Isolation and Characterization of a Novel Cross-Infective Rhizobia from Sesbania aculeata (Dhaincha)

Diversity and phenotypic analyses of salt- and heat-tolerant wild bean Phaseolus filiformis rhizobia native of a sand beach in Baja California and description of Ensifer aridi sp. nov

In northern Mexico, aridity, salinity and high temperatures limit areas that can be cultivated. To investigate the nature of nitrogen-fixing symbionts of Phaseolus filiformis, an adapted wild bean species native to this region, their phylogenies were inferred by MLSA. Most rhizobia recovered belong to the proposed new species Ensifer aridi. Phylogenetic analyses of nodC and nifH show that Mexican isolates carry symbiotic genes acquired through horizontal gene transfer that are divergent from those previously characterized among bean symbionts. These strains are salt tolerant, able to grow in alkaline conditions, high temperatures, and capable of utilizing a wide range of carbohydrates and organic acids as carbon sources for growth. This study improves the knowledge on diversity, geographic distribution and evolution of bean-nodulating rhizobia in Mexico and further enlarges the spectrum of microsymbiont with which Phaseolus species can interact with, including cultivated bean varieties, notably under stressed environments. Here, the species Ensifer aridi sp. nov. is proposed as strain type of the Moroccan isolate LMR001^T (= LMG 31426^T; = HAMBI 3707^T) recovered from desert sand dune.

A lectin from Sesbania aculeata (Dhaincha) roots and its possible function

A lectin was isolated from the roots of Sesbania aculeata. This is a glucose specific lectin having 39 kDa subunit molecular weight. The expression of this lectin was found to be developmentally regulated and observed to be the highest in the second week. The lectin was purified by affinity chromatography using Sephadex G-50 and found to have 28% homology with Arabidopsis thaliana lectin-like protein (accession No. CAA62665). The lectin binds with lipopolysaccharide isolated from different rhizobial strains indicating the plants interaction with multiple rhizobial species.

Purification and mass spectrometric characterization of Sesbania aculeata (Dhaincha) stem lectin

A glucose specific lectin (STA) was isolated from Sesbania aculeata stem by using Sephadex G-50 affinity column chromatography. The lectin is a glycoprotein having 29 kDa subunit molecular weight. Two dimensional gel electrophoresis analysis revealed that the lectin existed in two isomeric forms with varied carbohydrate content as analyzed by high performance anion exchange chromatography-pulsed amperometric detector (HPAEC-PAD). Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) and N-terminal sequence (LDSLSFTYNNFE) analysis of this lectin showed 95% homology with stem lectin SL-I (accession no. AJ585523) from peanut plant. The nucleotide sequence of the lectin (STA) was submitted to the gene bank (accession no. EU263636).