Drought stress during early seed germination severely impacts rice establishment and productivity, yet the molecular and metabolic mechanisms underlying drought tolerance at this stage remain poorly understood.

In a study published in BMC Plant Biology, researchers from Xishuangbanna Tropical Botanical Garden (XTBG)of the Chinese Academy of Sciences have identified the molecular and metabolic mechanisms that enable a drought-tolerant rice genotype, Luying 46 (LY46), to thrive under conditions that severely hinder a sensitive genotype, Haogenai (HGN). Their findings offer promising targets for breeding more resilient rice varieties.

The researchers integrated physiological, transcriptomic, and metabolomic analyses to elucidate the molecular and metabolic mechanisms underlying drought tolerance during seed germination in rice.

When exposed to polyethylene glycol (PEG)-induced drought stress, LY46 showed significantly higher germination rates, better shoot and root growth, and greater overall resilience compared to HGN. While drought stress typically reduces germination and growth in both genotypes, LY46 maintained robust physiological performance with minimal decline.

Metabolic pathway analysis revealed significant enhancement of glycolysis, glutathione metabolism, and phenylpropanoid biosynthesis pathways in LY46. Its upregulation of starch mobilization-related genes promoted energy supply, while increased antioxidant enzyme activity and flavonoid accumulation effectively mitigated oxidative damage.

In contrast, HGN showed weaker activation of these pathways, higher lipid peroxidation (measured by malondialdehyde, MDA), and greater cellular damage.

Further investigation demonstrated that glutathione and flavonoid metabolic pathways played central roles in activating the antioxidant enzyme system through a transcription factor regulatory network, while accumulation of osmoregulatory substances such as proline and phenolic acids helped maintain cell membrane integrity.

They also identified drought-specific accumulation of peptides, alkaloids, lipids, and other metabolites in LY46, which protected membrane structures by reducing lipid peroxidation levels.

"Our study systematically deciphers the multidimensional regulatory network of drought resistance during rice germination for the first time, providing a theoretical basis for developing direct-seeded rice varieties adapted to arid environments,” said XU Peng of XTBG.

Published: 09 March 2026