Priming effect of exogenous ABA on heat stress tolerance in rice seedlings is associated with the upregulation of antioxidative defense capability and heat shock-related genes

Heat stress is a major restrictive factor that suppresses rice production. In this study, we investigated the potential priming effect of exogenous abscisic acid (ABA) on heat tolerance in seedlings. Seedlings were pretreated with 10 µM ABA by root-drenched for 24 h and then subjected to conditions 40 °C day/35 night. pretreatment significantly decreased leaf withering 2.5–28.5% chlorophyll loss 12.8–35.1% induced also mitigated cell injury, as shown lower malondialdehyde content, relative electrolytic conductivity, expression death-related genes OsKOD1, OsCP1, OsNAC4, while OsBI1, death-suppressor gene, was upregulated pretreatment. Moreover, improved antioxidant defense capacity, an obvious upregulation ROS-scavenging decrease ROS content (O2? H2O2), downregulation OsRbohs genes. Application fluridone, biosynthesis inhibitor, increased membrane injury accumulation under stress. Exogenous antioxidants (proanthocyanidins) alleviated decreasing overaccumulation addition, superinduced ABA-responsive SalT OsWsi18, OsNCED3 OsNCED4, shock-related OsHSP23.7, OsHSP17.7, OsHSF7, OsHsfA2a. Taken together, these results suggest has enhancing seedlings mainly improving capacity