Department of Genomic Science, Central University of Kerala, Kasaragod, 671320, India.
Plant Cell Rep. 2024 Apr 20;43(5):122. doi: 10.1007/s00299-024-03203-0.
Extensive leaf transcriptome profiling and differential gene expression analysis of field grown and elicited shoot cultures of L. speciosa suggest that differential synthesis of CRA is mediated primarily by CYP and TS genes, showing functional diversity. Lagerstroemia speciosa L. is a tree species with medicinal and horticultural attributes. The pentacyclic triterpene, Corosolic acid (CRA) obtained from this species is widely used for the management of diabetes mellitus in traditional medicine. The high mercantile value of the compound and limited availability of innate resources entail exploration of alternative sources for CRA production. Metabolic pathway engineering for enhanced bioproduction of plant secondary metabolites is an attractive proposition for which, candidate genes in the pathway need to be identified and characterized. Therefore, in the present investigation, we focused on the identification of cytochrome P450 (CYP450) and oxidosqualene cyclases (OSC) genes and their differential expression during biosynthesis of CRA. The pattern of differential expression of these genes in the shoot cultures of L. speciosa, elicited with different epigenetic modifiers (azacytidine (AzaC), sodium butyrate (NaBu) and anacardic acid (AA)), was studied in comparison with field grown plant. Further, in vitro cultures with varying (low to high) concentrations of CRA were systematically assessed for the expression of CYP-TS and associated genes involved in CRA biosynthesis by transcriptome sequencing. The sequenced samples were de novo assembled into 180,290 transcripts of which, 92,983 transcripts were further annotated by UniProt. The results are collectively given in co-occurrence heat maps to identify the differentially expressed genes. The combined transcript and metabolite profiles along with RT-qPCR analysis resulted in the identification of CYP-TS genes with high sequence variation. Further, instances of concordant/discordant relation between CRA biosynthesis and CYP-TS gene expression were observed, indicating functional diversity in genes.
对野外生长和诱导的紫薇 shoot 培养物的广泛叶片转录组谱分析和差异基因表达分析表明，CRA 的差异合成主要由 CYP 和 TS 基因介导，表现出功能多样性。紫薇是一种具有药用和园艺属性的树种。从该物种中获得的五环三萜酸（CRA）广泛用于传统医学中糖尿病的管理。该化合物的高商业价值和有限的先天资源可用性需要探索 CRA 生产的替代来源。代谢途径工程是提高植物次生代谢物生物生产的有吸引力的提议，为此需要鉴定和表征途径中的候选基因。因此，在本研究中，我们专注于鉴定细胞色素 P450（CYP450）和角鲨烯环化酶（OSC）基因及其在 CRA 生物合成过程中的差异表达。比较野外生长植物，研究了不同表观遗传修饰剂（氮杂胞苷（AzaC）、丁酸钠（NaBu）和漆树酸（AA））诱导的紫薇 shoot 培养物中这些基因的差异表达模式。进一步，系统评估了不同 CRA 浓度（低至高）的体外培养物中 CYP-TS 和参与 CRA 生物合成的相关基因的表达，通过转录组测序。测序样本通过从头组装成 180290 个转录本，其中 92983 个转录本进一步通过 UniProt 注释。结果以共现热图的形式给出，以鉴定差异表达基因。综合转录组和代谢谱以及 RT-qPCR 分析导致鉴定出具有高序列变异的 CYP-TS 基因。此外，观察到 CRA 生物合成和 CYP-TS 基因表达之间存在一致/不一致关系的实例，表明基因的功能多样性。
