Microtubules (MTs), as transport tracks, play important roles in hyphal-tip growth in filamentous fungi, but MT-associated proteins involved in polarized growth remain unknown. Here, we found that one novel zinc finger protein, FgChy1, is required for MT morphology and polarized growth in Fusarium graminearum. The Fgchy1 mutant presented curved and directionless growth of hyphae. Importantly, the conidia and germ tubes of the Fgchy1 mutant exhibited badly damaged and less-organized beta-tubulin cytoskeletons. Compared with the wild type, the Fgchy1 mutant lost the ability to maintain polarity and was also more sensitive to the anti-MT drugs carbendazim and nocodazole, likely due to the impaired MT cytoskeleton. Indeed, the hyphae of the wild type treated with nocodazole exhibited a morphology consistent with that of the Fgchy1 mutant. Interestingly, the disruption of FgChy1 resulted in the off-center localization of actin patches and the polarity-related polarisome protein FgSpa2 from the hyphal-tip axis. A similar defect in FgSpa2 localization was also observed in the nocodazole-treated wild-type strain. In addition, FgChy1 is also required for conidiogenesis, septation, sexual reproduction, pathogenicity, and deoxynivalenol production. Overall, this study provides the first demonstrations of the functions of the novel zinc finger protein FgChy1 in polarized growth, development, and virulence in filamentous fungi. [ ] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Pathogenesis-related proteins (PRs) are essential for plant defense against both biotic and abiotic stresses. However, knowledge regarding PRs in pears remains limited. In this study, 637 PRs, classified into 16 families, were identified in Pyrus bretschneideri. Phylogenetic, sequence similarity, and secondary structure analyses enabled the classification of several PRs with conserved sequences, including PR-11, PR-8, PR-15, and PR-16. Genomic analysis revealed that the expansion of most PR families resulted from recent whole-genome duplication (WGD) events, occurring approximately 30–45 million years ago (Mya). Various gene duplication mechanisms have collectively contributed to the proliferation of PR families, with purifying selection indicated by the low Ka/Ks ratios. Examination of apoplastic fluid composition showed that only a subset of PRs was present in the apoplast. Transcriptomic data from Pyrus infected with Erwinia amylovora and Colletotrichum fructicola revealed the expression profiles of PR genes post-infection, underscoring the complexity of PR regulation. This study elucidates the evolutionary expansion, regulation, and functional roles of PRs in disease resistance, highlighting certain PRs as reliable markers of pear disease resistance. These findings offer valuable insights for future functional analyses and breeding strategies to enhance pear resistance to pathogens.