Volatile compounds (VCs) emitted by phylogenetically diverse microorganisms (including plant pathogens and microbes that do not normally interact mutualistically with plants) promote photosynthesis, growth, and the accumulation of high levels of starch in leaves through cytokinin (CK)-regulated processes. In Arabidopsis (Arabidopsis thaliana) plants not exposed to VCs, plastidic phosphoglucose isomerase (pPGI) acts as an important determinant of photosynthesis and growth, likely as a consequence of its involvement in the synthesis of plastidic CKs in roots. Moreover, this enzyme plays an important role in connecting the Calvin-Benson cycle with the starch biosynthetic pathway in leaves. To elucidate the mechanisms involved in the responses of plants to microbial VCs and to investigate the extent of pPGI involvement, we characterized pPGI-null pgi1-2 Arabidopsis plants cultured in the presence or absence of VCs emitted by Alternaria alternata We found that volatile emissions from this fungal phytopathogen promote growth, photosynthesis, and the accumulation of plastidic CKs in pgi1-2 leaves. Notably, the mesophyll cells of pgi1-2 leaves accumulated exceptionally high levels of starch following VC exposure. Proteomic analyses revealed that VCs promote global changes in the expression of proteins involved in photosynthesis, starch metabolism, and growth that can account for the observed responses in pgi1-2 plants. The overall data show that Arabidopsis plants can respond to VCs emitted by phytopathogenic microorganisms by triggering pPGI-independent mechanisms.

• MeSH
• Alternaria chemistry   radiation effects   MeSH
• Arabidopsis enzymology   growth & development   microbiology   physiology   MeSH
• Cell Wall metabolism   radiation effects   MeSH
• Cytokinins metabolism   MeSH
• Photosynthesis radiation effects   MeSH
• Glucose-6-Phosphate Isomerase metabolism   MeSH
• Mesophyll Cells drug effects   metabolism   radiation effects   MeSH
• Mutation genetics   MeSH
• Plastids drug effects   enzymology   MeSH
• Arabidopsis Proteins metabolism   MeSH
• Proteome metabolism   MeSH
• Starch metabolism   MeSH
• Light MeSH
• Volatile Organic Compounds pharmacology   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Cytokinins MeSH
• Glucose-6-Phosphate Isomerase MeSH
• Arabidopsis Proteins MeSH
• Proteome MeSH
• Starch MeSH
• Volatile Organic Compounds MeSH

The role of abscisic acid (ABA) during early development was investigated in tomato seedlings. The endogenous content of ABA in particular organs was analyzed in seedlings grown in the dark and under blue light. Our results showed that in dark-grown seedlings, the ABA accumulation was maximal in the cotyledons and elongation zone of hypocotyl, whereas under blue-light, the ABA content was distinctly reduced. Our data are consistent with the conclusion that ABA promotes the growth of etiolated seedlings and the results suggest that ABA plays an inhibitory role in de-etiolation and photomorphogenesis in tomato.

• Keywords
• abscisic acid, blue-light, etiolated growth, photomorphogenesis, tomato,
• MeSH
• Etiolation * MeSH
• Hypocotyl growth & development   MeSH
• Cotyledon growth & development   MeSH
• Abscisic Acid metabolism   MeSH
• Seedlings growth & development   metabolism   MeSH
• Solanum lycopersicum growth & development   metabolism   MeSH
• Light * MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Abscisic Acid MeSH