Chromosome Painting in Cultivated Bananas and Their Wild Relatives (Musa spp.) Reveals Differences in Chromosome Structure.

Denisa Šimoníková,Jana Čížková,Eva Hřibová,Alžběta Němečková,Rony Swennen,Jaroslav Doležel,Allan Brown

doi:10.3390/ijms21217915

Abstract

Edible banana cultivars are diploid, triploid, or tetraploid hybrids, which originated by natural cross hybridization between subspecies of diploid Musa acuminata, or between M. acuminata and diploid Musa balbisiana. The participation of two other wild diploid species Musa schizocarpa and Musa textilis was also indicated by molecular studies. The fusion of gametes with structurally different chromosome sets may give rise to progenies with structural chromosome heterozygosity and reduced fertility due to aberrant chromosome pairing and unbalanced chromosome segregation. Only a few translocations have been classified on the genomic level so far, and a comprehensive molecular cytogenetic characterization of cultivars and species of the family Musaceae is still lacking. Fluorescence in situ hybridization (FISH) with chromosome-arm-specific oligo painting probes was used for comparative karyotype analysis in a set of wild Musa species and edible banana clones. The results revealed large differences in chromosome structure, discriminating individual accessions. These results permitted the identification of putative progenitors of cultivated clones and clarified the genomic constitution and evolution of aneuploid banana clones, which seem to be common among the polyploid banana accessions. New insights into the chromosome organization and structural chromosome changes will be a valuable asset in breeding programs, particularly in the selection of appropriate parents for cross hybridization.

Highlights

Banana represents one of the major staple foods and is one of the most important cash crops with the estimated value of $25 billion for the banana industry
The first part of the study focused on comparative karyotype analysis in six subspecies of M. acuminata and in M. balbisiana
The only option was to use pools of bacterial artificial chromosome (BAC) clones, which were found useful in plant species with small genomes (e.g., [44,45])

Summary

Introduction

Banana represents one of the major staple foods and is one of the most important cash crops with the estimated value of $25 billion for the banana industry. Other Musa species such as Musa schizocarpa (2n = 2x = 22, SS genome) and Musa textilis (2n = 2x = 20, TT genome) contributed to the origin of some edible banana clones [4,5,6]. Based on morphology and geographical distribution, M. acuminata has been divided into nine subspecies (banksii, burmannica, burmannicoides, errans, malaccensis, microcarpa, siamea, truncata, and zebrina) and three varieties (chinensis, sumatrana, and tomentosa) [7,8,9]. It has been estimated that at least four subspecies of M. acuminata contributed to the origin of cultivated bananas [7,10]. Burmannica with the center of diversity in Myanmar [13]; ssp. Other subspecies were M. acuminata ssp. burmannica with the center of diversity in Myanmar [13]; ssp. malaccensis with the origin in Malay peninsula [7,14]; and ssp. zebrina, which originated in Indonesia [10]

Methods

Results

Conclusion