The ABNORMAL GAMETOPHYTES (AGM) Gene Product of Arabidopsis Demonstrates a Role in Mitosis During Gamete Development

Abstract

;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. BLAST homology searches identified two homologous proteins that are not redundant, as is clear from the existence of the agm mutant. Unexpectedly, expression studies using the β-glucuronidase reporter gene suggest that AGM and its closest Arabidopsis homolog are mostly expressed in cells undergoing mitosis. Thus, AGM is not a gametophytic gene as originally speculated on the basis of segregation distortion, but rather classified as an essential gene crucial to the process of mitosis in plants.

BcMF30a and BcMF30c, Two Novel Non-Tandem CCCH Zinc-Finger Proteins, Function in Pollen Development and Pollen Germination in Brassica campestris ssp. chinensis

“…However, mutations in most of other genes often lead to pollen degeneration and abortion at various developmental stages. For instance, mutations in Arabidopsis ABNORMAL GAMETOPHYTE ( AGM ), LONG-CHANIN BASE1 ( LCB1 )/ LCB2A / LCB2C , and cellulose synthase genes ( CESA1 / 2 / 3 / 6 / 9 ) can cause pollen abnormality at the microspore stage, bicellular stage, and tricellular stage, respectively [ 60 , 61 , 62 ]. Overall, proteins with a variety of functions are involved in various processes of pollen development, including chromatin organization, cell division and differentiation, cell wall construction, energy, metabolism, ion transport, and transcriptional regulation.…”

Genome-Wide Association Analysis Identifies Candidate Genes Regulating Seed Number per Silique in Arabidopsis thaliana

“…We identified 38 potential causal loci/genes for SNS regulation. Among the dozens of the genes screened by GWAS, one is AGM (ABNORMAL GAMETOPHYTES) (Table S2), a known gene that is involved in the regulation of seed set and SNS [61], indicating that additional candidate genes identified through GWAS are likewise involved in SNS regulation.…”