Plant polyamine metabolism and arbuscular mycorrhizal colonization

ECHEVERRÍA M., MARINA M., MENÉNDEZ A., MONTES M., RUIZ O., SANNAZZARO A., SCAMBATO A., SOSA M.

Granada. España

Congreso; 5th International Conference on Mycorrhiza.; 2006

Polyamines are small organic cations that are absolutely required for eukaryotic cell growth. These compounds are thought to play an important role in plant responses to a wide array of environmental and biotic stresses, however little is known about their rol on the regulation of arbuscular mycorrhizal (AM) colonization. Our work was aimed at evaluating: 1-the influence of colonization by Glomus intraradices on polyamine metabolism of Lotus spp. under salt stress, and 2- the effect of altered polyamine levels of Nicotiana tabacum on root colonization by Glomus intraradices. In 1-, the experiments consisted of a randomized block design with two factors: (1) mycorrhizal treatments (with or without AM fungus) and (2) two salinity levels of 0 and 200 mM NaCl. Total free polyamines contents were higher in mycorrhized plants compared to non-AM ones. These results are discussed with regard to improvements in plant growth. In 2- we used transgenic tobacco plants containing the Avena sativa L. (oat) arginine decarboxylase (ADC) gene under the control of a tetracycline-inducible promoter. Transformed tobacco plants without the transgene and non-induced plants were used as controls. Our results showed higher percentage of AM colonization and number of infection points and vesicles in induced plants carrying the transgene compared to controls. We discuss these results in relation to tobacco polyamine levels.