Anthocyanins, the pigments responsible for the vibrant red and purple hues of grape berries and wines, are highly sensitive to environmental conditions, particularly water availability. While moderate drought has long been observed to enhance anthocyanin levels, the molecular mechanisms underlying this phenomenon have remained elusive. Given the critical role of water management in viticulture, unlocking the regulatory pathways that govern anthocyanin accumulation under drought stress could provide game-changing insights for grape growers and winemakers worldwide.
A new study (DOI: 10.1093/hr/uhad293), published on January 2, 2024, in Horticulture Research, by researchers from Nanjing Agricultural University and Northwest A&F University, has now bridged this knowledge gap. The study reveals how drought stress stimulates anthocyanin biosynthesis in grape berries via the ABA signaling pathway and the microRNA miR156b. These findings offer crucial insights into how grapevines respond to water scarcity and provide a foundation for enhancing grape quality through precise genetic and environmental interventions.
Delving into the molecular intricacies, the researchers identified miR156b as a master regulator of anthocyanin biosynthesis under drought conditions. Their study showed that drought stress elevates the transcription factor VvAREB2, which directly binds to the promoter of the miR156b gene, switching on its expression. This activation is pivotal, as miR156b selectively targets and suppresses VvSBP8 and VvSBP13, two transcription factors known to inhibit the MYB-bHLH-WD40 (MBW) complex, a crucial driver of anthocyanin biosynthesis. By neutralizing these inhibitors, miR156b allows the MBW complex to function unimpeded, resulting in a significant boost in anthocyanin production. The study further demonstrated that manipulating miR156b levels in grape calli and berries directly impacts anthocyanin accumulation—with overexpression of miR156b leading to intensified pigmentation, while suppression reduced anthocyanin levels. This intricate regulatory network, involving ABA signaling, miR156b, and the MBW complex, provides a comprehensive model of how drought stress enhances anthocyanin production in grapes. Furthermore, it suggests miR156b as a potential genetic target for breeding drought-resilient, high-quality grape cultivars.
Dr. Tengfei Xu, one of the lead researchers, underscores the transformative nature of these findings: "Our study establishes a direct molecular link between drought stress and anthocyanin biosynthesis, mediated by the ABA signaling pathway and miR156b. This discovery opens new possibilities for improving grape quality and resilience in water-limited environments, offering a sustainable approach to viticulture in the face of climate change."
Beyond scientific discovery, this research carries profound implications for viticulture and grape breeding. Understanding the molecular mechanisms that drive anthocyanin accumulation under drought conditions can help growers refine irrigation strategies to maximize grape quality while conserving water. Additionally, the insights gained could accelerate the development of drought-tolerant grape varieties, ensuring more sustainable wine production in an era of increasing climate challenges. By harnessing the power of genetics and precision agriculture, this study offers a blueprint for a more resilient and vibrant future for the global wine industry.
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References
DOI
10.1093/hr/uhad293
Original Source URL
https://doi.org/10.1093/hr/uhad293
Funding information
This work was supported by the National Natural Science Foundation of China (grants 32371924, 32260727, and 31801811), the Key Research and Development Program of Shaanxi Province (grant 2023-GHZD-17), the Key Research and Development Programme of Xinjiang Province (grant 2022B02034-3), and the China Agriculture Research System (grant CARS-29-zp-6).
About Horticulture Research
Horticulture Research is an open access journal of Nanjing Agricultural University and ranked number one in the Horticulture category of the Journal Citation Reports ™ from Clarivate, 2022. The journal is committed to publishing original research articles, reviews, perspectives, comments, correspondence articles and letters to the editor related to all major horticultural plants and disciplines, including biotechnology, breeding, cellular and molecular biology, evolution, genetics, inter-species interactions, physiology, and the origination and domestication of crops.