Difference of rhizobacterial community structure between bacterial wilt infected and healthy tomato plants in a substrate culture system

Abstract:

[Objective] To investigate the relationship between rhizobacterial community structure and bacterial wilt occurrence of tomato plants in a substrate culture system with the integration of water,fertilizers,and biocontrol agents.[Methods] After the field survey,the disease incidence (DI) and disease severity index (DSI) of bacterial wilt were calculated.Furthermore,the high-throughput sequencing technology was adopted to compare the rhizobacterial diversity and composition between infected and healthy tomato plants.[Results] The DI (6.17%) and DSI (5.11) of tomato plants at the reproductive stage were significantly higher than those at the vegetative stage (DI of 2.5% and DSI of 1.25,respectively).The number of Ralstonia solanacearum in the rhizosphere of diseased tomato plants at the early infection stage (grades 1 and 2) was much higher than that at the later infection stage (grades 3 and 4).Both Chao 1 and Shannon indexes of bacteria in the rhizosphere of diseased tomato plants were significantly lower than those in the rhizosphere of health plants.Compared with that in the rhizosphere of healthy plants,the relative abundance of Proteobacteria increased while that of Acidobacteriota and Cyanobacteria decreased (P<0.01);the relative abundance of Rhodanobacter and Ralstonia significantly increased,which was positively correlated with the number of R. solanacearum as demonstrated by redundancy analysis;the relative abundance of Bradyrhizobium,Granulicella,Haliangium,and Devosia significantly decreased (P<0.05),which was negatively correlated with the number of R. solanacearum.[Conclusion] Compared with those in the rhizosphere of healthy plants,the bacterial diversity and beneficial bacteria in the rhizosphere of tomato plants infected with bacterial wilt significantly reduced.Therefore,the addition of beneficial bacteria to change rhizobacterial community structure would be an efficient method to control tomato bacterial wilt.

Key words:tomato bacterial wilt;Ralstonia solanacearum;rhizosphere;rhizobacterial community structure;high-throughput sequencing