Description of a fertilization-independent obligate apomictic species: Corunastylis apostasioides Fitzg.

The Australian midge orchid Corunastylis apostasioides of the tribe Diurideae has completely eliminated any male contribution in the process of seed formation, which occurs directly from the maternal tissue by a process termed apomixis. Here, we report C. apostasioides to be an obligate apomictic species devoid of any sexuality and compare its development to a close sexual relative C.

Temperature sensitive diphtheria toxin confers conditional male-sterility in Arabidopsis thaliana.

A gene encoding a temperature-sensitive diphtheria toxin A chain (DTA) polypeptide was fused to the Arabidopsis thaliana tapetum-specific A9 promoter. Expression of the chimaeric gene in transgenic A. thaliana lines resulted in plants that were male-sterile, but female-fertile, when grown at 18 degrees C, and fully self fertile at 26 degrees C.

The ABNORMAL GAMETOPHYTES (AGM) gene product of Arabidopsis demonstrates a role in mitosis during gamete development.

Screening a T-DNA mutagenized population of Arabidopsis thaliana for reduced seed set and segregation distortion led to the isolation of the ABNORMAL GAMETOPHYTES (AGM) mutant. Homozygous plants were never recovered, but heterozygous plants showed mitotic defects during gametogenesis resulting in approximately 50% abortion of both the male and female gametes. Isolation of the genomic sequence flanking the co-segregating T-DNA element led to the identification of a gene located on chromosome 5, predicted to encode a transmembrane protein.

SPL8, an SBP-box gene that affects pollen sac development in Arabidopsis.

SQUAMOSA PROMOTER BINDING PROTEIN-box genes (SBP-box genes) encode plant-specific proteins that share a highly conserved DNA binding domain, the SBP domain. Although likely to represent transcription factors, little is known about their role in development. In Arabidopsis, SBP-box genes constitute a structurally heterogeneous family of 16 members known as SPL genes.

The Arabidopsis ABORTED MICROSPORES (AMS) gene encodes a MYC class transcription factor.

Visual screening of a T-DNA mutagenised population of Arabidopsis thaliana for an absence of silique elongation lead to the isolation of the aborted microspores (ams) mutant that shows a sporophytic recessive male sterile phenotype. Homozygous mutant plants are completely devoid of mature pollen. Pollen degeneration occurs shortly after release of the microspores from the tetrad, prior to pollen mitosis I.