GENE FLOW FROM O. SATIVA CULTIVATED RICE TO WEEDY
3. COSTA RICA
A. GENE FLOW FROM O. SATIVA CULTIVATED RICE TO WEEDY (O. SATIVA) AND WILD (O. GLUMAEPATULA) RICE IN A TROPICAL CENTER OF DIVERSITY: GENETIC STRUCTURE OF WILD RICE NATURAL POPULATIONS AND FITNESS OF HYBRIDS BETWEEN CROP AND WEEDY FORMS.
Cultivation of Genetically Modified (GM) crops without affecting natural resources is a priori60 in Latin American and Caribbean (LAC) countries as centers of origin and diversity. The project, Multi-country capacity-building for compliance with the Cartagena Protocol on Biosafety (Colombia, Peru, Costa Rica, Brazil), is in harmony with this multilateral agreement covering the transboundary movement of living modified organisms (LMOs) that might have an adverse effect on biological diversity. The project identified five crops: rice, potato, beans, cassava and cotton; as models to cover relevant thematic areas on environmental biosafety.
In LAC countries where native Oryza species are present and weedy rice (O. sativa) is a prevalent weed in rice (also O. sativa), regulators must make important decisions dealing with environmental implications addressing the need to control weedy rice in direct seeded rice and the required protection of the biodiversity of wild ecosystems. Environmental biosafety ex-ante information about the dynamics between rice and weedy/wild relatives in terms of gene flow is highly relevant.
Similar to other rice growing regions in the world, rice production in LAC countries is severely constrained by several diseases, pests and, especially, weeds. Among them, weedy rice, also known as red or feral rice, constitutes a complex of Oryza (commonly O. sativa) biotypes that evolved as conspecific crop mimics that are harvested and resown with the rice crop. Furthermore, LAC countries are home of four wild Oryza species: the tetraploid (CCDD genome) O. alta, O. grandiglumis, O. latifolia, and the diploid (AA genome) O. glumaepatula which is more prone to hybridize with cultivated rice (also AA). O. glumaepatula has limited intrapopulation gene diversity but high levels of genetic differentiation among populations therefore making it of great relevance to quantify the magnitude of interspecific gene flow in natural populations of Oryza in tropical centers of biodiversity where information is scant.
Transgenic herbicide resistant (HR) rice may be used to facilitate the selective control of weeds with broad-spectrum herbicides. However its possible release and commercial cultivation has raised biosafety concerns due to the possibility of gene flow between GM varieties and weedy and wild relatives. Therefore, if transgenic rice is to be commercialized, regulators will require baseline studies designed to understand the dynamic interaction between cultivated, weedy and wild rice species; as potential receptors of transgenes or donors of wild-type traits, resulting in the production of intermediate type forms carrying transgenes.
The aim of this subproject is to assess the impact of gene flow from cultivated rice to wild O. glumaepatula and weedy O. sativa by first characterizing the genetic structure and determining gene flow though progeny analysis of natural populations of the wild species, followed by estimates of the relative fitness of hybrids between cultivated, weedy and wild-rice under controlled competitive conditions. By fulfilling these goals, this subproject will add to the thematic area for assessment and monitoring of gene flow in rice crop-biodiversity and its execution will contribute to the component for strengthening technical capacity in knowledge generation for biosafety risk assessment and management.
Contacto: Griselda Arrieta-Espinoza - UNIVERSIDAD DE COSTA RICA