Sugarcane bZIP16 regulates internode elongation by targeting gibberellic acid biosynthesis pathway

Abstract

Modern sugarcane cultivars are vegetatively propagated interspecific hybrids developed by extensive breeding and selection method to enhance sugar content, culm dimensions, desired plant architecture and disease resistance. Internode length greatly varies among existing sugarcane cultivars which determines culm length, biomass and sugar storage. Molecular factors responsible for this trait remains largely unknown in sugarcane. In this study, we characterized short and long internode sugarcane varieties and elucidated gene regulatory module interplaying with hormonal-network underneath the internodal growth. The genome size, pigment content and juice characteristics of short and long internode varieties differed with each other and correlated with gene expressions pattern. We established tissue and spatial transcriptome dataset, and comparative analyses demonstrated number of genes involved in cell cycle, cell expansion, transcription factors and hormone pathway including bZIP16 are differentially expressed between short and long internode varieties. Biochemical, DNA-protein interactions and molecular evidences revealed that ScbZIP16 inversely related to GA content by repressing transcripts of ent-isokaurene C2/C3-hydroxylase and GA20 Oxidase in sugarcane. The further genetic evidences confirmed role of ScbZIP16 in reducing GA biosynthesis pathway, flowering time and growth in Arabidopsis. This report of ScbZIP16 regulatory module offers a potential candidate for sugarcane improvement programs.