AUTHOR=Zhang Yafen , Hu Yingli , Cao Qianchao , Yin Yumei , Xia Wenqiang , Cui Haifeng , Yu Xiaoping , Ye Zihong 

TITLE=Functional Properties of the MAP Kinase UeKpp2 in Ustilago esculenta

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.01053

DOI=10.3389/fmicb.2020.01053

ISSN=1664-302X

ABSTRACT=<p><italic>Ustilago esculenta</italic> undergoes an endophytic life cycle in <italic>Zizania latifolia</italic>. It induces the stem of its host to swell, forming the edible galls called <italic>jiaobai</italic> in China, which are the second most commonly cultivated aquatic vegetable in China. <italic>Z. latifolia</italic> raised for <italic>jiaobai</italic> can only reproduce asexually because the <italic>U. esculenta</italic> infection completely inhibits flowering. The infection and proliferation in the host plants during the formation of edible gall differ from those of conventional pathogens. Previous studies have shown a close relationship between mitogen-activated protein kinase (MAPK) and fungal pathogenesis. In this study, we explored the functional properties of the MAPK UeKpp2. Cross-species complementation assays were carried out, which indicated a functional complementation between the <italic>UeKpp2</italic> of <italic>U</italic>. <italic>esculenta</italic> and the <italic>Kpp2</italic> of <italic>Ustilago maydis</italic>. Next, <italic>UeKpp2</italic> mutants of the UeT14 and the UeT55 sporidia background were generated; these showed an aberrant morphology of budding cells, and attenuated mating and filamentous growth <italic>in vitro</italic>, in the context of normal pathogenicity. Interestingly, we identified another protein kinase, UeUkc1, which acted downstream of UeKpp2 and may participate in the regulation of cell shape. We also found a defect of filamentous growth in <italic>UeKpp2</italic> mutants that was not related to a defect of the induction of mating-type genes but was directly related to a defect in <italic>UeRbf1</italic> induction. Overall, our results indicate an important role for UeKpp2 in <italic>U</italic>. <italic>esculenta</italic> that is slightly different from those reported for other smut fungi.</p>