title: RhEXPA4, a rose expansin gene, modulates leaf growth and confers drought and salt tolerance to Arabidopsis.
abstract: Drought and high salinity are major environmental conditions limiting plant growth and development. Expansin is a cell-wall-loosening protein known to disrupt hydrogen bonds between xyloglucan and cellulose microfibrils. The expression of expansin increases in plants under various abiotic stresses, and plays an important role in adaptation to these stresses. We aimed to investigate the role of the RhEXPA4, a rose expansin gene, in response to abiotic stresses through its overexpression analysis in Arabidopsis. In transgenic Arabidopsis harboring the Pro RhEXPA4 ::GUS construct, RhEXPA4 promoter activity was induced by abscisic acid (ABA), drought and salt, particularly in zones of active growth. Transgenic lines with higher RhEXPA4 level developed compact phenotypes with shorter stems, curly leaves and compact inflorescences, while the lines with relatively lower RhEXPA4 expression showed normal phenotypes, similar to the wild type (WT). The germination percentage of transgenic Arabidopsis seeds was higher than that of WT seeds under salt stress and ABA treatments. Transgenic plants showed enhanced tolerance to drought and salt stresses: they displayed higher survival rates after drought, and exhibited more lateral roots and higher content of leaf chlorophyll a under salt stress. Moreover, high-level RhEXPA4 overexpressors have multiple modifications in leaf blade epidermal structure, such as smaller, compact cells, fewer stomata and midvein vascular patterning in leaves, which provides them with more tolerance to abiotic stresses compared to mild overexpressors and the WT. Collectively, our results suggest that RhEXPA4, a cell-wall-loosening protein, confers tolerance to abiotic stresses through modifying cell expansion and plant development in Arabidopsis.
authors.affiliation: Department of Ornamental Horticulture, China Agricultural University, Beijing 100193, China.
authors.forename: Peitao
authors.initials: P
authors.lastname: Lü
authors.forename: Mei
authors.initials: M
authors.lastname: Kang
authors.forename: Xinqiang
authors.initials: X
authors.lastname: Jiang
authors.forename: Fanwei
authors.initials: F
authors.lastname: Dai
authors.forename: Junping
authors.initials: J
authors.lastname: Gao
authors.forename: Changqing
authors.initials: C
authors.lastname: Zhang
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology; D000222:Adaptation, Physiological / Q000187:drug effects / Q000235:genetics; D017360:Arabidopsis / Q000033:anatomy & histology / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D055864:Droughts; D017343:Genes, Plant / Q000235:genetics; D018525:Germination / Q000187:drug effects / Q000235:genetics; D010641:Phenotype; D019441:Plant Epidermis / Q000033:anatomy & histology / Q000187:drug effects; D018515:Plant Leaves / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D012098:Reproduction / Q000187:drug effects; D027826:Rosa / Q000235:genetics*; D055049:Salt Tolerance / Q000187:drug effects / Q000235:genetics; D036226:Seedlings / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D012965:Sodium Chloride / Q000494:pharmacology
chemical_list: D010940:Plant Proteins; C095825:expansin protein, plant; D012965:Sodium Chloride; D000040:Abscisic Acid