Soybean steroids improve crop abiotic stress tolerance and increase yield.

Sterols have long been associated with diverse fields, such as cancer treatment, drug development, and plant growth; however, their underlying mechanisms and functions remain enigmatic. Here, we unveil a critical role played by a GmNF-YC9-mediated CCAAT-box transcription complex in modulating the steroid metabolism pathway within soybeans. Specifically, this complex directly activates squalene monooxygenase (GmSQE1), which is a rate-limiting enzyme in steroid synthesis. Our findings demonstrate that overexpression of either GmNF-YC9 or GmSQE1 significantly enhances soybean stress tolerance, while the inhibition of SQE weakens this tolerance. Field experiments conducted over two seasons further reveal increased yields per plant in both GmNF-YC9 and GmSQE1 overexpressing plants under drought stress conditions. This enhanced stress tolerance is attributed to the reduction of abiotic stress-induced cell oxidative damage. Transcriptome and metabolome analyses shed light on the upregulation of multiple sterol compounds, including fucosterol and soyasaponin II, in GmNF-YC9 and GmSQE1 overexpressing soybean plants under stress conditions. Intriguingly, the application of soybean steroids, including fucosterol and soyasaponin II, significantly improves drought tolerance in soybean, wheat, foxtail millet, and maize. These findings underscore the pivotal role of soybean steroids in countering oxidative stress in plants and offer a new research strategy for enhancing crop stress tolerance and quality from gene regulation to chemical intervention.

Heat shock protein TaHSP17.4, a TaHOP interactor in wheat, improves plant stress tolerance.

Adaptation to drought and salt stresses is a fundamental part of plant cell physiology and is of great significance for crop production under environmental stress. Heat shock proteins (HSPs) are molecular chaperones that play a crucial role in folding, assembling, translocating, and degrading proteins. However, their underlying mechanisms and functions in stress tolerance remain elusive. Here, we identified the HSP TaHSP17.4 in wheat by analyzing the heat stress-induced transcriptome. Further analysis showed that TaHSP17.4 was significantly induced under drought, salt, and heat stress treatments. Intriguingly, yeast-two-hybrid analysis showed that TaHSP17.4 interacts with the HSP70/HSP90 organizing protein (HOP) TaHOP, which plays a significant role in linking HSP70 and HSP90. We found that TaHSP17.4- and TaHOP-overexpressing plants have a higher proline content and a lower malondialdehyde content than wild-type plants under stress conditions and display strong tolerance to drought, salt, and heat stress. Additionally, qRT-PCR analysis showed that stress-responsive genes relevant to reactive oxygen species scavenging and abscisic acid signaling pathways were significantly induced in TaHSP17.4- and TaHOP-overexpressing plants under stress conditions. Together, our findings provide insight into HSP functions in wheat and two novel candidate genes for improvement of wheat varieties.

GmDof41 regulated by the DREB1-type protein improves drought and salt tolerance by regulating the DREB2-type protein in soybean.

Despite their essential and multiple roles in biological processes, the molecular mechanism of Dof transcription factors (TFs) for responding to abiotic stresses is rarely reported in plants. We identified a soybean Dof gene GmDof41 which was involved in the responses to drought, salt, and exogenous ABA stresses. Overexpression of GmDof41 in soybean transgenic hairy roots attenuated H2O2 accumulation and regulated proline homeostasis, resulting in the drought and salt tolerance. Yeast one-hybrid and electrophoretic mobility shift assay (EMSA) illustrated that GmDof41 was regulated by the DREB1-type protein GmDREB1B;1 that could improve drought and salt tolerance in plants. Further studies illustrated GmDof41 can directly bind to the promoter of GmDREB2A which encodes a DREB2-type protein and affects abiotic stress tolerance in plants. Collectively, our results suggested that GmDof41 positively regulated drought and salt tolerance by correlating with GmDREB1B;1 and GmDREB2A. This study provides an important basis for further exploring the abiotic stress-tolerance mechanism of Dof TFs in soybean.