| The plant height is too high,which leads to low level of single yield and mechanization,which seriously hinders the good development of rape industry in China.Therefore,it is of strategic significance to reduce plant height properly for improving crop yield,promoting mechanization harvest of rape and promoting the development of rape industry.This study mainly used DZ(short stem)and GW(high pole)and different plant height Brassica napus L.as experimental materials to study the stalk characteristics of plant height and its relationship with lodging.The construction of plant height genetic map,QTL location,transcriptional analysis and mining candidate genes,cloning and expression mode of candidate genes were studied.The main results were as follows:1.Eight Brassica napus L.with different plant height were used to measure their plant type traits at maturity.The results showed that plant height was significantly correlated with primary effective branch height,primary main inflorescence length and top branch angle.Principal component analysis showed that the three factors affecting lodging were stem length factor,branch angle factor and branch number factor Microstructural analysis showed that the size of cells around pith of dwarf material was significantly larger than that of tall material,the average number of cortical cell layers,cortical thickness and vascular bundle number of tall material were higher than those of dwarf material,but the cells arranged higher in the main stem growth direction of dwarf material,the stem material was very neat and compact,and the cells were relatively small;the biochemical components of main stem at final flowering stage were analyzed,and the results showed that plant height was related to wood growth Path analysis showed that the direct contribution of lodging index was lignin.2.10 pairs of polymorphic SSR markers were screened from 16 pairs of SSR markers on both sides of plant height QTL mapped by Liu Xia(2018),which were used to encrypt Zhang Bingbing(2019)genetic map of plant height and high density,and an integrated genetic map containing 6 SSR molecular markers and 3161 SNP molecular markers was obtained.The integrated genetic map covered 19 linkage groups with a total distance of2443.04 cM and an average distance of 0.77 cM.Based on the integrated map,11 target QTLs were obtained,which located on six chromosomes,A02(qIL.A02)A03(qVBH.A03),C02(qPH.C02),C03(qIL.C03),C04(qPH.C04-1,qPH.C04-2,qMIL.C04 and qIL.C04),C06(qPH.C06-1,qPH.C06-2 and qVBH.C06).By comparing the reference genome of Brassica napus,814 candidate genes for plant height were obtained.3.The transcriptome of the stems and leaves of high stem(GW)and low stem(DZ)were sequenced at the initial and full flowering opening stages.The results showed that:3241 and 4579 stem specific differential expression genes(DEG)were selected between the two strains at the early and full flowering opening stages,respectively;go enrichment analysis showed that the response to hormone(GO: 0009725),to organic matter(GO:0010033),to auxin(GO: 0009733)and to endogenous stimulation(GO: 0009719)were at the early flowering stage Through KEGG enrichment pathway,we found that plant height can be regulated by multiple pathways,such as hormone signal transduction,metabolism of multiple amino acids,photosynthesis and so on.Combined with the re sequencing data,365 of the 814 candidate genes were different.Six plant height candidate genes were identified by comparing the function annotation of candidate genes in the database.BnaA03g35310D(AZF2),BnaC04g01170D(JAR1),BnaC02g36170D were related to plant hormone pathway;BnaC04g01470D(EXPA8)was related to cell wall synthesis;BnaC02g35800D(CLE27)was related to shoot tip meristem activity;BnaC06g00930D was related to plant hormone pathway Lignin biosynthesis pathway.4.Transcriptome analysis showed that hormone pathway,especially auxin pathway,was the most relevant to plant height.Therefore,the auxin related gene BnaC02g36170D was cloned from the high stem parent GW and the low stem parent DZ of Brassica napus.It was found that the gene was located on the C02 chromosome.The total length of the DNA fragment was 786 bp,and the length of the CDS fragment in the coding region was 1Sequence alignment showed that there were 8 amino acid residues differences between the two parents,8 of which were amino acid substitutions.The BnaC02g36170D gene obtained from the two parents was analyzed by bioinformatics.The analysis of physical and chemical properties showed that the difference of 8 amino acids did not cause the difference of physical and chemical properties of BnaC02g36170D in the two parents;hydrophobicity analysis showed that the two materials BnaC02g36170D The protein encoded by the gene is soluble and hydrophilic,and the hydrophobicity curves of the two materials are basically the same;transmembrane domain analysis shows that there is no transmembrane structure region in the protein,so it is predicted that the protein may be an extra membrane protein;for DZ and GW The three-dimensional structure of BnaC02g36170D protein was predicted,and the results showed that DZ and GW were identical;the predicted domain only contained an important domain "PB1 domain",which played an important role in auxin response mechanism,indicating that BnaC02g36170D may regulate the growth process of plant height. |
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