Detalle de: Study of the key interactions in the progamic phase. Implication for plant breeding of subtropical fruit crops (JIN)

The diploid tissues of the ovule, the sporophyte, consist of the proximal funiculus, the central chalaza and the distal nucellus surrounded generally by two integuments (outer and inner integument) that form the micropyle, the gate for the pollen tube. The transitions of the somatic cell to the reproductive cell (megasporogenesis) that will develop the female gametophyte (megagametogenesis) takes place within the nucellus. In the lasts fifteen years a number of sterile ovule mutants have been characterized in Arabidopsis. In these mutants different alterations along the ovule development process have been characterized and have involved key processes of ovule development such as integument development and megasporogenesis that affect pollen tube guidance, fertilization and fruit development. These processes have been mainly studied in Arabidopsis and are just beginning to be described in non-model species such as our previous study performed in a seedless genotype of Annona squamosa, a sister species of cherimoya. In that work, the genetic knowledge of an essential process in a model plant was successfully used to open a way to introduce the seedless trait in the subtropical fruit crop cherimoya. Similarly, in this project the genetic and molecular knowledge of Arabidopsis will be used to understand key process on programic phase such as pollen tube guidance and megasporogenesis in subtropical fruits that are basic products for food security in a wide range of developing countries and their commercial importance is increasing exponentially worldwide. Moreover, the particular situation of Spain as the only European country with a significant commercial production of subtropical fruits allows us to be a major player at the international level in scientific studies of these species. Thus, the main objective of this project is the study of the main interactions on programic phase; pollen tube guidance, and crosstalk and genetic regulation involved on megasporogenesis in subtropical crops such as mango, cherimoya and avocado that were selected due to their differences in reproductive development. Thus, mango, that shows chalazogamy and unitegmic (single integument) ovules, is an excellent candidate to study pollen tube guidance; cherimoya is an incipient crop, an early divergent angiosperm and with the seedleess gentotype of A. squamosa, a bonus to study pollen tube guidance and megasporogenesis; finally, avocado is also a primitive angiosperm with a special agronomic interest in seedless fruits called cukes where a study on sporophytic-gametophytic crosstalk is essential to understand the causes behind the absence of seeds. This project covers different species combining molecular techniques with cytological studies in a multidisciplinary approach. The results of this project will be of relevance both from an applied and basic point of views. On the one hand, the knowledge of the main interactions of key process in the reproductive phase of important crops will be essential to design strategies to improve fruit production. On the other hand, the results from cherimoya and avocado will contribute to the understanding of ovule development and evolution in angiosperms and the genetic regulation on this key process in flowering plants.