The manifestation of physiological stresses can lead to a variety of unfavorable outcomes, such as oxidative stress, imbalances in nutrient homeostasis, and, in extreme scenarios, plant mortality. Rose is a popular ornamental plant that exhibits vulnerability to crown gall, a pathological condition primarily attributed to the presence of Rhizobium radiobacter (also known as Agrobacterium tumefaciens). In a recent study, impacts of R. radiobacter inoculation on the graft strength, nutrient levels, and oxidative stress of two distinct rose cultivars (‘Angelina’ and ‘Pearl’) in relation to their sensitivity to R. radiobacter were investigated. The research was published in the Journal of Plant Growth Regulation.
Rhizobium radiobacter was inoculated at the grafting site, and the grafted plants were grown for a period of 90 days. The findings indicated that the presence of bacteria in the samples led to more robust graft unions, owing to the development of enlarged calluses (crown galls) that functioned as a potent inherent adhesive. The inoculation of R. radiobacter reduced shoot biomass while promoting root biomass.
The nutrient levels in the infected samples were higher than their levels in the non-infected samples. Consequently, the non-infected samples exhibited higher relative water content (RWC) than the RWC of infected samples.
The infection was caused by R. radiobacter-induced oxidative stress, as evidenced by the elevated levels of malondialdehyde and electrolyte leakage. Following bacterial infection, a decline in catalase (CAT) and an increase in guaiacol peroxidase (GPX) activity were detected. The inoculation of R. radiobacter into the host plant altered the sink/source balance, leading to more accumulation of nutrients in the leaves. Occurrence of oxidative stress, reduction in leaf area, and shoot biomass in the inoculated ‘Angelina’ cultivar were indicative of higher susceptibility of this cultivar to R. radiobacter infection, while the ‘Pearl’ cultivar exhibited higher resistance to R. radiobacter infection, as evidenced by its higher: soluble carbohydrates, soluble protein, and proline contents, and GPX activity compared to ‘Angelina’ cultivar.
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(2023). Impact of Rhizobium radiobacter Inoculation on Physiological Stresses and Nutrients of Grafted Rose (Rosa hybrida L.) Cultivars. Journal of Plant Growth Regulation. 1-13. 10.1007/s00344-023-11180-z.