Reproductive biology of wild and domesticated Ensete ventricosum: Further evidence for maintenance of sexual reproductive capacity in a vegetatively propagated perennial crop

Abstract

PREMISELoss of sexual reproductive capacity has been proposed as a syndrome of domestication in vegetatively propagated crops, but there are relatively few examples from agricultural systems. Compared to sexually propagated crops banked as seeds, vegetative crop diversity is typically conserved in living collections that are more costly and insecure. This vulnerability may disproportionately impact tropical crop diversity where vegetative reproduction predominates. In this study we assess sexual reproductive capacity in wild (sexual) and domesticated (vegetative) populations of enset (Ensete ventricosum (Welw.) Cheesman), a giant tropical banana relative and Ethiopian food security crop.METHODSWe harvested seeds from 20 wild and domesticated enset to survey variation in seed weight, viability, external and internal morphology. We germinated seeds across a range of constant and alternating temperature regimes to characterise optimum germination requirements, and evaluate differences in performance.KEY RESULTSWe found no significant difference between wild and domesticated enset seed viability, days to germination and internal morphological traits. However, we report a significant and unexpected shift in seed weight and germination behaviour, with seed from domesticated plants responding to cooler temperatures with greater diurnal range. Shifts in germination behaviour appear concordant with a climatic envelope shift in the domesticated distribution.CONCLUSIONSOur findings suggest sexual reproductive capacity has been maintained despite long-term near-exclusive vegetative propagation in domesticated enset. Furthermore, certain traits such as germination behaviour, may be under continued selection through rare sexually reproductive events. Improved understanding of sexual propagation in vegetative crops may have applications in germplasm conservation and plant breeding.

The Genetic Diversity of Enset (Ensete ventricosum) Landraces Used in Traditional Medicine Is Similar to the Diversity Found in Non-medicinal Landraces

“…Conserving domesticated enset diversity as seeds have been considered challenging for several reasons ( Tamrat et al, 2020b ), and the existing seed conservation measures of the enset crop and its wild relatives is insufficient ( Guzzon and Müller, 2016 ). The most common method of conserving the genetic resources of vegetatively propagated plants like enset is in a field gene bank, which is very costly in terms of requirements for land, maintenance, and labor.…”