title: A large-scale genetic screen in Arabidopsis to identify genes involved in pollen exine production.
abstract: Exine, the outer plant pollen wall, has elaborate species-specific patterns, provides a protective barrier for male gametophytes, and serves as a mediator of strong and species-specific pollen-stigma adhesion. Exine is made of sporopollenin, a material remarkable for its strength, elasticity, and chemical durability. The chemical nature of sporopollenin, as well as the developmental mechanisms that govern its assembly into diverse patterns in different species, are poorly understood. Here, we describe a simple yet effective genetic screen in Arabidopsis (Arabidopsis thaliana) that was undertaken to advance our understanding of sporopollenin synthesis and exine assembly. This screen led to the recovery of mutants with a variety of defects in exine structure, including multiple mutants with novel phenotypes. Fifty-six mutants were selected for further characterization and are reported here. In 14 cases, we have mapped defects to specific genes, including four with previously demonstrated or suggested roles in exine development (MALE STERILITY2, CYP703A2, ANTHER-SPECIFIC PROTEIN6, TETRAKETIDE α-PYRONE REDUCTASE/DIHYDROFLAVONOL-4-REDUCTASE-LIKE1), and a number of genes that have not been implicated in exine production prior to this screen (among them, fatty acid ω-hydroxylase CYP704B1, putative glycosyl transferases At1g27600 and At1g33430, 4-coumarate-coenzyme A ligase 4CL3, polygalacturonase QUARTET3, novel gene At5g58100, and nucleotide-sugar transporter At5g65000). Our study illustrates that morphological screens of pollen can be extremely fruitful in identifying previously unknown exine genes and lays the foundation for biochemical, developmental, and evolutionary studies of exine production.
authors.affiliation: Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, Illinois 60637, USA. dobritsa@uchicago.edu
authors.forename: Anna A
authors.initials: AA
authors.lastname: Dobritsa
authors.forename: Aliza
authors.initials: A
authors.lastname: Geanconteri
authors.forename: Jay
authors.initials: J
authors.lastname: Shrestha
authors.forename: Ann
authors.initials: A
authors.lastname: Carlson
authors.forename: Nicholas
authors.initials: N
authors.lastname: Kooyers
authors.forename: Daniel
authors.initials: D
authors.lastname: Coerper
authors.forename: Ewa
authors.initials: E
authors.lastname: Urbanczyk-Wochniak
authors.forename: Bennie J
authors.initials: BJ
authors.lastname: Bench
authors.forename: Lloyd W
authors.initials: LW
authors.lastname: Sumner
authors.forename: Robert
authors.initials: R
authors.lastname: Swanson
authors.forename: Daphne
authors.initials: D
authors.lastname: Preuss
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D001704:Biopolymers / Q000235:genetics / Q000378:metabolism*; D002338:Carotenoids / Q000235:genetics / Q000378:metabolism*; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D009154:Mutation; D010641:Phenotype; D011058:Pollen / Q000502:physiology*
chemical_list: D029681:Arabidopsis Proteins; D001704:Biopolymers; C482839:QUARTET 3 protein, Arabidopsis; C009800:sporopollenin; D002338:Carotenoids; D003577:Cytochrome P-450 Enzyme System; C523532:cytochrome P-450 703A2, Arabidopsis