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Tectona grandis (L) is a popular timber species cultivated in the Indian sub-continent and other countries because of its economic significance. However, the lack of quality planting material with special reference to defoliator herbivory is a major constraint because it negatively influences the establishment of thriving plantations. To address this, the so-called pest response in teak seedlings was investigated at the biochemical and molecular levels. The stress was levied by allowing defoliator infestation on 1-year-old seedlings for nine days at 3-day intervals, whereas control plants were maintained as uninfected. A considerable difference was observed for the considered traits among the infested plants at different intervals compared with the control. Total soluble protein, soluble sugars, tannin, and lignin accumulation increased with increasing stress intensity. Furthermore, catalase, polyphenol oxidase, and phenol content increased after defoliator feeding, whereas peroxidase activity decreased compared with control plants. In addition, six herbivory stress-responsive genes revealed the molecular response of teak. Among them, four genes viz. zinc finger protein (ZFP2), ethylene-responsive factor (ERF-1), catalase-1 (Cat1) and peroxidase super family protein (Psfp) were highly expressed in the infected plants as compared with the control plants. In contrast, the MYB-DNA binding domain gene was downregulated in infected plants compared to uninfected plants. Cytochrome P450 was up-regulated in T1 and T2 plants, while it was down-regulated in T3. Genes were highly expressed as the stress frequency increased. This study offers an improved understanding of biochemical and transcriptional defense responses against the teak defoliator, which could further support teak improvement for quality planting material production.
Venkatesh et al. (Wed,) studied this question.