Infection of cucumber seedling roots by Pseudomonas amygdali pv. lachrymans following artificial substrate inoculation

Abstract

There are few studies of cucumber roots at the seedling stage infected by Pseudomonas amygdali pv. lachrymans (Pal). We used growth chamber assays to determine the infection of cucumber seedling roots by Pal following artificial substrate inoculation. Symptoms on cucumber roots, leaves, and stems were observed over time. We used real-time fluorescent quantitative PCR (qPCR) to obtain accurate numbers of Pal copies in infected roots, and then statistically assessed the dynamics of Pal copies in roots, stems, and leaves. Results indicated that Pal not only caused root decay, but also damaged the whole plant. Following root infection, the bacteria were transmitted through stems to the leaves. Cucumber seedlings in a moist planting substrate showed lodging, leaf chlorosis and wilt, and rotted roots. This study provides evidence that in moist substrate, Pal can infect cucumber roots and be transmitted throughout the host plant. In addition, the results also provide a foundation for further research on the transmission and proliferation of Pal in cucumber plants under field conditions.