Abstract
Yam (Dioscorea spp.) is a monocotyledonous herbaceous vine plant grown in the tropics and subtropics. It is a multi-species plant with varied intra- and interspecific ploidy levels. Of the 600 species, 11 are cultivated supporting the livelihood of over 300 million people. The paucity of information on ploidy and the genomic constitution is a significant challenge to the crop’s genetic improvement through crossbreeding. The objective of this study was to investigate the ploidy levels of 236 accessions across six cultivated and two wild species using chromosome counting, flow cytometry and genotyping-based ploidy determination methods. Results obtained from chromosome counting and genotyping-based ploidy determination were in agreement. In majority of the accessions, chromosome counting and flow cytometry were congruent, allowing future rapid screening of ploidy levels using flow cytometry. Among cultivated accessions, 168 (71%) were diploid, 50 (21%) were triploid, and 12 (5%) were tetraploid. Two wild species included in the study were diploids. Resolution of ploidy level in yams offers opportunities for implementing successful breeding programmes through intra- and interspecific hybridization.
Highlights
Yam (Dioscorea spp.) is a monocot herbaceous vine plant grown in the tropical and subtropical regions of the globe
The chromosome counting results regarding the ploidy level were similar to DArTseq, except for accessions of two wild species for which DArTseq data were not generated (Table S1)
Our study has identified, for the first time, based on agreement in ploidy number among the three methods used in the study viz. yam/Chicken red blood cell nuclei (CRBC) peaks of the flow-cytometry method, chromosome number estimation through chromosome counting and genotyping through the DArTseq based technique, internal reference standards that can be used in future studies to determine the ploidy status in Dioscorea spp using flow cytometry alone
Summary
Yam (Dioscorea spp.) is a monocot herbaceous vine plant grown in the tropical and subtropical regions of the globe. Yam produces starchy underground tubers and ariel bulbils that provide dietary nutrients such as starch, protein, vitamins, and micro-nutrients for those who depend on it as a staple food [4]. In West Africa, yam is a highly priced tuber crop contributing about 15% of the daily per capita calorie intake and about 32% farm income for over 300 million people [5]. West Africa represents over 90% of global yam production [6]. Yam production in Africa is 40% lower than that of cassava, its gross economic value exceeds that for all other African staple crops and is equivalent to the summed value for maize, sorghum, and rice, the top three cereal crops [6]
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