Axillary proliferation and tuberisation of Dioscorea cayenensis–D. rotundata complex

Abstract

Yams (Dioscorea spp) are tuber crops used as staple food in Africa because of their nutritional value. However agronomic constraints, phytosanitary problems and the lack of good healthy planting material restrict their production. In contrast to the inefficiency of traditional method of planting, tissue culture techniques allow to increase the multiplication and the rapid production of pathogenfree plant material. This work was undertaken to provide farmers in African countries with healthy microplants and microtubers as seeds. In vitro nodal segments of two varieties of local yams D. cayenensis-D. rotundata complex (cv. 'Singo', cv. 'Singou' and cv. 'Gnidou') were micropropagated on the modified medium of Murashige and Skoog. The morphogenesis, the growth of microplants and microtuber formation have been found to be controlled by external factors that act individually and synergistically. Addition of kinetin (2 mg l À1 ) to the culture media could reduce multiplication rate (node number) of some clones. An increase of the sucrose concentration from 3% to 5% induced no change in the multiplication and tuberisation parameters. An important reduction of the multiplication (shoot number, height and node number) and the tuberisation (tuber number and length) was observed with 8% sucrose. Multiplication (shoot and node number) was increased in the presence of jasmonic acid (10 mM). JA also induced an increase of tuber number in the absence of Kin. Multiplication of yam by in vitro growth of nodal segments is a way for rapid clonal multiplication and could allow solving the problem of lack of seed material faced by farmers. This method could also be used for multiplication of elite cultivars, independently of the growing season.

Tuber formation and growth of Dioscorea cayenensis-D. rotundata complex: interactions between exogenous and endogenous jasmonic acid and polyamines

“…1a), resulting in the formation of one microtuber per explant as it was also previously described by Ondo Ovono et al (2007). During the following weeks, the size of the tuber increased.…”

In vitro tuberization and plant regeneration from multinodal segment culture of Habenaria bractescens Lindl., an Argentinean wetland orchid

“…Ar: absorbing roots; Dr: dropper; Ne: necrotic explant; Sh: shoot; Swb: swollen buds; Rtu: root tubers and van Staden 1984;Sarkar 2008). There are several reports about in vitro formation of different storage organs in monocots, e.g., in Amaryllidaceae (Ilczuk et al 2005), Alliaceae (Goleniowski et al 2001), Araceae (Ndoumou et al 1995), Colchicaceae (Ghosh et al 2007), Dioscoreaceae (Sengupta et al 1984;Oyono et al 2007) and Zingiberaceae (Shirgurkar et al 2001). However, in spite of the great number of Orchidaceae that undergo this physiological phenomenon, there are very few reports of the promotion of storage organs in vitro in these species.…”

Effects of reducing sugar concentration on in vitro tuber formation and sprouting in yam (Dioscorea cayenensis–D. rotundata complex)

“…We previously reported that microtubers could be obtained on yam nodal cutting explants, from an unique axillary bud, cultured in MS basal medium with or without plant growth regulators (Ondo Ovono et al 2007). The bud developed into a shoot and a weak enlargement at the base of the axillary bud was observed, resulting in the formation of a microtuber after 3 weeks on all the explants in control conditions.…”

“…Many factors are known to influence the tuberisation response in vitro. These may include day length (Vaillant et al 2005) and temperature (Grison 1991), the presence or absence of growth regulators either singly or in combination (Ondo Ovono et al 2007, or the presence of high sucrose (8%) concentration (Forsyth and Van Staden 1984).…”