Bioinformatics analysis and core member identification of proline metabolism gene family in Brassica napus L.

Proline accumulation is an important metabolic adaptative mechanism of plants under biotic and abiotic stress. P5CS, P5CR, PDH, and P5CDH are key enzymes in the glutamate-dependent proline biosynthesis pathway. Rapeseed, an important oil crop in the world, is often subjected to various biotic and abiotic stresses during its growth and development. However, no systematic analysis of these proline metabolic gene families has been reported in Brassica napus so far. In this study, 10 BnaP5CSs, 6 BnaP5CRs, 8 BnaPDHs, and 3 BnaP5CDHs were identified by using the genomic annotation information of 'Zhongshuang 11'. Phylogenetically, these gene families were divided into different evolutionary branches, and members of the same subgroups had similar physical and chemical properties, gene / protein structure, and conserved motifs. Evolutionary pressure analysis showed that these genes were subjected to strong purification selection. Cis-acting element analysis revealed that there were common and specific transcriptional regulatory mechanisms among the four kinds of gene families. In this study, rapeseed seedlings were respectively treated with salt stress, low potassium (K), low phosphate (P), and ammonium toxicity, and both shoots and roots were respectively sampled for transcriptomic analysis. The results indicated that the relative expression levels of genes related to proline synthesis were generally up-regulated under the above-mentioned four stresses, whereas the relative expression levels of genes regulating proline degradation were down-regulated under salt and low P stresses. Gene co-expression network analysis demonstrated that BnaC4.P5CS1a and BnaA5.P5CS1 might play central roles in the proline-mediated stress responsive networks in rapeseed. Through bioinformatics identification of proline metabolism gene family and analysis of transcription characteristics under various abiotic stresses, this study will provide a theoretical basis for further study of proline-mediated stress resistance, and will also provide excellent gene resources for genetic improvement of abiotic stress resistance mediated by proline metabolism in Brassica napus. [ABSTRACT FROM AUTHOR]