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Tuberculate fruit gene Tu encodes a C 2 H 2 zinc finger protein that is required for the warty fruit phenotype in cucumber ( Cucumis sativus L.)
Author(s) -
Yang Xuqin,
Zhang Weiwei,
He Huanle,
Nie Jingtao,
Bie Beibei,
Zhao Junlong,
Ren Guoliang,
Li Yue,
Zhang Dabing,
Pan Junsong,
Cai Run
Publication year - 2014
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.12531
Subject(s) - biology , cucumis , trichome , gene , zinc finger , phenotype , epidermis (zoology) , mutant , microbiology and biotechnology , botany , genetics , transcription factor , anatomy
Summary Cucumber fruits that have tubercules and spines (trichomes) are known to possess a warty (Wty) phenotype. In this study, the tuberculate fruit gene Tu was identified by map‐based cloning, and was found to encode a transcription factor (TF) with a single C 2 H 2 zinc finger domain. Tu was identified in all 38 Wty lines examined, and was completely absent from all 56 non‐warty ( nW ty) lines. Cucumber plants transgenic for Tu (TCP) revealed that Tu was required for the Wty fruit phenotype. Subcellular localization showed that the fusion protein GFP–Tu was localized mainly to the nucleus. Based on analyses of semi‐quantitative and quantitative reverse transcription polymerase chain reaction (RT‐PCR), and mRNA in situ hybridization, we found that Tu was expressed specifically in fruit spine cells during development of fruit tubercules. Moreover, cytokinin ( CTK ) content measurements and cytological observations in Wty and nW ty fruits revealed that the Wty fruit phenotype correlated with high endogenous CTK concentrations. As a result of further analyses on the transcriptomic profile of the nW ty fruit epidermis and TCP fruit warts, expression of CTK ‐associated genes, and hormone content in nW ty fruit epidermis, Wty fruit warts and epidermis, and TCP fruit warts and epidermis, we found that Tu probably promoted CTK biosynthesis in fruit warts. Here we show that Tu could not be expressed in the glabrous and tubercule‐free mutant line gl that contained Tu , this result that futher confirmed the epistatic effect of the trichome (spine) gene Gl over Tu . Taken together, these data led us to propose a genetic pathway for the Wty fruit trait that could guide future mechanistic studies.