Studies On Characteristics And Combining Ability Of The Restorer Lines With Homozygous Ipa1-1D Gene

The ideal plant type of rice is one of the important factors for high yield of rice.IPA1gene is one of the dominant genes to control the ideal plant type of rice and has great potential in breeding applications.In this study,a number of stable high-generation ipa1-1D restorer lines were obtained by further selection through hybrid and molecular marker-assisted selection from low-generation ipa1-1D restorer lines.On the basis of genotypic and phenotypic identification of transfered restoration materials,the resistance to toppling of stem of transfered restoration materials and the expression of ipa1-1D gene in stem and leaf tissues at tillering stage and heading stage were studied,and 5 transfered restoration materials and 6 sterile lines were used for incomplete diallel crossing to analyze the combining ability and heterosis of each trait.The specific results are as follows:?1?After 5 successive breeding seasons from 2015 to 2017 in Nan Chang and Hai Nan,156 restorer lines with homozygous ipa1-1D genes with better comprehensive agronomic traits were selected.?2?The studies on phenotypic characters and lodging resistance of stems at maturity showed that:The homozygous ipa1-1D/1D lines were compared with the untransformed homozygous IPA1/IPA1 lines,tillering decreased significantly,and the compressive strength of stem increased,while plant height,ear length,total grains per panicle and number of solid grains,length of single stem,fresh weight of aboveground single stem,cross-cut area of stem,basic tissue thickness,number of vascular bundles,The total number and total area of vascular bundle and the length of the third elongation node increased significantly.?3?The quantitative analysis of ipa1-1D gene expression in stems and leaves of rice at tillering stage and heading stage showed that ipa1-1D gene had high expression in the stem of two periods,but the expression in the leaves of the two periods was very low;wherein the expression amount in the stem of the heading stage is greater than the expression amount in the stem in the tillering stage.?4?The investigation and determination of main agronomic and yield characters and 7grain quality traits of 30 F₁ hybrids and 5 transgenic restoration materials show that,The plant height,ear length,number of solid grains per panicle,total grains per panicle,seed setting rate,1000-grain weight,alkali elimination value,gel consistency and amylose content were higher than those of F₁ hybrids,the average yield per plant,tiller,brown rice rate,milled rice rate,chalkiness rate and chalkiness were lower than those of 30 F₁ hybrids.?5?The heterosis and combining ability analysis showed that,each trait showed certain heterosis,in tillering,yield per plant,chalkiness rate and chalkiness,the positive heterosis was found in most of the traits,such as tillering,yield per plant,chalkiness rate and chalkiness.however,there were negative heterosis in seed setting rate,plant height,ear length,alkali elimination value and amylose content.The direction of Heterosis and combining ability effect of the same or different character of different or different restorer lines varies in different directions.There was no regular relationship between GCA of parents and SCA of combinations.?6?The analysis of combining ability variance showed that,the Vg of all yield related traits,gelatinization and amylose content were higher than that of Vs,the effect of additive effect is greater than that of non-additive effect.The Vg of brown rice,milled rice,chalkiness and alkali elimination were significantly lower than that of Vs,it is mainly affected by the non-additive effect,and he additive effect of chalkiness was similar to that of non-additive effect.Genotypic variance analysis showed that,the genetic contribution of female parents in plant height and 1000-grain weight was significant.the genetic contribution of parents in chalkiness,milled rice rate and alkali elimination was similar,however,the genetic contribution of male parents in other traits was significant.Heritability analysis showed that,the broad heritability of each yield trait is generally higher than that of its narrow sense heritability,and the broad and narrow heritability of 1000 grain weight is the highest,but the broad sense and narrow sense heritability of the total grains per panicle were the lowest.The broad heritability of each rice quality trait was more than 80%,which indicated that the genetic effect of each trait was greater than that of environment.But the narrow heritability ranged from high to low in order of thousand amylose content?73.55%?>gel consistency?57.58%?>chalky grain rate?44.47%?>chalkiness?37.82%?>alkali consumption value?30.72%?>brown rice rate?15.72%?>milled rice rate?13.02%?.