Study on the Magnesium Toxicity Inhibits Jasmonic Acid Signaling Pathway and Increases Arabidopsis Sensitivity to Meloidogyne incognita

PurposeTo study the changes of physiological processes in Arabidopsis under the stress of magnesium toxicity and the change of sensitivity of Arabidopsis in response to Meloidogyne incognita infection, and related molecular mechanisms.

MethodsThe poor nutrient culture medium vermiculite was used in pot experiments to conduct chlorophyll synthesis change analysis of Arabidopsis under the stress of magnesium toxicity (15 mmol/L MgCl₂), and to analyze the change in resistance or sensitivity of Arabidopsis to M. incognita infection. Through the transcriptome sequencing strategy, the relationships between the up- and down-regulated genes of Arabidopsis under the stress of magnesium toxicity was analyzed. Real-time fluorescence quantitative PCR (qPCR) were performed to verify the expressions of genes with significant differences.

ResultsUnder the stress of magnesium toxicity, the chlorophyll synthesis of Arabidopsis was significantly affected, the content of chlorophyll in leaves with magnesium toxicity treatment was significantly or extremely significantly lower than control (P<0.05 or P<0.01). Thirty days after inoculations, the numbers of females and galls developed in roots of Arabidopsis under magnesium toxicity treatment were significantly higher than control (P<0.05). It indicated that magnesium toxicity increased the sensitivity of Arabidopsis to nematodes. Transcriptome sequencing data revealed eight up-regulated genes involving in amino acid, carbohydrate, lipid, and vitamin metabolism, etc. And beyond down-regulated genes, there were five genes simultaneously belonged to signal transduction pathway, and involving in the bio-synthesis of jasmonic acid and the signal transduction of jasmonic acid mediate defense responses. Through qPCR verifications using two independent internal control genes, the expression trend of genes with significant expression changes were consistent with transcriptome sequencing data.

ConclusionThe stress of magnesium toxicity interferes with the normal physiological processes of Arabidopsis indicated through the chlorophyll synthesis, inhibits expressions of critical genes related to jasmonic acid bio-synthesis and signal transduction, increases the sensitivity of Arabidopsis to M. incognita. Magnesium may play an important role in the jasmonic acid mediated defense responses against M. incognita.