Microvirgasp. symbiovar mediterranense nodulatesLupinus cosentiniigrown wild in Morocco

Abstract

Aim To analyse the diversity of nodule‐forming bacteria isolated from Lupinus cosentinii naturally grown in the Maamora cork oak forest (Rabat, Morocco). Methods and Results Of the 31 bacterial strains, four were selected based on their REP‐PCR fingerprinting that were studied by sequencing and phylogenetic analysis of their 16S rRNA, gyrB, dnaK, recA and rpoB housekeeping genes as well as the nodC symbiotic gene. The nearly complete 16S rRNA gene sequence of the four representative strains showed that they are related to Tunisian strains of genus Microvirga isolated from L. micranthus with nucleotide identity values ranging from 98·67 to 97·13%. The single and concatenated sequences of the 16S rRNA, gyrB, dnaK, recA and rpoB housekeeping genes indicated that the L. cosentinii‐isolated strains had 99·2–99·9% similarities with the Tunisian L. micranthus microsymbionts. The nodC gene phylogeny revealed that the Moroccan strains clustered in the newly described mediterranense symbiovar, and nodulation tests showed that they nodulated not only L. cosentinii but also L. angustifolius, L. luteus and L. albus. Conclusions To the best of our knowledge, this is the first report concerning the isolation, molecular identification and phylogenetic diversity of L. cosentinii nodule‐forming endosymbionts and of their description as members of the Microvirga genus. Significance and Impact of the Study In this work, we show that Microvirga sp. can be isolated from root nodules of wild‐grown L. cosentinii in Northeast Africa, that selected strains also nodulate L. angustifolius, L. luteus and L. albus, and that they belong to symbiovar mediterranense. In addition, our data support that the ability of Microvirga to nodulate lupines could be related to the soil pH, its geographical distribution being more widespread than expected.

Characterization of Bradyrhizobium spp. Nodulating Lupinus cosentinii and L. luteus Microsymbionts in Morocco

“…The phenotypic analysis showed that all the strains assimilate different carbon sources including glucose, mannose, galactose, and sucrose, while no strain used starch or lactose; this result agrees with previously reported results (Rome et al, 1996;Missbah El Idrissi et al, 2020). Bradyrhizobium canariense BTA-1T does not use sucrose or lactose either (Vinuesa et al, 2005).…”

“…for a long time until Ardley et al (2012) reported the isolation and identification of three symbiotic Microvirga species from L. texensis and Listia angolensis root nodules. More recently, lupines were found to be nodulated by Microvirga strains in Tunisian, Moroccan, and American soils (Beligala et al, 2017;Msaddak et al, 2017Msaddak et al, , 2019Rejili et al, 2019;Missbah El Idrissi et al, 2020). Msaddak et al (2017) suggested that lupines would prefer Bradyrhizobium spp.…”

“…Lupines were first thought to be mainly nodulated by slowgrowing rhizobia of the genus Bradyrhizobium, although fastgrowing strains associated with lupines have been identified since 1988 (Miller and Pepper, 1988). Lupinus is currently reported as a promiscuous host that can be nodulated by different symbiotic bacteria belonging to the genera Bradyrhizobium, Ochrobactrum, Microvirga, Phyllobacterium, Neorhizobium, and Rhizobium (Jarabo- Lorenzo et al, 2003;Trujillo et al, 2005;Velázquez et al, 2010;Ardley et al, 2012;Bourebaba et al, 2016;Msaddak et al, 2018;Tounsi-Hammami et al, 2019;Missbah El Idrissi et al, 2020).…”

Lupin, a Unique Legume That Is Nodulated by Multiple Microsymbionts: The Role of Horizontal Gene Transfer

“…Despite the prevalence of slow-growing Bradyrhizobium species, fast-growing bacteria belonging to the genera Phyllobacterium [ 41 , 42 , 71 ], Ochrobactrum [ 27 ], Microvirga [ 42 , 44 , 71 , 84 ], Rhizobium , Neorhizobium, Agrobacterium [ 43 ], and Devosia [ 12 ] have also been described as lupin microsymbionts. Burkholderia , a genus that nodulates other legume species, has also been isolated from L. perennis nodules [ 85 ]; however, its symbiotic effectiveness after re-inoculation has yet to be confirmed.…”

“…Until the present century, lupin was assumed to be a microsymbiont-specific legume. However, owing to the evolution of molecular taxonomy, nowadays, lupin can be considered as a promiscuous legume that can be nodulated by different Bradyrhizobium lineages [ 38 , 39 , 40 ], and by bacteria within the genera Phyllobacterium [ 41 , 42 ], Ochrobactrum [ 27 ], Rhizobium, Neorhizobium, Agrobacterium [ 43 ], Microvirga [ 42 , 44 ], and Devosia [ 12 ]. The aim of this review was to collect the existing information on the diversity and taxonomy of the rhizobial bacteria associated with Lupinus spp.…”