Induction of systemic resistance in tomato against broomrape (Phelipanche aegyptiaca)

Rhizosphere dwelling bacteria can increase plant resistance to biotic and abiotic stresses, and they promote plant growth through various mechanisms. In this study, three bioassays were conducted including the following: (a) screening for effective bacterial isolates in the suppression of broomrape, (b) evaluating induced systemic resistance against broomrape and (c) comparing the selected bacterium isolate with plant chemical inducers. Fifteen plant growth‐promoting rhizobacteria (PGPR) were examined to assess their biocontrol potential against Egyptian broomrape (Phelipanche aegyptiaca). Ten isolates significantly reduced the broomrape biomass compared to the control. The Lysinibacillus boronitolerans B124 reduced the dry weight of broomrape plants from 2.15 g in control to 0.45 g. Bacillus megaterium B6 was the best isolate in reducing the number of broomrape tubercles. In addition, the activity of three selected bacterial isolates was investigated in induced systemic resistance to broomrape by split‐root method. The Bacillus pumilus INR7 reduced the number of visible broomrape tubercles by 90%, and B. megaterium B71 and L. boronitolerans B124 were the next two in rank. Compared with the control, L. boronitolerans B124 reduced the dry weight of broomrape from 1.49 g in control to 0.39 g. In a subsequent experiment, L. boronitolerans B124 was evaluated along with some resistance‐inducing volatile compounds. Lysinibacillus boronitolerans B124 decreased the number of broomrapes by 87% on average, while the lowest dry weight of broomrape was observed in methyl jasmonate treatment. In conclusion, PGPR have considerable potential to be used in the integrated management of broomrape. It is also possible to use a mixture of rhizobacteria and defence inducers, such as biogenic volatiles as a promising approach in the management of this noxious parasitic weed.