Medicago Truncatula Genotypes Research Articles

Micropropagation of Medicago truncatula Gaertn. cv. Jemalong and Medicago truncatula ssp. Narbonensis

A simple and reliable method was established for the maintenance of a permanent stock of several Medicago truncatula genotypes selected from a general seed stock by their in vitro culture amenability and embryogenic capacity. In the first step, multiple shoots were induced from the cotyledon axillary meristem meristem of pre-germinated seeds in Murashige and Skoog medium supplemented with cytokinins (9.3 μM zeatin, 22.2 μM benzylaminopurine or 4.5 μM thidiazuron). In the second step, the induced shoots were allowed to develop in growth-regulator-free medium. Benzylaminopurine at 22.2 μM supported the best combination of shoot quality and number of shoots produced. Rooting of microshoots depended on the cytokinin used for shoot induction and was faster for zeatin-treated shoots. In this work a propagation system was devised where the addition of growth regulators was restricted to the induction phase therefore reducing the risks of epigenetic and somaclonal variation.

Differential tolerance of genotypes of Medicago truncatula to low pH

Growth and nodulation of five Moroccan ecotypes of Medicago truncatula Gaertn. Collected from soils of different pH, Medicago truncatula cv. Cyprus and Medicago murex Willd. cv. Zodiac, were compared in soil and solution at different pH values. The seven genotypes tested varied greatly in their ability to grow and nodulate on acid soils. Increasing soil pH from 4.5 to 5.4 increased the shoot dry weight of Cyprus and three M. truncatula ecotypes but not Zodiac and two M. truncatula ecotypes. Cultivar Cyprus, with a shoot dry weight at pH 4.5 only 58% of that at pH 5.4, was the most affected by acidity. Nodulation was the most sensitive step as nodule numbers decreased with increasing acidity for sensitive genotypes. Several genotypes were more able to nodulate at low pH than the commercial cultivar Cyprus. Acid tolerance was not restricted to genotypes occurring naturally in acid soils.