Correlation of proline content and gene expression involved in the metabolism of this amino acid under abiotic stress

This study evaluated the metabolism of proline in rice based on the expression pattern of genes involved in biosynthesis and catabolism of amino acid and determined the correlation with the proline content produced under stress. In stage V4, genotypes with a differentiated response to salinity and low-temperature stresses were exposed separately to two test conditions: 150 mM NaCl and 13 °C. Proline increased in both genotypes and stresses. The expression of P5CS1 was increased in both genotypes and conditions, while P5CS2 was responsive in the sensitive genotype under salinity. High correlations between proline content/ P5CS1 , proline content/ P5CS2 , P5CS1/P5CR , and P5CS2/P5CR were observed for the tolerant genotype under salt stress. The correlation between proline content/ PDH was 0.42 and −0.13 (tolerant genotype) and −0.54 and 0.15 (sensitive genotype) under salinity and cold, respectively. P5CDH was positively correlated with proline content under salinity for both genotypes. Under salt stress, there was a positive correlation between proline content/ OAT in the tolerant genotype. It was concluded that the increase in proline content is greater for the tolerant genotype. Under salt stress, the levels of transcript genes are more correlated with the proline content in the tolerant genotype, while at 13 °C, the correlation of the sensitive genotype was higher.