Legume Genomics and Genetics 2025, Vol.16, No.5, 215-224 http://cropscipublisher.com/index.php/lgg 218 arbitrary base replacement, with higher flexibility and a lower off-target rate (Zhu and Zhu, 2022). Although these two new tools are still in the "experimental exploration" stage on lentils, judging from the results of other crops, they have every potential to precisely improve the traits of lentils without introducing exogenous genes. 3.3 Delivery methods and transformation systems in lentils Ultimately, no matter how advanced the editing tools are, they can only function effectively through the step of "sending in". And this is precisely the point that has always been a headache in lentil breeding. Agrobacterium-mediated method is still the most commonly used one at present. Usually, the hypocotyl or apical embryo is selected as the explant, which can increase the regeneration rate and transformation success rate. However, things did not go so smoothly. Like many leguminous plants, lentils are inherently difficult to "transform"-with low transformation efficiency and hard regeneration, which has almost become a common problem (Baloglu et al., 2022). To bypass this bottleneck, researchers are also exploring other routes, such as using gene guns to inject, using protoplasts for transient transfection, and even using nanoparticles as "couriers", attempting to complete the delivery without damaging the tissue (Ahmar et al., 2021). Although these methods are still being refined, at least the path of gene editing with broad beans is gradually moving from being "stuck" to being "open to traffic". 4 Current Progress in Herbicide-Resistant Lentil Development 4.1 Targeted editing of ALS and EPSPS genes In the herbicide-resistant breeding of lentils, the ALS gene can basically be said to be the "highlight". This path has already been targeted by many studies. In the past, researchers often treated lentils with chemical mutagens such as EMS or sodium azide, and then screened out variants that showed resistance to ALS-suppressing herbicides (such as metochon and metochon) (Rizwan et al., 2017). For instance, in some mutant strains, the ALS activity has increased, but the response to herbicides has weakened. Clearly, this provides a good starting point for resistance (Shivani et al., 2022). Of course, ALS is not the only target; EPSPS are also involved, although their role is relatively weak. Interestingly, a mutation named Ala251Thr was also discovered in the psbA gene within chloroplasts. This change led to resistance in certain lentil strains to the PSII inhibitor metochlor, representing a novel target resistance mechanism. 4.2 Development of gene-edited lines under field conditions Just conducting mutations in the laboratory is not enough; the lentils must be able to "withstand wind and rain". Therefore, some strains have been brought to the fields for testing and have also been compared and verified in different environments. Based on the current data, some lentils that have undergone mutagenesis or genetic modification treatment have shown stable performance. Not only do they have good resistance, but their agronomic traits have also not been compromised. For instance, ALS or psbA mutant strains with a 33-fold increase in resistance to metochlor not only performed well in greenhouses but also managed to hold their ground in real field conditions (McMurray et al., 2019). In addition, some people introduced the bar gene into lentils using Agrobacterium, and as a result, they successfully obtained plants that could survive under high-intensity herbicide pressure. This has enabled the herbicide-resistant breeding of lentils to move from a "theoretical plan" to "practical implementation". 4.3 Comparative performance with non-edited varieties Judging from the results, the edited lentils were indeed more resilient when herbicides were applied than the common varieties. The fact that the yield has not decreased, the plants are healthy, and the entire growth process is relatively stable all make resistant varieties more attractive in practical applications. But then again, not every resistant strain is so perfect. Especially for those gene mutations that occur in chloroplasts, sometimes there will be a decrease in photosynthetic efficiency or fluctuations in yield (McMurray et al., 2021). Overall, however, the performance of some mutant strains remains impressive, even surpassing that of the original varieties, which endows them with considerable potential for subsequent breeding and commercial promotion (McMurray et al., 2018).
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