Bio

Publications


2013

Lally, R, Moreira AS, Germaine K, Galbally P, Culhain J, Otieno N, Brazil D, Ryan D, Dowling D.  2013.  Development of endophytic bacterial inoculants possessing plant growth promotion traits for practical application in bio-energy plant species., 2-3 Dec 2013. Association of Applied Biologists (AAB) Conference 2013 - Positive plant microbial interactions: their role in maintaining sustainable agricultural and natural ecosystems. , Forest Pines Hotel, Brigg, North Linconshire, U.K Abstract

Endophytes are bacteria present in plants that form a symbiotic relationship with
their hosts and may promote plant growth and health (Ryan et al., 2008). We extracted
Pseudomonas endophytes from Miscanthus × giganteus; a series of strains were selected
for application to two oilseed rape (OSR) trials. Endophytes colonise plants (including
the root-surface) and allow the plant to utilise nutrients present in the rhizosphere. This
potentially provides a yield boost for colonised plants, allowing for efficient fertiliser
strategies and improved yield performance (Redondo-Nieto et al., 2013). This study has
provided evidence that the application of specialised live microbial biofertilisers can
enhance aspects of crop development when applied in the field. The results show that
there was a significant increase in crop stem and leaf of “Compass” a variety of Oilseed
rape. The results did not indicate that there was a significant increase within the overall
yield of the crop.

Otieno, NA, Culhane J, Germaine K, Brazil D, Ryan D, Dowling DN.  2013.  Screening of large collections of plant associated bacteria for effective plant growth promotion and colonisation, 2-3 Dec 2013. Positive Plant Microbial Interactions: Their role in maintaining sustainable and natural ecosystems. , Forest Pines Hotel, nr Brigg, orth Lincolnshire, UK Abstract

The use of potent and effective live microbial biofertilisers in agricultural has significant
potential to reduce the costs of crop production and in mitigating greenhouse gas emissions
and water pollution associated with excessive fertiliser use. Many plant associated
bacteria possess plant growth promotion traits. However, when used as plant inoculants
these bacteria often do not result in statistically significant plant growth promotion. This
paper describes the screening process used to identify a number of endophytic strains
with multiple plant growth promotion traits and effective plant colonisation ability in
Brassica napus crops.

2012

Germaine, KJ, Otieno N, Culhane J, Menton C, Keogh E, Brazil D, Dowling D.  2012.  Microbial communities associated with the bio-energy plant Miscanthus. 28th New Phytologists Symposium: Functions and ecology of the plant microbiome. :20., 18-21 May 2012, Aldemar Hotel, Rhodes, Greece: New Phytologist Organisation Abstract

in improving the phytoremediation capacity of plants. This study investigated the
culturable-aerobic bacterial diversity associated with the bio-energy plant
Miscanthus giganteus. 250 bacterial strains were isolated from Miscanthus and 70 of
these strains were identified through 16S rDNA sequencing. Eleven different species
were identified in Miscanthus originating from the leaf, stem and rhizome tissues.
The majority of these isolates were gamma-Proteobacteria with Pseudomonas and
Acinetobacter species dominating. Many of these strains expressed plant growth
promotion traits such as phytohormone production and phosphate solubilisation
ability. The majority of the isolates were found to possess resistance to heavy
metals and 7-13% possessed inherent organic xenobiotic degradation abilities. A
number of these isolates were tagged with a gfp:kanamycin marker and were found
to colonise the rhizosphere of inoculated plants. These isolates may prove to be
useful inoculants for improving plant biomass and phytoremediation efficiency of
Miscanthus.

Otieno, N, Culhane J, Germaine K, Brazil D, Ryan D, Dowling D.  2012.  Phosphate solubilisation and gluconic acid production by endophytic bacterial strains and ability to promote plant growth in oil seed rape (Brassica napus). 28th New Phytologists Symposium: Functions and ecology of the plant microbiome. :54., 18-21 May 2012, Aldemar Hotel, Rhodes, Greece: New Phytologist Organisation Abstract

Several studies have shown that the release of low molecular weight organic acids is
a major mechanism for solubilising insoluble phosphate by phosphate solubilising
bacteria (PSB). The production of gluconic acid during inorganic phosphate
solubilisation in conjunction with liberation of phosphate and the influence on plant
growth as a function of phosphate solubilisation by endophytic strains was analysed.
Solubilisation of Ca3(PO4)2 in National Botanical Research Institute’s Phosphate
(NBRIP) growth medium varied among the endophytes with P-liberated ranging from
1109.33 μg/ml to 67.3 μg/ml. In all cases, the final supernatant had a significant pH
decrease and this had a direct relation to P-liberated. High Performance Liquid
Chromatography (HPLC) analysis of the culture filtrate to quantify gluconic acid
produced by the strains ranged from 33.21±2.34 mg/ml to 2.2 ±0.18 mg/ml. The
results suggest that acidification was the main strategy for solubilising phosphate. In
this study, a clear relationship was observed between supernatant acidification and
P solubilisation from Ca3(PO4)2. However, no significant difference was observed for
key growth parameters in oil seed rape between treatments. The result of this study
indicates in planta expression of P solubilisation traits may be more complex than
those in vitro studies.

Otieno, NA, Culhain J, Germaine K, Brazil D, Ryan D, Dowling D.  2012.  Development of endophytic bacterial inoculants possessing plant growth promotion traits for practical application in bio-energy plant species. XV International Congress on Molecular Plant-Microbe Interactions. :57-58., 29 July-2 August,Kyoto, Japan: International Society for Molecular Plant-Microbe Interactions Abstract

Internal plant tissue colonisation has made endophytic bacteria valuable for agriculture as a tool to improve crop performance particularly for those bacteria having traits such as plant growth promotion (PGP). This project involved screening and identifying endophytic bacterial strains, sourced from the bacterial collection available at the Institute of Technology Carlow, with the potential to enhance growth rate in bio-energy plant crop species. In the initial stage under greenhouse condition, a total of 140 strains in master mix (MM) groups of 10 strains, were inoculated into Rye Grass. The inoculated Rye Grass seeds were sown in pots and arranged in complete randomised design and their growth was monitored for a period of 3 months. The plant fresh weights (FW) and dry weights (DW) were used as growth parameters. Three MMs (comprising 30 strains) showed PGP potential in Rye Grass, significantly increased the mean FW and DW of Rye Grass plants compared to the negative controls. The 30 selected strains were further characterised for PGP traits under in vitro study. Results showed three strains inhibited Pythium spp. growth in dual culture assay, whereas the culture filtrates to quantify gluconic acid production necessary for inorganic phosphate solubilisation, had six strains recording more than 20mg/ml of gluconic acid production. Ten strains showed Indole acetic acid (IAA) production in the range (10-18 µg/ml) while three strains showed 1-aminocylopropane-1-carboxylic acid (ACC) deaminase activity. This study indicates that the selected bacterial endophytes have the potential for PGP and development in plant crops.

NA, O, J C, K G, D B, D R, D D.  2012.  Development of endophytic bacterial inoculants possessing growth promotion traits for practical application in bio-energy plant species12. Molecular Plant-Microbe Interactions International Congress 2012. , Kyoto, Japan
Otieno, NA, Culhane J, K G, D B, D R, D D.  2012.  Phosphate solubilisation and gluconic acid production by endophytic bacterial strains and ability to promote plant growth in oilseed rape (Brassica napus).. 28th New Phytologist Symposium: Functions and ecology of the plant microbiome. , Rhodes, Greece
and Otieno Nicholas, Culhane John, CSMCBDRDGKDDJN.  2012.  Bacterial Endophytes for Improving sustainability of Bioenergy . 9th International Phytotechnology Society (IPS) . , Hasselt University, Belgium September 11th to 14th, 2012.bacterial_endophytes_for_improving_sustainability_of_bioenergy.pdf

2008

Otieno, NA, LeRu BP, Ong'amo GO, Moyal P, Dupas S, Calatayud P-A, Silvain J-F.  2008.  Diversity and abundance of wild host plants of lepidopteran stem borers in two agro-ecological zones of Kenya. The International Journal of Biodiversity Science and Management. 4(2):92-103. Abstract

A survey was carried out between 2005 and 2006 in two ecologically different localities, Suam and Mtito Andei, to assess diversity and abundance of wild host plants of lepidopteran stem borers during the cropping and non-cropping seasons. Suam in western Kenya is situated in the moist high tropics and is characterised by an Afromontane vegetation mosaic, while Mtito Andei is located in the dry mid-altitudes characterised by a Somalia Masai vegetation mosaic. In Suam, wild host plants and maize covered 11 and 50%, respectively, of the surveyed area. In Mtito Andei, 27% of the surveyed area was under maize during the cropping season, while wild host plant species covered 13% and 8% during the cropping and non-cropping seasons, respectively. There was no significant variation in the relative abundance and diversity of the wild grasses between the two seasons in either location. The abundance of host plants of B. fusca and C. partellus is low in natural habitats surrounding cereal crops. The abundance of C. partellus was low in its wild host plants and B. fusca was absent. Therefore, the role of wild vegetation surrounding cultivated areas in the carry-over of these pests during the non-cropping season is limited

Otieno, NA, LeRu BP, Ong'amo G, Moyal P, Dupas S, Calatayud P-A, Silvain J-F.  2008.  Diversity and abundance of wild host plants of lepidopteran stem borers in two agro-ecological zones of Kenya. International Journal of Biodiversity Science and Management. 4:1-12.

2006

Otieno, NA.  2006.  Diversity and Abundance of wild host plants of stem borers in two sites, Kakamega and Muhaka in Kenya.. , Nairobi: Jomo Kenyatta University of Agriculture and Technology
Otieno, NA, LeRu BP, Ong'amo GO, Dupas S, Calatayud P-A, Makobe M, Ochora J, Silvain J-F.  2006.  Diversity and Abundance of wild host plants of Lepidopteran stem borers in two different agroecological zones of Kenya. Annales de la Société entemologique de France. 42 (3-4):371-380. Abstract

A survey was carried out between 2004 and 2005 in two ecologically different locations, Kakamega and Muhaka to assess diversity and abundance of wild host plants of lepidopteran stem borers as compared to maize plots during the cropping and non-cropping seasons. Kakamega in Western Kenya is characterized by a Guineo-Congolian rain forest mosaic and Muhaka at the Kenyan coast by a Zanzibar Inhambane mosaic with secondary grassy and woody vegetation. In Kakamega, wild host plants and maize covered 2 and 43% of the surveyed area. No variation in diversity and relative abundance of wild host plants was observed between both the cropping and non-cropping seasons. In Muhaka, the diversity and relative abundance of wild host plant species differed between seasons, with the Shannon Weaver Index (H) of 1.67 and 0.95 for cropping and non-cropping seasons, respectively. Similarly in this location, wild host plant cover varied between cropping (23%) and non-cropping (17.9%). During both seasons, this was higher than the maize cover, with 10.7% and 0% for the cropping and non-cropping seasons, respectively. For both localities, the implication of the differences found in the abundance and diversity between the cropping and non-cropping seasons is discussed.

Otieno, NA, LeRu BP, G O'amo, P M, Dupas S, Calatayud P-A, Silvain J-F.  2006.  Diversity and abundance of wild host plants of lepidopteran stem borers in two different agro-ecological zones of Kenya. Annales de la Societe entomologique de France. 42(3-4):371-380.

2005

Otieno, NA.  2005.  Diversity and abundance of wild host plants of lepidopteran stem borers in two different agro-ecological zones of Kenya. International Conference on Lepidopterous Cereal Stem and Cob Borers In Africa. , International Centre of Insect Physiology and Ecology (ICIPE). Nairobi Kenya

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