6 research outputs found
Bridging the gap between mass media journalists and health research scientists in Tanzania
No full textNo Abstract
Inheritance of resistance traits to African stem borer in grain sorghum
No full textThe African stem borer ( Busseola fusca [Fuller]) is an important
insect pest of cereals, mainly maize, sorghum and millets. The pest
causes up to 80% reduction in grain yield, depending on the pest
population in the field, cultivar and the management practices
employed. This reduction in yield translates into food insecurity,
especially in semi-arid lands (ASALs) where sorghum is cultivated by
small holder farmers. This study investigated the inheritance of
resistance traits to the African stem borers in grain sorghum in Kenya.
The experimental material consisted of seventeen sorghum lines with
varying levels of resistance to the African stem borer. The mating
design employed was North Calorina Design 2, where 15 sorghum lines
were used as females on two males. The crosses were evaluated in two
seasons at University of Embu farm in 2011/2012 short and long seasons
replicated twice. Artificial infestation with African stem borer
neonates was done 30 days after planting using a camel brush. Data
collected included stem borer damage and agro-morphological traits.
Genetic analyses were performed using a line x tester method using
Genstat statistical software. It was found that both additive and
non-additive gene effects were important in conditioning resistance
traits to the African stem borer. This implies that expression of high
leaf glossiness, plant vigour and bloom waxiness in F1 hybrids is
conditioned by additive genes and these traits can be used as
morphological markers to select for resistance to the borer in sorghum.
ICSB 464 x ICSB 473 was the best combiner for stem borer resistance and
grain yield. Parents ICSA 464, ICSB 464 and ICSB 474, were among the
good combiners for resistance to the stem borer. These parents can be
utilised in developing superior sorghum hybrids resistant to the insect
pest.Le foreur africain de tiges ( Busseola fusca [Fuller]) est un insecte
ravageur important pour les c\ue9r\ue9ales, principalement le
ma\uefs, le sorgho et le mil. L\u2019 insecte r\ue9duit
jusqu\u2019\ue0 80% le rendement en grains, en fonction de la
population d\u2019 insecte dans le champ, du cultivar et des pratiques
de gestion employ\ue9es. Cette r\ue9duction de rendement cause une
ins\ue9curit\ue9 alimentaire, en particulier dans les zones
semi-arides (ASAL) o\uf9 le sorgho est cultiv\ue9 par de petits
agriculteurs. Cette \ue9tude a examin\ue9 la transmission des
caract\ue8res de r\ue9sistance aux foreurs africain de tiges chez
le sorgho \ue0 grains au Kenya. Le mat\ue9riel exp\ue9rimental
consistait en dix-sept lign\ue9es de sorgho pr\ue9sentant
diff\ue9rents niveaux de r\ue9sistance au foreur africain de tiges.
Le plan d\u2019accouplement utilis\ue9 \ue9tait le North Calorina
Design 2, o\uf9 15 lign\ue9es de sorgho \ue9taient utilis\ue9es
en tant que femelles sur deux m\ue2les. Les croisements ont
\ue9t\ue9 \ue9valu\ue9s au cours de deux saisons \ue0 la
ferme de l\u2019Universit\ue9 d\u2019Embu en 2011/2012 des saisons
courtes et longues ont \ue9t\ue9 r\ue9pliqu\ue9es deux fois.
L\u2019infestation artificielle de nouveau-n\ue9s avec des
t\ue9tranyques a \ue9t\ue9 r\ue9alis\ue9e 30 jours apr\ue8s
la plantation \ue0 l\u2019aide d\u2019une brosse \ue0 chameaux.
Les donn\ue9es collect\ue9es comprenaient les dommages caus\ue9s
par les foreurs de tiges et les caract\ue9ristiques
agro-morphologiques. Les analyses g\ue9n\ue9tiques ont
\ue9t\ue9 effectu\ue9es \ue0 l\u2019aide d\u2019une
m\ue9thode de test de ligne x utilisant le logiciel statistique
Genstat. Il a \ue9t\ue9 constat\ue9 que les effets
g\ue9n\ue9tiques additifs et non additifs \ue9taient importants
pour conditionner les caract\ue8res de r\ue9sistance au foreur de
tiges. Cela implique que l\u2019expression de g\ue8nes additifs
conditionne l\u2019expression d\u2019une brillance \ue9lev\ue9e
des feuilles, de la vigueur des plantes et du fart de la floraison chez
les hybrides F1. Ces caract\ue8res peuvent \ueatre utilis\ue9s
comme marqueurs morphologiques pour s\ue9lectionner la
r\ue9sistance au foreur du sorgho. ICSB 464 x ICSB 473 \ue9tait le
meilleur combineur pour la r\ue9sistance des foreurs de tiges et le
rendement en grains. Les parents ICSA 464, ICSB 464 et ICSB 474
figuraient parmi les bons combinateurs pour la r\ue9sistance au
foreur. Ces parents peuvent \ueatre utilis\ue9s pour
d\ue9velopper des hybrides de sorgho sup\ue9rieurs r\ue9sistants
\ue0 l\u2019insecte ravageur
Genetic variability characterisation of Tanzania sorghum landraces based on simple sequence repeats (SSRs) molecular and morphological markers
No full textMorphological and molecular markers were employed to study the genetic
variability among 40 sorghum landraces collected from Tanzania and two
from Zambia. A total of 14 morphological markers and seven simple
sequence repeats (SSRs) primers were used to (i) determine the genetic
relationships among landraces, and (ii) assess important agronomic
traits. Five principal components accounted for 73.60% of the total
variability. There were positive significant correlation between yield
and inflorescence width (r = 0.343*), five panicles averages and plot
yields (r = 0. 531*), leaf senescence and inflorescence length (r =
0.355*). Negative significant correlation between tiller numbers and
inflorescence length (r = -0.343*) was recorded. Cluster analysis based
on morphological traits revealed three major distinct groups with one
landrace forming independent cluster. Based on molecular markers,
eleven clusters were observed. Sorghum controls, N13, Ochuti and Adiwo
each formed independent clusters. Markers Xgap84 and Xtxp320 had high
alleles than other markers. These had seven and eight alleles
respectively. Molecular markers clearly separated landraces within and
between groups than morphological markers. There were no genotype
specific makers with the exceptions of Ochuti and N13 controls.Les marqueurs morphologiques et moléculaires ont été
utilisés pour étudier la variabilité génétique
de 40 variétés locales du sorgho collectées en Tanzanie
et 2 en Zambie. Au total 14 promoteurs pour les marqueurs
morphologiques et 7 pour les marqueurs microsatellites ou SSRs (simple
sequence repeats) ont été utilisés pour (1)
déterminer les rapports génétiques des
variétés (2) évaluer les traits à importance
agronomique. Cinq composantes principales correspondaient à 73.6%
du total de variabilité. Des corrélations linéaires
positives ont été trouvées entre les le rendement et la
largeur de l'inflorescence (r=0.343*) ; Cinq moyennes de panicules et
le rendement parcellaires (r=0.531*) ; et la sénescence des
feuilles et la longueur de l'inflorescence (0.355*). Une
corrélation négative a été enregistrée entre
le nombre de talles et la longueur de l'inflorescence (r=0.343*).
L'analyse cluster basée sur des traits morphologiques a
révélé 3 groupes distinctifs majeurs avec une
variété locale formant un cluster indépendant. En se
basant sur les marqueurs moléculaires, onze clusters été
observes. Les varietes témoins, N13, Ochuti et Adiwo chacune
formaient des clusters indépendants. Les marqueurs Xgap84 and
Xtxp320 avaient des allèles plus élevés que les autres
marqueurs, avec respectivement, sept et 8 allèles. Les marqueurs
moléculaires ont sépare clairement les varietes parmi et dans
les groups distinctifs que mieux les marqueurs morphologiques. Il n'y
avait pas de marqueurs phénotypiques spécifiques à
l'exception des témoins Ochuti et N13. L'information
générée par cette étude peut être
utilisée par des sélectionneurs pour l'amélioration du
sorgho
Characterization of blast resistance in a diverse rice panel from sub-Saharan Africa
No full textThere is a recent unparalleled increase in demand for rice in sub-Saharan Africa, yet its production is affected by blast disease. Characterization of blast resistance in adapted African rice cultivars can provide important information to guide growers and rice breeders. We used molecular markers for known blast resistance genes ( Pi genes; n = 21) to group African rice genotypes ( n = 240) into similarity clusters. We then used greenhouse-based assays to challenge representative rice genotypes ( n = 56) with African isolates ( n = 8) of Magnaporthe oryzae which varied in virulence and genetic lineage. The markers grouped rice cultivars into five blast resistance clusters (BRC) which differed in foliar disease severity. Using stepwise regression, we found that the Pi genes associated with reduced blast severity were Pi50 and Pi65, whereas Pik-p, Piz-t, and Pik were associated with increased susceptibility. All rice genotypes in the most resistant cluster, BRC 4, possessed Pi50 and Pi65, the only genes that were significantly associated with reduced foliar blast severity. Cultivar IRAT109, which contains Piz-t, was resistant against seven African M. oryzae isolates, whereas ARICA 17 was susceptible to eight isolates. The popular Basmati 217 and Basmati 370 were among the most susceptible genotypes. These findings indicate that most tested genes were not effective against African blast pathogen collections. Pyramiding genes in the Pi2/9 multifamily blast resistance cluster on chromosome 6 and Pi65 on chromosome 11 could confer broad-spectrum resistance capabilities. To gain further insights into genomic regions associated with blast resistance, gene mapping could be conducted with resident blast pathogen collections.[Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license
Morphological, morphometric and molecular characterization of Pratylenchus and Radopholus in Musa spp., in the coffee region and Valle del Cauca, Colombia
No full textIlustraciones, tablasLos nematodos fitoparásitos causan pérdidas entre 30 y 80% de la producción de
plátano (Musa AAB Simmonds - Dominico Hartón) y banano (Musa acuminata) en
campos altamente infestados. En las zonas de mayor producción de Musa en
Colombia, su manejo fitosanitario ha sido limitado por el desconocimiento de las
especies de nematodos presentes. Con el propósito de conocer las especies de
Pratylenchus y Radopholus asociadas a cultivos de plátano y banano en los
departamentos de Caldas, Quindío, y Valle del Cauca se colectaron muestras
compuestas de raíces y suelo rizosférico de diferentes sistemas de producción. En
el laboratorio de sanidad vegetal de la Universidad Nacional de Colombia, sede
Palmira, los nematodos fueron extraídos por el método de Cobb modificado e
identificados mediante análisis morfológico, morfométrico (mediciones de
caracteres diagnósticos) y molecular (amplificación por PCR y secuenciación del
segmento D2-D3 del ARN ribosomal y Citocromo oxidasa subunidad I [COI] del ADN
mitocondrial para Pratylenchus e Internal Transcribed Spacer-ITS del ARN
ribosomal para Radopholus). Los resultados mostraron, cinco poblaciones de P.
araucensis, así: dos del Valle del Cauca, dos de Quindío y una de Caldas, lo cual
indica que esta especie de nematodo, previamente reportada en Arauca (Colombia),
se encuentra ampliamente distribuida en el país. Mediante pruebas moleculares,
COI, las poblaciones se separaron por origen geográfico sugiriendo una amplia
variabilidad intraespecífica. Este estudio reporta las primeras secuencias de COI
para P. araucensis en el mundo. Por otro lado, tres poblaciones fueron identificadas
como R. similis, (dos de Caldas y una de Quindío) confirmándose la presencia de
esta especie de nematodo en las zonas estudiadas. A partir de esta información, a
futuro podrán plantearse eficientes programas de manejo integrado para las
especies identificadas. (Texto tomado de la fuente)Phytoparasitic nematodes cause losses between 30 and 80% of plantain (Musa AAB
Simmonds - Dominico Hartón) and banana (Musa acuminata) production in highly
infested fields. In the areas of greater production in Colombia, their phytosanitary
management has been limited by the wide ignorance of the nematode species
present. In order to know the Pratylenchus and Radopholus species associated with
plantain and banana crops in the departments of Valle del Cauca, Caldas and
Quindío, samples composed of roots and rhizospheric soil from different production
systems were collected. In the laboratory, the nematodes were extracted by the
modified Cobb method and identified by morphological, morphometric
(measurements of diagnostic characteristics) and molecular analysis (PCR
amplification and sequencing of the D2-D3 segment of ribosomal RNA and
Cytochrome oxidase I subunit [COI] of mitochondrial DNA for Pratylenchus and
Internal Transcribed Spacer-ITS of ribosomal RNA for Radopholus). According to
the results, five populations were identified as P. araucensis, two from Valle del
Cauca, two from Quindío and one from Caldas, which indicates that this nematode
species, previously reported in Arauca (Colombia), is widely distributed in the
country. Using molecular data, but especially COI, populations were separated by
geographic origin suggesting wide intraspecific variability. This study reports the first
COI sequences for P. araucencis in the world. On the other hand, three populations
(two from Caldas and one from Quindío) were identified as R. similis, confirming the
presence of this nematode species in the studied areas. Based on this information,
efficient integrated management programs for the identified species may be
proposed in the future.MaestríaMagíster en Ciencias AgrariasEn el laboratorio de sanidad vegetal de la Universidad Nacional de Colombia, sede
Palmira, los nematodos fueron extraídos por el método de Cobb modificado e
identificados mediante análisis morfológico, morfométrico (mediciones de
caracteres diagnósticos) y molecular (amplificación por PCR y secuenciación del
segmento D2-D3 del ARN ribosomal y Citocromo oxidasa subunidad I [COI] del ADN
mitocondrial para Pratylenchus e Internal Transcribed Spacer-ITS del ARN
ribosomal para Radopholus).Protección de cultivo
