Date: Sunday, January 15, 2012
Time: 11:00 AM
Time: 11:00 AM
Room: Pacific Salon 1
Avocado breeding by conventional means is slow due to heterozygosity and the long juvenile period of this species. Breeding programmes of avocado rootstocks have focused on enhanced resistance to fungal pathogens such as Phytophthora cinnamomi or Rosellinia necatrix and/or reduced tree size. Genetic manipulation could be an useful strategy to overcome these problems; e.g., disease resistance could be enhanced by transformation with genes coding for proteins involved in plant defense while tree size could be reduced through overexpression of genes involved in GAs catabolism such as GA2ox. In addition, transformation with the Flowering locus T (FT) gene could give rise to early flowering phenotypes which could be of great interest to speed up rootstock breeding by conventional methods. An efficient Agrobacterium-mediated transformation protocol, for avocado, using AGL1 Agrobacterium strain and somatic embryos as the target material has been established by our group, although embryo conversion rate into plants needs to be improved. Currently, more than 10 independent transgenic lines (derived from an embryogenic line of an immature Duke7 zygotic embryo) have been obtained with AtNPR1, a gene identified as a key regulatory factor of the SA-mediated systemic acquired resistance in Arabidopsis. Plants, from several species, constitutively expressing AtNPR1 showed a higher production of PR proteins and also enhanced resistance to a wide range of different pathogens. Avocado plants have been recovered from two independent transgenic lines and efforts are underway to recover plants from other lines, following micrografting of shoots from transgenic embryos onto in vitro germinated seedlings.
FINANCIAL SUPPORT: GRANT AGL2008-05453-C02-01/AGR.