Role of soluble, cell wall bound phenolics, tannin and flavonoid contents in maize resistance to pink stem borer Sesamia inferens Walker

The pink stem borer Sesamia inferens Walker is an important pest of winter maize which causes significant yield losses. In an attempt to identify the biochemical basis of resistance against S. inferens , total soluble phenolics, bound phenolics, cell wall-bound hydroxycinnamic acids-p-coumaric acid (p-CA), ferulic acid (FA), total tannin content and total flavonoid contents, were measured in leaf at 10, 20 days after germination (DAG); stem at 20, 40 DAG; pith and rind tissues at 60 DAG (stem differentiated). From the present study, it was found that bound phenolics, p-CA, ferulic acid and total tannin contents contribute to the maize defense mechanism against S. inferens. Total bound phenolic content showed negative correlation with Leaf Injury Rating (LIR). Highly significant strong positive correlation (+0.9750) was observed between LIR and total soluble phenolics in leaf tissue at 20 DAG. Similarly highly significant strong positive correlation between LIR and total tannins (+0.9354**) and flavonoids (+0.9582**) in pith at 60 DAG was observed. Further, a strong significant positive correlation was also observed between LIR and p-CA (+0.9199*) in pith at 60 DAG and total ferulic acid (+0.9051*) in rind at 60 DAG. The significant strong negative correlation between LIR and p-CA (-0.8441*) in stem at 40 DAG was observed. The total bound phenolics in rind at 60 DAG (0.756), in leaf at 20 DAG (0.681), and total soluble phenolics in the stem at 20 DAG (0.685) showed higher loadings with PC1, PC2, and PC3, respectively. Genotype-by-biochemical factor biplot showed that the data of biochemical parameters measured in different tissues and stages could be able to group the genotypes according to their reaction to S. inferens.