SMXL4/5-HsfA2 regulatory loop orchestrates plant growth-thermotolerance trade-off

Heat stress (HS) is often a recurring and constant threat to crop productivity worldwide. For optimal crop survival, a sensitive and dynamic balance between stress-response and growth-control is required. Previous studies have demonstrated unique properties of 22-nt siRNAs in plant adaptation to environmental stresses, yet much less is known about how DCL2 regulate mechanisms under stresses in detail. Here, we demonstrate that the production of 22-nt siRNAs, particularly from SMXL4/5, might be crucial for plants to adapt to HS. High-throughput sequencing of total mRNA from Col-0 (co), ski2 dcl4 (sd), ski2 dcl4 dcl2 (sdd), smxl4 smxl5 (s45), and smxl6 smxl7 smxl8 (s678) Arabidopsis seedlings with or without 44 ℃ 85 min heat stress