Cassava is a globally important food source. Given the increasing frequency of climate change-induced drought, enhancing the drought resilience of cassava is paramount. Chemical priming can bolster tolerance to stress factors. We previously determined that pretreatment with low concentrations of ethanol enhances abiotic stress tolerance in Arabidopsis, tomato, and cassava. Nevertheless, the efficacy of ethanol treatment in complex natural settings remains to be fully explored. In this study, we assessed the impact of ethanol treatment on cassava under varying light photon flux densities (PFDs) and drought conditions. We observed that drought tolerance was enhanced by ethanol pretreatment at high (∼400 µmol photons m⁻² s⁻¹) and medium (∼60 µmol photons m⁻² s⁻¹) light PFDs but not under low light PFD (∼4 µmol photons m⁻² s⁻¹). Ethanol pretreatment under high and medium light PFDs promoted stomatal closure and drought avoidance, thereby preserving higher water content in plant tissues. Furthermore, ethanol pretreatment under these PFDs upregulated expressions of genes associated with ABA signaling and heat shock proteins (HSPs) relative to water pretreatment. In addition, starch accumulation in leaves was observed under all light PFDs with ethanol pretreatment. We hypothesize that ethanol pretreatment at light PFDs exceeding 60 µmol photons m⁻² s⁻¹ facilitates ethanol-mediated drought avoidance in cassava by activating at least three pathways: 1) ABA signaling, 2) protein folding-related response via triggering of the HSP/chaperone network, and 3) alterations in sugar and starch metabolism. Our findings support the application of optimal light PFDs to enhance the benefits of ethanol-induced drought avoidance in cassava.

Plant-microbe interactions encompass a continuum from mutualism and commensalism to parasitism. Mutualists confer benefits such as nutrient acquisition or stress tolerance, whereas pathogens compromise host health, and commensals coexist without detectable harm or benefit. Importantly, these relationships are not fixed but are dynamic, shifting between interaction modes in response to host physiology, microbial adaptation, and environmental conditions. Such shifts can influence plant health, agricultural productivity, and ecosystem stability. This review synthesizes the mechanisms underlying these functional transitions and discusses how understanding the drivers of interaction shifts can inform sustainable agriculture and ecosystem management.

Arabinoxylan, a major hemicellulose in plant cell walls, particularly in grasses and cereals, plays a crucial role in structural integrity and biological functions, with diverse industrial applications such as food production and prebiotic development. Despite its significance, the molecular mechanism of arabinoxylan biosynthesis remains unclear. Here, we identified and characterized a xylan synthase catalytic subunit, Setaria viridis IRregular Xylem 10 (SvIRX10), from a new model plant for C₄-photosynthetic grasses, S. viridis A10.1. Bioinformatic analysis classified SvIRX10 as a glycosyltransferase 47 family member, conserved across various species. Recombinant SvIRX10 expressed in Expi293 cells exhibited xylan synthase activity for all tested xylotrimer (Xyl₃) acceptors with distinct fluorescent labels. The substrate conversion efficiency for 2-aminobenzoic acid-labeled Xyl₃ (Xyl₃-2AA) was highest, but those for other labeled Xyl₃ were lower. Nevertheless, the elongation efficiencies were comparable among tested acceptors when the xylan chains elongated enough. Structural prediction and docking simulations illustrated most frequently the productive conformations using Xyl₃-2AA and xylotetraose as ligands. The interactions between the two ligands and the active site were well-conserved, and all ligand units interacted with SvIRX10. These ligand conformations in the active site were similar, but those of other fluorescently labeled Xyl₃ differed except for the first xylosyl unit at the non-reducing end. Thus, SvIRX10 recognizes at least 4 xylosyl units in the xylan synthetic reaction. Together, these findings provide insights into the enzymatic mechanisms of SvIRX10 and the initiation of xylan elongation, offering potential applications for modifying plant cell walls in biomass utilization and functional food development.

Oxygen depletion due to submergence causes cellular energy starvation and severely restricts the growth of most plant species. To survive hypoxic and anoxic environments under submergence, rice (Oryza sativa L.) possesses various adaptive mechanisms including energy production from seed storage starch via anaerobic respiration and coleoptile elongation during early post-germinative growth. However, further investigation of the submergence tolerance mechanism is important for understanding its effect on plant physiology and agricultural production. Here, we found that pretreatment of rice seeds with organic acids, such as citrate and lactate, improved subsequent seedling growth under submergence. Citrate pretreatment promoted coleoptile elongation under submergence. Moreover, the expression of genes related to anaerobic respiration and phenylpropanoid biosynthesis was activated in the embryo of citrate treated seeds during submergence while the expression of genes encoding starch degradation enzymes and signaling factors was not significantly influenced. Accordingly, starch and soluble sugar amounts in the endosperm were not altered by citrate pretreatment. These results suggest that citrate pretreatment promotes coleoptile elongation in rice seeds under submergence via the transcriptional regulation of genes related to anaerobic energy production, possibly through an unknown mechanism related to phenylpropanoid metabolism.