CHROMOSOMAL ANALYSIS OF EIGHT CULTIVARS IN THREE SPECIES OF CULTIVATED YAM (DIOSCOREA) SPECIES IN NIGERIA

Joshua Matthew,Julius Faluyi

doi:10.36253/caryologia-840

Joshua Matthew, Julius Faluyi

Open Access

https://doi.org/10.36253/caryologia-840

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Abstract

The genus Dioscorea comprises of economically-important plant species known for their starch throughout the world; it is also a major source of food and income in Africa. The most important Dioscorea species cultivated and consumed in the West Africa belt include D. cayenensis, D. rotundata and D. alata. The plant materials used in this study were collected from Omu-Ekiti, Oye Local Government of Ekiti State, Nigeria using the On Farm Participatory Method (OFPM). Mitotic chromosome studies were carried out on three species viz, Dioscorea alata (‘ewura’), D. cayenensis (‘igangan’) and D. rotundata (‘areyingbakumo’, ‘gaungaun’, ‘ikumo’, ‘ogunmole’ and ‘sandpaper’). Mitotic chromosome studies were carried out on each of the cultivars using the root tip squash method made in modified Orcein stain (FLP-Orcein). Dormant tubers were cut to mini-setts and placed in carbonised rice husk for rooting. This study reports the basic chromosome number of x = 8, i.e. 2n = 4x =32 (D. alata), 2n = 4x =38 (D. rotundata) and 2n = 8x = 68 (D. cayenensis) for Dioscorea suggesting that both D. rotundata and D. cayenensis are aneuploids.

Highlights

The genus Dioscorea L. belongs to the family Dioscoreaceae which includes about 90% of the species in the family (Murti 2001)
None of the mitotic counts observed in this study is in agreement with the previous mitotic chromosome numbers reported for yam (Table 1). (Bousalem et al 2006) reported that the dot-like and varying chromosome sizes that occurred in the mitotic cells of Dioscorea made the definite determination of chromosome numbers difficult
This study reports the basic chromosome number of x = 8 in D. alata (2n = 4x =32), D. rotundata, (2n = 4x =38) and D. cayenensis (2n = 8x = 68)

Summary

Introduction

The genus Dioscorea L. belongs to the family Dioscoreaceae which includes about 90% of the species in the family (Murti 2001). The genus Dioscorea is principally tuber-bearing and has great economic value in the tropics as food, pharmaceutical, starch, socio-cultural uses and source of income to farmers in West and Central Africa (Asiedu et al 1998; Séka et al 2009). The most important Dioscorea species cultivated and consumed in the West Africa belt include D. cayenensis Lam., D. rotundata Poir. Dioscorea has presented a challenge to systematists for many years due to its great morphological diversity, its reproductive biology: dioecy, small flowers, low or no seed set and tuber propagation (Wilkin et al 2005).

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