Tolerance of Mesorhizobium type strains to different environmental stresses

Rhizobia, the bacterial legume symbionts able to fix atmospheric nitrogen inside root nodules, have to survive in varied environmental conditions. The aim of this study was to analyse the transcriptional response to heat shock of Mesorhizobium loti MAFF303099, a rhizobium with a large multipartite genome of 7.6 Mb that nodulates the model legume Lotus japonicus. Using microarray analysis, extensive transcriptomic changes were detected in response to heat shock: 30% of the protein-coding genes were differentially expressed (2067 genes in the chromosome, 62 in pMLa and 57 in pMLb). The highest-induced genes are in the same operon and code for two sHSP. Only one of the five groEL genes in MAFF303099 genome was induced by heat shock. Unlike other prokaryotes, the transcriptional response of this Mesorhizobium included the underexpression of an unusually large number of genes (72% of the differentially expressed genes). This extensive downregulation of gene expression may be an important part of the heat shock response, as a way of reducing energetic costs under stress. To our knowledge, this study reports the heat shock response of the largest prokaryote genome analysed so far, representing an important contribution to understand the response of plant-interacting bacteria to challenging environmental conditions.

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“…A previous study showed that this strain is tolerant to heat shock and cold conditions, and grows well at pH 5. 30 …”

Section: Introductionmentioning

confidence: 99%

Global Transcriptional Response to Heat Shock of the Legume Symbiont Mesorhizobium loti MAFF303099 Comprises Extensive Gene Downregulation

2013

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“…Effect of temperature on symbiotic nitrogen fixation. Unfavorable temperatures impair nodulation and nitrogen fixation resulting in low solute production, transportation and synthesis of various heat and cold-shock proteins compared to susceptible strains(Alexandre and Oliveira 2011;Laranjo and Oliveira 2011). The GroEL…”

mentioning

confidence: 99%

Temperature sensitivity of food legumes: a physiological insight

Bhandari

Sharma

Rao³

et al. 2017

Acta Physiol Plant

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Of the various environmental stresses that a plant can experience, temperature has the widest and most far-reaching effects on legumes. Temperature extremes, both high (heat stress) and low (cold stress), are injurious to plants at all stages of development, resulting in severe loss of productivity. In response to unfavorable temperatures, plant biomolecules such as stress proteins, enzymatic and non-enzymatic antioxidants, organic osmolytes and phytohormones come into play, usually, as a part of the plant defense mechanisms. The accumulation of these molecules, which may be useful as metabolic indicators of stress tolerance, depend on the plant species exposed to the temperature stress, its intensity and duration. Some of these molecules such as osmolytes, non-enzymatic antioxidants and phytohormones may be supplied exogenously to improve temperature stress tolerance. Legumes show varying degrees of sensitivity to high and low-temperature stresses, which reduces their potential performance at various developmental stages. To address the ever-fluctuating temperature extremes that various legumes are being constantly exposed, efforts are being made to develop tolerant plant varieties via conventional breeding methods as well as more recent molecular breeding techniques. In this review, we describe the progress made towards the adverse effects of abnormal temperatures on various growth stages in legumes and propose appropriate strategies to resolve these effects.

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“…Members of the genus Mesorhizobium can establish a nitrogen-fixing symbiosis with legume species found in many environments, including tropical, subtropical, temperate, and arctic areas (3). This large distribution suggests their adaptation to several ecoclimatic conditions (4, 5). Many different legume species have now been studied and shown to play several ecological roles which are essential to environmental sustainability.…”

Section: Genome Announcementmentioning

confidence: 95%