4 research outputs found
Molecular characterization of ' Candidatus Liberibacter' species/strains causing huanglongbing disease of citrus in Kenya
Get PDFThis study was undertaken to characterize the alpha subgroup of the
proteobacteria causing the huanglongbing (HLB) disease of citrus from
three different ecological zones of Kenya namely the Lower highlands
(LH2, LH3, 1800-1900 m above sea level); Upper midlands (UM3, UM4,
1390-1475m), Lower midlands (LM5, LM4, LM3 of 1290-1340-1390m), by
isolation and sequencing DNA encoding the L10 and L12 ribosomal
proteins and the intergenic region. A 7I6-basepair DNA fragment was
amplified and sequenced and consisted of 536 basepairs of DNA encoding
the L10 protein, 44 basepairs of DNA intergenic region and 136
basepairs of DNA that partially encodes the L12 protein. Sequences of
rpL10/L12 protein genes from Kenyan strains were 98% and 81% similar to
the South African ' Candidatus Liberibacter africanus strain
Nelspruit' and the Asian 'Candidatus Liberibacter asiaticus' strains,
respectively. The intergenic rDNA sequence of Kenyan strain from UM and
LM showed 84% similarity with 'Candidatus L. africanus strain
Nelspruit' and 50% similarity with 'Candidatus L. asiaticus' strain.
However, the LH strain had an 11- basepairs deletion, while the LM4 had
a 5- basepair deletion in the intergenic region compared to 'Candidatus
L. africanus strain Nelspruit'. The L10 amino acid sequence was 100%
homologous among HLB bacteria obtained from the agro-ecological zones
in Kenya and the L10 protein sequence was also homologus to 'Candidatus
L. africanus strain Nelspruit'. Nevertheless, the L10 amino acid
sequence of 'Candidatus L. asiaticus' and the 'Candidatus L. africanus
subsp. capensis' differed from the Kenyan strains by 18.36% and 11.82%,
respectively. Phylogenetic analysis of both the L10/L12 rDNA sequences
and the L10 amino acid sequences clustered the Kenyan strains of the
'Candidatus Liberibacter' species with members of alpha subdivision of
proteobacteria
Effect of levels and timing of application of gibberellic acid on growth and yield components of common beans
No full textThis study was conducted to determine the effect of levels and timing
of application of gibberellic acid (GA3) on growth and yield components
of common beans ( Phaseolus vulgaris L.). Experiments were conducted
at the Field Station Farm at the Faculty of Agriculture, University of
Nairobi, Kenya during 1997 and 1998. "Mwezi moja" bean cultivar was
used in study. Gibberellic acid (GA3) was sprayed at 0, 2.5, 5.0 and
7.5 mg l-1 to whole bean plants at 7, 14 or 28 days after emergence
(DAE). The effect of GA3 and timing of application on growth, yield and
yield components was significant (P≤0.05). Applications of GA3
led to increased plant height, leaf area index (LAI), fractional solar
radiation interception, root, shoot and the total dry mass. It also
increased yield per plant, pods per plant, 100-seed mass and harvest
index. The highest seed yields were equivallent to 1854 kg ha-1 in 1997
and 5890 kg ha-1 in 1998. These yields are high as compared to average
national yields of 500 kg ha-1. Significant differences in the
parameters measured were generally observed at 14 DAE in GA3 treated
plants.Cette étude était conduite pour déterminer les effets
des doses et le moment d'application de l'acide gibberellique (GA3) sur
la croissance et les composantes de rendement de l'haricot commun
(Phraseolus vulgaris L.). Les expériences étaient conduites
dans les champs de la station agricole de la Faculté de
l'Agriculture, Université de Naïrobi-Kenya entre 1997 et
1998. La variété « mwezi moja » était
utilisée dans cette étude. L'acide gibberellique était
appliquée à des doses de 0, 2.5, 5.0 et 7.5 mg l-1 à
toute les plantes de haricots à 7, 14 ou 28 jours après
l'émergence (DAE). Les effets de GA3 et le temps d'application sur
la croissance, le rendement et les composantes du rendement
étaient significatifs (P<0.05). L'application de GA3 entraina
l'augmentation de la taille des plantes, indice de surface des
feuilles, la fraction de l'énergie solaire interceptée, les
racines, shoot et la masse total de la matière sèche. Elle
entraina aussi l'augmentation du rendement par plante, gousse par
plante, la masse de 100 graines et l'indice de la récolte. Les
rendements les plus élévés étaient équivalents
à 1854 kg ha-1 en 1997 et 5890 kg ha-1 en 1998. Ces valeurs de
rendements sont élévées par rapport à la myenne
nationale de 500 kg ha-1. Des différences significatives
concernant les paramètres mesurés étaient
généralement observées à 14 jours après
émergence dans les plantes traitées au GA3
Molecular characterization of ' Candidatus Liberibacter' species/strains causing huanglongbing disease of citrus in Kenya
No full textThis study was undertaken to characterize the alpha subgroup of the
proteobacteria causing the huanglongbing (HLB) disease of citrus from
three different ecological zones of Kenya namely the Lower highlands
(LH2, LH3, 1800-1900 m above sea level); Upper midlands (UM3, UM4,
1390-1475m), Lower midlands (LM5, LM4, LM3 of 1290-1340-1390m), by
isolation and sequencing DNA encoding the L10 and L12 ribosomal
proteins and the intergenic region. A 7I6-basepair DNA fragment was
amplified and sequenced and consisted of 536 basepairs of DNA encoding
the L10 protein, 44 basepairs of DNA intergenic region and 136
basepairs of DNA that partially encodes the L12 protein. Sequences of
rpL10/L12 protein genes from Kenyan strains were 98% and 81% similar to
the South African ' Candidatus Liberibacter africanus strain
Nelspruit' and the Asian 'Candidatus Liberibacter asiaticus' strains,
respectively. The intergenic rDNA sequence of Kenyan strain from UM and
LM showed 84% similarity with 'Candidatus L. africanus strain
Nelspruit' and 50% similarity with 'Candidatus L. asiaticus' strain.
However, the LH strain had an 11- basepairs deletion, while the LM4 had
a 5- basepair deletion in the intergenic region compared to 'Candidatus
L. africanus strain Nelspruit'. The L10 amino acid sequence was 100%
homologous among HLB bacteria obtained from the agro-ecological zones
in Kenya and the L10 protein sequence was also homologus to 'Candidatus
L. africanus strain Nelspruit'. Nevertheless, the L10 amino acid
sequence of 'Candidatus L. asiaticus' and the 'Candidatus L. africanus
subsp. capensis' differed from the Kenyan strains by 18.36% and 11.82%,
respectively. Phylogenetic analysis of both the L10/L12 rDNA sequences
and the L10 amino acid sequences clustered the Kenyan strains of the
'Candidatus Liberibacter' species with members of alpha subdivision of
proteobacteria
