title: Improvement of drought tolerance in maize: towards the functional validation of the Zm-Asr1 gene and increase of water use efficiency by over-expressing C4-PEPC.
abstract: Water availability is one of the major limiting factors for plant growth. Maize is particularly sensitive to water stress at reproductive stages with a strong impairment of photosynthesis and grain filling. Here, we describe the use of genetic transformation first to assess the role of a candidate gene Asr1-a putative transcription factor-as an explanation for genetically linked drought tolerance Quantitative Trait Loci (QTLs), and second to modify CO(2) fixation rates in leaves through changes of C(4) phosphoenolpyruvate carboxylase (C(4)-PEPC) activity. Transgenic Asr1 over-expressing lines show an increase in foliar senescence under drought conditions. The highest C(4)-PEPC overexpressing line exhibited an increase (+30%) in intrinsic water use efficiency (WUE) accompanied by a dry weight increase (+20%) under moderate drought conditions. Opposite effects were observed for transgenic plants under-expressing the corresponding proteins. The data presented here indicate the feasibility to increase the level of endogenous biochemical activities related to water economy and/or drought tolerance, and opens a way to develop maize varieties more tolerant to dry growing conditions.
authors.affiliation: Institut de Biotechnologie des Plantes, UMR CNRS 8618, Université Paris-Sud, 91405 Orsay cedex, France.
authors.forename: M
authors.initials: M
authors.lastname: Jeanneau
authors.forename: D
authors.initials: D
authors.lastname: Gerentes
authors.forename: X
authors.initials: X
authors.lastname: Foueillassar
authors.forename: M
authors.initials: M
authors.lastname: Zivy
authors.forename: J
authors.initials: J
authors.lastname: Vidal
authors.forename: A
authors.initials: A
authors.lastname: Toppan
authors.forename: P
authors.initials: P
authors.lastname: Perez
mesh_terms: D000064:Acclimatization / Q000235:genetics*; D004190:Disasters; D010730:Phosphoenolpyruvate Carboxylase / Q000235:genetics; D018515:Plant Leaves / Q000502:physiology*; D030821:Plants, Genetically Modified / Q000502:physiology; D014867:Water / Q000378:metabolism*; D003313:Zea mays / Q000235:genetics* / Q000254:growth & development / Q000502:physiology
chemical_list: D014867:Water; D010730:Phosphoenolpyruvate Carboxylase