AaCaMKs Positively Regulate Development, Infection Structure Differentiation and Pathogenicity in Alternaria alternata, Causal Agent of Pear Black Spot

Abstract

Calcium/calmodulin-dependent protein kinase (CaMK), a key downstream target protein in the Ca2+ signaling pathway of eukaryotes, plays an important regulatory role in the growth, development and pathogenicity of plant fungi. Three AaCaMKs (AaCaMK1, AaCaMK2 and AaCaMK3) with conserved PKC_like superfamily domains, ATP binding sites and ACT sites have been cloned from Alternaria alternata, However, their regulatory mechanism in A. alternata remains unclear. In this study, the function of the AaCaMKs in the development, infection structure differentiation and pathogenicity of A. alternata was elucidated through targeted gene disruption. The single disruption of AaCaMKs had no impact on the vegetative growth and spore morphology but significantly influenced hyphae growth, sporulation, biomass accumulation and melanin biosynthesis. Further expression analysis revealed that the AaCaMKs were up-regulated during the infection structure differentiation of A. alternata on hydrophobic and pear wax substrates. In vitro and in vivo analysis further revealed that the deletion of a single AaCaMKs gene significantly reduced the A. alternata conidial germination, appressorium formation and infection hyphae formation. In addition, pharmacological analysis confirmed that the CaMK specific inhibitor, KN93, inhibited conidial germination and appressorium formation in A. alternata. Meanwhile, the AaCaMKs genes deficiency significantly reduced the A. alternata pathogenicity. These results demonstrate that AaCaMKs regulate the development, infection structure differentiation and pathogenicity of A. alternata and provide potential targets for new effective fungicides.

A tau class glutathione S‐transferase in tea plant, CsGSTU45, facilitates tea plant susceptibility to Colletotrichum camelliae infection mediated by jasmonate signaling pathway

“…Total RNA was extracted from tea plant leaves using the FastPure Plant Total RNA Isolation Kit (Polysaccharides and Polyphenolics‐rich) (Nanjing Vazyme Biotech Co., Ltd., China), and single‐strand cDNA was synthesized by the HiScript II 1st Strand cDNA Synthesis Kit (+gDNA wiper) (Nanjing Vazyme Biotech Co.). qRT–PCR analysis was performed as previously described (Jiang, Cao, et al., 2023; Jiang, Li, et al., 2023). The data were normalized to the expression of CsPTB (Cao et al., 2022).…”

Genome sequencing and comparative genomics reveal insights into pathogenicity and evolution of Fusarium zanthoxyli, the causal agent of stem canker in prickly ash

“…For example, Mps1p , a PKc gene in M. oryzae , is a stealth factor that conceals the cell wall of infectious hyphae and prevents recognition by hosts [ 80 ]. Previous studies have shown that three AaCaMKs genes encoding PKc_like kinases in A. alternata regulate infection structure differentiation and pathogenicity [ 81 ]. The APH_ChoK_Like family employs ATP-mediated phosphate transfer to chemically modify and inactivate aminoglycoside antibiotics such as streptomycin and kanamycin [ 82 ].…”

Aabrm1-mediated melanin synthesis is essential to growth and development, stress adaption, and pathogenicity in Alternaria alternata

“…Research has also found that both melanin synthesis and infection of cotton by V. dahliae are coupled through transmembrane protein VdSho1 , and the MAPK signal module Ste50-Ste11-Ste7 is involved in this coupling process ( Li et al, 2019 ). In A. alternata , sho-MAPK, cAMP, and Ca 2+ signaling pathways are involved in infection structure formation induced by physicochemical cues from pear fruit peel wax, affecting the synthesis of melanin at the same time ( Liu et al, 2021 ; Zhang et al, 2021 ; Jiang et al, 2023 ). The above reports suggest that melanin may be directly or indirectly involved in infection structure formation or infection process in plant pathogenic fungi, which only form colorless appressorium.…”