Ldi‐miR396‐LdPMaT1 enhances reactive oxygen species scavenging capacity and promotes drought tolerance in Lilium distichum Nakai autotetraploids

Abstract

AbstractDrought is a key environmental stress that inhibits plant growth, development, yield and quality. Whole‐genome replication is an effective method for breeding drought resistant cultivars. Here, we evaluated the tolerance of Lilium distichum Nakai diploids (2n = 2× = 24) and artificially induced autotetraploids (2n = 4× = 48) to drought simulated by polyethylene glycol (PEG) stress. Autotetraploids showed stronger drought tolerance than diploids, and high‐throughput sequencing during PEG stress identified five differentially expressed miRNAs. Transcriptome analysis revealed significantly different reactive oxygen species (ROS)‐scavenger expression levels between diploids and autotetraploids, which increased the drought tolerance of autotetraploids. Specifically, we identified ldi‐miR396b and its only target gene (LdPMaT1) for further study based on its expression level and ROS‐scavenging ability in response to drought stress (DS). Autotetraploids showed higher expression of LdPMaT1 and significantly downregulated expression of ldi‐miR396b under DS compared with diploids. Through a short tandem target mimic (STTM) in transgenic lilies, functional studies revealed that miR396b silencing promotes LdPMaT1 expression and the DS response. Under PEG stress, STTM393 transgenic lines showed improved drought resistance mediated by lowered MDA content but exhibited high antioxidant enzyme activity, consistent with the autotetraploid results. Collectively, these findings suggest that ldi‐miR396b‐LdPMaT1 potentially enhances ROS‐scavenging ability, which contributes to improved stress adaptation in autotetraploid lilies.