A Susceptible Scion Reduces Rootstock Tolerance to Ralstonia solanacearum in Grafted Eggplant

Abstract

The bacterial wilt pathogen (Ralstonia solanacearum) is a highly pathogenic soil-borne bacterium that invades the vascular system of a host plant leading to plant wilting and death. In agricultural systems, tolerant rootstocks are usually used to enhance disease resistance and tolerance in crop plants to soil-borne pathogens. Here, two distinct eggplant cultivars with different tolerances to R. solanacearum infection, the disease-tolerant cultivar 'S21 and the disease-susceptible cultivar 'Rf', were used to investigate if scion tolerance level can affect tolerance of rootstock upon an infection of the same pathogen. Three scion/rootstock grafted combinations were considered: Rf/S21, S21/S21, and Rf/Rf. Plants that resulted from the combination Rf/S21, composed of the susceptible scion grafts, showed weak tolerance to R. solanacearum infection, and exhibited the poorest growth compared to the tolerant scion grafts (S21/S21). As expected, the combination Rf/Rf showed the lowest level of disease tolerance. Furthermore, a high level of exopolysaccharides (EPSs) and cell wall degrading enzymes (CWDEs) were detected in susceptible scion grafts. These factors are involved in plant growth inhibition due to blocking transport between scion and rootstock and damage of vascular tissues in the plant. A high level of reactive oxygen species (ROS) and active oxygen scavenging enzymes were also detected in susceptible scion grafts. Excess accumulation of these substances harms the dynamic balance in plant vascular systems. These results indicated that the use of a susceptible scion in scion/rootstock eggplant grafts contributed to a reduction in rootstock tolerance to Ralstonia solanacearum.

Solanum palinacanthum Dunal as a potential eggplant rootstock resistant to root‐knot nematodes

“…This implies that defence intensity to pathogens might be altered depending on the compatibility between grafted plants. Actually, although there are no available research findings on PPN resistance or tolerance as far as we know, one study using reciprocal grafting with eggplant scions and rootstocks found that the susceptible scions impaired rootstock tolerance to the soilborne pathogen Ralstonia solanacearum species complex (Huang et al, 2019). Baker, 1985).…”

The effects of pumpkin rootstock on photosynthesis, fruit mass, and sucrose content of different ploidy watermelon (Citrullus lanatus)

“…It remains possible that the genes encoding IAI, SPS, and SuSy in grafted watermelon lines were downregulated by pumpkin rootstock. The grafted plant always maintains the exchange of substances between scion and rootstock, for example, various types of plant RNA species move from cell to cell or systemically to potentially regulate grafted plant physiological processes (Lewsey et al 2016, Huang et al 2019. Pumpkins generally accumulate lower amounts of sugar in fruit than cultivated watermelon varieties.…”

Defense Response to Hemileia vastatrix in Susceptible Grafts onto Resistant Rootstock of Coffea arabica L.

“…This shows that the susceptibility of the plant to pathogens can vary, depending on the characteristics of the graft and rootstock used. For example, it was observed that a susceptible graft could affect the response to the soil borne pathogen Ralstonia solanacearum in an eggplant rootstock [76]. This would indicate that the expression of the NBS-LRR genes associated with the gene-forgene resistance [77][78][79][80] in grafted plants could be mediated by the rootstock.…”