Genomics Identifies Origins of Naturally Occurring Seedless Bananas

Jenn Hoskins
13th July, 2024

Genomics Identifies Origins of Naturally Occurring Seedless Bananas

Image Source: Natural Science News, 2024

Key Findings

  • Researchers at National Taiwan University found a way to produce seeds from nearly sterile triploid bananas
  • The seeds grew into tetraploid seedlings, which have four sets of chromosomes, suggesting a method to increase genetic diversity
  • Hybridization between triploid bananas and wild diploid species could lead to more resilient banana varieties
Bananas are a crucial crop for food security and global consumption, but their genetic improvement has been challenging due to their sterility and complex breeding history. A recent study conducted by researchers at National Taiwan University has made significant strides in addressing these challenges by investigating the genetic mechanisms behind seed production in triploid bananas[1]. Triploid bananas, which have three sets of chromosomes, are nearly sterile. However, the researchers managed to harvest seeds from two edible triploid banana individuals (Genotype: ABB) in their conservation repository, where various wild diploid bananas were also grown. The resulting rare offspring survived to the seedling stages and were found to be tetraploid, meaning they have four sets of chromosomes. This discovery is significant because it suggests a potential method for increasing genetic diversity in banana breeding programs. To trace the hybridization history of these tetraploid seedlings, the researchers sequenced and assembled the plastomes (chloroplast genomes) and mitogenomes (mitochondrial genomes) of the seedlings. In bananas, chloroplasts are maternally inherited, and mitochondria are paternally inherited[2][3]. By analyzing the coding sequences of both organellar genomes, the researchers constructed phylogenetic trees that indicated the tetraploid seedlings resulted from hybridization between edible triploid bananas and wild diploid Musa balbisiana (BB) individuals. The study's findings suggest that the triploid maternal bananas may produce viable seeds through a process called apomeiosis, where female triploid gametes are generated without undergoing normal meiosis. This mechanism allows for the formation of hybrid embryos, leading to the development of tetraploid offspring. This is particularly interesting in the context of earlier studies that have shown the importance of cytoplasmic inheritance in the advantageous phenotypic traits of plants, such as disease resistance and crop yield[2]. The discovery of tetraploid seedlings from triploid bananas offers a practical avenue for expanding genetic recombination and increasing genetic diversity in banana breeding programs. This is crucial because half of the current banana production relies on somaclones derived from a single triploid genotype, making them vulnerable to pests and diseases[4]. By introducing new genetic variations through hybridization with wild diploid species, it may be possible to develop more resilient banana varieties. Further cellular studies are needed to understand the fusion and developmental processes that lead to the formation of hybrid embryos in banana reproduction, polyploidization, and evolution. Understanding these mechanisms could provide valuable insights for agricultural and biotechnological applications, such as reverse breeding and clonal seeds[5]. In summary, the study by National Taiwan University highlights a potential method for overcoming the sterility of triploid bananas and increasing their genetic diversity through hybridization with wild diploid species. This research builds on previous findings about the genetic complexity of bananas and offers a promising direction for future banana breeding programs.

FruitsGeneticsPlant Science

References

Main Study

1) Phylogenomics identifies parents of naturally occurring tetraploid bananas.

Published 12th July, 2024

https://doi.org/10.1186/s40529-024-00429-9

Related Studies

2) Identification of cytoplasmic ancestor gene-pools of Musa acuminata Colla and Musa balbisiana Colla and their hybrids by chloroplast and mitochondrial haplotyping.

https://doi.org/10.1007/s00122-008-0875-3

3) Ascertaining maternal and paternal lineage within Musa by chloroplast and mitochondrial DNA RFLP analyses.

Journal: Genome, Issue: Vol 45, Issue 4, Aug 2002

4) The banana (Musa acuminata) genome and the evolution of monocotyledonous plants.

https://doi.org/10.1038/nature11241

5) Sexual polyploidization in plants--cytological mechanisms and molecular regulation.

https://doi.org/10.1111/nph.12184


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