D6 protein kinase in root xylem benefiting resistance to Fusarium reveals infection and defense mechanisms in tung trees

Abstract

Fusarium oxysporum, a global soil-borne pathogen, causes severe disease in various cultivated plants. The mechanism underlying infection and resistance remains largely elusive. Vernicia fordii, known as the tung tree, suffers from disease caused by F. oxysporum f. sp. fordiis (Fof-1), while its sister species V. montana displays high resistance to Fof-1. To investigate the process of infection and resistance ability, we demonstrated that Fof-1 can penetrate the epidermis of root hairs and then centripetally invade the cortex and phloem in both species. Furthermore, Fof-1 spread upwards through the root xylem in susceptible V. fordii trees, whereas it failed to infect the root xylem in resistant V. montana trees. We found that D6 PROTEIN KINASE LIKE 2 (VmD6PKL2) was specifically expressed in the lateral root xylem and was induced after Fof-1 infection in resistant trees. Transgenic analysis in Arabidopsis and tomato revealed that VmD6PKL2 significantly enhanced resistance in both species, whereas the d6pkl2 mutant displayed reduced resistance against Fof-1. Additionally, VmD6PKL2 was identified to interact directly with synaptotagmin (VmSYT3), which is specifically expressed in the root xylem and mediates the negative regulation responding to Fof-1. Our data suggested that VmD6PKL2 could act as a resistance gene against Fof-1 through suppression of VmSYT3-mediated negative regulation in the lateral root xylem of the resistant species. These findings provide novel insight into Fusarium wilt resistance in plants.

Genome-wide association study for resistance to Pseudomonas syringae pv. garcae in Coffea arabica

“…The gene g000 (Chr0) has a functional annotation for serine/threonine-protein kinase D6PKL2. In Zhang et al. (2021) this protein was described as specifically expressed after Fusarium oxysporum infection in Vernicia montana resistant trees.…”

“…The gene g000 (Chr0) has a functional annotation for serine/threonine-protein kinase D6PKL2. In Zhang et al (2021) this protein was described as specifically expressed after Fusarium oxysporum infection in Vernicia montana resistant trees. Furthermore, transgenic analysis in Arabidopsis and tomato revealed that D6PKL2 significantly enhanced resistance in both species, whereas the d6pkl2 mutant displayed reduced resistance against F. oxysporum (Zhang et al, 2021).…”

“…In Zhang et al (2021) this protein was described as specifically expressed after Fusarium oxysporum infection in Vernicia montana resistant trees. Furthermore, transgenic analysis in Arabidopsis and tomato revealed that D6PKL2 significantly enhanced resistance in both species, whereas the d6pkl2 mutant displayed reduced resistance against F. oxysporum (Zhang et al, 2021). The gene g000156 (Chr_10_sg_C) has orthology with an Arabidopsis gene that encondes a serine/threonine-kinase endoribonuclease IRE1alike protein.…”