Ralstonia solanacearum differentially modulates soil physciochemical properties and rhizospheric bacteriome of resistant and susceptible flue cured tobacco cultivars

Ralstonia solanacearum, a devastating soilborne pathogen, poses significant yield and economic losses to tobacco production globally. Little is known about the effect of R. solanacearum on rhizopshere bacteriome and soil bio-chemcial properties of resistant and susceptible tobacco cultivars. This study elucidating the impact of R. solanacearum on soil physicochemical properties and rhizosphere bacteriome of resistant (K326) and susceptible (Hongda) tobacco cultivars at different growth periods. Results demonstrated that the contents of available potassium and available phosphorus and as well as soil pH significantly increased in K326 soils (CK and T2) compared with Hongda at 21, 42, and 63 days after post-inoculation (dpi) of R. solanacearum except for available nitrogen which showed an opposite trend. The qPCR findings indicated a substantial reduction in the population of R. solanacearum in the rhizosphere soil of the K326 (T2) compared to the Hongda (T1) at 21 and 63 days post-inoculation (dpi). However, no significant change in R. solanacearum population was seen at 42 dpi. Furthermore, 16S rRNA amplicon sequencing analysis of the rhizosphere bacteriome revealed that the rhizosphere bacterial community composition significantly changed between the two flue-cured tobacco cultivars (Hongda and K326), and that this effect was more persistent after 63 dpi (93 days after post-transplantation), suggesting that each cultivar recruits a unique set of bacterial communities. There was no discernible difference between CK (K326) and T2 (K326), which might perhaps be attributed to the same genetic makeup and inherent resistance of K326 to bacterial wilt infection. Analysis of co-occurrence networks revealed that the microbial network in T1 (Hongda) was more complicated than those in T2 (K326) and CK (K326), while the networks in CK and T2 were almost identical. The present research elucidated the time-course relationship between environmental factors and rhizosphere bacteriome of different flue-cured tobacco cultivars having contrasting resistance to bacterial wilt disease. We conclude that studying the plant-soil-microbe interaction system in succeptible and resistant flue-cured tobacco cultivars may helps use to develop effective integrated disease control plans for healthy production of tobacco crop.