| Heading date(HD)and photoassimilate are critical factors affecting rice yield,and both of them are closely related in controlling rice growth and development,organ formation and material accumulation.Hd1 and Ghd7 are pleiotropic genes that regulate the heading date.Hd1,one of the core genes controlling the heading date of rice,provides an important basis for the genetic diversity of rice.Ghd7 is a pleiotropic gene that can simultaneously control the heading date,plant height and grains per panicle.However,there are few studies on the genetic effects of the heading date geness on photoassimilation,the key process of rice yield formation.In this study,a set of nearisogenic line R3 genetic population isolated from Zhenshan 97 / Miyang 46 recombinant inbred line population at Hd1 and Ghd7 loci was used to investigate the changes of agronomic traits,photoassimilation metabolism and yield traits of rice at heading date and mature period(MP)under natural long-day conditions.The main research results are as follows:1.Genetic effects of Hd1 and Ghd7 on agronomic traits of riceIt was detected that Hd1 and Ghd7 had main effects on the agronomic traits at HD and MP.Both functional Hd1 and functional Ghd7 could increase the dry matter accumulation of sheath and stem,leaves and panicles,and functional Ghd7 had a more obvious effect.Meawhile,the geneticn,effects of the interaction of Hd1 and Ghd7 on the dry matter accumulation of sheath and stem,leaves and panicles(grains)at HD and MP were also detected.Hd1 and Ghd7 had different effects on dry matter accumulation in different parts of rice at different growth stages,and had different effects on plant height(PH)and tiller.2.Genetic effects of Hd1 and Ghd7 on rice photosynthesis productsBased on the determination of the carbohydrate content(sucrose,total sugar,starch,fructose and glucose)of different parts(sheath and stem,leaf and panicle)of rice in different growth periods(HD and MP),it was found that Hd1 and Ghd7 had the main effects,and interaction effects,their effect values and contribution rate were obviously different.For the carbohydrate metabolism of the sheath and stem,the genetic effects of Ghd7 are higher than that of Hd1,and the double gene interaction had a significant effect on the contents of sucrose,starch and glucose at two growth stages.For the carbohydrate metabolism of the leaf,Ghd7 had a higher contribution rate,and the contributition rate of gene interaction to sucrose and starch content was greater at MP.For the carbohydrates in the panicles(grains),the genetic effect of Ghd7 on the sucrose content at HD was higher than that of Hd1,while only Hd1 had the main effect on sucrose at MP.The genetic effect of Ghd7 on glucose content was lower than that of Hd1 at the HD,and only Ghd7 had the main effect on glucose at MP.These results showed that-there were significant differences in the effect of Hd1 and Ghd7 on carbohydrate metabolism in different growth stages,and his differences were well correlated with the strength of rice photosynthesis in different growth stages,the accumulation of carbohydrate components and the physiological activity in different parts.3.Genetic effects of Hd1 and Ghd7 on rice yield traitsThe experiments showed that Hd1 and Ghd7 have main effects and interaction effects on rice yield traits(number of panicles per plant,number of spikelets per panicle,number of grains per panicle,yield per plant and 1000-grain weight).The functional Hd1 effectively increased the number of spikelets per panicle,the number of grains per panicle and the 1000-grain weight,and reduced the number of panicles per plant.The functional Ghd7 increased the number of panicles per plant,yield per plant and the1000-grain weight.Meanwhile,the genetic effects of interaction between Hd1 and Ghd7 on yield per plant and 1000-grain weight were also detected.The results showed that the effects of Hd1 and Ghd7 on yield traits were different.Only when functional Hd1 and functional Ghd7 existed simultaneously,the interaction effect on yield per plant and 1000-grain weight of rice could be exerted.Hd1 and Ghd7,the core genes of rice heading date,have main effects on rice heading date and yield traits.Meanwhile,the interaction between Hd1 and Ghd7 has genetic effects on rice agronomic traits,carbohydrate and yield traits. |
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