the cross of Sasanishiki/Y1348,another is from a cross Guichao 2/NIL-SSIII-2,and fine-mapping were carried out for qPC1.2 and qPC8.1,respectively.The main results are as follows1.The protein content of brown rice was detected in 12 expansion lines derived from SL402 of Sasanishiki/Habataki CSSL population,and the results showed that the variation range of the protein content of brown rice was 9.27%～10.63%.Among them,the protein content of brown rice Y1348 was extremely significantly increased and was stable.It is suggested that there is a QTL,named qPC1.2,which controls the protein content of brown rice This indicated that the allele from Habataki significantly increased the protein content of brown rice.2.The BC1F2 population was obtained by backcrossing and self-crossing of Y1348 and Sasanishiki,and was planted in Yangzhou in the positive season.The protein content of each single brown rice plant in the population was investigated,and the results showed that the protein content showed a continuous change and a normal distribution.The results of QTL mapping showed that qPC1.2 was located in the range of 3679kb between HY76 and HY90 of rice chromosome 1.3.In order to further narrow the localization interval of qPC1.2,single plant with heterozygous genotype in the target region was selected from the BC1F2 population to form BC1F3 population.Polymorphic markers were further designed between HY76 and HY90 to precisely locate qPC1.2.Gene prediction showed that there were 33 candidate genes in this region.4.The total protein content of Y1348 and Sasanishiki and the protein content of each component in the storage protein were analyzed.There were no significant differences in albumin,globulin and gliadin contents,but there were significant differences in gluten contents.This suggests that the allele from Habataki may only specifically regulate the gluten content,and has little effect on the other three proteins.5.In the early stage,two QTLs(qPC8.1 and qPC8.2)were detected in the 8th chromosome using a set of proximal gene lines NIL-SSIII-2(Guichao 2 as the background and Su Yu Nuo as the donor)related to starch synthesis as materials.This experiment continues to fine position qPC8.1,and the results show that qPC8.1 is accurate to the range of about 52kb between XY-7 and HY-6.Comprehensive analysis shows that there are 7 ORFs in this section.6.The analysis of protein content in brown rice and white rice of qPC8.1 gene line showed that there were significant differences between them.Further analysis of the protein content of each component showed that there were no significant differences in albumin,globulin and gliadin,except for the significant differences in gluten content. |
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