Genetic Analysis Of Pericarp Color Of Rice And Preliminary Research On Influence Mechanism Of Pericarp Color On Yield Characters

Colored rice not only contains abundant nutritional components and physiologically-active compounds, but also is rich in edible pigment necessary for food manufacture industry. However, the yield of colored rice varieties is low, in comparison to conventional inbred and hybrid rice. Consequencely production and consumption of colored rice are hard to meet the demand in rice market. Thus, it is very important to study the mechanism of yield formation of colored rice.In present research, NILs for pericarp color were constructed based on genetic analysis of pericarp color using a population derived from Zixiangnuo and Chunjiangnuo 2. Phenotyping and genotyping using molecular markers were carried out further in evaluation on near isogenicity of NILs. To analyze the effects of pericarp color on grain yield, 5 pairs of NILs different in Pb were used for studies on panicle characters, chlorophyll content of flag leaf, grain filling rate, chlorophyll content of grain, anthocyanin content of grain, grain water content, and grain plumpness. The results are as follows:1. Genetic analysis of pericarp color and agronomic traits of the plants from F1, F2, F3 and BC1F1 showed that the pericarp color of F1 plants was purple, and segregation ratio of pericarp color of the plants from F2, F3 and BC1F1 showed that the color of purple pericarp was controlled by two complementary genes, Pb and Pp, located on chromosome 4 and 1, respectively.2. Based on the genotypes of pericarp color, the plants carrying Pb-PpPp or PbPbPp-were selected from segregation population at BC1F9 by successive inbreeding after backcrossing with Chunjiangnuo 2. At BC1F10 generation, the selected seven pairs of NILs did not show any segregation on pericarp color.3. SSR genotyping was introduced to acesse the near isogenicity for the NILs, and the results showed that 5 pairs of NILs showed high near isogenicity with the polymorphic SSR markers detected only in target regions near Pb. However, the remaining two pairs of NILs different in Pp, showed low near isogenicity as the polymorphic markers were detected as well as in non-target segments of chromosomes 11 and 12, respectively.4. Based on the degree of near isogenicity of NILs, 5 pairs of NILs different in Pb were used to study influence mechanism of pericarp color on yield in colored rice, and the results showed that there were significant differences in 1000-grain weight, but no significant difference in other agronomic characters such as number of productive panicles per plant, grain number per panicle, filled grains per panicle and seed setting rate. The difference in grain weight mainly embodied in difference in length, width, thickness of brown rice, that is, the length, width and thickness of purple grain were all significantly lower than those of white grain.5. There were no significant differences in chlorophyll content of flag leaf, chlorophyll content of grain, net photosynthetic rate of flag leaf, and length and width of grain between 5 pairs of NILs different in Pb. But grain filling percentage and maximum filling rate of white grain was significantly higher than those of purple grain at 0.05 and 0.01 levels.Thus, it was inferred preliminarily that biosynthesis of anthocyanin influenced accumulation of photosynthate during the process of grain filling, which led to lower grain filling rate and poorer grain filling rate, and eventually influenced grain weight and yield.