Knocking out OsNAC050 Expression Causes Low-Temperature Tolerance in Rice by Regulating Photosynthesis and the Sucrose Metabolic Pathway

Abstract

Because rice is native to tropical and subtropical regions, it is generally more sensitive to cold stress compared to other cereals. Low-temperature stress has a strong influence on the growth, development, and yield of rice. Plant NAM, ATAF1/2 and CUC(NAC) transcription factors (TFs) play significant regulatory roles in stress response. In our research, we found that OsNAC050 (LOC_Os03g60080) is mainly expressed in leaves. Cold (4 °C), heat (42 °C), PEG 6000 (20%, w/v), NaCl (200 mM), H2O2 (1%), IAA (100 μM), ABA (100 μM) and GA3 (100 μM) were used to treat wild type (WT) plants. A low temperature further up-regulated OsNAC050 expression. OsNAC050 mutants created using CRISPR-Cas9 gene editing technology showed significantly enhanced tolerance to the low-temperature treatment. The measurement of enzyme activities related to the redox pathway also showed that mutants have stronger viability under low-temperature stress. Comparative transcriptome analysis showed that photosynthesis and soluble sugar metabolism were significantly affected in OsNAC050 mutant lines, suggesting that OsNAC050 may participate in the above molecular pathways in response to low-temperature stress. The results expand our understanding of the molecular mechanisms underlying the responses to cold stress in rice and can provide new strategies for engineering cold tolerance in high-yielding rice varieties.