The IGROW project as discussed at ITMI-Minneapolis May 2004

These notes record discussions on Monday evening meeting (May 24^th) and follow up discussions during the ITMI at Minneapolis,

• Monday evening meeting (May 24^th), clarification on the report on the November 2003 IGROW meeting was sought.  Bikram Gill provided background to the November meeting and explained that Forrest Chumley (KSU) was now handling the final points of the report, including compiling the results of a ballot to decide the target for a long term aim of the wheat genome project (hexaploid wheat or a diploid wheat).  The report is to be published in GENETICS,
• Discussion on the hexaploid vs diploid wheat issue, noted that in Europe there was no interest in diploid wheats – hexaploid wheat is the key crop and needs to be targeted.  In addition, it was noted that with chromosomes being purified for BAC libraries, the justification for not doing hexaploid wheat (namely that it is too complex) disappears.  Some discussion revolved around the focus on a homoeologous group (eg 3A, 3B, 3D) vs a set of chromosomes from a given genome group (eg1A, 2A, 3A, 4A, 5A, 6A, 7A).  In view of the size of the challenge, the across homoeologous group focus was considered to limit the size of the project more effectively,
• The clear message from the ITMI/IGROW group was that hexaploid wheat should be the target.  Several comments were made that the driver for the chromosome regions analysed should be the location of agronomically significant traits.  This would ensure enthusiastic support from breeders and would probably require commitments to generating BAC libraries from particular cultivars.
• Definition of gene space (words in the report) was sought and concern was expressed that the definition of this term should not be simply limited to the parts of the genome uncovered by the methyl filtration procedures.  The term “gene space” was agreed to simply refer to the portion of the genome carrying the expressed genes,
• The 3B chromosome initiative based at INRA (France) was discussed and it is evident that this would also benefit by a more direct link to the scab initiative already funded in the USA, the analysis of rice 1, barley 3H (Rph7 region), sorghum 3 and maize 3/maize 8 (the chromosome groups showing significant synteny).  Groups in the USA and Australia are already working with the INRA group to compile contigs and are carrying out sample sequencing on the chromosome 3B BAC library.  Groups in the USA, in Texas A&M and Cold Spring Harbor, are also are focused on the detailed physical analysis of sorghum chromosome 3. Studies on 3B of wheat are also intending to identify BAC pools containing ESTs (ie gene-rich BAC pools) and locate them to the physical map.
• There was considerable discussion about the focus of  the pilot international consortium project. A considerable amount of effort has gone into developing a group 3 consortium project to be built around the 3B physical mapping project now underway in France. The idea has been to make BAC libraries from chromosomes 3A and 3D to complement the 3B project, make physical maps and also sample sequence BACs selected from homoeologous regions across the group 3 chromosomes.  Ideally many countries can participate in this project.  There was an alternative proposal to develop a wheat group 4 project in the US including sequencing of corresponding homoeologous regions in barley.  On the positive side it was mentioned the investment already made in the US on sequencing of rice chromosome 3 which is syntenic to wheat group 4. On the negative side it was mentioned that it will dilute the effort already underway on group 3 to demonstrate the feasibility of the chromosome fractionation approach to wheat genome sequencing.