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Overexpression of a flower‐specific aerolysin‐like protein from the dioecious plant Rumex acetosa alters flower development and induces male sterility in transgenic tobacco
Author(s) -
Manzano Susana,
Megías Zoraida,
Martínez Cecilia,
García Alicia,
Aguado Encarnación,
Chileh Tarik,
LópezAlonso Diego,
GarcíaMaroto Federico,
Kejnovský Eduard,
Široký Jiří,
Kubát Zdeněk,
Králová Tereza,
Vyskot Boris,
Jamilena Manuel
Publication year - 2017
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.13322
Subject(s) - biology , gynoecium , microspore , stamen , tapetum , pollen , genetics , gene , dioecy , botany , transgene , sterility , genetically modified crops , ectopic expression
Summary Sex determination in Rumex acetosa , a dioecious plant with a complex XY 1 Y 2 sex chromosome system (females are XX and males are XY 1 Y 2 ), is not controlled by an active Y chromosome but depends on the ratio between the number of X chromosomes and autosomes. To gain insight into the molecular mechanisms of sex determination, we generated a subtracted cDNA library enriched in genes specifically or predominantly expressed in female floral buds in early stages of development, when sex determination mechanisms come into play. In the present paper, we report the molecular and functional characterization of FEM 32 , a gene encoding a protein that shares a common architecture with proteins in different plants, animals, bacteria and fungi of the aerolysin superfamily; many of these function as β pore‐forming toxins. The expression analysis, assessed by northern blot, RT ‐ PCR and in situ hybridization, demonstrates that this gene is specifically expressed in flowers in both early and late stages of development, although its transcripts accumulate much more in female flowers than in male flowers. The ectopic expression of FEM 32 under both the constitutive promoter 35S and the flower‐specific promoter AP 3 in transgenic tobacco showed no obvious alteration in vegetative development but was able to alter floral organ growth and pollen fertility. The 35S:: FEM 32 and AP 3:: FEM 32 transgenic lines showed a reduction in stamen development and pollen viability, as well as a diminution in fruit set, fruit development and seed production. Compared with other floral organs, pistil development was, however, enhanced in plants overexpressing FEM 32 . According to these effects, it is likely that FEM 32 functions in Rumex by arresting stamen and pollen development during female flower development. The aerolysin‐like pore‐forming proteins of eukaryotes are mainly involved in defence mechanisms against bacteria, fungi and insects and are also involved in apoptosis and programmed cell death ( PCD ), a mechanism that could explain the role of FEM 32 in Rumex sex determination.