Physiological and genetic analysis of root responsiveness to auxin-producing plant growth-promoting bacteria in common bean (Phaseolus vulgaris L.). Plant Soil 302:149-161 DOI 10.1007/s11104-007-9462-7

Plant and Soil (Impact Factor: 3.24). 01/2007; 302(1):149-161. DOI: 10.1007/s11104-007-9462-7

ABSTRACT Plant root development can be largely affected through the association of roots with plant growth-promoting rhizobacteria
(PGPR). However, little is known about the identity of plant genes enabling such PGPR-plant root associations. Differences
in the responsiveness to PGPR among cultivars suggest genetic variation for this trait within germplasm. In this study, two
genotypes of common bean (Phaseolus vulgaris L.), BAT477 and DOR364, were identified showing contrasting responsiveness in root development to inoculation with the PGPR
Azospirillum brasilense Sp245. Inoculation with an A. brasilense Sp245 mutant strain strongly reduced in auxin biosynthesis or addition of increasing concentrations of exogenous auxin to
the plant growth medium, indicated that the differential response to A. brasilense Sp245 among the bean genotypes is related to a differential response to the bacterial produced auxin. To further assess the
role of the plant host in root responsiveness, a population of Recombinant Inbred Lines (RILs) of the DOR364×BAT477 cross
was used to evaluate the efficacy of exogenous auxin on root development. We detected significant phenotypic variation among
the RILs for basal root formation during germination upon addition of auxin to the growth medium. Genetic analysis revealed
two quantitative trait loci (QTLs) associated with basal root responsiveness to auxin of which one explained 36% of the phenotypic
variation among the RILs. This latter QTL mapped to the same location as a QTL for root tip formation at low P, suggesting
that the host effect on root responsiveness to IAA interacts with specific root development. Also, significant correlations
between basal root responsiveness to auxin and growth, root tips and root dry weight at low P were identified. To our knowledge,
this is the first report on QTL detection for root responsiveness to auxin.

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Available from: Roseline Remans, Aug 23, 2014
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    • "Similarly, Fagaria et al. reported higher N use efficiency in 50 mgN treated with Rhizobium inoculation as compared to that obtained from 200 mgN treatment). On top of fixing N from atmosphere, many species of rhizobia can secrete growth hormone and thereby improving root growth (Antoun et al. 1998; Canbolat et al. 2006; Remans et al. 2008; Ahemad and Khan 2012) and nutrients uptake. This could also be due to increases the plant access to soil nutrients and, improving P availability through solubilizing unavailable P (Zaidi et al. 2009) and thus enhancing the N use efficiency of common bean. "
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    ABSTRACT: Due to common bean derives lower nitrogen (N) from symbiotic N 2 -fixation, it requires N either from inorganic fertilizer or soil N. Field experiments were conducted at four locations to evaluate the effect of Rhizobium leguminosarum bv. phaseoli inoculation on agronomic efficiency of N of common bean var. Dursitu major growing areas of eastern Ethiopia. Six levels of inorganic N (0, 20, 40, 60, 80 and 100 kg N ha −1 ) and two inoculation treatments (uninoculated and inoculated) were factorially combined and laid out in randomized completely block design, replicated three times. AE-N, nodule number per plant (NN) and nodule dry weight per plant (NDW) decreased with N rates of application beyond 20 kg N ha −1 . The highest AE-Ns at Babillae, Fedis and Haramaya sites were obtained from 20 kg N ha −1 applied with Rhizobium inoculation while 40 kg N ha −1 supplied with Rhizobium inoculation at Hirna site. Regardless of experimental sites, inoculation improved AE-N. A positive relationship between AE-N and NDW was also observed in all experimental sites. Significant increase in grain yield with increasing rates of N application was also observed. Hence, it can be concluded that inoculation is recommendable to increases the efficient utilization of applied Mineral N.
    12/2015; 4(1). DOI:10.1186/s40068-015-0036-z
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    • "Nevertheless, the role of IAA appears to be more complex . Low concentration of pure IAA or low titer of IAAproducing bacteria enhanced root growth and nodulation (Remans et al. 2008) whereas high concentration of pure IAA or high titer of IAA producing bacteria inhibited root growth and nodulation (Plazinski et al. 1985). "
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    ABSTRACT: Background and Aims Salt stress is an increasing problem in agricultural soils in many parts of the world, and salt tolerant cropping systems are in great demand. We investigated the effect of co-inoculation of G. officinalis with Rhizobium galegae and two plant growth promoting Pseudomonas species on plant growth, nodulation and N content under salt stress. Methods The effect of inoculation with R. galegae HAMBI 1141 alone and in combination with the root colonizing P. trivialis TSAU20 or P. extremorientalis 3Re27 on the growth of G. officinalis exposed to salt stress (50 and 75 mM NaCl) was studied under gnotobiotic and greenhouse conditions. Results The growth of goat’s rue was reduced at 50 and 75 mM, NaCl both in gnotobiotic sand system and in potting soil in greenhouse. Co-inoculation of unstressed and salt-stressed goat’s rue either with R. galegae HAMBI 1141 and P. trivialis 3Re27 or P. extremorientalis TSAU20 significantly improved root, shoot growth and nodulation of plant roots grown in gnotobiotic sand system and low-fertilized potting soils compared to that of plants inoculated with R. galegae alone. The nitrogen content of co-inoculated plant roots was significantly increased at 75 NaCl in potting soil Co-inoculation of G. officinalis with either of the two PGPR Pseudomonas strains also improved root tip-colonization by R. galegae cells. Conclusion Thus, the co-inoculation of goat’s rue with Rhizobium and PGPR Pseudomonas strains was able to alleviate salt stress of plants grown in salt-affected gnotobiotic sand system and in potting soil in the greenhouse. Key words: goat's rue, Galega officinalis, Galega orientalis, Rhizobium galegae, Pseudomonas, plant growth promotion, salt stress, bacterial colonization
    Plant and Soil 08/2013; 369(1-2). DOI:10.1007/s11104-013-1586-3 · 3.24 Impact Factor
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    • "Greenhouse Root growth increased Remans et al. (2008) Bacillus sp. Paenibacillus sp. "
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    ABSTRACT: Plant growth promoting rhizobacteria are the soil bacteria inhabiting around/on the root surface and are directly or indirectly involved in promoting plant growth and development via production and secretion of various regulatory chemicals in the vicinity of rhizosphere. Generally, plant growth promoting rhizobacteria facilitate the plant growth directly by either assisting in resource acquisition (nitrogen, phosphorus and essential minerals) or modulating plant hormone levels, or indirectly by decreasing the inhibitory effects of various pathogens on plant growth and development in the forms of biocontrol agents. Various studies have documented the increased health and productivity of different plant species by the application of plant growth promoting rhizobacteria under both normal and stressed conditions. The plant-beneficial rhizobacteria may decrease the global dependence on hazardous agricultural chemicals which destabilize the agro-ecosystems. This review accentuates the perception of the rhizosphere and plant growth promoting rhizobacteria under the current perspectives. Further, explicit outlooks on the different mechanisms of rhizobacteria mediated plant growth promotion have been described in detail with the recent development and research. Finally, the latest paradigms of applicability of these beneficial rhizobacteria in different agro-ecosystems have been presented comprehensively under both normal and stress conditions to highlight the recent trends with the aim to develop future insights.
    Journal of King Saud University - Science 01/2013; 26(1). DOI:10.1016/j.jksus.2013.05.001
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