Volatile organic compounds from the fungi Fusarium verticillioides as natural inductor of maize kernel defense

JACQUAT A; J. A. ZYGADLO; PORPORATTO CARINA; PIZZOLITTO ROMINA; VANESSA A. ARECO; DAMBOLENA JS; USSEGLIO V; MARÍA P. ZUNINO; BOHL LUCIANA

valparaiso

Congreso; 5th Congress of the Latin American Association of Chemical Ecology; 2018

Asociacion Latinoamerica de Ecologia Química

The silo is a man-made environment where a large number of biological interactions,such as insect-fungal associations, are produced and these cause significant economiclosses. This is the case of the interaction between the maize weevil (Sitophilus zeamais)and the maize-infecting fungus Fusarium verticillioides. Due to the problems caused bysynthetic pesticides, interest has grown in the use of alternative strategies based onsemiochemicals such as those derived from communication between attacked plants andhealthy neighboring plants, activating the defense system. In this work it is proposed thatvolatile organic compounds (VOCs) emitted by F. verticillioides, could condition healthymaize kernels, increasing the activity of the LOX path, affecting the behavior of S.zeamais. In tests of susceptibility to attack of the insect, made in two-way olfactometersin which unconditioned maize grains (control) with conditioned grains (treatment) wasobserved that, after 20 days, the treatment kernels are less attacked by S. zeamais. In asecond instance, the LOX activity, from treated and control corn kernels, was measuredspectrophotometrically. In these tests, a 1.755-fold increase in the activity of the LOXenzymes of treated kernels with respect to control kernels was obtained. In agreementwith this result, when a semi-quantitative analysis of the polypeptide profile of the treatedand control maize kernels was made, an increase was observed in the area of the bandwhose molecular weight corresponds to the LOX enzymes, in conditioned kernels.Finally, the results of gene expression analysis confirmed an increase in the expression ofgenes coding for LOXs in conditioned kernels with fungal VOCs. Together theseexperiments allow to suppose an induction of the defense system of maize kernel whenexposed to VOCs produced by F. verticillioides, suggesting that the kernels couldidentify these compounds and increase their defense mechanisms and the production ofVOCs derived from the LOX pathway.