Regulation Of DEP1 On Yield And Its Aggregation Effect With NRT1.1B In Rice

Erect panicle architecture in rice is an important morphologicalimprovement after semi-dwarf and ideal plant architecture.DENCE AND ERECT PANICEL1(DEP1)locus is pleiotropic for the erectpanicle,the number of grains per panicle,and nitrogen uptakeand metabolism.It has important theoretic importance and practice value in rice high-yield breeding to study the genetic basis and physiological mechanism of DEP1 gene.At present,DEP1 has been widely used in rice breeding.However,there are still some problems to be thorough researched,in order to further enhanceutilization of DEP1 in japonica and indica rice.In this study,the following three tests were conducted to definitephysiological mechanism of DEP1regulated yield and its aggregation effect with NRT1.1B(Nitrogen efficient gene)in rice,to provide the theoretical basis for rice high-yield breeding and sustainable development of environment.Results showed that:1.Variations in DEP1contribute to the diversity of the panicle trait in high-yielding japonica rice varieties.We used a rice germplasm collection of 72 high yieldingjaponica rice varieties to analyze the contribution of DEP1 to the panicle traits.We found 45 SNPs and 26 InDels within the DNA fragment of DEP1.We further detected 7 haplotypes and foundthat the replacement of 637 bp by a 12 bp fragment could explain the erect panicle architecture in all 72 germplasms.An SNP(G/C)at the-1253 bp of the promoter region caused a core sequence shift(TGGGCC)of asite Ⅱ transcriptional regulatory element.The association analysis showed that the SNP(G/C)largely affectsthe number of primary and secondary branches,and grain number per panicle.Our results provide novel insightsinto the function and genetic diversity of DEP1.2.Effect of DEP1 on the carbon-nitrogen metabolic,yield,and quality in rice.The depl fragment was ligated into the pBWA(V)HSvector,driven by cauliflower mosaic virus(CaMV)35S promoter,and then transformed into thewildtype rice cultivarAkitakomati.Under low N and high N condition,the expression levels of GS1;1,GS1;2 and NADH-GOGAT1were upregulated in transgenicdep1 plants,which resulted in higher total nitrogen and soluble protein content.But the expression levels of RUBISCO,PEPC2,PEPC6 and PEPC7were downregulated in transgenicdep1 plants,which resulted in decrease of photosynthetic rate,sucrose,starch and soluble sugar content.Although the carbon-nitrogen metabolic status was unbalancedin transgenicdep1 plants,the grain yield was not decreased because the dep1 allele had pleiotropy to increase branch numbers and grain numbers per panicle.However,the unbalanced carbon-nitrogen metabolic status decrease the seed setting rate,grain-filling rate,1000-grain weight and grain quality.3.Effect of gene pyramiding for DEP1 and NRT1.1B on nitrogen utilization and yield in rice.Four genotypes included DEP1/NRT1.1B,DEP1/nrt1.1b,dep1/NRT1.1 Band dep1/nrt1.1b,were identified under japonica or indica background in 151 RILs.Under japonica background,the dep1/nrt1.1b lines showed higher panicle numbers,yield,total nitrogen content of stem-sheath,and nitrate reductase activity in low N condition than the dep1/NRT1.1B lines,but these traits were not changed inhigh N condition.Under indica background,the dep1/nrt1.1b lines showed higher grain numbers per panicle,yield,total nitrogen content of stem-sheath,and glutamine synthetaseactivity than the dep1/NRT1.1B lines in both low N and high N conditions.