Transcriptomic, proteomic, and physiological comparative analyses of flooding mitigating low temperature stress on direct-seeded early indica rice at seedling stage

Abstract

Background Low temperature (LT) often occurs at seedling stage in early rice-growing season, especially for direct-seeded early-season indica rice seedlings, and adopting flooding irrigation could mitigate LT damage. However, it is not clear on the response mechanisms of a mitigating effect on LT stress at early rice seedling stage. Results In this study, LT stress with 10/6°C (day/night), LT accompanied by flooding (LTF) and CK (control) treatments were established for 3d to aim to determine the response mechanisms on physiological, transcriptomic, and proteomic of direct-seeded rice seedlings at seedling stage. The results showed that the chloroplasts was severely degraded, thylakoid lamellae were seriously damaged and osmiophilic body increased gradually in LT contrast to CK, but LTF could alleviate the damage of low temperature on chloroplast structure. Compared with LT, LTF significantly increased the contents of Rubisco, chlorophyll, PEPCK, ATP and GA3 of rice seedlings whereas significantly decreased soluble protein, MDA and ABA content, suggesting the higher photosynthetic traits, antioxidant ability and better growth characteristic, although it could also affect the physiological activity contrast to CK. The identified differentially expressed genes and differentially expressed proteins indicated that photosynthesis metabolism pathway, reactive oxygen species and metabolic regulation had significant differences between LT and LTF stress, which were the main reasons that reduced the LT damage of rice seedlings for LTF. Conclusions Our results could provide comprehensive interpretation of physiological characteristics, genes and proteins expression changes in low temperature and low temperature flooding.