Physiological mechanisms of pre-anthesis waterlogging priming on waterlogging stress tolerance under post-anthesis in wheat

Abstract

<p id="C3">In order to investigate the responses and mechanisms of different wheat varieties to waterlogging stress and waterlogging priming, waterlogging priming was conducted for two days at the four-leaf and six-leaf stages, respectively, and waterlogging stress was performed for five days at post-anthesis using wheat varieties with different responses to waterlogging stress and waterlogging priming as experimental materials. Results showed that waterlogging stress significantly reduced chlorophyll content (SPAD) and actual photochemical efficiency (<italic>Φ</italic>_PSII), inhibited the accumulation of post-anthesis photosynthetic assimilation accumulation (PAA), decreased kernel weight and grain yield. Compared with the waterlogging-sensitive varieties, the waterlogging-tolerance varieties could maintain higher SPAD, <italic>Φ</italic>_PSII and PAA, and higher activities of superoxide dismutase (SOD), Catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR), lower contents of H₂O₂, O₂^܋production rate and malondialdehyde (MDA) under post-anthesis waterlogging stress. Compared with non-primed plants, primed plants could maintain higher chlorophyll fluorescence performance and higher activities of antioxidant enzymes. Compared with the waterlogging priming-insensitive varieties, the priming-sensitive varieties increased SPAD (8.8%) and <italic>Φ</italic>_PSII (17.6%), decreased the non-regulated energy dissipation <italic>Φ</italic>_NO (10.7%) and the regulation energy dissipation <italic>Φ</italic>_NPQ (16.5%), increased the activities of SOD (15.8%), CAT (17.8%), APX (8.9%) and GR (30.7%), increased the contents of total soluble sugar (17.5%) and sucrose (21.6%), increased remobilization efficiency of pre-anthesis stored dry matter (REP, 20.0%) and PAA (10.8%). The waterlogging tolerant varieties could maintain higher photosynthesis rate, dry matter translocation capacity and activities of antioxidant enzymes. Compared with waterlogging sensitive varieties, the increase amplitude of photosynthetic ability and antioxidant enzyme activity of priming-sensitive cultivars was higher under waterlogging stress.