Plant & Animal Genome V Conference
Town & Country Hotel, San Diego, CA, January 12-16, 1997.
PAG-V: W4 - QTLS FOR DROUGHT TOLERANCE IN BARLEY
W4
QTLS FOR DROUGHT TOLERANCE IN BARLEY
THIS, DOMINIQUE(1), Beatrice Teulat(1), Gemma Arnau(1), Christiane Borries(1), Irenee Souyris(1), Charlotte Borel(2), Carine Ragot(3), Philippe Leroy(3), Mireille Khairallah(4), Philippe Monneveux(4), Andre Charrier(4)
1. UFR de Genetique et Amelioration des plantes, ENSA-INRA, 2, place P. Viala, 34060 Montpellier cedex, France
2. Ecophysiologie des Plantes sous Stress Environnementaux, ENSA-INRA, 2, place P. Viala, 34060 Montpellier cedex, France
3. Station d'Amelioration des Plantes, INRA, Domaine de Crouelle, 63039 Clermont-Ferrand cedex, France
4. Centro de Mejoramiento de Mais y Trigo, Lisboa, 27, Apartado Postal 664, 66000 Mexico D.F., Mexico
Drought tolerance, defined as yield stability, is a major goal for cereal breeding in mediterranean environments. Considering such a complex trait, a marker assisted introgression could be useful to develop more tolerant genotypes. A genetic approach was initiated in barley to localize key chromosomal regions involved in tolerance parameters. In a first step, different morphophysiological criteria, considered in the litterature as tolerance factors, were assessed on several genotypes showing a contrasted yield stability. Stomatal closure and xylemic ABA increase during water stress could not be considered as tolerance factors. On the opposite, photosynthesis maintenance and osmotic adjustment capacity appeared to be major mechanisms involved in drought tolerance in barley. In a second step, a segregating population derived from a cross between Tadmor (tolerant) and Er/Apm (susceptible) was used to identify molecular markers linked to QTLs related to osmotic adjustment parameters, chlorophyll amount, tillers number, fresh and dry aerial matter, as well as yield components. Several "candidate" genes were also mapped. At the same time, known function genes expression was studied during water stress on different lines, by Northern blotting, to provide information on their direct or indirect role in the tolerance mechanisms. The mRNA accumulation corresponding to the small subunit of RubisCo was less depressed in tolerant lines, which was consistent with physiological data. Several QTLs for relative water content, chlorophyll amount and leaves number variation were mapped. Some of them were identified at the same loci than yield components QTLs. Results will be discussed during the oral presentation.