Grapevine Gene VvbHLH10 Doubles as a Salt-Alkali Shield and Bud Growth Switch

A single transcription factor in grapevine has emerged as a double agent in plant biology, simultaneously arming vines against one of agriculture’s most punishing soil stresses while also coaxing dormant buds into active growth. In a study published in BMC Plant Biology, researchers at the Shandong Academy of Grape, part of the Shandong Academy of Agricultural Sciences, together with colleagues at Shandong Agricultural University, report that VvbHLH10, a member of the basic helix-loop-helix (bHLH) transcription factor family, acts as a positive regulator of salt-alkali tolerance in grape (Vitis vinifera). The finding is notable because salt-alkali stress, which combines ionic toxicity, osmotic duress and high pH, severely constrains grape growth and productivity, yet the molecular machinery that vines use to cope with it has remained largely elusive.

The team began by charting where and when VvbHLH10 switches on. Under laboratory conditions, its transcription was rapidly and strongly induced by both salt and alkali treatments, a pattern consistent with a gene recruited into the front line of the stress response. Intriguingly, the gene is also predominantly expressed in actively growing tissues, including latent buds, young stems and young tendrils, placing it at the intersection of stress defense and development. Using a VvbHLH10-GFP fusion protein, the researchers confirmed that the protein localizes to the nucleus, the expected working address for a transcription factor that binds promoter regions and orchestrates the expression of downstream target genes.

To test function rather than mere correlation, the researchers deployed two complementary experimental systems. The first was homologous overexpression in grape callus cultures, an in vitro system derived from the plant itself. When grape calli engineered to overexpress VvbHLH10 were challenged with salt and alkali stress, they survived and grew significantly better than control calli. Biochemical assays pointed to the mechanism behind that resilience: the engineered tissues accumulated markedly lower levels of reactive oxygen species (ROS) and malondialdehyde (MDA), two classic signatures of oxidative damage. Because salt and alkali stress disrupt photosynthesis and electron transport, plants typically respond with bursts of ROS that damage membranes, proteins and DNA; reducing that oxidative burden is a central goal of stress-resilience breeding.

The second system took the gene out of grapes altogether. In a heterologous expression approach, the team introduced VvbHLH10 into tomato, a widely used surrogate that allows plant scientists to ask whether a gene’s function is conserved across species. The answer was a clear yes. Transgenic tomato lines overexpressing VvbHLH10 showed markedly improved tolerance to salt-alkali treatment compared with wild-type controls, again with reduced oxidative damage and better overall growth. Cross-species validation of this kind matters for breeders because it suggests the underlying regulatory module is not a grape-specific quirk but a portable stress-protection circuit that could, in principle, be engineered into other horticultural crops facing the same soil chemistry problems.

Then came the surprise. Beyond its protective function, ectopic expression of VvbHLH10 in tomato promoted axillary bud outgrowth and altered the plants’ vegetative architecture. Axillary buds are the embryonic shoots that sit in the angle between leaf and stem, and whether they remain dormant or break out into branches is governed by a tight hormonal and transcriptional network involving strigolactones, auxin and cytokinin. A transcription factor that simultaneously modulates this developmental switch and the stress response is unusual, and it hints that VvbHLH10 belongs to a growing group of bHLH proteins whose roles have diversified beyond single functions. In practical terms, the same gene that helps a vine survive degraded soil could also be tuned to change how the plant allocates its growth, a lever for shaping canopy structure and productivity.

The dual identity of VvbHLH10 fits into a broader emerging picture of the bHLH family. With hundreds of members in most plant genomes, bHLH transcription factors have been implicated in everyone’s favorite processes, from iron uptake and flavonoid biosynthesis to light signaling and hormone crosstalk. Group 9 bHLH factors, the subclass to which VvbHLH10 belongs, have drawn particular interest for their roles in abiotic stress responses. What this study adds is evidence that in a woody perennial crop of global economic importance, one group 9 member can be rapidly mobilized by salinity and alkalinity cues, act in the nucleus to dampen oxidative injury, and at the same time remodel shoot architecture by freeing axillary buds from dormancy.

For viticulture, the implications are concrete. Salt-alkali soils are expanding in many grape-growing regions as irrigation, climate change and intensive cultivation push pH and sodium levels upward, and vineyards on marginal land often suffer stunted vines, poor bud break and yield losses. A gene that improves survival under both saline and alkaline conditions, verified in both homologous and heterologous systems, offers a candidate target for marker-assisted selection or genome editing. Because VvbHLH10 is naturally expressed in latent buds, breeders could also exploit its developmental role to improve bud fertility and branching in varieties where shy bud break limits yield. The authors position VvbHLH10 as a promising candidate for the genetic improvement of both salt-alkali tolerance and plant architecture in grapevine.

The research, led by Rui Xu and Huiping Liu as co-first authors and corresponding author Ke Li, was published open access on 12 September 2026 after acceptance on 9 September, and was supported by the Key Research and Development Project of Shandong Province, the National Natural Science Foundation of China, the Shandong Provincial Natural Science Foundation and several programs at the Shandong Academy of Agricultural Sciences. The team also released transcriptomic datasets from VvbHLH10-overexpressing tomato as supplementary material, giving the community a resource to trace which downstream pathways the transcription factor rewires, from antioxidant defenses to branching hormones.

What remains to be resolved is the direct target repertoire of VvbHLH10 and how its stress-protective and developmental outputs are mechanistically linked. If the same set of bound promoters underlies both ROS quenching and bud release, that would suggest an elegant coupling in which growth resumption under stress is actively licensed rather than merely permitted. If the two functions run through separate downstream circuits, breeders may be able to dial in salt tolerance without unwanted changes in vine shape. Either outcome broadens understanding of the functional diversification of bHLH transcription factors in horticultural crops and brings grape growers one gene closer to vines that thrive where the soil fights back.

Subject of Research: Functional characterization of the VvbHLH10 transcription factor in grapevine salt-alkali stress tolerance and axillary bud growth regulation

Article Title: VvbHLH10 promotes axillary bud growth and salt-alkali tolerance in grapevine

Article References: Xu, R., Liu, H., Mu, Q., Li, A., Wang, F., & Li, K. (2026). VvbHLH10 promotes axillary bud growth and salt-alkali tolerance in grapevine. BMC Plant Biology. https://doi.org/10.1186/s12870-026-09949-x

Image Credits: AI Generated

DOI: 10.1186/s12870-026-09949-x

Keywords: grapevine, VvbHLH10, bHLH transcription factor, salt-alkali stress, axillary bud growth, reactive oxygen species, abiotic stress tolerance, Vitis vinifera, plant architecture, viticulture, plant molecular biology, transgenic plants