Molecular Analysis of Enzymes and Metabolites Regulated Under Drought Stress in the Wild Plant Senna (Cassia Angustifolia)

Abstract

This study aimed at studying differential presence of enzymes metabolites via KEGG analysis of trasncriptomes of the wild plant species senna (Cassia angustifolia Vahl.) due to watering. Senna is a shrub of the family Caesalpiniaceae with important applications in pharmaceuticals. Firstly, RNA-Seq datasets were produced by next-generation sequencing (NGS) of Illumina Miseq of leaf (day 1) in order to detect the influence of watering at day 2. Samples were harvested at three time points (e.g., dawn, midday and dusk) of the two days. de novo assembled datasets and number of annotated genes exceeded 2000 genes. As cluster analysis of gene expression almost showed no discrete differences at the transcriptome level due to watering within time points of dawn and dusk, the study focused mainly on those of the midday across the two days. KEGG analysis for genes whose differential expression between the two days was ≥5 FC resulted in a number of enzymes that were found repressed due to watering, thus likely participate in the molecular mechanisms utilized by the organism to adapt to the long-lasting drought stress. The recovered regulated metabolites and enzymes included abscisic acid (ABA) receptor PYL4 and PYL9, auxin response factor (ARF) 5 and 15, ARF (or Aux/IAA) proteins IAA7 and IAA14, indole-3-pyruvate (or flavin) monooxygenase, phosphoinositide phosphatase SAC1 and SAC6, pre-mRNA splicing factors 8, 8A, 19, 40A and ISY1, and serine/arginine-rich splicing regultors SCL33, RS31 and RS34. The two pathways tryptophan metabolism and plant hormone signal transduction likely crosstalk in senna (C. angustifolia) towards the maintenance of normal growth under adverse condition. Many other regulated metabolites and proteins in senna (C. angustifolia) including brassinosteroid, heat shock protein 95s, ATPase, several protein kinases such as mitogen-activated protein kinase (MAPK) and cytochrome c oxidase. Other enzymes include phospholipase C2 and allene oxide cyclase as well as isochorismate pathway were also regulated in senna (C. angustifolia). In conclusion, we think that we have scoped the light on the possible regulated metabolites under drought stress that might confer drought stress tolerance in the wild plant senna (C. angustifolia).