Defense Related Gene Expression and Biochemical Responses in Cymbopogon nardus Under Stresses

Abstract

Cymbopogon nardus employs complex molecular and biochemical mechanisms to adapt to biotic and abiotic stresses through regulation of gene expression, antioxidant activity, and ion transport. This study analyzed the expression of CnWRKY12, CnSOD, and CnHKT1 genes along with the enzymatic activities of phenylalanine ammonia-lyase (PAL) and superoxide dismutase (SOD). Methods used Quantitative PCR and biochemical assays and enzymatic responses with HPLC. Results showed that CnWRKY12 was strongly upregulated under drought (5.75-fold) and fungal infection (5.05-fold), confirming its role as a transcription factor regulating the phenylpropanoid defense pathway. The SOD gene exhibited the highest induction under drought (3.0-fold). Meanwhile, CnHKT1 expression has been highly induced under salinity (7.31-fold) but has been repressed under drought and fungal stress, thereby indicating its role in maintaining Na⁺/K⁺ ionic homeostasis. Enzymatic assays to have supported: PAL activity to have been highest during fungal infection (1.03 unit mg⁻¹ protein), whereas SOD activity to have peaked under drought conditions (0.99 unit mg⁻¹ protein). The correlation between gene expression and enzyme activity has demonstrated an integrated defense mechanism in C. nardus, in which CnWRKY12-PAL interactions have strengthened biotic resistance and CnHKT1 has regulated ionic balance under salinity. These conclusions into stresspecific defense responses have contributed to a broader understanding of tolerance mechanisms in aromatic and medicinal grasses. This research to growth SDG’s Good Health and Well being because this research has the potential to increase the production of bioactive compounds from plants that are beneficial for human health.