Microorganisms emit a plethora of volatile compounds (VCs) that promote plant growth and photosynthesis as well as strong developmental and metabolic changes. Recently, we showed that small VCs of molecular masses of less than ca. 45 Da are important determinants of plant responses to microbial volatile emissions. In Arabidopsis, the plastidial isoform of phosphoglucose isomerase PGI1 mediates photosynthesis, metabolism and development, probably due to its involvement in the synthesis of isoprenoid-derived signals in vascular tissues. Like in wild-type (WT) plants, small VCs promote growth and photosynthesis as well as starch and CK accumulation in PGI1-lacking pgi1-2 plants. A striking alteration in the transcriptome of leaves of small fungal VC-treated plants involves strong up-regulation of levels of transcripts of GPT2 (At1g61800), a gene that codes for a plastidial G6P/Pi transporter. We hypothesized that the PGI1-independent response to microbial volatile emissions involves GPT2 action. To test this hypothesis, we characterized responses of WT, GPT2-null gpt2-2, PGI1-null pgi1-2 and pgi1-2gpt2-2 plants to small fungal VCs. In addition, we characterized responses of pgi1-2gpt2-2 plants expressing GPT2 under the control of a vascular tissue- and root tip-specific promoter to small fungal VCs. We found that the small VC-promoted changes in pgi1-2gpt2-2 plants were substantially weaker than in WT, gpt2-2 and pgi1-2 plants but reverted to WT levels by vascular and root tip-specific GPT2 expression. Proteomic analyses did not detect enhanced levels of GPT2 protein in VC-exposed leaves. Results presented in this work provide evidence that, under conditions in which PGI1 activity is reduced, long-distance action of GPT2 plays an important role in the response of plants to small VCs through mechanisms involving resetting of the photosynthesis-related proteome in leaves and complex GPT2 regulation.

This work was supported by the Ministerio de Ciencia e Innovación (MCIN) and Agencia Estatal de Investigación (AEI) / 10.13039/501100011033/ (grants BIO2016-78747-P, PID2019-104685GB-100 and PID2019-107657RB-C22) and the Ministry of Education, Youth and Sport of the Czech Republic and ERDF project entitled “Plants as a tool for sustainable global development” (No. CZ.02.1.01/0.0/0.0/16_019/0000827)

Resumen del trabajo presentado en el International Symposium: Microbe-Assisted Crop Production - Opportunities, Challenges & Needs (MICROPE 2022), celebrado en Viena (Austria), del 11 al 14 de julio de 2022