Engineering Nodulation Competitiveness of Rhizobial Bioinoculants in Soils

Archana, G.

doi:10.1007/978-3-211-99753-6_8

Cited by 7 publications

(7 citation statements)

References 203 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Once identified, the construction of a broad host range plasmid carrying these genes could contribute to the development of 'personalized bioinoculants'. A primary cause of the failure of rhizobial inoculants to significantly improve legume crop growth is the failure of these inoculants to compete well in the soil/rhizosphere with the indigenous microbiome (Archana, 2010). This often results in the inoculants being unable to establish a good foothold in the soil microbiome, and they often fail to persist in the population over long periods.…”

Section: Discussionmentioning

confidence: 99%

“…Phylogenies of the species of interest were constructed with the MEGA 5.2.2 package (Tamura et al, 2011), multiple sequence alignments were constructed with MUSCLE (Edgar, 2004) and phylogenetic trees were produced from the resulting alignments as described. All accession numbers for the genomes/ contigs used in this study are listed in Table S5 (Galibert et al, 2001;González et al, 2006;Reeve et al, 2006;2010;Schmeisser et al, 2009;Galardini et al, 2011;Schneiker-Bekel et al, 2011;Schuldes et al, 2012;Weidner et al, 2012;Martínez-Abarca et al, 2013;Sallet et al, 2013;Mora et al, 2014;Rudder et al, 2014;Toro et al, 2014).…”

Section: Sequence Analysis Of the Etr Regionmentioning

confidence: 99%

“…For decades, the study of the steps and underlying genetics of this interaction has been of interest to many researchers, with a long-term goal of manipulating this process for agricultural gains. This includes developing improved biological inoculants as well as engineering symbiotic nitrogen fixation (SNF) in non-legumes such as cereals (Archana, 2010;Oldroyd and Dixon, 2014;Rogers and Oldroyd, 2014). Doing so will require intimate knowledge of the genetic basis of the interaction throughout all stages of the relationship.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Genomic resources for identification of the minimal N₂‐fixing symbiotic genome

diCenzo

Zamani

Milunovic

et al. 2016

Environmental Microbiology

View full text Add to dashboard Cite

The lack of an appropriate genomic platform has precluded the use of gain-of-function approaches to study the rhizobium-legume symbiosis, preventing the establishment of the genes necessary and sufficient for symbiotic nitrogen fixation (SNF) and potentially hindering synthetic biology approaches aimed at engineering this process. Here, we describe the development of an appropriate system by reverse engineering Sinorhizobium meliloti. Using a novel in vivo cloning procedure, the engA-tRNA-rmlC (ETR) region, essential for cell viability and symbiosis, was transferred from Sinorhizobium fredii to the ancestral location on the S. meliloti chromosome, rendering the ETR region on pSymB redundant. A derivative of this strain lacking both the large symbiotic replicons (pSymA and pSymB) was constructed. Transfer of pSymA and pSymB back into this strain restored symbiotic capabilities with alfalfa. To delineate the location of the single-copy genes essential for SNF on these replicons, we screened a S. meliloti deletion library, representing > 95% of the 2900 genes of the symbiotic replicons, for their phenotypes with alfalfa. Only four loci, accounting for < 12% of pSymA and pSymB, were essential for SNF. These regions will serve as our preliminary target of the minimal set of horizontally acquired genes necessary and sufficient for SNF.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Sequence Analysis Of the Etr Regionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Genomic resources for identification of the minimal N₂‐fixing symbiotic genome

diCenzo

Zamani

Milunovic

et al. 2016

Environmental Microbiology

View full text Add to dashboard Cite

show abstract

“…Despite currently being a significant contributor of fixed nitrogen in agricultural crops, symbiotic nitrogen fixation (SNF) has not yet reached its full potential. This is due in part to commercial inoculants failing to compete well with the indigenous soil microbiome (Archana, 2010) and several key crops (i.e. cereals) being unable to enter into symbiotic relationships with rhizobia (Oldroyd & Dixon, 2014).…”

Section: Introductionmentioning

confidence: 99%

“…cereals) being unable to enter into symbiotic relationships with rhizobia (Oldroyd & Dixon, 2014). As technologies have improved, an increasing interest has re-emerged in engineering improved inoculants and transferring symbiosis to non-legumes (Archana, 2010;Oldroyd & Dixon, 2014). These ambitious goals require a complete understanding of the symbiotic relationship.…”

Section: Introductionmentioning

confidence: 99%

Proline auxotrophy in Sinorhizobium meliloti results in a plant-specific symbiotic phenotype

diCenzo¹,

Zamani²,

Cowie³

et al. 2015

Microbiology

View full text Add to dashboard Cite

In order to effectively manipulate rhizobium-legume symbioses for our benefit, it is crucial to first gain a complete understanding of the underlying genetics and metabolism. Studies with rhizobium auxotrophs have provided insight into the requirement for amino acid biosynthesis during the symbiosis; however, a paucity of available L-proline auxotrophs has limited our understanding of the role of L-proline biosynthesis. Here, we examined the symbiotic phenotypes of a recently described Sinorhizobium meliloti L-proline auxotroph. Proline auxotrophy was observed to result in a host-plant-specific phenotype. The S. meliloti auxotroph displayed reduced symbiotic capability with alfalfa (Medicago sativa) due to a decrease in nodule mass formed and therefore a reduction in nitrogen fixed per plant. However, the proline auxotroph formed nodules on white sweet clover (Melilotus alba) that failed to fix nitrogen. The rate of white sweet clover nodulation by the auxotroph was slightly delayed, but the final number of nodules per plant was not impacted. Examination of white sweet clover nodules by confocal microscopy and transmission electron microscopy revealed the presence of the S. meliloti proline auxotroph cells within the host legume cells, but few differentiated bacteroids were identified compared with the bacteroid-filled plant cells of WT nodules. Overall, these results indicated that L-proline biosynthesis is a general requirement for a fully effective nitrogen-fixing symbiosis, likely due to a transient requirement during bacteroid differentiation.

show abstract