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.
Highlights
Fusarium oxysporum, one of the top ten fungal plant pathogens[1], is the causal agent of vascular wilt diseases of more than 120 plant species, provoking severe losses to crop production and the world economy[2,3]
V. montana trees To track the infection process, the Fof-1 pathogen was transformed with the GFP (Green fluorescent protein) label
The hyphae initially attached themselves to the lateral root surface and grew along the junctions of epidermal cells to form a dense network intermingled with root hairs
Summary
One of the top ten fungal plant pathogens[1], is the causal agent of vascular wilt diseases of more than 120 plant species, provoking severe losses to crop production and the world economy[2,3]. Colonization of plants by F. oxysporum leads to necrosis of the infected tissues, collapse of vascular vessels, stunting, progressive wilting and defoliation of leaves, and decay of the plant[4]. Vernicia fordii and Vernicia montana are the two main cultivated species. Compared to V. montana, V. fordii displays faster maturation periods and superior oil characteristics[6]. Tung wilt disease caused by F. oxysporum f. V. montana shows notable resistance against Fusarium wilt disease[8].
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