Comparative transcriptome analysis of axillary buds in response to the shoot branching regulators gibberellin A3 and 6-benzyladenine in Jatropha curcas

Cytokinin (CK) is the primary hormone that positively regulates axillary bud outgrowth. However, in many woody plants, such asJatropha curcas, gibberellin (GA) also promotes shoot branching. The molecular mechanisms underlying GA and CK interaction in the regulation of bud outgrowth inJatropharemain unclear. To determine how young axillary buds respond to GA3and 6-benzyladenine (BA), we performed a comparative transcriptome analysis of the young axillary buds ofJatrophaseedlings treated with GA3or BA. Two hundred and fifty genes were identified to be co-regulated in response to GA3or BA. SevenNACfamily members were down-regulated after treatment with both GA3and BA, whereas these genes were up-regulated after treatment with the shoot branching inhibitor strigolactone. The expressions of the cell cycle genesCDC6,CDC45andGRF5were up-regulated after treatment with both GA3and BA, suggesting they may promote bud outgrowth via regulation of the cell cycle machinery. In the axillary buds, BA significantly increased the expression of GA biosynthesis genesJcGA20oxsandJcGA3ox1, and down-regulated the expression of GA degradation genesJcGA2oxs. Overall, the comprehensive transcriptome data set provides novel insight into the responses of young axillary buds to GA and CK.