BRASSINAZOLE-RESISTANT 1 family proteins (BZRs) are central transcription factors that govern brassinosteroid (BR)-regulated gene expression and plant growth. However, it is unclear whether there exists a BZR-independent pathway that mediates BR signaling. In this study, we found that disruption of all BZRs in Arabidopsis generated a hextuple mutant (bzr-h) displaying vegetative growth phenotypes that were almost identical to those of the null mutant of three BR receptors, bri1brl1brl3 (bri-t). By RNA sequencing, we found that global gene expression in bzr-h was unaffected by 2 h of BR treatment. The anthers of bzr-h plants were loculeless, but a similar phenotype was not observed in bri-t, suggesting that BZRs have a BR signaling-independent regulatory role in anther development. By real-time PCR and in situ hybridization, we found that the expression of SPOROCYTELESS (SPL), which encodes a transcription factor essential for anther locule development, was barely detectable in bzr-h, suggesting that BZRs regulate locule development by affecting SPL expression. Our findings reveal that BZRs are indispensable transcription factors required for both BR signaling and anther locule development, providing new insight into the molecular mechanisms underlying the microsporogenesis in Arabidopsis.

耐油菜籽素1家族蛋白（BZRs）是控制油菜素类固醇（BR）调控的基因表达和植物生长的中央转录因子。但是，尚不清楚是否存在介导BR信号传导的BZR独立途径。在这项研究中，我们发现所有的中断BZR S IN拟南芥中产生的hextuple突变体（BZR-H ）中显示的是几乎相同的那些无效突变体的3种BR受体，营养生长表型bri1brl1brl3（BRI-T ）。通过RNA测序，我们发现bzr-h中的整体基因表达不受BR处理2 h的影响。bzr-h的花药植物是无小室的，但在bri-t中未观察到类似的表型，这表明BZRs在花药发育中具有不依赖BR信号的调节作用。通过实时PCR和原位杂交，我们发现在bzr-h中几乎检测不到编码花药小室发育所必需的转录因子的SPOROCYTELESS（SPL）的表达，这表明BZRs通过影响SPL表达来调节小室的发育。。我们的发现表明，BZRs是BR信号传导和花药小室发育所必需的转录因子，为深入了解小孢子发生的分子机制提供了新的见解。拟南芥。