MYB31 triggers water stress memory responses in maize
Résumé
Water deficit directly impacts the ability of plants to intercept and convert light into biomass. Because leaf growth is one of the first processes affected by water deficit, many physiological studies concentrated in short-term responses and associated mechanisms. They demonstrated the roles of cellular and metabolic processes such as changes in cell turgor, hydraulic conductance and cell wall plasticity. However, our understanding of how water deficit impacts cell wall biosynthesis is still fragmentary. Here, we report that ZmMYB31, a R2R3-MYB transcription factor implicated in the regulation of lignin biosynthesis [1-2], is induced by water deficit in the growing zone of maize leaves. Consistent with this finding, we also showed that ZmMYB31 colocates with quantitative trait loci for growth responses to water deficit and anthesis-silking interval (ASI) under water deficit conditions. To assess the potential contribution of ZmMYB31 to maize responses to water deficit, we generated transgenic maize overexpressing ZmMYB31. We showed that increasing ZmMYB31 expression in maize maintained ASI under water deficit conditions. On the basis of these data, we generated transcriptomic and proteomic data to detect transcripts and proteins that show substantial changes in abundance in the leaf growing zone of three representative independent transgene-positive homozygous maize lines compared with that of transgene-negative sibling plants grown in PhenoArch under well-watered and water deficit conditions. We identified 352 genes that were transcriptionally regulated by ZmMYB31 under well-watered conditions and displayed opposite transcription levels under water deficit conditions, suggesting that ZmMYB31 may function in a water stress memory response pathway, which likely helps the transgenic maize enduring the water deficit stress. Our studies further revealed co-expression relationships between these genes and others from the proteome and a cell wall data sets, suggesting potential regulatory influence.
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