The DYT1‐interacting proteins bHLH010, bHLH089 and bHLH091 are redundantly required for Arabidopsis anther development and transcriptome

Summary The anther is the male reproductive organ of flowering plants, and the Arabidopsis bHLH transcription factors encoded by DYSFUNCTIONAL TAPETUM 1 ( DYT 1 ) and ABORTED MICROSPORE ( AMS ) are required for control of the complex transcriptional networks regulating anther development. Knowledge of the mechanisms by which the bHLH proteins affect this diverse gene expression is quite limited. We examine here three recently duplicated Arabidopsis bHLH genes, bHLH 010 , bHLH 089 and bHLH 091 , using evolutionary, genetic, morphological and transcriptomic approaches, and uncover their redundant functions in anther development. These three genes are relatively highly expressed in the tapetum of the Arabidopsis anther; single mutants at each of the bHLH 010 , bHLH 089 and bHLH 091 loci are developmentally normal, but the various double and triple combinations progressively exhibit increasingly defective anther phenotypes (abnormal tapetum morphology, delayed callose degeneration, and aborted pollen development), indicating their redundant functions in male fertility. Further transcriptomic and molecular analyses suggest that these three proteins act slightly later than DYT 1, and also form protein complexes with DYT 1, subsequently affecting the correct expression of many DYT 1 target genes in the anther development transcriptional network. This study demonstrated that bHLH 010, bHLH 089 and bHLH 091 together are important for the normal transcriptome of the developing Arabidopsis anther, possibly by forming a feed‐forward loop with DYT1.