Influence of the arbuscular mycorrhizal fungus Glomus intraradices on the saline stress physiology of Lotus glaber

ANALÍA SANNAZZARO; EDGARDO ALBERTÓ, OSCAR A RUIZ Y ANA B. MENÉNDEZ

Chascomús. Buenos Aires. Argentinas

Taller; TALLER INTERDISCIPLINARIO SOBRE ASPECTOS GENETICOS, MOLECULARES Y FISIOECOLOGICOS DEL LOTUS SPP. Y SUS SIMBIONTES.; 2004

IIB-INTECH. Chascomús. buenos Aires. Argentina

Lotus glaber is a glycophytic, perennial legume from Europe that occurs widely in saline habitats. Previous observations indicate the occurrence of genotypes highly tolerant to salinity in different populations of L. glaber (Mujica & Rumi, 1998). Several workers have shown that AM protect the plant against salinity (Al-Karaki et al., 2001; Feng et al., 2002) and a high diversity of AM fungal colonization patterns in roots of L. glaber was found in fields characterized by their high salinity (Sannazzaro et al., 2004). Our aim was to evaluate the effect of mycorrhizal colonization on growth response to salt stress in two genotypes of L. glaber differing in their tolerance to salinity. We also hypothesized that polyamines, small organic cations that are thought to play a role in the plant responses to salt stress (Bouchereau et al., 1999; Simon- Sarkadi et al., 2002) are involved in such a process. The experiment 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. L. glaber plants colonized by G. intraradices grow better than non- AM ones, particularly under saline condition, where they showed higher values of net growth, shoot/root ratio, K/Na rate, and protein and chlorophyll contents. An increase in total free polyamine content of mycorrhized L. glaber plants compared to nonmycorrhized ones, suggests that these amines may be involved in the salt stress alleviation of this species. The increment in spermine levels in sensitive L. glaber plants grown under salt stress condition could be due to de novo synthesis from its metabolic precursors. In addition, high proline levels were observed under salt stress conditions in both genotypes. Our results interestingly indicate that G. intraradices established a more efficient symbiosis with the tolerant than with the sensitive genotype. Results suggest that the fungal symbiont could play an important role in the adaptation of L. glaber plants to salt stress under field conditions. References. Bouchereau, A., et al. 1999. Plant Science 140: 103-125. Mujica, M.M. & Rumi, C.P. 1998. Lotus Newsletter 29. Feng, G., et al. 2002. Mycorrhiza 12: 185-190. Simon-Sarkadi L, Kocsy G, Sebestyén Z. 2002. Acta Biol Szeged 46: 73-75. Sannazzaro, A., et al. 2004. FEMS Microbiol Lett 230: 115-121.