Plant Gene and Traits 2024, Vol.15, No.4, 162-173 http://genbreedpublisher.com/index.php/pgt 170 Additionally, the fitness and agronomic performance of hybrids between transgenic rice and weedy rice require more comprehensive evaluation. While some studies have indicated that hybrids do not exhibit increased fitness or seed fecundity (Zhang et al., 2003), others have shown that certain hybrid generations can possess higher composite fitness than their transgenic parents (Zhang et al., 2018). Understanding these fitness dynamics is crucial for developing effective management practices to prevent the spread of herbicide resistance in weedy rice. 9.3 Long-term goals and perspectives In the long term, the goal is to develop sustainable weed management systems that minimize the risk of herbicide resistance while maintaining high crop yields. One promising strategy is the use of mitigation technologies that genetically link herbicide resistance genes with traits that render hybrids unfit to compete, such as non-shattering and dwarfism (Gressel and Valverde, 2009). This approach could help contain herbicide resistance within the crop and prevent the spread to weedy rice populations. Moreover, continuous monitoring and evaluation of herbicide resistance in weedy rice populations are essential. Studies have shown that certain weedy rice accessions exhibit reduced sensitivity to herbicides like glyphosate and flumioxazin, highlighting the need for ongoing surveillance and adaptive management strategies (Shrestha et al., 2019). Integrating these practices with conventional weed management techniques could provide a holistic solution to the challenges posed by glufosinate-tolerant weedy rice. In conclusion, while significant advancements have been made in the development of glufosinate-tolerant rice, addressing the current research gaps and focusing on long-term sustainable practices will be key to overcoming the challenges and fully realizing the potential of this technology. 10 Concluding Remarks The breeding potential and challenges of glufosinate-tolerant rice have been extensively studied, revealing several critical insights. Firstly, the transfer of glufosinate resistance from transgenic rice to weedy rice occurs at low frequencies but poses significant ecological risks. Studies have shown that outcrossing rates between transgenic glufosinate-resistant rice and weedy rice can be as low as 0.3% to 0.488%. Despite the low frequency, the resulting hybrids can exhibit increased fitness and weediness traits, which complicates management strategies. Additionally, genetic analyses indicate that glufosinate resistance behaves as a single, dominant gene, which can be stably inherited across generations. The findings underscore the necessity for robust management practices to mitigate the spread of glufosinate resistance in weedy rice populations. The bidirectional gene flow between transgenic and weedy rice highlights the potential for rapid emergence of herbicide-resistant weedy rice, which can outcompete cultivated varieties and reduce crop yields. Effective management strategies should include monitoring and controlling weedy rice populations, especially in fields planted with herbicide-resistant rice. Additionally, integrating multiple herbicide-tolerant crops and alternating herbicide use can help delay the evolution of resistant weeds. The development of dual herbicide-tolerant crops, such as those tolerant to both glufosinate and bensulfuron methyl, offers a promising approach for sustainable weed management. The breeding of glufosinate-tolerant rice cultivars presents both opportunities and challenges. While the development of herbicide-tolerant crops can significantly enhance weed control and crop productivity, the potential for gene flow to weedy rice necessitates careful consideration and management. Future research should focus on understanding the ecological impacts of herbicide-resistant weedy rice and developing comprehensive management strategies to mitigate these risks. The integration of genetic, agronomic, and ecological approaches will be crucial in ensuring the sustainable use of herbicide-tolerant technologies in rice cultivation.
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