CiXTH29 and CiLEA4 Role in Water Stress Tolerance in Cichorium intybus Varieties

Abstract

Drought causes massive crop quality and yield losses. Limiting the adverse effects of water deficits on crop yield is an urgent goal for a more sustainable agriculture. With this aim, six chicory varieties were subjected to drought conditions during seed germination and at the six week-old plant growth stage, in order to identify some morphological and/or molecular markers of drought resistance. Selvatica, Zuccherina di Trieste and Galatina varieties, with a high vegetative development, showed a major germination index, greater seedling development (6 days of growth) and a greater dehydration resistance (6 weeks of growth plus 10 days without water) than the other ones (Brindisina, Esportazione and Rossa Italiana). Due to the reported involvement, in the abiotic stress response, of xyloglucan endotransglucosylase/hydrolases (XTHs) and late embryogenesis abundant (LEA) multigene families, XTH29 and LEA4 expression profiles were investigated under stress conditions for all analyzed chicory varieties. We showed evidence that chicory varieties with high CiXTH29 and CiLEA4 basal expression and vegetative development levels better tolerate drought stress conditions than varieties that show overexpression of the two genes only in response to drought. Other specific morphological traits characterized almost all chicory varieties during dehydration, i.e., the appearance of lysigen cavities and a general increase of the amount of xyloglucans in the cell walls of bundle xylem vessels. Our results highlighted that high CiXTH29 and CiLEA4 basal expression, associated with a high level of vegetative growth, is a potential marker for drought stress tolerance.

Transcriptome Analysis Reveals Drought-Responsive Pathways and Key Genes of Two Oat (Avena sativa) Varieties

“…To resume growth and adapt to water stress, plant cells must regain their ability to loosen the cell wall and incorporate new polymers over an extended period of time; this helps to avoid cell-wall disruption [ 26 , 27 ]. For example, increased xyloglucan content in the cell walls of bundle xylem vessels is a potential feature of resistance to drought stress in some chicory varieties [ 28 ]. Expression of xyloglucan endo-transglycosylase/hydrolases (XTHs) genes AtXTH4, AtXTH9 and CiXTH29 promoted cell-wall remodeling and contributed to better plant tolerances to drought stress [ 26 , 27 , 28 , 29 ].…”

“…For example, increased xyloglucan content in the cell walls of bundle xylem vessels is a potential feature of resistance to drought stress in some chicory varieties [ 28 ]. Expression of xyloglucan endo-transglycosylase/hydrolases (XTHs) genes AtXTH4, AtXTH9 and CiXTH29 promoted cell-wall remodeling and contributed to better plant tolerances to drought stress [ 26 , 27 , 28 , 29 ]. In this study, transcriptome sequencing analyses revealed that a large number of genes related to the synthesis/degradation of cell-wall constituents as well as genes regulating wax synthesis were specifically enriched in both oat varieties with different drought resistances, indicating that the up- or downregulation of those genes is closely related to an increase in cell-wall composition and wax crystals.…”

Impact of Climate Change on Agroecosystems and Potential Adaptation Strategies

“…Maize was also intolerant of waterlogging stress, and the trefoil stage was the most sensitive period for it [118,119]. Water stress has a different impact on crops mainly based on the stage of plant development; such stress is especially critical during reproductive development, and seed germination is drastically affected by water availability [120,121]. Furthermore, drought experienced during flowering has been reported to lead to infertility in wheat [122].…”

“…Principally, the identification of stress-related genes provides a strong tool for improving water stress tolerance. Indeed, a large number of stress-response genes are activated through complex signal transduction networks, promoting the synthesis of many functional proteins related to the capability to resist water stress in the tolerance mechanisms [120,[155][156][157][158][159]. Several genes have been identified to increase drought tolerance in plants: high basal levels of the CiLEA4 and CiXTH29 genes in chicory seem to enhance drought tolerance [120]; a transcription factor involved in the pathway of LEA and dehydrin gene expression, TaNAC69, has the same effect in wheat [159]; and the heat shock protein HSP70-1 activates the drought stress tolerance mechanisms in tobacco [160].…”

“…Indeed, a large number of stress-response genes are activated through complex signal transduction networks, promoting the synthesis of many functional proteins related to the capability to resist water stress in the tolerance mechanisms [120,[155][156][157][158][159]. Several genes have been identified to increase drought tolerance in plants: high basal levels of the CiLEA4 and CiXTH29 genes in chicory seem to enhance drought tolerance [120]; a transcription factor involved in the pathway of LEA and dehydrin gene expression, TaNAC69, has the same effect in wheat [159]; and the heat shock protein HSP70-1 activates the drought stress tolerance mechanisms in tobacco [160]. Nevertheless, more details on plants' water status [161], abiotic stress biology [162], stress targets for modern genetic manipulation [163], new breeding crops for drought-affected environments, and climate resilience [164] can be found in the mentioned bibliography.…”