Recently, a research team led by Professor Zhang Yongshan from the Cotton Research Institute of the Chinese Academy of Agricultural Sciences identified an important plant type-related gene, GhSBI1, that regulates the length of cotton fruit branches. This discovery lays a theoretical foundation for the genetic improvement of cotton plant types. The relevant research findings were published online in the well-known journal "Plant Biotechnology Journal" (IF=10.1) under the title "GhSBI1, a CUP-SHAPED COTYLEDON 2 homologue, modulates branch internode elongation in cotton."

Branch length is an important plant architecture trait in cotton ( Gossypium ) breeding. Development of cultivars with short branch has been proposed as a main object to enhance cotton yield potential, because they are suitable for high planting density. Here, we report the molecular cloning and characterization of a semi-dominant quantitative trait locus,  Short Branch Internode 1 ( GhSBI1 ), which encodes a NAC transcription factor homologous to CUP-SHAPED COTYLEDON 2 (CUC2) and is regulated by microRNA ghr-miR164. We demonstrate that a point mutation found in  sbi1  mutants perturbs ghr-miR164-directed regulation of  GhSBI1 , resulting in an increased expression level of  GhSBI1 . The  sbi1  mutant was sensitive to exogenous gibberellic acid (GA) treatments. Overexpression of  GhSBI1  inhibited branch internode elongation and led to the decreased levels of bioactive GAs. In addition, gene knockout analysis showed that  GhSBI1  is required for the maintenance of the boundaries of multiple tissues in cotton. Transcriptome analysis revealed that overexpression of  GhSBI1  affects the expression of plant hormone signalling-, axillary meristems initiation-, and abiotic stress response-related genes.  GhSBI1  interacted with GAIs, the DELLA repressors of GA signalling.  GhSBI1  represses expression of GA signalling- and cell elongation-related genes by directly targeting their promoters. Our work thus provides new insights into the molecular mechanisms for branch length and paves the way for the development of elite cultivars with suitable plant architecture in cotton.

This work was supported by the National Natural Science Foundation of China (31871680), the Natural Science Foundation of Henan Province (242300421340), and Biological Breeding-Major Projects in National Science and Technology (2023ZD04041).

http://doi.org/10.1111/pbi.14439