Plant hormones: a fungal point of view

Abstract

SUMMARYMost classical plant hormones are also produced by pathogenic and symbiotic fungi. The way in which these molecules favour the invasion of plant tissues and the development of fungi inside plant tissues is still largely unknown. In this review, we examine the different roles of such hormone production by pathogenic fungi. Converging evidence suggests that these fungal-derived molecules have potentially two modes of action: (i) they may perturb plant processes, either positively or negatively, to favour invasion and nutrient uptake; and (ii) they may also act as signals for the fungi themselves to engage appropriate developmental and physiological processes adapted to their environment. Indirect evidence suggests that abscisic acid, gibberellic acid and ethylene produced by fungi participate in pathogenicity. There is now evidence that auxin and cytokinins could be positive regulators required for virulence. Further research should establish whether or not fungalderived hormones act like other fungal effectors.

Root cortical anatomy is associated with differential pathogenic and symbiotic fungal colonization in maize

“…Adequate consideration of root architecture, root anatomy, and the spatiotemporal distribution of roots and fungal propagules would be useful. Also, defining the relative importance of root phenotypes in the context of other plant phenotypes affecting root–microbe interactions such as plant phytohormone signalling (Chanclud & Morel, ; Pozo, López‐Ráez, Azcón‐Aguilar, & García‐Garrido, ; Venturi & Keel, ) deserves attention.…”

Cytokinin Metabolism of Pathogenic Fungus Leptosphaeria maculans Involves Isopentenyltransferase, Adenosine Kinase and Cytokinin Oxidase/Dehydrogenase

“…Different fungi, both pathogenic or symbiotic, have been reported to produce CKs (Crafts and Miller, 1974; Murphy et al, 1997; Jameson, 2000; Chanclud and Morel, 2016). We have shown that L. maculans produces a wide spectrum of CKs in vitro , present both in the mycelium ( Figure 1 ) and culture medium (Supplementary Figure 1), as well as in planta upon infection in B. napus ( Table 1 ).…”

Cross-talk of the biotrophic pathogen Claviceps purpurea and its host Secale cereale

“…Generally, effectors can modulate the host’s metabolism and directly influence defense reactions thus helping with establishing compatible interactions [5–7]. In addition to these proteinaceous effectors, secreted fungal low-molecular weight compounds like reactive oxygen species [8] or secondary metabolites, like plant hormones [9] have turned out to be important for compatible interactions.…”