Combined Analysis of Root Transcriptome, Metabolome and physiology on the mechanism of rapid growth recovery for rice seedlings after low temperature stress

Abstract

Background Late spring cold is a disastrous weather phenomenon that often occurs during the early rice seedling stage in southern China, which poses a significant threat to open direct seeding of early rice seedlings. We found the differences in growth recovery performance between rice varieties after low temperature stress, but the differences in recovery between roots and stems/leaves are still unclear. 12 ℃ low temperature treatment of 4 days was set to investigate the growth phenotype and physiological changes of rice seedling roots during rewarming, as well as Transcriptome and metabolome were analyzed. Results Root growth was significantly inhibited after low temperature stress. During the rewarming process, the root length recovered the fastest, followed by the number of main roots. The fastest growth recovery period was in the first 3 days of rewarming; overall, the growth rate of B116 was higher than that of B811. The content of H2O2 and MDA in the root system of B116 decreased faster than that of B811 during the recovery process. The activities of POD and SOD showed an initial increase followed by a decrease, and returned to the control level after 6 days for the two varieties; Transcriptome analysis showed that the differential genes were mainly enriched in plant endogenous signal transduction, MAPK signal pathway, nitrogen metabolism and other biological pathways; The differential metabolites mainly included organic acids and their derivatives, organic oxygen compounds, and lipids and lipid molecules. Correlation analysis between Transcriptome and metabolome showed that plant endogenous signal transduction, starch and sucrose metabolism were the main metabolic pathways, and the differential expression of auxin response factors AUX/IAA, ARF and sucrose synthase SUS4, SPS1 was related to root growth. Conclusion The recovery of rice seedling growth after low temperature stress is related to the rapid clearance of ROS, utilization of auxin, and rapid metabolism of sucrose. The root system recovers growth earlier than the aboveground part, and the root system should be the main response to the harm of late spring cold in production.