Study On The Mechanism Of Light Signal And BR Regulating The Development Of Peanut Pod

Peanut(Arachis hypogaea L.)is an important oil and economic crop,which is rich in protein and oil,and has high utilization value.Peanut has the unique characteristics of flowering above ground and completes pod development underground.Light signal play key roles during peanut pod development.PhyA and phyB are two important photoreceptors of light signal.Studies in Arabidopsis showed that photoactivated phyB can directly interact with BES1 to regulate hypocotyl elongation.Brassinosteroids(BRs)regulate multiple growth and development processes of plants,and BES1 is a key transcription factor of BR signal transduction.However,whether light signal and BR coordinately regulate the development of peanut pods is unclear.In our laboratory,we found that multiple phyARNAi transgenic lines showed above ground pod formation.Through the determination of hormone content and gene expression profiling at different development stages of above ground pegs and pods,we speculate that BR is a key hormone involved in regulating the peanut pod development.In this study,AhBES1 was cloned and its expression was studied.Functional studies of AhBESl were carried out by Arabidopsis transformation and interaction between AhBES1 and AhphyA and AhphyB.These results provided information for understanding the mechanism that light signal and BR regulating peanut pod development.The main results of this study were summarized as follows:1.Determination of the hormone content of peanut pegs in different growth stages:During the expansion process after pegs penetrate into the soil,the content of IAA decreased.The content of 6-deoxybrassinosteroid in BRs decreased and reached the lowest level after 6 d of soil penetration(DOSP).After pegs expansion,the content of BRs increased again.The ABA content was high before the peg expension,and then the ABA content decreased when the pegs started to expand.The content changing trend of GAi,GA3 and GAs was similar,showing a significant increase at 6 DOSP.These results indicated that BR and GA may play key roles to promote the enlargement of peanut pods.2.Transcriptome analysis results showed that in LH14 and phARNAi peanut pegs,the expression levels of auxin,GA,ABA,ethylene and BR related genes changed.Compared with LH14,many differentially expressed genes(DEGs)in phyARNAi peanut were identified,including 26 auxin-related genes,13 gibberellin-related genes,18 ethylene-related genes and 15 BR-related genes.Among the BR related DEGs,4 genes were down-regulated and 11 genes were up-regulated,including genes related to BR synthesis and signal transduction pathway.The significant differences in the expression levels of these genes indicated that hormones play key roles in the regulation of peanut pod development.Among them,BR may be a key hormone involved in regulating peanut pod enlargement.3.Cloning and functional analysis of AhBESI gene:The 948 bp full length CDS of AhBES1,encoding a protein with 315 aa,was cloned from cultivated peanut LH14.The over expression,RNAi and CRISPR vectors were constructed for functional study of AhBESl gene.4.The interaction between BR and light signal:By constructing the recombinant plasmids of AhphyA?AhBES1,and using yeast two-hybrid to explore their interaction.The results showed that AhBES1 can not interact with AhphyA-N.