Chitinase Profile of Arabidopsis, Subjected to the Combined Stress of Soil Salinity, Cuscuta campestris Parasitism and Herbivores

Abstract

Plants are continuously subjected to changing environmental factors, often growing in suboptimal conditions. Due to the negative impact on agricultural yield numerous researches are published every year, studying the stress response and adaptation in plants to stress factors. Most of the studies, however, are dedicated to a single stress factor. In the present study, we examined the effect of a different combination of stresses on the chitinase profile of Arabidopsis plants. First, soil salinity (abiotic stress) was applied by irrigation with 150 mM NaCl. The plants were either infected or not with the parasitic flowering plant Cuscuta campestris Yunck. (dodder) and further challenged with the herbivorous attack – the larvae of either the sciarid fly Lycoriella ingenua (Dufour, 1839) or the citrus flatid planthopper Metcalfa pruinosa (Say, 1830). It was found that salinity and Cuscuta parasitism suppressed the response of Arabidopsis to sciarid flies, simultaneously with induction of chitinases in terms of the number of isoforms and relative activity in the parasite itself. Meanwhile, in the presence of Cuscuta, M. pruinosa tend to feed predominantly on the parasitic plant, completely ignoring the host. This was accompanied by the appearance of new chitinases, also suppressed by salinity. These results suggest complicated, antagonistic interactions between abiotic and different biotic stresses. It was also shown that the parasite is sensing the herbivore attack indirectly (in the case of L. ingenua) and transferring the stress signal to the host (in the case of M. pruinosa).