Functional genomics and transgenesis applied to sunflower breeding

MOSCHEN SEBASTIAN; RADONIC LAURA; EHRENBOLGER F; FERNANDEZ PAULA; VERONICA LIA; NORMA PANIEGO; LOPEZ BILBAO MARISA; RUTH HEINZ; ESTEBAN HOPP

Sunflowers: growth and development, environmental influences and pest/diseases

Nova Science Publishers, Inc.

Lugar: Nueva York; Año: 2014; p. 1 - 15

The advances in genomics and post genomics in the last decade allowed the discovery and functional characterization of many genes simultaneously on a genome-wide scale. However, the sunflower genome was not systematically sequenced until the recent advent of next-generation sequencing technologies and is still in progress. In parallel, comprehensive EST datasets were developed and used to design oligonucleotide-based microarrays focusing both in genotyping and expression analysis purposes, which in turn, help to study the transcriptomic response to different growing conditions as water deficit, senescence or response to pathogens. In addition, first metabolomics analyses of tolerance to diseases started few years ago. This chapter reviews the functional genomic analysis of several important sunflower characters including the development and application of bioinformatic approaches to explore massive data derived from high throughput sequencing technologies to elucidate complex traits and identify candidate genes playing a key role in metabolic pathways with special emphasis in the generation of new breeding tools. In addition, functional strategies for candidate gene validation either by TILLING approach and/or by overexpression in model and sunflower plants, are also reviewed and discussed. In vitro tissue culture techniques, like immature embryo rescue, were incorporated in sunflower breeding before the existence of the functional genomics disciplines allowing the development of four inbreeding generations per year and helping breeders to sort sterility or incompatibility barriers in wide interspecies crossings. Even so, sunflower was considered a recalcitrant species for genetic transformation due to difficulties in plant regeneration procedure Sunflower transformation protocols have improved in the last years, but they are still time consuming and produce low numbers of transgenic regenerants per assay. For some applications, like complementation studies, these difficulties were solved by transient transformation and the stable transformation of lettuce, as model system. Still, the introduction of agronomically useful genes successfully delivered transgenic lines with herbicide tolerance, insect resistance, disease resistance and improved oil composition. They were developed by seed companies and nearly reached commercial stage. However, since pollen from cultivated sunflower can spread to adjacent wild populations, any intended release of transgenic sunflowers requires a previous analysis of the population biology of wild relatives to assess the potential added fitness or detrimental effects that agronomic traits might have on the ecosystem. This has impeded the intended release of commercial transgenic sunflowers until now. However, as a consequence of the appearance of the non-transgenic imidazolinone resistant sunflower and its global marketing, many of the concerns about the release of transgenic sunflowers are rapidly decreasing.