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Accueil du site → Doctorat → Belgique → Amélioration de la tolérance de la pomme de terre (Solanum tuberosum L.) a la salinité (NaCl) par voie biotechnologique

Universiteit Gent (1996)

Amélioration de la tolérance de la pomme de terre (Solanum tuberosum L.) a la salinité (NaCl) par voie biotechnologique

Hannachi, Cherif Ben Mohamed

Titre : Amélioration de la tolérance de la pomme de terre (Solanum tuberosum L.) a la salinité (NaCl) par voie biotechnologique

Auteur : Hannachi, Cherif Ben Mohamed

Université de soutenance : Universiteit Gent

Grade : Doctor of Philosophy (PhD) 1996

In Tunisia, salinisation of soil is caused by low rainfall, high evaporation, salinity of irrigation water and important quantities of fertilizers. Therefore we initiated this research, in order to regenerate plants tolerant to salinity (NaCl) from potato varieties, ’Spunta’ and ’Claustar’. Cultures were initiated from apical meristems. To produce good quality explants, leafpieces (area : 100 to 200 mm$\sp2)$ and internodes (diameter : 1 to 2 mm ; length : 2 to 5 mm), mother plants were cultivated under favourable environmental growth conditions : vertical light, 16h photoperiod of 122 $\rm\mu mol.m\sp-2.s\sp-1$ PAR, temperature 23$\sp\circ$C. Calli of ’Claustar’, which is more reactive than ’Spunta’, obtained from leaves or internodes, were incubated on regeneration medium (BA 5 mg.l$\sp-1$ + NAA 0.05 mg.l$\sp-1$ + AgNO$\sb3$ 10 mg.l$\sp-1),$ supplemented with sodium chloride (NaCl) 1.5 to 9 g.l$\sp-1 ;$ 3-0-methyl-D-glucopyranose (MGP) 0.1 to 5 g.l$\sp-1$ or polyethylene glycol (PEG) 5 to 400 g.l$\sp-1.$ After adaptation to NaCl 3 g.l$\sp-1,$ PEG 50 g.l$\sp-1$ or MGP 1 g.l$\sp-1,$ the number of calli, able to regenerate shoots, was very low : 3 calli (1 or 2 shoots) for a total number of 17280 calli. Greenhouse culture on a nutrient solution (NFT) containing NaCl 3 g.l$\sp-1$ showed that only plantlets regenerated from calli adapted to NaCl 3 g.l$\sp-1$ in vitro, would tolerate this concentration in NFT (best in dry matter yield). Their tolerance is due to the accumulation of chlorine and sodium ions, which are involved in their osmotic adjustment. Moreover, in the field, these plantlets had no difference in yield with control plantlets when both were irrigated with water containing NaCl 3 g.l$\sp-1.$ In fact, an abnormal rainfall of 582 mm in 1995 (average of Sousse : 330 mm.year$\sp-1),$ during the culture period (3 months), probably diluted the NaCl. But stimulation of their growth in a young stage (culture on NFT) and its stability (field conditions) are indicators that this tolerance to NaCl isn’t a simple physiological adaptation, but a real genetic adaptation obtained in vitro. Among 5 clones $\rm(S\sb1,\ S\sb2,\ S\sb3,\ S\sb4\ and\ S\sb5)$ regenerated from the same callus of ’Spunta’, only 3 clones $\rm(S\sb3,\ S\sb4\ and\ S\sb5)$ showed morphological variations in size of the leaves and the tubers. This polymorphism which was also revealed by isoenzyme analysis of phosphatases, wasn’t modified by environmental changes (soil, climate), since the experiment was done in Gent (Belgium) and Chott-Mariem (Tunisia). Therefore, it is suggested that these somaclonal variations were genetic. Size reduction of tuber $\rm(S\sb3,\ S\sb4\ and\ S\sb5),$ increasing tuber number per plant (S$\sb3)$ and altered number of leaflets in the leaves $\rm(S\sb3,\ S\sb4\ and\ S\sb5)$ are agronomic characters. In fact, tuber yield per plant is positively correlated with growth. Nevertheless, these 3 clones can’t be used directly as agronomic varieties, as they are sensitive to potato leaf blight (Phythophtora infestans). But, this new genetic variability could be incorporated, via selection in traditional programs.

Mots clés : Agronomy, sodium chloride, Solanum tuberosum, Biological sciences, Plant propagation, tissue culture

Accès au document : Proquest Dissertations & Theses

Page publiée le 10 février 2015, mise à jour le 28 novembre 2018