棉花是我国仅次于粮食作物的第二大农作物。我们在前期工作中发现GhFP1等bHLH转录因子在棉纤维中特异或优势表达，并涉及到BR信号调控而影响棉纤维伸长发育，但其作用机制尚不清楚。本项目拟系统地探讨GhFP1等bHLH转录因子介导的BR信号网络及其在棉纤维伸长发育中的作用。通过研究这些转录因子对棉纤维细胞伸长发育过程中BR合成和信号相关基因的调控，探讨该类转录因子之间以及与其他蛋白之间的相互作用，解析它们是否与一些BR信号相关基因(蛋白)共同组成一个复杂的信号调控网络，决定棉纤维细胞伸长发育，影响棉纤维品质。本项目试图揭示bHLH转录因子介导的BR相关的棉纤维伸长发育的调控机制，为棉纤维发育的分子遗传基础理论研究提供重要科学资料，同时也为棉纤维品质改良的分子育种提供新的理论依据和有价值的转基因棉花材料。

Behind the grain crops, cotton is the second crop in China. In recent years, we identified some fiber-preferential bHLH transcription factors (including GhFP1 and others), and found they may participate in BR biosynthesis and signaling pathway during fiber elongation of cotton. However, the molecular mechanism of these proteins regulating brassinosteroids (BR) signaling in fibers still remains unclear in detail. Therefore, this project plan to investigate the roles of the GhFP1 and other bHLH transcription factors in fiber cell elongation as well as these bHLH proteins-mediated BR signaling network in elongating fibers. We will study how these transcription factors modulate the BR biosynthesis- and signaling-related proteins that are involved in fiber cell elongation, and interact with their partner proteins, so that we can elucidate the molecular mechanism of the bHLH transcription factors regulating fiber cell elongation via modulating BR signaling, thereby determining fiber quality of cotton. This study will provide new scientific data in understanding molecular mechanism of cotton fiber development, and for molecular breeding of fiber quality improvement.