Swinton, Jenny

Wang, Yixing

Yang, Ming

English

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A new gene for regulation of epidermal cell production in Arabidopsis cotyledonsJenny Swinton, Yixing Wang, Ming YangDepartment of Plant Biology, Ecology, and Evolution | Oklahoma State University | Stillwater, OKBackgroundObjectiveMethods ResultsDiscussion & ConclusionsReferenceFunding Sources:  American Society of Plant BiologistsSummer Undergraduate Research FellowshipOklahoma Center for the Advancement of Science and technologyContact:                  Jenny Swinton                     Oklahoma State University                     jenny.swinton@okstate.edu • Epidermis of Arabidopsis cotyledons is an excellent material for studying cell proliferation because the epidermal cells, including pavement cells, guard cells, and meristemoids (Fig. 1), are easily accessible and cell divisions cease at an early developmental stage.• The Landsberg erecta (Ler-0) accession of Arabidopsis  has more pavement cells, guard cells, and meristemoids than Columbia-0 (Col-0) in the cotyledon (Yang, 2016).• Identification of the genes responsible for the epidermal cell number differences between Ler-0 and Col-0 will likely advance the understanding of the molecular mechanism regulating cell proliferation in plant organs. • Analyzed F1 and F2 plants from the crosses between Col-0 and Ler-0.• Determined cell densities, cotyledon areas, and cell numbers to characterize phenotypes of F1 and F2 individuals.• Extracted DNA samples from F2 individuals with the Ler-0 epidermal phenotype.• Mapped a gene of interest using these DNA samples and InDel polymorphic primers (Fig. 2).• Harvested F3 seeds from individuals of the mapping population for confirming their F2 phenotyping results if needed.To determine which genes are responsible for the differences in the epidermal cell numbers between Col-0 and Ler-0.• In the region between At2G27130 and At2G29120, there is no gene that is known to be involved in the regulation of epidermal cell production. Therefore, a novel gene is responsible for the Ler-0-like phenotype.• According to the genetic analysis, two linked genes underlie the Ler-0-like epidermal phenotype.• ERECTA or At2G26330, the gene encoding a Leucine-rich repeat receptor kinase involved in the regulation of stomatal lineage formation, is close to the gene of interest, which is consistent with the above prediction.Yang M. (2016) The FOUR LIPS (FLP) and MYB88 genes conditionally suppress the production of nonstomatal epidermal cells in Arabidopsis cotyledons. Am J Bot, 103: 1559-66.Results• F1 plants showed an epidermal phenotype intermediate between those of Col-0 and Ler-0, indicating that the gene(s) in Ler-0 responsible for the epidermal phenotype is(are) semi-dominant (Fig. 4). • The ratio of non-Ler-0-like plants to Ler-0-like plants in the F2 was 7.2 : 1 (311 : 43), which rejects the hypotheses that one gene or two unlinked genes underlie the Ler-0-like phenotype, (χ2 tests, χ2 ≥20.99, P < 0.005).Fig. 2. Example for mapping a PCR marker on chromosome 2 with F2 individuals and controls.From left to right: Col-0, Col-0/Ler-0, and Ler-0. Fig. 5. Fine mapping of a gene of interest on Chromosome 2. Fig. 1. Epidermal cells in an Ler-0 cotyledon.• Number & densities of pavement cells and meristemoids significantly differ between Ler-0 and Col-0 in mature cotyledons (Figs. 3 and 4; t-tests, p < 0.001, n = 40).• Average cotyledon areas are not statistically different between Ler-0 and Col-0 (t-test, p = 0.17; n = 40).Fig. 3. Mature cotyledon abaxial epidermis, showing more meristemoids in Ler-0 than in Col-0. (A) Col-0. (B) Ler-0.• A gene of interest is mapped to a ~900 kb region on chromosome 2 between At2G27130 & At2G29120 (Fig. 5).A BFig. 4. Total cell number of Ler-0, Col-0, and F1 mature cotyledons. (A) Meristemoids. (B) Pavement cells and guard Cells.AB0100020003000400050006000GuardCellsPavementCellsGuardCellsPavementCellsGuardCellsPavementCellsCol-0 Ler-0 F1# of Cells/CotyledonGenotype020406080100120140160180Col-0 Ler-0 F1# of Cells/CotyledonGenotypeLoci

A new gene for regulation of epidermal cell production in Arabidopsis cotyledons

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A new gene for regulation of epidermal cell production in Arabidopsis cotyledons

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