Suppression of cuticular wax biosynthesis mediated by rice LOV KELCH REPEAT PROTEIN 2 supports a negative role in drought stress tolerance

Abstract

Drought tolerance is important for grain crops, including rice (Oryza sativa); for example, rice cultivated under intermittent irrigation produces less methane gas compared to rice grown in anaerobic paddy field conditions, but these plants require greater drought tolerance. Moreover, the roles of rice circadian-clock genes in drought tolerance remain largely unknown. Here, we show that the mutation of LOV KELCH REPEAT PROTEIN 2 (OsLKP2) enhanced drought tolerance by increasing cuticular wax biosynthesis. Among ZEITLUPE family genes, OsLKP2 expression specifically increased under dehydration stress. OsLKP2 knockdown (oslkp2-1) and knockout (oslkp2-2) mutants exhibited enhanced drought tolerance. Cuticular waxes inhibit non-stomatal water loss. Under drought conditions, total wax loads on the leaf surface increased by approximately 10% in oslkp2-1 and oslkp2-2 compared to the wild type, and the transcript levels of cuticular wax biosynthesis genes were upregulated in the oslkp2 mutants. Yeast two-hybrid, bimolecular fluorescence complementation, and coimmunoprecipitation assays revealed that OsLKP2 interacts with GIGANTEA (OsGI) in the nucleus. The osgi mutants also showed enhanced tolerance to drought stress, with a high density of wax crystals on their leaf surface. These results demonstrate that the OsLKP2-OsGI interaction negatively regulates wax accumulation on leaf surfaces, thereby decreasing rice resilience to drought stress.

Metabolic priming in G6PDH isoenzyme‐replaced tobacco lines improves stress tolerance and seed yields via altering assimilate partitioning

“…sphingolipids) and may also be stored in oil bodies as triacylglycerol (TAG). Being the precursors of cutin and wax, VLCFAs play important roles in plant responses to abiotic and biotic stress (reviewed in Batsale et al., 2021), with wax biosynthesis recently shown to improve drought tolerance in rice (Shim et al., 2023). On the other hand, phosphatidic acid (PA), an intermediate of lipid biosynthesis and important signalling molecule in plants (reviewed in Yu et al., 2017) may also contribute to improved stress responses in the transgenic lines.…”

Molecular Mechanisms and Regulatory Pathways Underlying Drought Stress Response in Rice

“…OsLKP2 interacts with OsGI and negatively regulates wax accumulation on the surface of rice leaves, reducing the recovery ability of rice to drought stress. The cuticular wax content of oslkp2 or osgi mutants increases, thus enhancing their drought tolerance [125]. OsCHR4 regulates cuticular wax formation by epigenetically regulating the expression of wax biosynthesis genes.…”

The Circadian Clock Coordinates the Tradeoff between Adaptation to Abiotic Stresses and Yield in Crops

“…The null mutations of OsLKP2 displayed enhanced drought tolerance by increasing cuticular wax biosynthesis, which subsequently inhibited nonstomatal water loss. Furthermore, it was found that OsLKP2 could physically interact with another clock component, OsGI, in the nucleus, and the null mutation of OsGI also showed enhanced drought tolerance with a high density of wax crystals, suggesting that the interaction of OsGI and OsLKP2 negatively regulates wax accumulation to decrease rice resilience to drought stress [49] (Figure 4). This evidence jointly suggests that rice clock components are important for regulating drought tolerance, either in ABA-dependent or ABA-independent pathways.…”