Spermidine enhances heat tolerance of rice seeds during mid-filling stage and promote subsequent seed germination

Introduction Heat stress is a vital factor which restricts rice seed quality and yield. However, the response mechanism to heat in mid filling stage of unclear. Methods In present study we integrated phenotypic analysis with biochemical, hormone, gene expression order explore technologies for improving seeds tolerance subsequent germination. Results Spermidine (Spd) application effectively alleviated damage treatment during mid-filling (HTM, 12-20 days after pollination) on development, promoted germination seedlings establishment. Spd significantly increased dry weight, starch amylose contents development under stress, improved germinate, establishment seedling characteristics time. Biochemical indicated that, HTM decreased activities several synthase enzymes led decrease content. While enhanced ADP-glucose pyrophosphorylas granule-bound synthase, as well corresponding-genes expressions seeds, resulting increases total contents. addition, catalase glutathione reductase together expressions, lowered overaccumulation H2O2 malondialdehyde seeds. process, HTM+Spd exhibited dramatically up-regulated levels soluble sugars, glucose, ATP energy charges. Consistently, showed α-amylose α-glucosidase early Moreover, evidently abscisic acid (ABA) content, gibberellin (GA) accordingly declined GA/ABA ratio did not affect metabolism GA ABA stage. Discussion The suggested that could alleviate negative impact germination, might be closely correlated synthesis antioxidant defense period, decomposition supply period.