| Rice mesocotyl can provide the power for the rice sprouting,Breeding long mesocotyl rice can promote the popularization of rice direct seeding technology.Therefore,it is of great theoretical and practical significance to study the mesocotyl elongation of rice.Therefore,studying rice mesocotyl elongation is of important theoretical and practical significance.In this study,the Asominori and IR24recombinant inbred line population（RIL）were used as materials to locate QTLs for the length of the mesocotyl,and the CSSLs were used to test of the existence of QTL loci.In addition,the mesocotyl elongation is mainly determined by the cell elongation and cell division.The microtubule skeleton plays an important role in the process of cell division.To investigate the role of microtubules in mesoderm elongation,the microtubule-associated gene OsMAP1 was edited by the CRISPR/Cas9 technology to investigate the role of tubulin in the mesocotyl elongation.The main findings of this paper are as follows:（1）Three QTLs were detected which were located on chromosomes 2,3 and 7 respectively,and the LOD ranged from 2.34 to 3.41.The contribution rate of QTL to phenotype is between 7.25%and11.07%.At the same time,the result was tested by the CSSLs.The CSSL12 corresponding to qML2 was significantly elongated compared with Asominori,and the CSSL37 mesocotyl corresponding to qML7significantly shortened compared which proved the result of the QTLs qML2 and qML7 to be right.At the same time,QTL mapping of plant height trait was carried out and two QTLs were found and the two QTLs were not coincident with QTLs for the length of mesocotyl,indicating that controlling mesocotyl elongation and controlling plant height have different genetic basis.（2）Using the Shennong 265 as the genetic background,the tubulin gene OsMAP1 was edited by CRISPR/Cas9 technology.The mesocotyl of the T1 mutant was significantly shortened.By Paraffin Section experiment,we found that a higher proportion of abnormal cells were existed in the mutant.The expression of polyamine oxidase（PAO）gene and the secondary wall-related genes were up-regulated.Through the RNA-Sequence sequencing analysis,a large number of stress response genes were found and the expression of cell wall assembly genes and hormone metabolism related genes were significantly different,which indicated that OsMAP1 gene played an important role in regulating cell morphology.The results of gibberellin treatment showed that the mesocotyl of the mutant elongated more significantly than the wild type,and the expression of CESA was down-regulated,suggesting that gibberellin affected the mesotyl elongation by affecting cell wall assembly. |
