Endophytic Lelliottia nimipressuralis G24: A Potential Biocontrol Agent for Managing Phelipanche aegyptiaca

The root parasitic weed Phelipanche aegyptiaca poses a serious threat to tomato production in arid regions of Northwest China, yet effective and environmentally friendly control measures remain limited. In this study, an endophytic bacterial strain G24 with strong inhibitory activity against P. aegyptiaca seed germination was isolated from healthy tomato tissues. In vitro germination assays showed that both the fermentation broth and cell-free supernatant of G24 completely inhibited seed germination even at 1000-fold dilution, indicating that the active metabolites are extracellularly produced or released. Pot experiments further demonstrated that G24 inoculation significantly reduced the number, fresh weight, and dry weight of parasitic broomrape nodules on tomato roots, with reductions of 69.4%, 89.0%, and 88.6%, respectively, compared with the control. Moreover, G24 significantly increased tomato stem diameter, indicating its intrinsic plant growth-promoting capacity. Although both sterile NB medium and G24 suspension increased whole-plant fresh weight, no statistically significant difference was observed between the two treatments (p > 0.05). The reduced leaf chlorophyll concentration per unit fresh weight in G24-treated tomatoes was a typical growth dilution effect and did not suppress overall plant performance, and no phytotoxicity was detected. Based on morphological, physiological-biochemical, and multilocus phylogenetic analyses (16S rDNA, gyrB, and rpoB), strain G24 was identified as Lelliottia nimipressuralis. As a native endophyte of tomato, L. nimipressuralis G24 exhibits excellent host compatibility, biocontrol efficacy, and growth-promoting activity, with no adverse effects on tomato development. This study expands the application potential of the genus Lelliottia in parasitic weed management and provides a novel microbial resource for the integrated and sustainable control of P. aegyptiaca.