The Regulates Drought Tolerance and Flavonoid Synthesis in Apple Calli and .

Drought is the major abiotic stress that limits apple productivity and quality. To date, many important and divergent regulatory functions of miR156/SBP genes in plant growth and development have been well understood. However, little is known about the role of apple miR156 in response to abiotic stress. To better understand the functions of in abiotic stress tolerance, we constructed the overexpression (OE) and short tandem target mimic (STTM) vector of and performed its functional analysis through the characterization of transgenic apple calli and plants. In this study, overexpression significantly increased the length of primary roots and the number of lateral roots in transgenic Arabidopsis plants under drought stress. In addition, transgenic Arabidopsis and apple calli had a lower electrolyte leakage rate and less cell membrane damage than WT and STTM156 after drought stress. Further studies showed that overexpression promoted the accumulation of flavonoids and scavenging of reactive oxygen species (ROS) under drought conditions in transgenic apple calli and plants. Taken together, overexpression enhances drought tolerance by regulating flavonoid synthesis and ROS signaling cascades in apple calli and .