Genetic Research On The Content Of Amylose In Paddy Rice

There are many reports on the research of quality traits in Indica rice but relatively few in Japonica rice. Based on previous study some northern japonica varieties and recombination-inbred lines from Indica-Japonica cross were tested to study the genetic effect, genetic model, QTL location and combining ability on the content of amylose. The main results were as follows:1.Genetic Difference and Correlation on Some Quality Traits in Paddy Rice1.1 The content of amylose had highly significantly positive correlation with protein content, chalk area and chalk percentage, but significantly negative correlation with gelatination and milling quality. Sellecting low amylose content and low protein content variety was good at increase of. gelatination.1.2 The starch content, ratio of head rice, ratio of chalk rice, chalk area and gelatination were the key quality traits in paddy rice according to the result of principle component analysis.2.Genetic Difference and Model Analysis on the amylose content in Japonica Rice2.1 The amylose content would increase with the number of high value gene while the effect of individual gene would decrease.2.2There was no cyto-genetic effect on the content of amylose. The difference between reciprocal FI was duo to the triploid effect of endosperm. The high amylose content was dominant or partial dominant to low ones.2.3The genetic behave of the amylose content was fit to the additive-dominant genetic model. Additive effect was the leading effect, which possessed 81.72% of the total genetic variation. Both low parents should be used in the hybridization utility to avoid wide regression because the seed in FI was F2-3.The Gene Location on the Content of Amylose in Paddy Rice3.1 The Gene Location on the Content of AmyloseThere were 6 QTLs related to the content of amylose in chromosome 1, 4, 5, 8, 9 and!2 (Am-1-1, Am-4-1, Am-5-1, Am-8-1, Am-9-1 and Am-12-1). The total contribution of the 6 QTLs was 88.4%. The effects of these QTLs were relatively same and there was no main effect gene, which indicatedthat the amylose content was a quantitative trait controlled by the micro-effect genes.3.2The Relationship between Amylose Content Genes and Other GenesThere were 2 QTLs controlling chalk percentage (Ch-4-1 and CH-8-1) in the chromosomes containing QTLs of amylose content. The distance between amylose content QTLs and chalk percentage QTLs were 6.5 cM and 40.6cM, indicating that there was close linkage between Am-4-1 and Ch-4-1 but no linkage between Am-8-1 and Ch-8-1. It is possible to decrease chalk rice percentage when selecting low amylose content.There were 2 QTLS in chromosome 8 and 1 QTL in chromosome 12 to control protein (Pr-8-1, Pr-8-2 and Pr-12-1) and they were far from those AC genes. There was no close linkage or the one-factor-to-many-effects relationship between the amylose content and protein content though there existed significantly negative correlation. When developing low amylose content variety by Japonica-Indica crosses excellent offspring with low protein content might also be selected.4.The Combining Ability of the Content of Amylose4.1 The ANOVA on combining ability indicated that the additive effect was the chief effect in the genetics of amylose content, which appeared more and more important as the increment of generation.4.2The combining ability effect of p4 and FS was more stable than that of FS. Cross parents with negative combining ability should be selected such as Shangyu 397, Fuji Light and Dongnong 419 when developing low amylose content rice. Selecting on amylose content should start from Fa generation.4.3The amount of amylose was not closely related with combining ability effect of parents in FS generation but significantly related in p4 and F5.