title: Molecular evolution and functional divergence of tubulin superfamily in the fungal tree of life.
abstract: Microtubules are essential for various cellular activities and β-tubulins are the target of benzimidazole fungicides. However, the evolution and molecular mechanisms driving functional diversification in fungal tubulins are not clear. In this study, we systematically identified tubulin genes from 59 representative fungi across the fungal kingdom. Phylogenetic analysis showed that α-/β-tubulin genes underwent multiple independent duplications and losses in different fungal lineages and formed distinct paralogous/orthologous clades. The last common ancestor of basidiomycetes and ascomycetes likely possessed two paralogs of α-tubulin (α1/α2) and β-tubulin (β1/β2) genes but α2-tubulin genes were lost in basidiomycetes and β2-tubulin genes were lost in most ascomycetes. Molecular evolutionary analysis indicated that α1, α2, and β2-tubulins have been under strong divergent selection and adaptive positive selection. Many positively selected sites are at or adjacent to important functional sites and likely contribute to functional diversification. We further experimentally confirmed functional divergence of two β-tubulins in Fusarium and identified type II variations in FgTub2 responsible for function shifts. In this study, we also identified δ-/ε-/η-tubulins in Chytridiomycetes. Overall, our results illustrated that different evolutionary mechanisms drive functional diversification of α-/β-tubulin genes in different fungal lineages, and residues under positive selection could provide targets for further experimental study.
authors.affiliation: NWAFU-PU Joint Research Center, State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China.
authors.forename: Zhongtao
authors.initials: Z
authors.lastname: Zhao
authors.affiliation: NWAFU-PU Joint Research Center, State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China.
authors.forename: Huiquan
authors.initials: H
authors.lastname: Liu
authors.affiliation: NWAFU-PU Joint Research Center, State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China.
authors.forename: Yongping
authors.initials: Y
authors.lastname: Luo
authors.affiliation: Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907, USA.
authors.forename: Shanyue
authors.initials: S
authors.lastname: Zhou
authors.affiliation: NWAFU-PU Joint Research Center, State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China.
authors.forename: Lin
authors.initials: L
authors.lastname: An
authors.affiliation: NWAFU-PU Joint Research Center, State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China.
authors.forename: Chenfang
authors.initials: C
authors.lastname: Wang
authors.affiliation: NWAFU-PU Joint Research Center, State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China.
authors.forename: Qiaojun
authors.initials: Q
authors.lastname: Jin
authors.affiliation: College of Plant Protection, Nanjing Agricultural University, Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Key Laboratory of Pesticide, Nanjing, Jiangsu 210095, China.
authors.forename: Mingguo
authors.initials: M
authors.lastname: Zhou
authors.affiliation: 1] NWAFU-PU Joint Research Center, State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi 712100, China [2] Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907, USA.
authors.forename: Jin-Rong
authors.initials: JR
authors.lastname: Xu
mesh_terms: D019143:Evolution, Molecular; D005658:Fungi / Q000235:genetics*; D014644:Genetic Variation; D005810:Multigene Family / Q000235:genetics*; D010802:Phylogeny; D014404:Tubulin / Q000235:genetics* / Q000378:metabolism
chemical_list: D014404:Tubulin