A morphological study of populations of Lotus glaber Mill. (Fabaceae)

Abstract

The pasture legume Lotus glaber Mill. has colonized the Flooding Pampa (Argentina) in spite of high environmental heterogeneity. Morphological characters of plants from different populations were compared to evaluate if plastic or genetic differentiation could have contributed to such a widespread geographic distribution. Plants were collected at random from six different sites and grown in a greenhouse for five months. Clonal replicates of those plants were cultivated in pots on a native and a common soil. Populations were replicated three times and each replicate (pot) had three plants from the same clone. The number of primary shoots, internode length, leaf length and width and shoot length were recorded and the significance of population mean differences determined. All characters, except for leaf width, differed between populations on each sampling in both sets of experiments. This variability is therefore best explained by genetic differentiation of the populations. morphological variation / environmental heterogeneity / naturalized species / Lotus glaber Mill. / genetic differentiation Résumé-Étude de la variabilité morphologique dans les populations de Lotus glaber Mill. (Fabaceae). La légumineuse fourragère Lotus glaber Mill a colonisé la Pampa inondée en Argentine malgré la très grande hétérogénéité des conditions environnementales. Dans cette étude nous comparons la morphologie de différentes populations afin de déterminer si une plasticité phénotypique ou une différenciation écotypique ont permis une aussi large dispersion géographique de l'espèce. Des plantes représentatives de 6 sites ont été transplantées et cultivées en serre durant 5 mois. Des boutures de ces différents plants ont également été cultivées dans des pots remplis avec le sol original des sites correspondants ainsi qu'avec un sol unique provenant d'un autre site. Le nombre de pousses primaires, la longueur des inter-noeuds, la longueur et la largeur des feuilles et la longueur des pousses ont été mesurées et la validité statistique des différences à la moyenne de la population a été déterminée. Toutes les caractéristiques morphologiques, sauf la largeur des feuilles ont montré des différences pour chaque échantillon et dans chaque série d'expériences. Ce type de variabilité pourrait être mieux expliqué par une différenciation d'écotypes que par une plasticité phénotypique. variabilité morphologique / hétérogénéité environnementale / adaptation des espèces / Lotus glaber Mill. / écotype

Flavonoids of Lotus tenuis (Waldst. & Kit.) as markers of populations growing in soils of different saline and hydrologic conditions

“…It is clear that the flavonoid profile of population from site 3 differed with the other populations sampled. The CCA study support this conclusion showing that quercetin 7-methyl ether and kaempferol 7-methyl ether present in leaves were particularly important in L. tenuis plants growing in soils of high pH, EC and ESP (Figure 2) Taking into account our previous works 21, 22 and the results obtained herein, it could be deduced that the San Vicente (site 3) population represents an ecotype of very well defined soil chemical characteristics, plant morphological characters and distinguished by its efficiency to absorb phosphorus from the soil. Owing to their uniqueness it would be interesting to investigate the presence of the methylated flavonoids in roots or root exudates as they might be useful as markers to study interactions with mycorrhiza, specially considering that roots of L. tenuis growing in site 3 were heavily colonized by arbuscular mycorrhizas even when the site was flooded during 7 months.…”

“…This characteristic shows a remarkable difference with the population from site 3 coinciding with the differences in the observed morphological characteristics and their phosphorus absorbing capacity reported in previous works. 21,22 According to the results obtained in this work, it is possible to establish differences between the populations based on the structure of the flavonoid aglycones and their glycosides. Differences in the aglycone composition were observed in populations from all the sites studied.…”

“…In addition, L. tenuis from populations of site 3 showed longer shoots, internodes and leaflets when compared to the ones belonging to the other five populations (sites 1, 2 and 4 were included) when growing in both the original and a common soil. 22 The authors concluded that these characteristics were due to the existence of a genetic control that suggested the presence of ecotypes adapted to specific soil conditions. The principal differences between sites are referred to the glycoside content and the type of chromatographic profile of the leaf and flower extracts.…”

Genetic Diversity and Host Range of Rhizobia Nodulating Lotus tenuis in Typical Soils of the Salado River Basin (Argentina)

“…Lotus tenuis is a valuable forage legume native to the Mediterranean region which has become naturalized in the Salado River Basin during the last few decades and has shown good potential for adaptation to the soils there (32,44). Thus, cultivation of L. tenuis could contribute to improvements in forage quality and production in the Salado River Basin.…”

Agrobacterium tumefaciens-mediated transformation of Lotus tenuis and regeneration of transgenic lines

“…Due to its high nutritive value and adaptive plasticity to the edaphic and environmental stresses characterised by the presence of heavy and saline soils, this species is considered an important alternative source of cattle feed. Genetic improvement of abiotic stress tolerance in L. tenuis through conventional breeding methods has been limited due to the heterozygous nature of the existing wild populations (Kade et al 2003). However, in recent years, emphasis has been placed on the use of in vitro culture approaches for the multiplication and improvement of this genus through genetic transformation techniques.…”