Elevated CO2 Influences Nematode-Induced Defense Responses of Tomato Genotypes Differing in the JA Pathway

Abstract

Rising atmospheric CO2 concentrations can affect the induced defense of plants against chewing herbivores but little is known about whether elevated CO2 can change the induced defense of plants against parasitic nematodes. This study examined the interactions between the root-knot nematode Meloidogyne incognita and three isogenic tomato (Lycopersicon esculentum) genotypes grown under ambient (390 ppm) and elevated (750 ppm) CO2 in growth chambers. In a previous study with open-top chambers in the field, we reported that elevated CO2 increased the number of nematode-induced root galls in a JA-defense-dominated genotype but not in a wild-type or JA-defense-recessive genotype. In the current study, we tested the hypothesis that elevated CO2 will favor the salicylic acid (SA)-pathway defense but repress the jasmonic acid (JA)-pathway defense of plants against plant-parasitic nematodes. Our data showed that elevated CO2 reduced the JA-pathway defense against M. incognita in the wild-type and in a genotype in which defense is dominated by the JA pathway (a JA-defense-dominated genotype) but up-regulated the SA-pathway defense in the wild type and in a JA-defense-recessive genotype (jasmonate-deficient mutant). Our results suggest that, in terms of defense genes, secondary metabolites, and volatile organic compounds, induced defense of nematode-infected plants could be affected by elevated CO2, and that CO2-induced changes of plant resistance may lead to genotype-specific responses of plants to nematodes under elevated CO2. The changes in resistance against nematodes, however, were small relative to those reported for chewing insects.

Climate Change: Resetting Plant-Insect Interactions

“…In tomato (Solanum lycopersicum), elevated CO 2 enhances induced defenses derived from the SA-signaling pathway, such as the pathogenesisrelated proteins, and reduces JA-signaling and defenses (Sun et al, 2011;Guo et al, 2012). Moreover, whereas enriched CO 2 atmosphere increased the susceptibility of soybean to Japanese beetle and western corn rootworm (Diabrotica virgifera virgifera) by downregulating JA and ET, elevated CO 2 increases SA levels in field-grown soybeans and in leaves and rhizomes in two varieties of ginger (Zingiber officinale; Zavala et al, 2008;Ghasemzadeh et al, 2010; Fig.…”

“…Whereas the elicitation of the JA pathway may repress SA defense responses, SA-inducing insects and biotrophic pathogens inhibit JA-dependent defenses (Spoel and Loake, 2011). This antagonism is evident under elevated CO 2 , which down-regulates JA and ET pathways and increases susceptibility to herbivore attack Zavala et al, 2008;Sun et al, 2011). However, SA accumulates in enriched CO 2 atmospheres and induces Figure 3.…”

“…other chemical defense pathways that are not regulated by JA (Ghasemzadeh et al, 2010;Sun et al, 2011). Moreover, the SA-signaling pathway initiates the synthesis of defense compounds against plant pathogens, and this enhanced resistance correlates with a lower incidence of disease in soybeans under field conditions (Eastburn et al, 2010).…”

Impact des changements climatiques sur les interactions moléculaires entre le nématode à kyste du soya (Heterodera glycines) et son hôte principal, le soya (Glycine max)

“…peut avoir un effet additif, synergique ou antagoniste sur les diverses voies métaboliques des phytohormones qui confèrent la résistance au stress chez les plantes ( et al 2008). Précisément, il a été démontré que ces stress environnementaux, qui entraînent l'activation des signaux chimiques ABA, influencent négativement la résistance, la croissance et le rendement des cultures en raison des réactions antagonistes associées à l'activation des voies de signalement des AJ et AS initiée par la présence du nématode (Sun et al 2010(Sun et al , 2011. En revanche, il semblerait que des températures basses pourraient favoriser la résistance de certaines espèces de plantes, dont la pomme de terre (Solanum spp.…”

“…connus pour être résistants à différentes espèces de nématodes à galles du genre Meloidogyne (Ferris et al 2013;Jablonska et al 2007;Newton et al 2012). De plus, chez la tomate, la hausse du CO2 atmosphérique aurait également un effet inhibiteur sur les taux de production des phytohormones (AJ et AS) qui lui confèrent une résistance à différents nématodes à galles (Cooper et al 2005;Sun et al 2010Sun et al , 2011. Pour le soya, les températures élevées ont un effet négatif sur plusieurs gènes de défense contre différents champignons pathogènes (Upchurch et Ramirez 2011).…”