Abstract
Plants defend themselves against infection by biotic attackers by producing distinct phytohormones. Especially jasmonic acid (JA) and salicylic acid (SA) are well known defense-inducing hormones. Here, the effects of MeJA and SA on the Arabidopsis thaliana kinome were monitored using PepChip arrays containing kinase substrate peptides to analyze posttranslational interactions in MeJA and SA signaling pathways and to test if kinome profiling can provide leads to predict posttranslational events in plant signaling. MeJA and SA mediate differential phosphorylation of substrates for many kinase families. Also some plant specific substrates were differentially phosphorylated, including peptides derived from Phytochrome A, and Photosystem II D protein. This indicates that MeJA and SA mediate cross-talk between defense signaling and light responses. We tested the predicted effects of MeJA and SA using light-mediated upward leaf movement (differential petiole growth also called hyponastic growth). We found that MeJA, infestation by the JA-inducing insect herbivore Pieris rapae, and SA suppressed low light-induced hyponastic growth. MeJA and SA acted in a synergistic fashion via two (partially) divergent signaling routes. This work demonstrates that kinome profiling using PepChip arrays can be a valuable complementary ∼omics tool to give directions towards predicting behavior of organisms after a given stimulus and can be used to obtain leads for physiological relevant phenomena in planta.
Highlights
Plants defend themselves against a multitude of biotic attackers in several ways
PR1 expression was up regulated by salicylic acid (SA) and SA/ MeJA, whereas PDF1.2 expression was up regulated by MeJA and down regulated in the SA/MeJA combination treatment, compared to jasmonic acid (JA)-treatment alone [3,9,42,43]
We profiled the kinome of Arabidopsis plants treated with the defense inducing hormones MeJA and SA
Summary
Plants defend themselves against a multitude of biotic attackers in several ways. Besides passive barriers, such as wax-layers, needles and trichomes, a variety of induced responses are utilized. These responses rely on defense signaling molecules made by the plant itself. The most prominent of these are salicylic acid (SA), jasmonic acid (JA) and ethylene (ET), and relative levels of these phytohormones depend on the attacker encountered and determine which specific defense response is activated [1,2,3,4]. SA can repress JA responses [9,10], and vice versa, JA can repress SA responses [2,3,4,11]
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