A new study has recently revealed how soybean roots and leaves employ distinct metabolic strategies under nitrogen deficiency and high-temperature stress, which may help guide the development of soybean varieties with enhanced heat tolerance and improved nitrogen-use efficiency.

Led by Associate Prof. Mohsin Tanveer from the Xinjiang Institute of Ecology and Geography (XIEG) of the Chinese Academy of Sciences (CAS), in collaboration with Prof. Alisdair R. Fernie from the Max-Planck-Institute of Molecular Plant Physiology, the study was published in Journal of Advanced Research on August 7.

Climate change is increasing the co-occurrence of nutrient limitations and elevated temperatures, which together pose a serious threat to crop productivity. However, most previous studies have focused on individual plant organs, and the coordinated metabolic responses of roots and leaves remain poorly understood.

In this study, the researchers subjected soybean plants to control, nitrogen-deficient (–N), high-temperature (HT), and combined conditions (HT–N). They integrated physiological assessments with untargeted metabolomic profiling of roots and leaves.

They found that combined HT–N stress caused the most severe growth inhibition, with shoot length reduced by 67%, root fresh weight by 52%, and photosynthetic efficiency (Fv/Fm) by 51%, relative to the control.

Notably, the two tissues responded in markedly different ways. Under –N conditions, roots prioritized nitrogen assimilation and accumulated glutamate, proline, and aspartate. Under HT stress, leaves accumulated more flavonoids, suggesting enhanced antioxidant protection. Under combined HT–N stress, roots mainly adjusted amino acid and proline metabolism, whereas leaves reprogrammed phenylpropanoid and glutathione metabolism.

The study further identified glucose, proline, flavonoids, and several amino acids as key candidate metabolites associated with physiological performance under stress.

According to the researchers, this study demonstrates that soybean roots and leaves perform complementary but functionally distinct roles in responding to simultaneous nutrient and temperature constraints.

"The identified metabolic signatures may support the development of soybean varieties with improved tolerance to high temperatures and greater nitrogen-use efficiency," said Hamza Tariq from XIEG, first author of the study.

A proposed model shows the tissue-specific coordination of metabolite profiling conferring combined high temperature and nitrogen deficiency stress. (Image by XIEG)