Phenotypic plasticity in relation to Lotus tenuis response to saline stress: the role of arbuscular mycorhizal and rhizobial symbiont

ECHEVERRÍA, M; SCAMBATO AGUSTINA; MAIALE S; SANNAZZARO A; RUIZ O; MENÉNDEZ A

Chascomús

Taller; IV Interdisciplinary Workshop of Lotus: Aspectos Genéticos, Moleculares y Ecofisológicos de Lotus Spp. y sus Simbiontes, 2008, Chascomus. IV Interdisciplinary Workshop of Lotus: Aspectos Genéticos, Moleculares y Ecofisológicos de Lotus Spp. y sus Simbiont; 2008

Our hypothesis is that Lotus glaber (a glycophytic species, highly tolerant to saline?alkaline soils) displays a plastic root phenotypic response to soil salinity that may be influenced by mycorrhizal and rhizobial microorganisms. Uninoculated plants and plants colonised by Glomus intraradicesLotus glaber (a glycophytic species, highly tolerant to saline?alkaline soils) displays a plastic root phenotypic response to soil salinity that may be influenced by mycorrhizal and rhizobial microorganisms. Uninoculated plants and plants colonised by Glomus intraradices?alkaline soils) displays a plastic root phenotypic response to soil salinity that may be influenced by mycorrhizal and rhizobial microorganisms. Uninoculated plants and plants colonised by Glomus intraradicesGlomus intraradices or Mesorhizobium loti were exposed to either 150 or 0 mM NaCl. General plant growth and root architectural parameters (morphology and topology) were measured and phenotypic plasticity determined at the end of the salt treatment period. Two genotypes differing in their salt tolerance capacity were used in this study. G. intraradices and M. lotiMesorhizobium loti were exposed to either 150 or 0 mM NaCl. General plant growth and root architectural parameters (morphology and topology) were measured and phenotypic plasticity determined at the end of the salt treatment period. Two genotypes differing in their salt tolerance capacity were used in this study. G. intraradices and M. lotiG. intraradices and M. loti reduced the total biomass of non-salinised, sensitive plants, but they did not affect that of corresponding tolerant ones. Root morphology of sensitive plants was greatly affected by salinity, whereas mycorrhiza establishment counteracted salinity effects. Under both saline conditions, the external link length and the internal link length of mycorrhizal saltsensitive plantswere higher than those of uninoculated control and rhizobial treatments. The topological trend (TT) was strongly influenced by genotype × symbiosis interaction. Under non-saline conditions, nodulated root systems of the sensitive plant genotype had a more herringbone architecture than corresponding uninoculated ones. At 150 mM NaCl, nodulated root systems of tolerant plants were more dichotomous and those of the corresponding sensitive genotype more herringbone in architecture. Notwithstanding the absence of a link between TTs and variations in plant growth, it is possible to predict a dissimilar adaptation of plants with different TTs. Root colonisation by either symbiotic microorganisms reduced the level of root phenotypic plasticity in the sensitive plant genotype. We conclude that root plasticity could be part of the general mechanism of L. glaber salt tolerance only in the case of non-symbiotic plants.L. glaber salt tolerance only in the case of non-symbiotic plants.