Poster: Integrated Plant Biology
Abs #
86: Overexpression of the vacuolar H+-pump AVP1 increases cell proliferation and de novo organogenesis in Arabidopsis
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Presenter: |
Li, Jisheng , jisheng.li@uconn.edu |
Authors | Li, Jisheng (A) Gaxiola, Roberto A (A) | | Affiliations: |
(A): University of Connecticut
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The space-filling role of the vacuole is essential for the growth of plant cells. Turgor-dependent cell expansion relies on water uptake that follows solute accumulation in the vacuole. The primary driving force for this solute accumulation is the proton gradient generated by the tonoplast H+-pumps, V-ATPase, and V-PPase (Gaxiola et al. 2002, Plant Physiol.129:967). Arabidopsis plants that ectopically express the V-PPase, AVP1, exhibit increased tolerance to drought and to salt stress (Gaxiola et al. PNAS 2001, 98:11444). The salt-and drought-tolerant phenotypes of transgenic lines overexpressing AVP1 have been associated with an increased proton gradient across the vacuole (Gaxiola et al. 2002). In this work we present evidence that shows that the ectopic overexpression of AVP1 leads not only to abiotic stress tolerance, but also to enhanced cell proliferation and de novo organogenesis. The ectopic expression of a 35S::AVP1 transgene enlarges shoot organ size by increasing cell number. Data regarding the expression profiles of molecular markers relevant to cell proliferation in expanding rosette leaves will be shown. Furthermore, incubation in shoot induction media of cotyledons, true leaves, inflorescence stems, hypocotyls and root explants from the AVP1 trasngenic lines results in a dramatic enhancement of their de novo organogenesis capacity. Expression patterns of key molecular markers relevant to cell division (CycD3), cytokinin sensing (CRE1), and formation and maintenance of the meristem (STM) were monitored during the de novo formation of organs. The differential expression patterns of these genes in control and transgenic explants are consistent with a central role of AVP1 in the early events leading to de novo organogenesis.
