Molecular mechanism of Verticillium dahliae-induced leaf senescence

Verticillium dahliae is a soil-borne hemibiotrophic fungus that affects a wide range of hosts, including important crops (such as cotton, tomato, potatoes, cauliflower, and sunflower) and the model plant Arabidopsis (Fradin and Thomma, 2006Fradin E.F. Thomma B.P. Physiology and molecular aspects of Verticillium wilt diseases caused by V. dahliae and V. albo-atrum.Mol. Plant Pathol. 2006; 7: 71-86Crossref PubMed Scopus (593) Google Scholar). V. dahliae infections can result in significant crop losses as no effective fungicides are available at the moment. Upon infection, V. dahliae causes verticillium wilt, leaf chlorosis and cell death, and precocious senescence in host plants (Fradin and Thomma, 2006Fradin E.F. Thomma B.P. Physiology and molecular aspects of Verticillium wilt diseases caused by V. dahliae and V. albo-atrum.Mol. Plant Pathol. 2006; 7: 71-86Crossref PubMed Scopus (593) Google Scholar). Leaf senescence is known to be regulated by developmental age, plant hormones (e.g., ethylene), and a variety of environmental factors (Woo et al., 2019Woo H.R. Kim H.J. Lim P.O. Nam H.G. Leaf senescence: systems and dynamics aspects.Annu. Rev. Plant Biol. 2019; 70: 347-376Crossref PubMed Scopus (233) Google Scholar), but how V. dahliae induces leaf senescence in its host plants is not clear. In this issue, Zhang et al., 2021Zhang Y. Gao Y. Wang H.-L. Kan C. Li Z. Yang X. Yin W. Xia X. Nam H.G. Li Z. et al.Verticillium dahliae secretory effector PevD1 induces leaf senescence by promoting ORE1-mediated ethylene biosynthesis.Mol. Plant. 2021; https://doi.org/10.1016/j.molp.2021.07.014Abstract Full Text Full Text PDF Scopus (22) Google Scholar investigated the molecular mechanism of V. dahliae-mediated leaf senescence in Arabidopsis. The authors discovered that the V. dahliae secretory effector protein, PevD1 (Protein elicitor from V. dahliae 1, a member in the Alt A 1 protein family), positively regulates V. dahliae-induced leaf senescence. Interestingly, they found that PevD1 interacts with ORE1 (ORESARA1), a senescence-associated NAC transcription factor, and stabilizes ORE1 through disrupting its interaction with the RING-type ubiquitin E3 ligase NLA (NITROGEN LIMITATION ADAPTATION). Genetic analysis showed that ORE1 acts downstream of NLA and is also required for PevD1-induced leaf senescence. Furthermore, they showed that ORE1 mediates PevD1-induced ethylene biosynthesis by directly targeting the promoter of ACS6 (1-aminocyclopropane-1-carboxylate synthase 6), a key ethylene biosynthetic gene, to induce its expression (Figure 1). In addition, Zhang et al., 2021Zhang Y. Gao Y. Wang H.-L. Kan C. Li Z. Yang X. Yin W. Xia X. Nam H.G. Li Z. et al.Verticillium dahliae secretory effector PevD1 induces leaf senescence by promoting ORE1-mediated ethylene biosynthesis.Mol. Plant. 2021; https://doi.org/10.1016/j.molp.2021.07.014Abstract Full Text Full Text PDF Scopus (22) Google Scholar extended their study into cotton and revealed a potentially conserved mechanism in V. dahliae-induced leaf senescence between Arabidopsis and cotton. In summary, Zhang et al., 2021Zhang Y. Gao Y. Wang H.-L. Kan C. Li Z. Yang X. Yin W. Xia X. Nam H.G. Li Z. et al.Verticillium dahliae secretory effector PevD1 induces leaf senescence by promoting ORE1-mediated ethylene biosynthesis.Mol. Plant. 2021; https://doi.org/10.1016/j.molp.2021.07.014Abstract Full Text Full Text PDF Scopus (22) Google Scholar identified a PevD1-ORE1-ACS6-ethylene regulatory module and illustrated a molecular mechanism of V. dahliae-induced leaf senescence, thus providing new insights into biotic stress-induced leaf senescence in plants. No conflict of interest declared.