PGPRs and nitrogen-fixing legumes: a perfect team for efficient Cd phytoremediation?

Abstract

Cadmium (Cd) is a toxic, biologically non-essential and highly mobile metal that has become an increasingly important environmental hazard to both wildlife and humans. In contrast to conventional remediation technologies, phytoremediation based on legume–rhizobia symbiosis has emerged as an inexpensive decontamination alternative which also revitalize contaminated soils due to the role of legumes in nitrogen cycling. In recent years, there is a growing interest in understanding symbiotic legume–rhizobia relationship and its interactions with Cd. The aim of the present review is to provide a comprehensive picture of the main effects of Cd in N 2 -fixing leguminous plants and the benefits of exploiting this symbiosis together with plant growth promoting rhizobacteria to boost an efficient reclamation of Cd-contaminated soils.

Combined effects of mutualistic rhizobacteria counteract virus-induced suppression of indirect plant defences in soya bean

“…There are several potential mechanisms by which such effects might be produced, including PGPR facilitation of additional colonization sites for rhizobia, PGPR production of plant hormones, direct effects of PGPR colonization on ethylene levels, and PGPR stimulation of flavonoid production by roots [39]. The failure to observe strong effects of D. acidovorans in isolation is consistent with the latter explanation, as in this scenario the benefits of D. acidovorans for the host occur indirectly via the induced [39,41] to improve the performance of B. japonicum. A similar effect was reported in a recent study involving the application of Delftia in coinoculation with Sinorhizobium meliloti, which found that Medicago truncatula roots produced significantly higher levels of several flavone signalling molecules (which enhance rhizobial expression of nodulation genes) under co-infection relative to microbe-free or single inoculation treatments [38].…”

Rangeland Use Change to Agriculture Has Different Effects on Soil Organic Matter Fractions Depending on the Type of Cultivation

“…Beside the biomass input, above-ground vegetation might affect SOM and nitrogen through other ways. For instance, legumes have the ability to form a mutually beneficial (symbiotic) relationship with certain soil bacteria of the type or genus Rhizobia (Oueslati et al, 2013;Gómez-Sagasti & Marino, 2015). These bacteria can take nitrogen from the air and add to soil.…”

Comprehensive Account of Inoculation and Coinoculation in Soybean

“…Moreover, Azospirillum has been used to increase the rhizobia-legume symbiotic relationship in soybean to improve its nutritive value [12]. For coinoculation, in vitro strain selection or genetically engineered strains are commonly used [17]. It is generally assumed that one rhizobacterium may be less effective in diverse environmental conditions.…”