Effect Of Watermelon Companion With Wheat On Fusarium Wilt And Soil Microorganism

Watermelon?Citrullus lanatus?Thunb.?Matsum & Nakai?was defined as a kind of common greenhouse crops,in which the incidences of watermelon diseases?especially for the watermelon fusarium wilt?induced by expansions of the cultivation were increased with the area in recent years.Previously,the researchers pointed that the incidences of watermelon fusarium wilt were reduced by companion with the wheat,indicating that the photosynthetic performance and related enzyme activity were elevated and simultaneously the growth of Fusarium oxyxporum f.sp niveum?FON?was suppressed by the wheat root exudates.However,literatures about efficacy of watermelon root exudates on the FON and changes of the soil microorganism community were not illustrated by planting watermelon companion with wheat.In this research,the effects of watermelon root exudates on spore germination and mycelium growth of FON in vitro were investigated;Furthermore,the abundance,structure and composition of rhizosphere soil microbial communities were measured by q-PCR and Miseq,respectively.We aimed to unravel the effects of watermelon root exudates on FON and the soil microorganism,thus providing the theoretical basis and technical support.The main results were as follows:?1?Under hydroponic conditions the dry weight of shoot in watermelon companion with wheat was significantly decreased?p<0.05?.However,inoculating FON significantly promoted the growth of roots?p<0.05?.Plus,under pot culture the growth of watermelon with inoculation FON was significantly enhanced by companion with wheat?p<0.05?.?2?There were no significant differences in incidences of the watermelon fusarium wilt between the monoculture and companion?p>0.05?,while the index of disease was significantly attenuated?p<0.05?.?3?The root exudates of watermelon companion with wheat notably suppressed colony growth and spore germination of FON by inoculation of FON or not?p<0.05?.The inhibition rates of FON colony growth and spore by inoculating FON were 7.1% and 32.9%,respectively.?4?By q-PCR analysis the results demonstrated that there existed no differences inrelative abundance of Pseudomonas and FON in the monoculture and companion of watermelon root exudates?p>0.05?.The relative abundance of Pseudomonas were not changed under the condition of companion and inoculation FON?p>0.05?.Under inoculation FON,compared with monoculture,the companion significantly decreased the relative abundance of Fusarium?p<0.05?;the relative abundance of Fusarium was lower in the companion with wheat side thanwithout wheat side?p<0.05?,while there were no differences inoculation FON or not in the companion with wheat side?p>0.05?,indicating that the wheat played the important role in companion system for pathogens.?5?Miseq sequencing results showed that at the phylum level,the main communities were Proteobacteria,Bacteroidetes,Actinobacteria,Acidobacteria in the bacterial and Ascomycota,Zygomycota,Basidiomycota in the fungal.The bacterial and fungal structures among the monoculture were similar in the companion system at the genus level.As for bacterial,with compared of the monoculture with inoculation and the companion with inoculation FON?without wheat side?,the relative abundant of Devosia were higher in the companion with inoculation FON?wheat side??p=0.017?.However,there were no differences between the monoculture with inoculation FON and the companion with inoculation FON?without wheat side??p>0.05?.The companion with non-inoculation FON?with wheat side?increased the abundant of Devosia,Dyadobacter,Luteimonas,Lysobacte?p=0.017,p=0.047,p=0.021,p=0.046?and decreased the abundant of norank_oSubgroup₆,Haliangium,Rhodoplanes,norank_fRB41 with compared the monoculture without inoculation FON?p=0.016,p=0.026,p=0.015,p=0.040?.The abundant of communities between the monoculture without inoculation FON and the companion with non-inoculation FON?without wheat side?were no different?p>0.05?.There were similar abundant of communities between the monoculture and the companion weather inoculation or not?p>0.05?.At the genus level of fungal,the relative abundant of Olpidium was higher in the companion with inoculation FON?without wheat side?than the monoculture with inoculation FON?p=0.043?.The companion with inoculation FON had lower relative abundant of Fusarium and Nectriaceae-unclassified?p=0.036,p=0.012?while it were no differences among the treatment in the companion system?p>0.05?.Under non-inoculation FON condition,the companion changed the structure of bacterial community and the companion?with wheat side?decreased the Shannon of bacteria?p<0.05?.Under inoculation FON condition,the companion changed the structure and constitute of fungal community and decreased the Shannon of fungal?p<0.05?.In summary,companion with wheat promoted the growth of watermelon and attenuated the disease indexes of watermelon fusarium wilt.The companion with wheat side decreased the abundances of Fusarium,and the companion changed the fungal community under inoculation FON condition,however,it was not effect on the bacterial community.