The genetic complexity in the genus
Musa has been subject of study in many breeding programs worldwide. Parthenocarpy, female sterility, polyploidy in different cultivars
and limited amount of genetic and genomic information make the production of new banana cultivars difficult and time consuming.
In addition, it is known that part of the cultivars and related wild species in the genus contain numerous chromosomal rearrangements.
In order to produce new cultivars more effectively breeders must better understand the genetic differences of the potential
crossing parents for introgression hybridization, but extensive genetic information is lacking. As an alternative to achieve
information on genetic collinearity we make use of modern chromosome map technology known as high-resolution fluorescent in
situ hybridization (FISH). This article presents the technical aspects and applications of such a technology in
Musa species. The technique deals with BAC clone positioning on pachytene chromosomes of Calcutta 4 (
Musa acuminata ssp.
burmanicoides, A genome group, section Eumusa) and
M. velutina (section Rodochlamys). Pollen mother cells digestion with pectolytic enzymes and maceration with acetic acid were optimized
for making cell spread preparations appropriate for FISH. As an example of this approach we chose BAC clones that contain
markers to known resistance genes and hybridize them for establishing their relative positions on the two species. Technical
challenges for adapting existing protocols to the banana cells are presented. We also discuss how this technique can be instrumental
for validating collinearity between potential crossing parents and how the method can be helpful in future mapping initiatives,
and how this method allows identification of chromosomal rearrangements between related
Musa species and cultivars.
Keywords
Musa acuminata
-
Musa velutina
- BAC-FISH - Chromosome mapping - Banana