CLO/GFA1 and ATO are novel regulators of gametic cell fate in plants.
The formation of gametes is a key step in the life cycle of any sexually reproducing organism. In flowering plants, gametes develop in haploid structures termed gametophytes that comprise a few cells. The female gametophyte forms gametic cells and flanking accessory cells. During a screen for regulators of egg-cell fate, we isolated three mutants, lachesis (lis), clotho (clo) and atropos (ato), that show deregulated expression of an egg-cell marker. We have previously shown that, in lis mutants, which are defective for the splicing factor PRP4, accessory cells can differentiate gametic cell fate. Here, we show that CLOTHO/GAMETOPHYTIC FACTOR 1 (CLO/GFA1) is necessary for the restricted expression of egg- and central-cell fate and hence reproductive success. Surprisingly, infertile gametophytes can be expelled from the maternal ovule tissue, thereby preventing the needless allocation of maternal resources to sterile tissue. CLO/GFA1 encodes the Arabidopsis homologue of Snu114, a protein that is considered to be an essential component of the spliceosome. In agreement with their proposed role in pre-mRNA splicing, CLO/GFA1 and LIS co-localize to nuclear speckles. Our data also suggest that CLO/GFA1 is necessary for the tissue-specific expression of LIS. Furthermore, we demonstrate that ATO encodes the Arabidopsis homologue of SF3a60, a protein that has been implicated in pre-spliceosome formation. Our results thus establish that the restriction of gametic cell fate is specifically coupled to the function of various core spliceosomal components.
Moll
Cordula
C
ZMBP Developmental Genetics, University of Tübingen, D-72076 Tübingen, Germany.
von Lyncker
Ludwig
L
Zimmermann
Steffi
S
Kägi
Christina
C
Baumann
Nadine
N
Twell
David
D
Grossniklaus
Ueli
U
Gross-Hardt
Rita
R
D017360:Arabidopsis / Q000166:cytology / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation; D003001:Cloning, Molecular; D005718:Gametogenesis; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005816:Genetic Complementation Test; D010063:Ovum / Q000166:cytology*; D017381:Spliceosomes / Q000235:genetics / Q000378:metabolism
D029681:Arabidopsis Proteins