Research And Application Of Rice With Different Alleles Of IPA1

Plant type is one of the important factors for high yield of rice.The IPA1 gene is a major gene for controlling the ideal plant type of rice.Its ipa1 mutant has the effects of increasing rice plant height,strengthen stalk,decreasing tiller number,significantly increasing the number of spikes per kernel,and has great potential in hybrid rice breeding applications.In this study,agronomic and yield traits,stalk strength,IPA1 gene expression patterns of six ipa1-1D,six ipa1-2D,and six IPA1,three allelic of IPA1 gene,restorer materials were studied;six ipa1-1D and six ipa1-2D restorer line materials were combined with five sterile line materials to heterosis and combining ability analysis;conventional hybridization combined with molecular marker-assisted selection,the ipa1-1D and ipa1-2D restorer line materials were subjected to disease-resistant insect breeding.The specific research results are as follows:(1)Compared with IPA1 material,ipa1-1D material showed increased plant height,decreased effective ears,increased primary branches,increased number of real grains and total grains,but the seed setting rate decreased significantly,and there was no significant difference in ear length and thousand-grain weight.Compared with the IPA1 material,the ipa1-2D material had primary branches increase,and the number of solid grains and total grains increased significantly.However,there were no significant differences in plant height,effective ear,ear length,seed setting rate,and thousand-grain weight.Compared with ipa1-1D material,ipa1-2D material has significantly reduced plant height,effective ears increased,primary branches increased,the number of solid grains and total grains increased,and the seed setting rate increased.This shows that the plant type of ipa1-2D is more ideal than ipa1-1D.(2)The stalk strength studies of different genotype restoration lines showed that the homozygous ipa1-1D and ipa1-2D restoration lines had a significant increase in the resistance to stalk breaking in the field compared to the homozygous IPA1 restoration lines;in terms of inter-node traits,the length of each extended inter-node increased significantly,the inter-node bending resistance increased significantly,and the stalk cross-sectional area increased significantly.Correlation analysis of stalk traits found that,except for the water content of the stalk,most of the internode traits were significantly positively correlated with the field breaking resistance in varying degrees.The internode traits are strongly correlated with the stem breaking resistance.(3)Real-time PCR analysis of the gene expression of the three genotype restorer lines showed that the relative expression levels of genes in ipa1-1D and ipa1-2D materials were up-regulated in different parts of the plant compared to IPA1 materials.In the tillering stage,both ipa1-1D and ipa1-2D genotype restorers were highly expressed in the stem base.In the fourth stage of panicle differentiation,the ipa1-1D and ipa1-2D genotype restorer lines were highly expressed in the panicle.In the fifth and sixth phases,the expression level in the young spikes continued to decrease,and the expression of ipa1-1D in the young ear differentiation was high in the fifth and sixth phases,resulting in a significant reduce of setting rate of the restored lines of the ipa1-1D genotype.In the fourth,fifth,and sixth phases of young panicle differentiation,the expression level of ipa1-1D genotype restorer lines in stems was significantly higher than that of ipa1-2D genotype restorer lines,and the plant height of ipa1-1D genotype restorer lines was significantly Increase related.(4)Correlation analysis showed that plant height was significantly positively correlated with gene expression in the stalk.The effective panicle number was significantly negatively correlated with the expression level of the stem base at the tillering stage.The number of full grains per panicle and the total number of grains were significantly positively correlated with the gene expression in the young panicle of fouth panicle differentiation stage and the leaf of sixth panicle differentiation stage.Seed setting rate was significantly negatively correlated with the expression of stems and young panicle in the fifth and sixth stages of panicle differentiation.There is a significant positive correlation between the resistance to stalks in the field and the expression of IPA1 in stalks in different periods.The correlation between stem IPA1 expression and the first internode length,first internode cross-sectional area,second internode length and other internode traits also reached a significant level.(5)Heterosis and combining ability analysis of nine main agronomic and yield traits of60 F1 hybrids of 12 test restorer materials and their hybrid combinations,PF01 had the highest total number of grains per panicle among six ipa1-1D restorer,PF03 had the highest effective panicle,primary shoots,real grains per panicle,total grains per panicle,seed setting rate and yield per plant.Among the six ipa1-2D restorer lines,PF07 had the highest yield per plant,total grains per panicle,real grains per panicle and ear length,and PF12 had the highest plant height and thousand kernel weight.The traits such as effective panicle,panicle length,thousand-grain weight,and yield per plant in the 60 combinations showed a certain heterosis.Among the parents,the restorer lines PF01 and PF07 have good generally combining ability for traits such as panicle length,number of real grains per panicle,total number of grains per panicle,seed setting rate and yield per plant.PF05’s single plant effective panicle and 1000-grain weight traits have good generally combining ability.PF08 and PF10 and the sterile line Changxiang A had relatively good generally combining ability for the traits such as effective panicle per plant,real grains per panicle,total grains per panicle,seed setting rate and yield per plant.(6)The analysis of combining ability variance shows that the paternal contribution rate of the ipa1-1D recovery system is mainly concentrated in the traits of seed set rate.The contribution rate of the male parent of the ipa1-2D restoration line is mainly concentrated in plant height,number of solid grains per panicle,seed setting rate,thousand-grain weight and other traits;the narrow sense heritability analysis shows that the improvement of ipa1-1D and ipa1-2D restorer lines on the ear length traits of hybrid progeny is suitable for early selection of parents;the improvement of plant height,effective panicle,primary shoots,number of real grains per panicle,total number of grains per panicle,seed setting rate,thousand-grain weight and yield per plant should be mainly achieved through the selection of hybrid combinations.(7)After two-season cross breeding of Nanchang mid season rice in August 2018,Hainan southern propagation season in March 2019 and molecular marker assisted selection of Nanchang mid season rice in August 2019,41 single plant with four genes ipa1-1D or ipa1-2D,Pigm,Bph14 and Bph15 were selected and sent to Hainan for self cross breeding.