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The Arabidopsis F-box/Kelch-Repeat Protein At2g44130 Is Upregulated in Giant Cells and Promotes Nematode Susceptibility

We report that the F-box/Kelch-repeat protein At2g44130 is specifically induced by the root-knot nematode Meloidogyne incognita during the initial stages of the initiation and maintenance of the feeding site. In addition, we show that the expression of this gene promotes susceptibility of infection because knocking down the F-box gene (At2g44130) drastically reduces nematode attraction to and infection of roots. In contrast, F-box overexpressing (OE) lines had a hypersusceptible phenotype, with an increase of 34% in nematode attraction and 67% in nematode infection when grown in soil. This hypersusceptibility might be the result of an increased attraction of the second-stage juveniles toward root exudates of the F-box OE, which would suggest that the blend of compounds in the root exudates of the OE line was somewhat different from the ones present in the root exudates of the wild type and the F-box knockout and tilling lines. Although the function of the F-box/Kelch-repeat protein (At2g44130) is not known, we postulate that its activation by nematode effectors released during the infection process leads to the formation of SCF^(At2g44130) (Skp1-Cullin1-F-box protein) complexes, which are involved in facilitating successful infection by the nematode through targeting specific proteins for degradation.