New insights into mango evolution: Study reveals extensive hybridization within the Mangifera genus
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A research team investigated whole chloroplast genomes and nuclear gene sequences from 14 species, uncovering new insights into the genetic diversity and hybrid origins of mango species. They used the evolutionary relationships within the Mangifera genus, revealing extensive cross-hybridization among species and offering implications for breeding and conservation efforts.
Mangifera indica, commonly known as mango, is the most widely cultivated species of the Mangifera genus, a group of 69 species in the Anacardiaceae family. Mangoes are a major global fruit crop, with India leading the world in production, followed by Indonesia, Mexico, China, and Pakistan. While most Mangifera species are identified based on physical characteristics, growing evidence suggests that some species may have hybrid origins. This discovery has the potential to transform the understanding of mango evolution and its genetic diversity.
A study published in Tropical Plants on 12 October 2024, provides a more accurate genetic map for breeders to identify and select for desirable traits, potentially leading to the development of new mango cultivars that can better withstand environmental challenges.
The research employed Illumina sequencing to analyze chloroplast genomes of 19 samples from 14 Mangifera species, producing between 55,999,560 to 181,601,786 raw reads, with a mean read length of 150 bp.
After trimming to a Phred score >20, the data size for each sample exceeded 20 times the genome size, making them suitable for chloroplast assembly. Additional data from NCBI was included for five species.
Using the Get Organelle pipeline and Clone Manager Professional 9, chloroplast genomes were aligned to the reference genome of Mangifera indica. Results showed chloroplast genome sizes ranged from 151,752 to 158,965 bp across species, with a typical quadripartite structure and 115 genes (80 protein-coding, 31 tRNA, 4 rRNA).
Although genome sizes varied, some species, such as three cultivars of M. indica and two M. laurina samples, had identical chloroplast genomes.
In some species, minor structural differences were noted, such as the two M. odorata samples, which exhibited a 6 bp difference due to deletions in non-coding regions.
Comparative analysis of nuclear gene phylogenies indicated genetic clustering into distinct clades, suggesting close evolutionary relationships, particularly among wild species like M. lalijiwa and M. applanata with domesticated M. indica. Variations between chloroplast and nuclear gene-based trees pointed to hybridization events within the genus.
According to the study's senior researcher, Dr. Robert J. Henry, "Our research provides a detailed genetic framework for understanding how hybridization has shaped the Mangifera genus. The evidence of gene flow among species not only enhances our knowledge of mango evolution but also has practical applications for mango breeding programs aimed at improving fruit quality and stress resilience."
This study offers the most comprehensive genetic analysis of Mangifera species to date, shedding light on the hybridization processes that have shaped the evolution of mangoes.
By deepening our understanding of the genetic relationships among mango species, these findings pave the way for more efficient mango breeding strategies and improved crop resilience, ensuring the continued success of this beloved fruit in a changing climate.
More information: Upendra Kumari Wijesundara et al, Phylogenetic relationships in the genus Mangifera based on whole chloroplast genome and nuclear genome sequences, Tropical Plants (2024). DOI: 10.48130/tp-0024-0031
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