Recurrent evolution of cryptic triploids in cultivated enset increases yield

Area of Science:

• Plant genetics
• Crop domestication
• Polyploidy research

Background:

• Polyploidy (multiple chromosome sets) is frequent in crops, potentially due to selection for desirable traits during domestication.
• Enset (Ensete ventricosum), a staple crop in Ethiopia, was previously believed to be exclusively diploid.

Purpose of the Study:

• To investigate the ploidy levels in cultivated enset and explore the role of polyploidy in its domestication.
• To identify and characterize triploid enset clones and assess their significance in the Ethiopian agrosystem.

Main Methods:

• Utilized a new chromosome-scale reference genome for enset.
• Analyzed sequence data from 723 wild and domesticated enset individuals from Ethiopia.
• Investigated ploidy levels, genetic diversity, and phenotypic traits (pseudostem volume).

Main Results:

• Approximately 20% of cultivated enset clones are triploid, with triploidy arising independently multiple times.
• Triploid enset lineages have distinct landrace names and are disproportionately cultivated.
• Triploid enset clones exhibit larger pseudostem volumes compared to diploids, indicating selection for this trait.

Conclusions:

• The study provides evidence for the selection of polyploids during enset domestication, challenging previous assumptions about its ploidy.
• Identified valuable genetic diversity within triploid enset lines, crucial for future breeding programs.
• Triploid enset resources can enhance food security in Ethiopia and Sub-Saharan Africa.