Enhanced Waterlogging Tolerance in Kiwifruit Through Specific Gene Responses

Jenn Hoskins
19th May, 2024

Enhanced Waterlogging Tolerance in Kiwifruit Through Specific Gene Responses

Image Source: Natural Science News, 2024

Key Findings

  • Researchers at Zhejiang University studied two kiwifruit species to understand their response to waterlogging
  • The waterlogging-resistant "Dunn" maintained higher root activity and controlled enzyme levels better than the sensitive "DH"
  • Key transcription factors like AcMYB68 were identified, which regulate enzymes crucial for survival under waterlogged conditions
Kiwifruit, a highly popular fruit cultivated extensively in China, faces significant challenges due to waterlogging, particularly in the southern regions. This issue has markedly affected yields, making it crucial to understand the mechanisms underlying kiwifruit's response to waterlogging. A recent study conducted by researchers at Zhejiang University sheds light on this problem by comparing two kiwifruit species: the waterlogging-sensitive Actinidia chinensis cv. Donghong ("DH") and the waterlogging-resistant Actinidia valvata Dunn ("Dunn")[1]. In this study, the researchers observed that "Dunn" maintained higher root activity under prolonged waterlogging conditions compared to "DH", which exhibited weakened growth and root activities. The team focused on the transcript levels of two key enzymes: pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH). These enzymes play a critical role in anaerobic metabolism, which is essential for plant survival under low oxygen conditions caused by waterlogging. The study found significant differences in the expression of PDC and ADH between the two species. In "DH", both PDC and ADH levels increased markedly in response to waterlogging, while in "Dunn", their expression was only slightly elevated after two days of stress and then subsided. This suggests that "Dunn" has a more controlled and efficient response to waterlogging, which contributes to its tolerance. To further understand the molecular mechanisms, the researchers isolated 19 differentially expressed transcription factors (DETFs) using weighted gene co-expression network analysis combined with transcriptomics. Among these DETFs, AcMYB68 was identified as a key regulator that binds to and activates the AcPDC2 promoter, as confirmed by dual luciferase and electrophoretic mobility shift assays. Overexpression of AcMYB68 significantly up-regulated PDC transcript levels but also inhibited plant growth, particularly in the roots. Additionally, enzyme activity assays showed that PDC activity was significantly enhanced in waterlogged plants overexpressing AcMYB68 compared to wild-type plants. Interestingly, the study also revealed that the expression patterns of AcMYB68 and two previously characterized transcription factors, AcERF74 and AcERF75, which regulate ADH, showed no or very limited responses in "Dunn". This restricted response of these transcription factors in "Dunn" is believed to contribute to its waterlogging tolerance. These findings align with previous research highlighting the role of transcription factors in plant stress responses. For instance, group VII ethylene response factors (ERFVIIs) have been identified as important regulators of low-oxygen stress in plants[2]. ERFVIIs are stabilized in the absence of oxygen and nitric oxide, allowing them to coordinate plant responses to hypoxia by regulating genes involved in anaerobic metabolism. This mechanism is part of the N-end rule pathway, a targeted proteolysis system that acts as an oxygen sensor in plants[3]. The current study expands on these earlier findings by providing specific insights into the transcriptional responses of kiwifruit to waterlogging. It identifies key transcription factors and their target genes, offering potential targets for breeding waterlogging-tolerant kiwifruit varieties. The restricted response of AcMYB68 and AcERF74/75 in "Dunn" highlights a novel aspect of waterlogging tolerance, emphasizing the importance of controlled gene expression in stress adaptation. In summary, this research from Zhejiang University provides valuable insights into the molecular mechanisms underlying waterlogging tolerance in kiwifruit. By identifying key transcription factors and their regulatory networks, the study offers potential strategies for developing waterlogging-resistant kiwifruit cultivars, which could significantly improve yields in waterlogged regions. These findings also contribute to the broader understanding of plant stress responses, building on previous research on transcription factors and oxygen sensing pathways in plants[2][3][4].

FruitsGeneticsPlant Science

References

Main Study

1) Restricted responses of AcMYB68 and AcERF74/75 enhanced waterlogging tolerance in kiwifruit.

Published 18th May, 2024

https://doi.org/10.1111/tpj.16816

Related Studies

2) Group VII Ethylene Response Factors Coordinate Oxygen and Nitric Oxide Signal Transduction and Stress Responses in Plants.

https://doi.org/10.1104/pp.15.00338

3) Homeostatic response to hypoxia is regulated by the N-end rule pathway in plants.

https://doi.org/10.1038/nature10534

4) Comparative transcriptome provides insight into responding mechanism of waterlogging stress in Actinidia valvata Dunn.

https://doi.org/10.1016/j.gene.2022.146843


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