| Beauveria bassiana,a kind of entomopathogenic fungi,is widely distributed in nature and used for pest biological control.Recent studies have shown that B.bassiana could enter plants through different ways,and promoted plant growth,improved plant resistance against pathogenic fungi and pest stress.At present,the conidia of B.bassiana are the main research object,while there are few reports on the endophytic colonization and disease resistance of the fungal blastspores.In this study,the blastspores of B.bassiana and tomato plants were selected as research objects to explore the fuangal colonization in plants,and the effects on plant growth and fruits yield,as well as the mechanism on improving the resistance of host plants against Botrytis cinerea,a plant pathogenic fungi with a wide host range.It provided a useful reference and a new way for the control of B.cinerea.The main results of this study are as follows:(1)After 2 d of tomato inoculation with B.bassiana,the colonization rates of different types of spores were determined using tissue isolation,both B.bassiana blastospores and aerial conidia could successfully colonize tomato,the colonization rate of the blastospores was higher than that of the aerial conidia,which up to more than 40%,by the root irrigation method.Notebly,the germinated hyphae was observed after the balstspores colonized in tomato leaves.(2)Endophytic colonization with B.bassiana significantly enhanced tomato resistance against B.cinerea,and which of the blastospores was higher than that of the aerial conidia.Pot and plot experiments showed that the disease incidence in the group treated with B.bassiana +B.cinerea(hereafter referred to as BS + Bc)was significantly lower than that in the group treated with B.cinerea alone(hereafter referred to as Bc)after B.cinerea inoculation on tomato,with 43.33% and 53.34% lower disease incidence in pot experiments,and 33.47% lower disease incidence in the plot experiment,respectively.(3)After tomato inoculated with B.bassiana blastospores for 21 d,the contents of B.bassiana in the root soil of the treated group with BS + BC were detected to be significantly higher than that in the group inoculated with blastospores(hereafter referred to as BS)and the contents of B.cinerea were higher than those of the treated group with Bc.These results showed that after endophytic colonization by B.bassiana,B.bassiana concentrated in the tomato plants under the stress of B.cinerea and inhibited B.cinerea infection to enhance tomato resistance against B.cinerea.(4)B.bassiana could enhance the resistance of tomato against B.cinerea by regulating resistance-associated gene.The content of oxalic acid in the suspension of B.bassiana spores was 1.26 g/l.Oxalate oxidase(OXO)gene was up-regulated in the BS + Bc group 7 days after inoculation with B.cinerea and in the BS group before inoculation with B.cinerea,the expression levels of salicylic acid(SA)pathway-related gene chitinase(CHI)gene and jasmonic acid(JA)pathway-related gene ATP synthase(atp A)gene were significantly up-regulated.(5)B.bassiana colonization in tomato could significantly increase the number of fruits per plant.Compared with the control,BS showed no significant effect on plant height,root development and underground biomass of tomato after colonization by B.bassiana.However,after harvest,the number of fruits per plant in BS treatment was significantly higher than that in control,and the total yield of fruit in BS treatment were significantly higher than that in control. |
