Root-knot nematodes (RKNs) are plant pests that infect the roots of host plants. Bacillus thuringiensis (Bt) nematicidal proteins exhibited toxicity to nematodes. However, the application of nematicidal proteins for plant protection is hampered by the lack of effective delivery systems in transgenic plants. In this study, we discovered the accumulation of leucoplasts (root plastids) in galls and RKN-induced giant cells. RKN infection causes the degradation of leucoplasts into small vesicle-like structures, which are responsible for delivering proteins to RKNs, as observed through confocal microscopy and immunoelectron microscopy. We showed that different-sized proteins from leucoplasts could be taken up by Meloidogyne incognita female. To further explore the potential applications of leucoplasts, we introduced the Bt crystal protein Cry5Ba2 into tobacco and tomato leucoplasts by fusing it with a transit peptide. The transgenic plants showed significant resistance to RKNs. Intriguingly, RKN females preferentially took up Cry5Ba2 protein when delivered through plastids rather than the cytosol. The decrease in progeny was positively correlated with the delivery efficiency of the nematicidal protein. In conclusion, this study offers new insights into the feeding behavior of RKNs and their ability to ingest leucoplast proteins, and demonstrates that root leucoplasts can be used for delivering nematicidal proteins, thereby offering a promising approach for nematode control.

中文翻译：

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通过在根白质体中表达 Bt 杀线虫蛋白来有效控制根结线虫


根结线虫 （RKN） 是感染寄主植物根部的植物害虫。苏云金芽孢杆菌 （Bt） 杀线虫蛋白对线虫具有毒性。然而，由于转基因植物中缺乏有效的递送系统，杀线虫蛋白在植物保护中的应用受到阻碍。在这项研究中，我们发现了白质体 （根质体） 在瘿和 RKN 诱导的巨细胞中的积累。RKN 感染导致白质体降解成小囊泡状结构，这些结构负责将蛋白质递送到 RKN，如共聚焦显微镜和免疫电子显微镜观察到的那样。我们表明，来自白质体的不同大小的蛋白质可以被 Meloidogyne incognita 雌性吸收。为了进一步探索白质体的潜在应用，我们将 Bt 晶体蛋白 Cry5Ba2 与转运肽融合，将其引入烟草和番茄白质体中。转基因植物对 RKN 表现出显着的抗性。有趣的是，当通过质体而不是胞质溶胶递送时，RKN 雌性优先吸收 Cry5Ba2 蛋白。后代的减少与杀线虫蛋白的递送效率呈正相关。总之，本研究为 RKNs 的摄食行为及其摄取白细胞蛋白的能力提供了新的见解，并证明了根白质体可用于递送杀线虫蛋白，从而为线虫控制提供了一种有前途的方法。