Unlocking eggplant's defense: discovery of key gene in bacterial wilt resistance
image: The SmDDA1b regulatory module enhances plant resistance to BW. For disease resistance plants, during Ralstonia solanacearum stress, the SmDDA1b proteins were induced by R. solanacearum. SmNAC were recognized by SmDDA1b and then degraded by the SmDDA1b-mediated ubiquitin/26S proteasome system (UPS). Consequently, the feedback regulatory of SmNAC on SmDDA1b were a failure and the suppression of SmNAC on ICS1 was also relieved, SA is accumulated and the SA signaling genes are activated, thus system-acquired resistance (SAR) is induced in plants. For susceptible plants, during R. solanacearum stress, SmDDA1b proteins were restrained, SmNAC cannot be recognized and degraded by ubiquitin/26S proteasome system (UPS). The released SmNAC proteins inhibits the expression of SmDDA1b in return and the suppression of SmNAC on SmICS1 was enhanced, SA and SA signaling pathway was repressed.
Credit: Horticulture Research
Researchers have pinpointed a critical gene, SmDDA1b, in eggplants that boosts resistance to bacterial wilt, a major threat to solanaceous crops. The study demonstrates that SmDDA1b degrades the SmNAC protein, triggering the plant’s immune defenses against this pathogen. This breakthrough could facilitate the breeding of more resilient eggplant varieties.
Bacterial wilt, caused by Ralstonia solanacearum, impairs plant water transport, leading to crop devastation. The disease is challenging to manage due to its spread via irrigation and infected plant materials, and traditional controls often fall short. As a result, uncovering genetic pathways that bolster resistance is essential. Given these issues, advancing genetic research to enhance eggplant resistance has become imperative.
Published (DOI: 10.1093/hr/uhad246) in Horticulture Research on November 27, 2024, and conducted at South China Agricultural University’s Key Laboratory of Biology and Genetic Improvement of Horticultural Crops, this study reveals how the SmDDA1b receptor, an ubiquitin ligase (E3) ubiquitin ligase complex component, interacts with SmNAC to enhance bacterial wilt resistance. By regulating salicylic acid (SA) production, the research unveils a key resistance mechanism, opening pathways for breeding disease-resistant crops.
The researchers found that SmDDA1b, as an E3 ubiquitin ligase receptor, enhances eggplant resistance to bacterial wilt through a detailed interaction with transcription factor SmNAC, which controls SA production—a crucial hormone for plant immunity. When bacterial infection or SA treatment occurs, SmDDA1b expression increases, activating the plant’s immune system and containing the pathogen. In plants where SmDDA1b was silenced, SA levels and resistance dropped, while overexpression of SmDDA1b significantly strengthened resistance by controlling pathogen spread. SmDDA1b further supports SA signaling pathways that drive systemic acquired resistance (SAR), fortifying the plant’s defenses. This SmDDA1b-SmNAC regulatory loop underlines a crucial mechanism in plant immunity, suggesting promising avenues for breeding disease-resistant crops.
Professor Zhengkun Qiu, lead researcher, noted, “Our findings reveal a dynamic interaction between SmDDA1b and SmNAC that strengthens bacterial wilt resistance by regulating the SA pathway. This mechanism not only enhances eggplant resilience but also lays groundwork for developing transgenic approaches for managing disease in other susceptible crops.”
The findings on SmDDA1b’s role in disease resistance pave the way for genetic engineering and breeding strategies to develop more robust crops. By targeting E3 ubiquitin ligase pathways, breeders may enhance plant defenses across species, bolstering food security against bacterial wilt and similar pathogens. This research represents a significant advancement in understanding plant immunity and supports broader agricultural disease management strategies.
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References
DOI
Original Source URL
https://doi.org/10.1093/hr/uhad246
Funding information
This research was funded by the Key R&D Projects in Guangdong Province (2022B0202080003), the Key Project of Guangzhou (202103000085), the seed industry revitalization project of Guangdong (2022NPY00026), Fruit and Vegetable Industry System Innovation Team Project of Guangdong (2021KJ110), and the National Natural Science Foundation of China (31672156).
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.