261Impact of Gall Midge, Orseolia
Oryzae (Wood-Mason) Infestation
on Total Phenols, Proline and
Indole Acetic Acid in Paddy ( Oryza
Sativa Linn.) Genotypes
Vijay Kumar Lingaraj, A. K. Chakravarthy and Siddanagowda
Ujjanagowda Patil
A. K. Chakravarthy (ed.), New Horizons in Insect Science: Towards Sustainable Pest Management,
DOI 10.1007/978-81-322-2089-3_23, © Springer India 2015
AbstractThe impact of gall midge infestation on total phenols, proline and in-
dole acetic acid (IAA) contents in rice genotypes was investigated under
laboratory conditions. The resistant rice genotypes showed an increased
phenol and decreased proline and IAA contents in the growing apical
meristem due to infestation. Significant and rapid accumulation of total
phenols (0.24–0.59 mg/g) was observed at the third, seventh, and the ninth
day after midge infestation in resistant genotypes compared to suscep-
tible ones. The rapid accumulation of phenols in resistant genotypes fol-
lowing gall midge infestation highlights the inducible biochemical path-
ways involving synthesis of phenolic precursors and further oxidation
into toxic quinones. Even in the susceptible genotypes, a slight increase
(0.22–0.31 mg/g) was observed initially. It may be associated with gall
initiation process because phenols act as IAA-oxidase inhibitors result-
ing in hyper-auxinity in gall tissue that leads to formation of nutritive
tissue on which the gall midge feed. Significant and rapid accumulation
of proline (2.96−13.50 μg/g) from the third, seventh and ninth day after
infestation was recorded only in susceptible genotypes indicating their
role under stress conditions. Likewise, the higher accumulation of IAA
(3.16−8.18 μg/g) was observed in all the susceptible genotypes. Thus,
rapid accumulation of IAA in relation to insect infestation in susceptible
genotypes clearly indicated their role in gall formation because IAA acts
as a growth regulator.Keywords
Asian rice gall midge · Rice genotypes · Resistance