Enhancement of Nitrogen-fixing Activity of Enterobacteriaceae Strains Isolated from Sago Palm (Metroxylon sagu) by Microbial Interaction with Non-nitrogen Fixers

Shrestha, Archana; Toyota, Koki; Okazaki, Masanori; Suga, Yuko; Quevedo, Marcelo A.; Loreto, Alan B.; Mariscal, Algerico A.

doi:10.1264/jsme2.22.59

Cited by 22 publications

(28 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…These invasive endophytes may be useful as more stable vehicles to deliver genes into host plant cells. In addition, it has been reported that starch-degrading strains stimulate the activities of nitrogen-fixing bacteria, both of which were isolated from the same samples of sago palm (41). The starch-degrading endophytes detected in rice plants may have similar functions.…”

Section: Resultsmentioning

confidence: 96%

Rice Seeds as Sources of Endophytic Bacteria

Mano²,

et al. 2009

View full text Add to dashboard Cite

Endophytic bacteria are considered to originate from the external environment. To examine the hypothesis that rice (Oryza sativa, cultivar Kinuhikari) seeds are a source of endophytic bacteria, we isolated endophytic bacteria from the shoots, remains of the seeds, and roots of rice seedlings that were aseptically cultivated in vitro from surfacedisinfected seeds. Of the various bacterial strains isolated, the closest relatives, identified by 16S rRNA gene sequencing, were: Bacillus firmus, B. fusiformis, B. pumilus, Caulobacter crescentus, Kocuria palustris, Micrococcus luteus, Methylobacterium fujisawaense, Me. radiotolerans, and Pantoea ananatis. The latter three species have been detected frequently inside both rice seedlings and mature rice plants. These results indicate that rice seeds are an important source of endophytic bacteria. The bacteria that colonize the seed interior appear to infect the subsequent generation via rice seeds and become the dominant endophytic species in the mature plant.Key words: culturable endophytic bacteria, rice seed, infection from seed to shoot, 16S rRNA gene sequence Various types of microorganisms, including fungi, actinomycetes, and other bacteria, are found inside plants and designated endophytes. In general, microorganisms having visibly harmful effects on plants are not considered endophytes. Some endophytic bacteria have beneficial effects on the host, e.g., promoting plant growth, strengthening resistance to pathogens, and increasing the supply of fixed nitrogen to the plant (9). Studies are underway to exploit these beneficial features for agriculture. However, our knowledge of endophytic bacterial ecology, including the origins of these bacteria, remains incomplete.Endophytic bacteria are considered to originate from the external environment and to enter the plant through the stomata, lenticles, wounds (including broken trichomes), areas of emergence of lateral roots, and germinating radicles (12). The notion of seeds as a source of endophytic bacteria remains controversial (9). Sato (39) did not detect endophytic bacteria in rice seeds. Mundt and Hinkle (27) obtained endophytes only from the damaged seeds of 28 plant types other than rice. Endophytic bacteria were detected in cotton seeds at viable population densities that ranged from 1×10 3 to 1×105 CFU g −1 fresh weight, as well as in the seeds of sweet corn at viable population densities of <1×10 CFU g −1 fresh weight (26). Endophytic bacterial populations increased from nondetectable levels in cotton seeds to detectable levels in radicles 4 days after placing surface-disinfected cotton seeds on water agar (1).Rice (Oryza sativa) is the most important cereal crop in the world, feeding more than 50% of the global population (8). In our search for endophytic bacteria in rice plants, we detected culturable endophytic bacteria in rice seeds at viable population densities that ranged from 10 2 to 10 6 CFU g −1 fresh weight (22,31). Endophytes in seeds may be carried over to the subsequent generation. Thus, in the p...

show abstract

Section: Resultsmentioning

confidence: 96%

Rice Seeds as Sources of Endophytic Bacteria

Mano²,

et al. 2009

View full text Add to dashboard Cite

show abstract

“…Diazotrophic bacteria may accumulate, depending on their environment, and their role in the acquisition of N for M. malabathricum may also differ among soil types. Furthermore, the co-culture of diazotrophic bacteria and non-diazotrophic bacteria was reported to enhance or induce nitrogen-fixing activity (21,29). So we need to pay attention to microbial interactions between diazotrophic bacteria and other indigenous bacteria in the rhizosphere of M. malabathricum.…”

Section: Resultsmentioning

confidence: 99%

Analysis of Diversity of Diazotrophic Bacteria Associated with the Rhizosphere of a Tropical Arbor, Melastoma malabathricum L.

et al. 2009

View full text Add to dashboard Cite

The diversity of diazotrophic bacteria in the rhizosphere of Melastoma malabathricum L. was investigated by cloning-sequencing of the nifH gene directly amplified from DNA extracted from soil. Samples were obtained from the rhizosphere and bulk soil of M. malabathricum growing in three different soil types (acid sulfate, peat and sandy clay soils) located very close to each other in south Kalimantan, Indonesia. Six clone libraries were constructed, generated from bulk and rhizosphere soil samples, and 300 nifH clones were produced, then assembled into 29 operational taxonomic units (OTUs) based on percent identity values. Our results suggested that nifH gene diversity is mainly dependent on soil properties, and did not differ remarkably between the rhizosphere and bulk soil of M. malabathricum except in acid sulfate soil. In acid sulfate soil, as the Shannon diversity index was lower in rhizosphere than in bulk soil, it is suggested that particular bacterial species might accumulate in the rhizosphere.

show abstract

“…Microbes like bacteria and fungi which live inside healthy plant tissues without causing apparent symptoms, known as endophytes 33) are also known to form mutually beneficial relationships with their hosts 23) . Being mutualists, these microbial populations are known to be beneficial to host plants by enhancing the absorption of soil nutrients such as phosphorus and other inorganic elements, nitrogen-fixing efficiency 38,43) and plant growth with the production of hormones like auxins, abscisins, ethylene, gibberellins, and kinetins 20,29) . They provide protection to their hosts against insect pests 27) , herbivores 11) , and microbial pathogens 39,42,44) .…”

mentioning

confidence: 99%

Fungal Communities in Herbaceous Medicinal Plants from the Malnad Region, Southern India

2008

View full text Add to dashboard Cite

Fungal communities were isolated from surface sterilized leaf segments of nine ethnopharmaceutically important medicinal herbs collected from the Bhadra River Project Area, the Malnad region, Southern India. A total of 2159 isolates belonging to 55 different fungal species were isolated from 3600 leaf segments collected during the wet and dry seasons. Chaetomium globosum (7.3%), Aureobasidium pullulans (6.1%), Cladosporium cladosporioides (3.9%), Curvularia lunata (1.9%), Nigrospora oryzae (1.7%), Alternaria alternata (1.3%), Botryosphaeria subglobosa (1.1%), Phoma multirostrata (0.9%), Aspergillus niger (0.8%), Fusarium oxysporum (0.7%), Rhizoctonia solani (0.4%), and Sphaeropsis sapenea (0.3%) were the most frequently isolated fungal species. Colonization rates of fungal species varied significantly between the two seasons. Host specificity was observed in some host plants.Key words: diversity, fungi, medicinal herbs, seasonality, Malnad Region Plant and microbial symbiotic interactions and how these interactions influence plant communities and environments have been well explored 6,10,22) . Rhizospheric and mycorrhizal associations play a major role in physiological and biochemical properties owing to the growth and ecological fitness of hosts 15) . Microbes like bacteria and fungi which live inside healthy plant tissues without causing apparent symptoms, known as endophytes 33) are also known to form mutually beneficial relationships with their hosts 23) . Being mutualists, these microbial populations are known to be beneficial to host plants by enhancing the absorption of soil nutrients such as phosphorus and other inorganic elements, nitrogen-fixing efficiency 38,43) and plant growth with the production of hormones like auxins, abscisins, ethylene, gibberellins, and kinetins 20,29) . They provide protection to their hosts against insect pests 27) , herbivores 11) , and microbial pathogens 39,42,44) . Fungi present in healthy tissues of plants can promote the invasion of host plant communities with greater species diversity 37) and alter the nutrient cycle in individual plants 18) and in ecosystems 24) . The isolation and characterization of fungal communities will help us to estimate the diversity of fungi 2) , since the true scale of fungi is open to debate 21,26) . Most importantly, fungi isolated from healthy tissues may be a source of various secondary metabolites, alkaloids, and biologically active compounds 35,45) . Bacterial endophytes have been screened from many agricultural, horticultural and forest plant species 1,23,25,28) . In India, medicinal plants have long been used in the ailment of various diseases. In view of the importance of microbial populations which live inside healthy plant tissues, we investigated the distribution of fungal communities and seasonal colonization patterns in medicinal herbs of the Malnad Region, Karnataka state, Southern India. Materials and methods Sample collectionThe leaf samples of Catharanthus roseus India, which is a part of the Western Ghat region, a hot spo...

show abstract

Enhancement of Nitrogen-fixing Activity of Enterobacteriaceae Strains Isolated from Sago Palm (Metroxylon sagu) by Microbial Interaction with Non-nitrogen Fixers

Cited by 22 publications

References 39 publications

Rice Seeds as Sources of Endophytic Bacteria

Rice Seeds as Sources of Endophytic Bacteria

Analysis of Diversity of Diazotrophic Bacteria Associated with the Rhizosphere of a Tropical Arbor, Melastoma malabathricum L.

Fungal Communities in Herbaceous Medicinal Plants from the Malnad Region, Southern India

Contact Info

Product

Resources

About