Herbivory-responsive calmodulin-like protein CML9 does not guide jasmonate-mediated defenses in Arabidopsis thaliana

Abstract

Calcium is an important second messenger in plants that is released into the cytosol early after recognition of various environmental stimuli. Decoding of such calcium signals by calcium sensors is the key for the plant to react appropriately to each stimulus. Several members of Calmodulin-like proteins (CMLs) act as calcium sensors and some are known to mediate both abiotic and biotic stress responses. Here, we study the role of the Arabidopsis thaliana CML9 in different stress responses. CML9 was reported earlier as defense regulator against Pseudomonas syringae. In contrast to salicylic acid-mediated defense against biotrophic pathogens such as P. syringae, defenses against herbivores and necrotrophic fungi are mediated by jasmonates. We demonstrate that CML9 is induced upon wounding and feeding of the insect herbivore Spodoptera littoralis. However, neither different CML9 loss-of-function mutant lines nor overexpression lines were impaired upon insect feeding. No difference in herbivore-induced phytohormone elevation was detected in cml9 lines. The defense against the spider mite Tetranychus urticae was also unaffected. In addition, cml9 mutant lines showed a wild type-like reaction to the necrotrophic fungus Alternaria brassicicola. Thus, our data suggest that CML9 might be a regulator involved only in the defense against biotrophic pathogens, independent of jasmonates. In addition, our data challenge the involvement of CML9 in plant drought stress response. Taken together, we suggest that CML9 is a specialized rather than a general regulator of stress responses in Arabidopsis.

Transcriptomic and Metabolomic Responses of Rice Plants to Cnaphalocrocis medinalis Caterpillar Infestation

“…CML37 positively regulates S. littoralis- induced defense responses in Arabidopsis by activating the JA pathway [ 37 ], while CML42 negatively regulates plant defense by suppressing the JA pathway and aliphatic glucosinolate contents [ 38 ]. Interestingly, although CML9 is significantly induced by S. littoralis infestation, it is not involved in Arabidopsis defense against this pest and contributes to the defense against biotrophic pathogens independent of the JA pathway [ 39 ]. Currently, the functions of Ca 2+ sensors in plant-herbivore interactions has mainly been investigated in Arabidopsis , and hence the role of Ca 2+ sensors in rice defense against herbivores requires further investigation.…”

A Holistic Approach to Analyze Systemic Jasmonate Accumulation in Individual Leaves of Arabidopsis Rosettes Upon Wounding

“…RNA extraction, DNase treatment, reverse transcription and qRT-PCR were carried out as described in Heyer et al (2018) . The expression level of JAZ10 was quantified with the 2 -ΔCT method ( Livak and Schmittgen, 2001 ; Ohlen et al, 2016 ) using RPS18B as housekeeping gene, were 2 -ΔCT = 2 CT RPS18 /2 CT JAZ10 .…”

Pyrrolic and Dipyrrolic Chlorophyll Degradation Products in Plants and Herbivores

“…Spodoptera littoralis (Boisd.,L epidoptera, Noctuidae) larvae were provided by Bayer Cropscience Germany and reared on an artificial diet. [49,50] The larvae were separated and starved 24 hp rior to each feeding assay. Feces and spit collection:F eces were collected from five different sets of Spodoptera littoralis larvae.…”