Roles of YABBY tanscription factors in the regulation of leaf development and abiotic stress responses in <i>Camellia sinensis</i>

Abstract

The formation of leaf polarity directly determines the development of leaf spreading and type, and affects the physiological functions of photosynthesis, transpiration and stress resistance of plants. Many famous Chinese teas are highly dependent on the morphological characteristics and size of the tea leaves. To date, there have been few reports on the establishment of tea leaf polarity and leaf type development. The plant-specific transcription factor YABBY family gene has been reported to be involved in the formation of leaf polarity and growth. Herein we describe the isolation and functional characterization of transcription factor YABBY genes of the tea plant (<i>Camellia sinensis</i>). Six YABBY transcription factors were isolated from tea plants and classified into five clusters in the protein phylogenetic tree. Among them, <i>CsFILa</i> and <i>CsFILb</i> were highly expressed in buds and mature petals, and their expression decreased with the stage of leaf development. The Arabidopsis transgenic lines of <i>CsFILa</i> and <i>CsFILb</i> showed abaxial curled and long-narrow leaves. The above results indicated that <i>CsFILa</i> and <i>CsFILb</i> regulated the leaf growth of tea plants. The growth and expansion rate of leaf on the picked shoots decreased significantly after being plucked from tea plants, especially those suffering from drought stress. In this process, <i>CsFILa</i> expression levels decreased 60%−80% compared to the control. These data indicated YABBY genes play important roles in the leaf development of <i>Camellia sinensis</i>.