Cytokinin Inhibits Fungal Development and Virulence by Targeting the Cytoskeleton and Cellular Trafficking

Abstract

Cytokinins (CKs), important plant growth/developmental hormones, have previously been associated with host disease resistance. Here, we demonstrate that CK directly inhibits the growth, development, and virulence of B. cinerea ( Bc ) and many additional phytopathogenic fungi.

Cytokinin Regulates Energy Utilization in Botrytis cinerea

“…2 ), as the Lifeact-transformed B. cinerea has abnormal growth ( 39 ) and did not grow well in our defined media. As reported previously by our group ( 38 ), we observed mislocalization of actin, which is normally localized to growing hyphal tips ( 40 , 41 ), upon CK treatment in full PDB. Fungal cells grown in 1/4 medium displayed reduced actin polarization compared with those grown in full medium ( Fig.…”

“…Although medium acidification was slightly stronger in media 3 and 4, the levels were similar in full medium (medium 1) and medium with restricted glucose (medium 2), suggesting that the medium pH is not the source of the observed alterations in CK activity upon glucose restriction. Growth inhibition of B. cinerea by CK in rich medium was previously reported by our group ( 38 ).…”

“…We previously conducted transcriptome profiling on B. cinerea treated with CK (6-BAP), finding downregulation upon CK treatment of a variety of growth and developmental pathways in B. cinerea , including inhibition of cell division, DNA replication, endocytosis, and the actin cytoskeleton ( 38 ). Given that we found the effect of CK to depend on the nutritional context ( Fig.…”

“…Recently, we have found that CK inhibits the growth of a variety of plant-pathogenic fungi. In-depth characterization of the phenomenon in B. cinerea revealed that CK in plant physiological concentrations can inhibit the sporulation, spore germination, and virulence ( 38 ) of B. cinerea . We also found CK to affect both budding and fission yeast.…”

“…We also found CK to affect both budding and fission yeast. Transcriptome profiling of B. cinerea grown with CK revealed that DNA replication and the cell cycle, cytoskeleton integrity, and endocytosis, are all repressed by CK ( 38 ).…”