Working Groups

  1. Technology advancement for gametic embryogenesis.
  2. Functional genomics of gametic embryogenesis.
  3. Deployment of gametic embryogenesis in crop improvement.



WORKING GROUP 1
TECHNOLOGY ADVANCEMENT FOR GAMETIC EMBRYOGENESIS

The focus here is on basic research on gametic embryogenesis, using excised anthers, isolated microspores or egg cells to regenerate homozygous plants in various genotypes and species. Although gametic embryogenesis has been known and researched for more than twenty years many problems remain. The application in many species is hampered by low frequencies of embryo induction, albinism and plant regeneration, and in some species only certain genotypes (lines) respond. In species like barley and brassica gametic embryogenesis works well and has become an integral part of many breeding programmes throughout the world. The main breakthroughs in barley came with the use of maltose in the culture media and the experience in how to handle the donor plants.

Much progress in gametic embryogenesis has been empirical, e.g. small modifications of protocols. Much of this knowledge will never be published, but a COST Action provides a medium for information transfer among scientist and end users. For example, in potato, the main problem is that existing protocols work only for a few genotypes. More experimentation is needed to develop better, more genotype independent protocols. Because of successful European collaboration there have been major breakthroughs, e.g. technology transfer of tobacco to apple microspore culture, and this has had a positive knock-on effect on other woody species. The successful transfer of technology across plant genera highlights a unifying theme in gametic embryogenesis, an example being the preparation and induction of competent cells via pre-treatment. Currently this is achieved by in vitro stress treatments of excised anthers or ovules, or by in vivo manipulation of the environment of donor plants. Further research is expected to clarify the critical plant developmental stages and processes involved.

The COST Action aims to place the technology of gametic embryogenesis on a firm scientific basis. One means of technological advancement is through the study of gene expression in responding and non-responding cell cultures given alternative treatments (e.g. maltose instead of sucrose). This approach will help elucidate genes and biochemical pathways necessary for successful gametic embryogenesis. The results of functional genomic approaches can then be tested by designing tissue culture protocols with predicted effects. This will in lead to the tailoring of tissue culture methods for specific genotypes for use in molecular breeding. This area of work will therefore be interactive with WG2 and WG3.

Major goals

  1. Currently species are classified as completely recalcitrant (e.g. legumes), low-moderately responsive (where efficiency is hampered by problems of embryo formation, albinism an genotypic dependency), or highly responsive. A milestone here is to move more (5 – 10) species into the high efficiency bracket. (Successful application of gametic embryogenesis technology to legumes would be a major achievement).
  2. Demonstration of tailoring culture conditions to genotype.
  3. Application of automated technology through interaction with COST 843.
  4. Development of improved technology for deployment in plant breeding.



WORKING GROUP 2
FUNCTIONAL GENOMICS OF GAMETIC EMBRYOGENESIS

Recent advancements in genomics allow genes involved in specific functions to be identified. The methods include subtractive hybridisation, production of cDNA libraries, expressed sequence tag sequences (ESTs), gene expression on microarrays and proteomics. These techniques are being used in gene discovery for various traits, and the importance of embryogenesis in pure and applied biology places this high on the priority list for research. The major agri-biotech companies have invested heavily in “in house” generation of ESTs of major crop plants. This has yielded impressive results in the production of several hundred thousand ESTs. A number of governments have realised the importance of academic based genomics programmes. In Europe the French government in collaboration with industry launched “Geneoplante”, a 1,400 million franc plant genome initiative. In Germany a similarly large functional genomics programme has been announced for Arabidopsis research. In Finland there is joint government/industry collaboration of genomics of cereals, and in the UK government funding has supported the Arabidopsis genome sequence initiative and community based cereal and brassica gene function resource. Many of these initiatives address fundamental biological question and include embryo. Major breakthroughs in the identification of genes involved in natural and induced embryogenesis are therefore expected. This work will enable verification of candidate genes and identify the most important ones for further basic and applied research. These funded national and international programmes will help underpin the COST Action. This area of work will have consequences for technological advancement (WG1), in helping to maximise genotype/technology combinations, which can then be exploited in deployment strategies (WG3).

Major goals

  1. Identification of genes controlling gametic embryogenesis: Functional genomic approaches will produce many gene sequences associated with gametic embryogenesis. These will be used to search data-bases for homologous genes and large numbers of gene candidates will be revealed. This is a relatively easy task, the trick however, is to sift through this wealth of information to find critical genes with main effects, which require great care and effort. The main milestone for members of this working group is to identify these genes.
  2. Compare genes and alleles with major effects on gametic embryogenesis across a range of genotypes, genomes and species.
  3. Compare gene functions in normal (seed) embryogenesis with that of induced gametic embryogenesis.




WORKING GROUP 3
DEPLOYMENT OF GAMETIC GAMETIC EMBRYOGENESIS IN CROP IMPROVEMENT

Genes of commercial interest fall into two categories, those controlled by single genes, e.g. disease resistance, and those controlled by many genes, e.g. yield. In some species in which good genetic maps have been developed, many major single genes are known and mapped. For other species, and for polygenes in general, genetic mapping remains a basic requirement for which genetic mapping populations in the form of doubled haploids will be required. The development of doubled haploids to map the location of commercially important genes will continue as a research objective as this forms a foundation for their deployment. Once areas of the genome have been identified they can be targeted and manipulated. Detailed investigations include saturation mapping in targeted regions with the aim of getting at the genes of interest, to either develop tightly linked markers or to sequence the important genes and design direct markers for them.

Doubled haploidy is already used in breeding of several crops in Europe, notably brassicas and cereals. As improved protocols are developed through WG1 and WG2, the use of doubled haploidy will become more widespread. Doubled haploidy is used by breeders to produce true breeding lines in material developed in their crossing programmes and as such is an important component of conventional breeding. However, doubled haploidy in conjunction with genetic markers opens up the new strategies of ‘molecular breeding’. It is known, for instance, that doubled haploidy in forage grasses provides a means of producing new allele combinations that are never seen in conventional backcrossing programmes. There will be increasing interest in manipulating specific genes for crop improvement, these can be either single genes or polygenes identified in donor cultivars, wild progenitors of crop or related species, or transgenes from unrelated sources. A number of protocols and variations on protocols will be developed where the logistics of double haploid deployment will depend on the genotype/tissue culture combinations, species, recombination frequency, genetic marker, laboratory facilities and breeding cycle. The development and assessment of these strategies is a major research task.


Major goals

  1. Provide a demonstration of more efficient plant breeding by combining doubled haploidy with genetic marker technology for at least one monocot. and one dicot. species.
  2. Facilitate the transfer of new technologies to plant breeders thereby widening the exploitation of gametic embryogenesis.
  3. Develop new doubled haploid populations for genetic mapping.
  4. Compare the results of molecular breeding with more conventional methods and to develop innovative methods of producing desired genotypes.