Wild banana in mainland Southeast Asia reveal hidden diversity and need to conserve natural genetics
NEWS - There are many Musa L. species in the natural diversification area of Southeast Asia, but the actual number is still debated because the botanical characterization, distribution and intraspecific variability are still poorly known which endangers the conservation and exploitation as wild relatives of cultivated forms.
To address the unexplored Musa diversity in mainland Southeast Asia, researchers examined 208 specimens collected in Vietnam, Laos and China which mostly belong to Musa balbisiana, Musa itinerans, Musa acuminata and Musa yunnanensis.
Mainland Southeast Asia as the main center of diversification for the Musa section shows a very contrasting distribution. M. yunnanensis is localized in the specific ecology of the Yunnan plateau, while Musa acuminata is only endemic to the Burmannica complex in upper Laos but has occasionally been transported over long distances.
M. itinerans has a strong presence with a much wider distribution throughout Southeast Asia. M. balbisiana has an even wider distribution and is now found in all areas with a benign ecology, thus posing a challenge in distinguishing spontaneous from wild forms.
Genomic characterization shows intraspecific diversity in all species that does not seem to correlate with morphological diversity, except in the case of M. yunnanensis. Interestingly, these genomic data have shown the existence of hybrid forms between M. acuminata and M. yunnanensis.
The hybridization was spontaneous between wild species or without human intervention which has not been documented before. The hybridization proves the possibility of spontaneous interspecific hybridization inferred for the early phase of domestication of cultivated banana.
Intraspecific genetic diversity has revealed a distinct diversity structure in internal variability and heterozygosity levels. This structure is also geographically organized, at least for M. balbisiana and M. itinerans, more related to human factors than to environmental constraints.
The exploitation of natural populations by local people has had an impact on species diversity. Uses other than fruit consumption were certainly the main drivers in the early stages of Musa domestication, as they probably were for other important crop species.
M. yunnanensis is a typical wild form, but it is already used as animal feed. M. acuminata subsp. burmannica is also always found in the wild. Geographical distribution is still limited, but sporadic distribution sites may be related to human movement.
M. itinerans which has a wide distribution is not cultivated, but is subjected to intense human exploitation of natural populations with minimal agricultural practices such as transplantation and possible selection for certain traits.
M. balbisiana is at the most advanced stage of the process. This species can be considered to have been domesticated due to its various uses resulting in a very wide distribution and diversity that is strongly influenced by human activities.
These findings lead to a reconsideration of the boundaries between the concepts of wild, cultivated and domesticated bananas by referring to the concept of ‘wild cultivation’ and defined as wild plants that are cultivated and translocated by humans.
Original research
Jenny C, Sachter-Smith G, Breton C, Rivallan R, Jacquemoud-Collet J-P, Dubois C, et al. (2024). Musa species in mainland Southeast Asia: From wild to domesticate. PLoS ONE 19(10): e0307592, DOI:10.1371/journal.pone.0307592
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