| Rapeseed(Brassica napus L.)is one of the most important oil crops in the world.Despite the highly value of nutritive and dietary,rapeseed is also used as raw materials for biodiesel production.The cultivation of rapeseed in China is mainly depended on the traditional way.With the increasing of labor costs,this kind of time-consuming planting method had seriously restricted the enthusiasm of farmers in China.So,the breeders have been focusing on improving the plant architecture,making it suitable for mechanized sowing and harvesting,which is beneficial to reduce labor costs.In addition,the improvement of plant architecture is also conductive to the increase of rapeseed yield.Plant architecture is composed of aerial organs,which generate from the shoot apical meristem(SAM).Research on the molecular mechanism of SAM development is of great significance to improve crop architecture and mechanized planting.In the past decades,plentiful achievements have achieved on the SAM study in Arabidopsis and rice.However,the research on rapeseed is still rare.In this study,we present dt,a more main stems mutant of rapeseed,which is an ideal material to study the molecular mechanism of SAM development.Transcriptomic analysis and proteomic analysis were adopted to reveal the molecular mechanism of SAM development in dt mutant.Main results of this study were listed as follows:(1)At seedling stage,dt exhibited increased leaf number and lateral roots.After bolting,more main stems were formed in dt mutant.Abnormal differentiation of flowers and dwarf phenomenon were also observed in dt mutant.These phenotype indicated an abnormal development of SAM in dt mutant.(2)The number of leaves in dt mutant significant exceed wild type at 15 days after germination.After further development of the plant,the difference between dt and wild type became quite pronounced,which indicated higher activity of SAM in dt mutant.(3)Tissue sections of SAM from dt and wild type revealed significant differences.The shoots in dt exhibited an irregular shape and formed more than one SAM at shoot area.These results explained that the dt mutant could form more than one stem.(4)RNA-sequencing was used to explore the abnormal development of SAM in dt at transcriptional level.We found 426 DEGs were up regulated and 593 DEGs were down regulated in the mutant.According to the results of GO enrichment and KEGG pathway analysis,these DEGs mainly involved in metabolism,response to stress and biosynthesis of secondary metabolites.Further analysis indicated that genes participant in SAM development,CK biosynthesis and signal transduction displayed significant variation.For example,LOG5 and ARR20,were up regulated by 84 and 102 fold,respectively.We can concluded that the abnormal development of SAM in dt mutant might cause by the differently expression of these genes.(5)Compare to the wild type,the main component of CKs,such as tZ and IP,were increased in dt mutant.The result showed that the accumulation of CKs affected the normal development of SAM in dt mutant.(6)2-DE was used to analyze the protein changing of SAM between dt and wild type.More than 1200 protein pots were separated,50 of them displayed significant variation,which contain 25 up regulated proteins,12 down regulated proteins and 13 proteins unique to the dt SAM.After MALDI-TOF-MS analysis,41 spots were identified successfully.These proteins were mainly involved in energy metabolism,cytoskeleton formation and ROS metabolism.FSD1 and SOD2 are involved in the maintenance of stem cells,and the change of their expression level could affect the development of SAM in dt mutant.This study revealed the possible molecular mechanism regulating the development of SAM in dt mutant.It also provided theoretical foundation to rapeseed development,which is of practical significance to improve the plant architecture,mechanization and production of rapeseed. |
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