66 research outputs found
Optimisation of in vitro techniques for cassava brown streak virus elimination from infected cassava clones
Cassava brown streak disease (CBSD), caused by Cassava brown streak virus (CBSV), is an economically important disease of cassava (Manihot esculenta Crantz) in East Africa. The objective of this study was tooptimise in vitro techniques for CBSV elimination from infected Ugandan cassava cultivars. Using semi-solid halfstrength Murashige and Skoog (MS) basal medium, hormone concentration and heat treatment regimes wereoptimised for micropropagation of farmer’s preferred cassava cultivars and CBSV elimination. Single nodes from young cassava stems were cultured for four weeks on ½MS medium supplemented with 6-benzyl amino purine(BAP) and 2,4-dichlorophenoxy acetic acid (2,4-D). The BAP and 2,4-D concentration (mg l-1) combinations used were 0.0 and 0.0, 0.5 and 0.1, 1.0 and 0.2, 1.5 and 0.3, and 2.0 and 0.4, respectively. The optimum medium was used for in vitro thermotherapy using four temperature regimes, namely 30-34, 34-38, 36-40 and 38-42 oC for 8 hoursdarkness and 16 hours light, respectively, for four weeks. The best plantlet growth in terms of height was observed on MS medium supplemented with 0.5 mg l-1 BAP and 0.1 mg l-1 2,4-D. Highest CBSV elimination efficiency of 40%, with 49% plantlet survival was observed at 36 oC for 8 hours darkness and 40 oC for 16 hours light. These results indicate that in vitro techniques can greatly enhance CBSV elimination and, thus, provide a means of CBSD management through dissemination and conservation of popular but CBSD susceptible cultivars
Optimisation of in vitro techniques for Cassava brown streak virus elimination from infected cassava clones
Cassava brown streak disease (CBSD), caused by Cassava brown streak
virus (CBSV), is an economically important disease of cassava ( Manihot
esculenta Crantz) in East Africa. The objective of this study was to
optimise in vitro techniques for CBSV elimination from infected Ugandan
cassava cultivars. Using semi-solid half-strength Murashige and Skoog
(MS) basal medium, hormone concentration and heat treatment regimes
were optimised for micropropagation of farmer's preferred cassava
cultivars and CBSV elimination. Single nodes from young cassava stems
were cultured for four weeks on 1/2MS medium supplemented with 6-benzyl
amino purine (BAP) and 2,4-dichlorophenoxy acetic acid (2,4-D). The BAP
and 2,4-D concentration (mg 1-1) combinations used were 0.0 and 0.0,
0.5 and 0.1, 1.0 and 0.2, 1.5 and 0.3, and 2.0 and 0.4, respectively.
The optimum medium was used for in vitro thermotherapy using four
temperature regimes, namely 30-34, 34-38, 36-40 and 38-42 \ub0C for 8
hours darkness and 16 hours light, respectively, for four weeks. The
best plantlet growth in terms of height was observed on MS medium
supplemented with 0.5 mg 1-1 BAP and 0.1 mg 1-1 2,4-D. Highest CBSV
elimination efficiency of 40%, with 49% plantlet survival was observed
at 36 \ub1C for 8 hours darkness and 40 oC for 16 hours light. These
results indicate that in vitro techniques can greatly enhance CBSV
elimination and, thus, provide a means of CBSD management through
dissemination and conservation of popular but CBSD susceptible
cultivars.La maladie de la striure brune du manioc (CBSD) caus\ue9e par le
virus de la striure brune (CBSV), est une maladie \ue9conomiquement
importante du manioc ( Manihot esculenta Crantz) en Afrique de
l'Est. L'objectif de cette \ue9tude \ue9tait d'optimiser les
techniques in vitro pour l'\ue9limination du CBSV des cultivars
ougandais infect\ue9s. En utilisant le m\ue9dium basal semi-solid
half strength Murashige and Skoog, la concentration d'hormone et les
regimes de traitement de chaleur \ue9taient optimis\ue9s pour la
micropropagation des cultivars de manioc pr\ue9f\ue9r\ue9s par
les fermiers et l'\ue9limination du CBSV. Les nodes simples des
jeunes tiges de manioc \ue9taient cultiv\ue9s pendant quatre
semaines sur le m\ue9dium 1/2 MS suppl\ue9ment\ue9s avec 6-benzyl
amino purine (BAP) et 2,4-dichlorophenoxy acetic acid. Les combinaisons
de concentrations (mg 1-1) de BAP et de 2.4-D utilis\ue9es
\ue9taient 0.0 et 0.0, 0.5 et 0.1, 1.0 et 0.2, 1.5 et 0.3, et 2.0 et
0.4, respectivement. Le m\ue9dium optimum \ue9tait utilis\ue9
pour la thermoth\ue9rapie utilisant quatre regimes de
temp\ue9rature dont 30-34, 34-38, 36-40 et 38-42 \ub0C pendant 8
heures en obscurit\ue9 et 16 heures sous lumi\ue8re, respectivement
pendant quatre semaines. La meilleure croissance en hauteur des
plantules \ue9tait observ\ue9e sur le m\ue9dium MS
suppl\ue9ment\ue9 avec 0.5 mg 1-1 BAP et 0.1 mg 1-1 2,4-D.
L'efficience la plus \ue9lev\ue9e de 40 % en terme
d'\ue9limination du CBSV, avec 49 % de la survie de plantules
\ue9tait observ\ue9e \ue0 36 \ub0C pendant 8 heures sous
obscurit\ue9 et 40 \ub0C pendant 16 heures sous lumi\ue8re. Les
r\ue9sultats indiquent que les techniques in vitro peuvent grandement
promouvoir l'\ue9limination du CBSV et offrent ainsi un moyen de
gestion de CBSD \ue0 travers la dissemination et la conservation des
cultivars aussi populaires que susceptibles au SBSD
Risk factors for non-communicable diseases in rural Uganda: a pilot surveillance project among diabetes patients at a referral hospital clinic
Introduction: Despite an increasing recognition of non- communicable diseases (NCDs) in sub-Saharan Africa, there is lack of well established surveillance systems for these diseases. In an effort to understand burden of NCDs in low-resource settings, the African Field Epidemiology Network launched a pilot project in 2009 to routinely capture patient data in the diabetes clinic of Mbarara Regional Referral Hospital. The objective of this study was to determine the prevalence and, the gender- and age- specific distributions of common NCD risk factors among diabetic patients attending a referral hospital in rural Uganda. Methods: A relational Access database was designed to collect information on NCD risk factors. These included smoking, alcohol use, family history of diabetes, hypertension and body mass index. Univariate analyses were done and differences in proportions tested using chi-square P-values in STATA version 10.0. Results: A total of 1,383 patient records were analyzed, with 61% being female and mean age of 39.6 years (SD 15.8). About 24% had a family history of diabetes. Smoking and alcohol use were more prevalent among males (16.6 % vs. 8.3%; p<0.0001) and (30.7 vs. 13%; p<0.0001) respectively. Overweight, obesity and hypertension were more prevalent in women (18.6% vs. 9.7%, 8.6% vs. 2.6%; p<0.0001, and 40.3% vs. 33%, p=0.018) respectively. Conclusion: This pilot project shows that use of hospital-based data is a valuable initial step in setting up surveillance systems for NCDs in Uganda. Risk factors for NCDs were both age and gender-specific and predominantly related to lifestyle. This suggests the need to design gender-sensitive prevention interventions that target lifestyle modification in this setting
Performance and inheritance of yield and maize streak virus disease resistance in white maize and yellow conversions
In sub Saharan Africa, past effort has registered success in developing
high yielding and foliar disease resistant maize ( Zea mays L.)
varieties, which are deficient in pro-vitamin A. A new initiative is to
develop maize varieties, tolerant to foliar diseases and rich in
pro-vitamin A carotenoids. To achieve this, yellow conversions of white
testers and other elite maize varieties have been developed by the
International Center for Maize and Wheat Development (CIMMYT). Unlike
the white lines, limited information on agronomic performance and
disease resistance is available for yellow maize conversions. This
study was conducted to evaluate the performance of white maize and
their corresponding yellow maize conversions for yield and tolerance to
Maize streak virus (MSV) disease; and determine the inheritance
patterns of these traits. Fourty seven three-way hybrids generated in a
Line by tester mating design (North Carolina 2), 12 inbred lines (used
as male parents), 4 single crosses (used as female parents) and 3
commercials checks were screened for resistance to Maize streak virus
(MSV) disease at the National Crop Resources Research Institute
(NaCRRI) in Uganda. The same genotypes were evaluated in a 9x5 alpha
lattice design in three locations of Uganda (National Crop Resources
Research Institute (NACRRI), National Semi Arid Resources Research
Institute (NaSARRI) and Bulambuli) for agronomic performance. Results
confirmed tolerance to MSV in testers CML202, CML395, CML444, CML445
and CML312-SR (white). Genotypes performed significantly differently
for yield, anthesis days, plant height, ear height, husk cover, grain
texture, reaction to Gray leaf spot (GLS) (P<0.001) and ear aspect
(P<0.01). However, pairwise comparison of white and yellow
conversions indicated no significant difference (P>0.05) in
agronomic performance and tolerance to diseases. General combining
ability (GCA) was more important than specific combining ability (SCA)
for most traits, except for anthesis days, Turcicum leaf blight (TLB),
GLS and yield. GCA effects for yield were not significant in both lines
(male parents) and single cross testers (female parents) of white and
yellow conversions. However, two unique cases were observed for
diseases; yellow conversion of line CML444 significantly combined for
susceptibility to TLB; while tester CML312/CML442 combined for
resistance to GLS. Additionally, there was low heritably estimates for
tolerance to MSV and yield. Generally, there was no significant
difference between white and corresponding yellow maize conversion,
implying that there is no significant loss in MSV resistance and yield
performance while converting white into yellow maize.En Afrique sub-Saharienne, les efforts ant\ue9rieurs ont connu de
grands succ\ue8s dans le d\ue9veloppement des vari\ue9t\ue9s
tr\ue8s productives et tol\ue9rantes aux maladies foliaires du
ma\uefs ( Zea mays L.), mais qui sont pauvres en provitamine A. La
nouvelle vision est de d\ue9velopper des vari\ue9t\ue9s de
ma\uefs r\ue9sistantes aux principales maladies foliaires, et riche
en carot\ue9no\uefdes provitamine A. Pour y arriver, les
conversions jaunes issues des testeurs blancs de ma\uefs ainsi que
les vari\ue9t\ue9s \ue9lite ont \ue9t\ue9
d\ue9velopp\ue9es par le Centre International pour
l\u2019Am\ue9lioration du Ma\uefs et du Bl\ue9 (CIMMYT).
Contrairement aux lign\ue9es blanches de ma\uefs, la performance
agronomique et le niveau de r\ue9sistance aux maladies des
lign\ue9es jaunes reste m\ue9connue. Cette \ue9tude a
\ue9t\ue9 men\ue9e dans le but d\u2019\ue9valuer la
performance au niveau du rendement et la r\ue9sistance \ue0 la
maladie des bandes (MSV) des vari\ue9t\ue9s de ma\uefs \ue0
grain de couleur blanche et leurs conversions de couleur jaune et
d\ue9terminer le mode d\u2019h\ue9ritabilit\ue9 de ces deux
param\ue8tres \ue9tudi\ue9s. Quarante-sept hybrides trois voies
produits dans un mode de croisement Lign\ue9e par testeur (North
Carolina II), 12 lign\ue9es \ue9pur\ue9es (utilis\ue9es comme
parents m\ue2les), 4 hybrides simples (utilis\ue9s comme parents
femelles) et 3 t\ue9moins ont \ue9t\ue9 inocul\ue9s par
l\u2019agent causal de la maladie des bandes \ue0 NaCRRI (National
Crop Ressources Research Institute) en Ouganda. La performance
agronomique des m\ueames g\ue9notypes a \ue9t\ue9
\ue9valu\ue9e dans un dispositif exp\ue9rimental d\u2019alpha
lattice (5parcelles \ue9l\ue9mentaires x 9 blocks) dans 3 sites de
l\u2019Ouganda \ue0 savoir NaCRRI (National Crop Ressources Research
Institute), NaSARRI (National Semi Arid Resources Research Institute)
et Bulambuli. Les r\ue9sultats ont confirm\ue9 la tol\ue9rance
\ue0 la MSV des testeurs \ue0 grains blancs CML202, CML395, CML444,
CML445 et CML 312-SR. La performance des g\ue9notypes \ue9tait
hautement significativement diff\ue9rente pour le rendement, le
nombre de jours de floraison m\ue2le, la hauteur des plants, le
niveau d\u2019insertion des \ue9pis sur les plants, la couverture
des \ue9pis par les spathes, la texture des grains, la r\ue9action
\ue0 la GLS (Glay leaf spot) (P<0.001) ainsi que pour
l\u2019aspect des \ue9pis (P<0.01). Cependant, la comparaison
entre le ma\uefs blanc et sa conversion jaune a montr\ue9 une
diff\ue9rence non significative (P>0.05) au niveau de leur
performance agronomique et la tol\ue9rance aux maladies.
L\u2019aptitude g\ue9n\ue9rale \ue0 la combinaison (GCA)
\ue9tait plus importante que l\u2019aptitude sp\ue9cifique \ue0
la combinaison (SCA) pour la plupart des param\ue8tres \ue0
l\u2019exception du nombre de jours \ue0 floraison m\ue2le, la
tol\ue9rance \ue0 l\u2019helminthosporiose (TLB), GLS et le
rendement. Les effets dus \ue0 la GCA pour le rendement
n\u2019\ue9taient pas significatifs pour les parents m\ue2les
(lign\ue9es) et femelles (hybrides simples) des g\ue9notypes \ue0
grain de couleur blanche et leurs conversions \ue0 grain de couleur
jaune. N\ue9anmoins, deux cas exceptionnels ont \ue9t\ue9
observ\ue9s pour la tol\ue9rance aux maladies: la conversion jaune
de la lign\ue9e CML444 \ue9tait un mauvais combinateur pour la TLB,
alors que le testeur CML312/CML442 combinait bien pour la
tol\ue9rance \ue0 la GLS. En plus, l\u2019h\ue9ritabilit\ue9
\ue9tait faible pour la tol\ue9rance \ue0 la MSV et le rendement.
En g\ue9n\ue9ral, il n\u2019y avait pas de diff\ue9rence
significative entre les g\ue9notypes \ue0 grain blanc et leurs
conversions jaunes respectives, ce qui signifie que, lors de la
conversion des vari\ue9t\ue9s \ue0 grain blanc en
vari\ue9t\ue9s \ue0 grain jaune, il n\u2019y a aucune perte
significative en ce qui est de la tol\ue9rance \ue0 la MSV et la
performance en rendement des grains
Evaluation of tomato genotypes for tolerance to major diseases in Uganda
Tomato ( Solanum lycopersicum L.) is a priority vegetable in Uganda,
but due to its limited genetic base, its cultivated types are prone to
a variety of diseases. The objective of this study was to evaluate new
tomato genotypes for resistance to major tomato diseases under hotspot
conditions in Uganda. Fourty-five tomato genotypes were evaluated for
reactions to tomato bacterial wilt, tomato bacterial speck, early
blight and late blight. The study was conducted for two rainy seasons
in 2019, at the National Crops Resources Research Institute, Namulonge
in Uganda. Data for severity and incidence were collected at two-week
intervals after transplanting. Twelve genotypes (Nouvella F1, Rambo F1,
Commando F1, AVTO1315, AVTO922, AVTO1701, AVTO1219, AVTO1464, MT56,
ADV1287A, Pruna and Vega) exhibited high levels of tolerance to
bacterial wilt; while bacterial speck presented mild symptoms majorly
seen on Vega, Zodiac and AVTO9802. Rhino, AVTO1418, AVTO1314, Eureka,
Roma VFN, MT56, Pinktop, Assila F1, Money-maker, AVTO0922 and AVTO1464
were the least affected by early blight; while AVTO1219, AVTO1701,
ADV12021, ADV12076 and ADV1287A expressed low AUDPC values for late
blight. Overall, AVTO1315 was the best yielder (30.8 metric tonnes
ha-1), followed by AVTO0301 (29.0 t ha-1) and Nouvella F1 (26.1 t
ha-1). Among the tomato genotypes evaluated, we recommend AVTO1701,
AVTO0922, AVTO1464, AVTO0301 AVTO1315, AVTO1219, Pruna, Vega, ADV1287A
and MT56 for the national performance trials.La tomate ( Solanum lycopersicum L.) est un l\ue9gume prioritaire
en Ouganda, mais en raison de sa base g\ue9n\ue9tique limit\ue9e,
ses types cultiv\ue9s sont sujets \ue0 une vari\ue9t\ue9 de
maladies. L\u2019objectif de cette \ue9tude \ue9tait
d\u2019\ue9valuer des g\ue9notypes de tomates
s\ue9lectionn\ue9s pour leur r\ue9sistance aux principales
maladies de la tomate dans des conditions de hotspot en Ouganda.
Quarante-cinq g\ue9notypes de tomates ont \ue9t\ue9
\ue9valu\ue9s pour leurs r\ue9actions au fl\ue9trissement
bact\ue9rien de la tomate, \ue0 la tache bact\ue9rienne de la
tomate, au mildiou et au mildiou. L\u2019\ue9tude a \ue9t\ue9
men\ue9e pendant deux saisons des pluies en 2019, au National Crops
Resources Research Institute, \ue0 Namulonge en Ouganda. Les
donn\ue9es de gravit\ue9 et d\u2019incidence ont \ue9t\ue9
recueillies \ue0 des intervalles de deux semaines apr\ue8s la
transplantation. Douze g\ue9notypes (Nouvella F1, Rambo F1, Commando
F1, AVTO1315, AVTO922, AVTO1701, AVTO1219, AVTO1464, MT56, ADV1287A,
Pruna et Vega) pr\ue9sentaient des niveaux \ue9lev\ue9s de
tol\ue9rance au fl\ue9trissement bact\ue9rien; tandis que la
tache bact\ue9rienne pr\ue9sentait des sympt\uf4mes b\ue9nins
principalement observ\ue9s sur Vega, Zodiac et AVTO9802. Rhino,
AVTO1418, AVTO1314, Eureka, Roma VFN, MT56, Pinktop, Assila F1,
Money-maker, AVTO0922 et AVTO1464 ont \ue9t\ue9 les moins
touch\ue9s par le mildiou; tandis que AVTO1219, AVTO1701, ADV12021,
ADV12076 et ADV1287A ont exprim\ue9 de faibles valeurs AUDPC pour le
mildiou. Dans l\u2019ensemble, AVTO1315 a \ue9t\ue9 le meilleur
producteur (30,8 tonnes m\ue9triques ha-1), suivi par AVTO0301 (29,0
t ha-1) et Nouvella F1 (26,1 t ha-1). Parmi les g\ue9notypes de
tomates \ue9valu\ue9s, nous recommandons AVTO1701, AVTO0922,
AVTO1464, AVTO0301 AVTO1315, AVTO1219, Pruna, Vega, ADV1287A et MT56
pour les essais de performance nationaux
Portable PCR field-based detection of sweetpotato viruses
Sweetpotato ( Ipomoea batatas Lam.) production is greatly constrained
by viral infections, especially Sweet potato feathery mottle virus and
Sweet potato chlorotic stunt virus that synergistically cause a severe
sweetpotato virus disease. The impact of viruses is aggravated by the
vegetative nature of the crop and inaccessibility to dependable
diagnostic tools in rural areas where sweetpotato production is done.
This makes it hard for seed inspectors to perform quality checks prior
to use of vines for planting. The objective of this study was to
develop a procedure that allows for detection of sweetpotato viruses
on-site. This involved modification of the Lodhi et al. (1994) nucleic
acid extraction procedure, by omitting some of the laboratory specific
steps and varying the incubation time in liquid nitrogen, instead of
the freezer. Incubation in liquid nitrogen for only 1.5 hours yielded
as high quality RNA compared to that of the original protocol, when
incubation was done at 4\ub0C overnight in a freezer. Reverse
transcriptase (RT) was run using a portable miniPCR thermocycler; and
the resulting cDNA was amplified using this miniPCR machine instead of
using a laboratory stationed conventional PCR thermocycler. The cDNA
was efficiently amplified and amplicons were similar to those obtained
with the original extraction protocol and subsequent amplification by
the conventional RT-PCR. Our protocol reduced extraction time from
about 16 hours for the original protocol, to about 2 hours and 45
minutes. If this tool is utilised by the crop protection departments,
we believe it will contribute greatly towards sustainable sweetpotato
production through making timely recommendations.La production de la patate douce ( Ipomoea batatas Lam.) est
fortement limit\ue9e par les infections virales, en particulier le
virus de la marbrure plumeuse de la patate douce et le virus du stunt
chlorotique de la patate douce qui provoquent en synergie une maladie
virale grave de la patate douce. L\u2019impact des virus est
aggrav\ue9 par la nature v\ue9g\ue9tative de la culture et
l\u2019inaccessibilit\ue9 des outils fiables pour le diagnostic dans
les zones rurales o\uf9 la production de patate douce est
r\ue9alis\ue9e. Cela rend difficile les inspecteurs des semences
d\u2019effectuer des contr\uf4les de qualit\ue9 avant
l\u2019utilisation des vignes par les agriculteurs. L\u2019objectif
de cette \ue9tude \ue9tait de d\ue9velopper une proc\ue9dure
permettant la d\ue9tection des virus de la patate douce sur place.
Cela impliquait une modification de Lodhi et al. (1994) proc\ue9dure
d\u2019extraction d\u2019acide nucl\ue9ique, en omettant certaines
des \ue9tapes sp\ue9cifiques du laboratoire et en faisant la
variation de temps d\u2019incubation dans l\u2019azote liquide, au
lieu du cong\ue9lateur. L\u2019incubation dans l\u2019azote liquide
pendant seulement 1,5 heure a donn\ue9 un ARN de haute qualit\ue9
comme le protocole d\u2019origine, lorsque l\u2019incubation a
\ue9t\ue9 effectu\ue9e \ue0 4 \ub0 C pendant une nuit dans un
cong\ue9lateur. La transcriptase inverse (RT) a \ue9t\ue9 faite
en utilisant un thermocycleur mini PCR portable et l\u2019ADNc, et
r\ue9sultant a \ue9t\ue9 amplifi\ue9 en utilisant cette machine
mini PCR au lieu d\u2019utiliser un thermocycleur PCR conventionnel
stationn\ue9 en laboratoire. L\u2019ADNc a \ue9t\ue9
efficacement amplifi\ue9 et les amplicons \ue9taient similaires
\ue0 ceux obtenus avec le protocole d\u2019extraction original et
l\u2019amplification ult\ue9rieure par la RT-PCR conventionnelle.
Notre protocole a r\ue9duit le temps d\u2019extraction
d\u2019environ 16 heures pour le protocole d\u2019origine, \ue0
environ 2 heures et 45 minutes. Si cet outil est utilis\ue9 par le
d\ue9partement de la protection des cultures, nous pensons
qu\u2019il contribuera grandement \ue0 la production durable de
patate douce en faisant des recommandations en temps opportun
EFFECTIVE ISOLATION DISTANCE FOR PREVENTION OF CASSAVA VIRUS INFECTIONS IN UGANDA
Cassava brown streak disease (CBSD) and cassava mosaic disease (CMD)
are the major viral diseases of cassava in Uganda. Although isolation
distance of \u201c50 m\u201d has been recommended by MAAIF in Uganda
for prevention of virus infections in crops, the minimum isolation
distance has not been verified for effectiveness in cassava. This study
assessed the effective isolation distance for management of viral
diseases in cassava. Virus-clean cassava cultivars (NASE 03, NASE 14
and NAROCASS 1) from farmers\u2019 fields were used as field sourced
(FS) planting materials. Tissue culture (TC) material of the same
cultivars were sourced from the National Crops Resources Research
Institute and Makerere University Agricultural Research Institute
tissue culture laboratories. Both FS and TC materials were tested at
isolation distances of 50, 100, 150 and 250 m for virus prevention. The
experiment was laid out in a randomised complete block design and was
run for 12 months after planting (MAP). Mean CBSD/CMD prevalence
significantly varied (P<0.05) among isolation distances in both FS
and TC plants, and the 250 m isolation distance was the most effective
in reducing disease prevalence. Across cultivars and planting material
category at 12 MAP, the 50 m isolation distance had the highest foliar
incidence for CBSD (29.2%) and CMD (16.1%); while severity for CBSD was
1.4 and 1.2 for CMD. At 250 m, all FS and TC plants had CBSD/CMD
severity of 1.0 and 0% incidence. These results show that 250 m
isolation distance can provide an option to disseminate popular, but
CBSD/CMD susceptible cassava cultivars thereby manage CBSD/CMD.La maladie des stries brunes du manioc (CBSD) et la maladie de la
mosa\uefque du manioc (CMD) sont les principales maladies virales du
manioc en Ouganda. Bien qu\u2019une distance d\u2019isolement de
\uab50 m\ubb ait \ue9t\ue9 recommand\ue9e par le MAAIF en
Ouganda pour la pr\ue9vention des infections virales dans les
cultures, l\u2019efficacit\ue9 minimale de la distance
d\u2019isolement n\u2019a pas \ue9t\ue9 v\ue9rifi\ue9e dans
le manioc. Cette \ue9tude a \ue9valu\ue9 la distance
d\u2019isolement efficace pour la gestion des maladies virales dans le
manioc. Des cultivars de manioc sans virus (NASE 03, NASE 14 et
NAROCASS 1) provenant des champs des agriculteurs ont \ue9t\ue9
utilis\ue9s comme le source de mat\ue9riel de plantation (FS). Le
mat\ue9riel de culture tissulaire (TC) des m\ueames cultivars
provenait des laboratoires National Crops Resources Research Institute
and Makerere University Agricultural Research Institute tissue culture.
Les mat\ue9riaux FS et TC ont \ue9t\ue9 test\ue9s \ue0 des
distances d\u2019isolement de 50, 100, 150 et 250 m pour la
pr\ue9vention des virus. L\u2019exp\ue9rience a \ue9t\ue9
pr\ue9sent\ue9e dans un bloc complet randomis\ue9 et a
\ue9t\ue9 r\ue9alis\ue9e pendant 12 mois apr\ue8s la
plantation (MAP). La pr\ue9valence moyenne de CBSD / CMD variait
significativement (P <0,05) entre les distances d\u2019isolement
dans les plantes FS et TC, et la distance d\u2019isolement de 250 m
\ue9tait la plus efficace pour r\ue9duire la pr\ue9valence de la
maladie. \uc0 travers les cultivars et la cat\ue9gorie de
mat\ue9riel de plantation \ue0 12 MAP, la distance
d\u2019isolement de 50 m avait l\u2019incidence foliaire la plus
\ue9lev\ue9e pour le CBSD (29,2%) et le CMD (16,1%); tandis que la
gravit\ue9 pour CBSD \ue9tait de 1,4 et 1,2 pour CMD. \uc0 250 m,
toutes les plantes FS et TC avaient une gravit\ue9 CBSD / CMD de 1,0
et une incidence de 0%. Ces r\ue9sultats montrent qu\u2019une
distance d\u2019isolement de 250 m peut fournir une option pour
diss\ue9miner des cultivars de manioc sensibles au CBSD / CMD, ce qui
permet de g\ue9rer le CBSD / CMD
Pathogenicity and virulence of Ugandan isolates of common bacterial blight disease pathogen ( Xanthomonas spp.)
Breeding for resistance is a major component in the integrated
management of common bacterial disease of beans ( Phaseolus vulgaris
L.). Use of less virulent strains or strains with attenuated virulence
may lead to selection of resistant genotypes with intermediate
response, when exposed to more virulent strains of the pathogen. The
objective of this study to identify and characterise Ugandan isolates
of common bacterial blight disease-causing pathogens for virulence.
Bacteria were isolated from leaf samples collected from districts of
Kabale, Masaka, Bukomansimbi, Mubende, Mbale, Bulambuli and Apac, all
in Uganda, during the first season of 2016. The bacteria were tested
for pathogenicity, as well as virulence on both breeding and local
varieties. The study identified three most virulent isolates, namely
MBL020, KAB-3 and BUL-14, all belonging to Xathomonas citri pv
fuscans. These isolates are very similar to those previously identified
from Uganda (NCPB 670 and NCCPB 1402) more than 50 years ago. The study
further revealed that NAROBEAN1, NAROBEAN 2, NAROBEAN 4, VAX 3, VAX5
and NE 2- 14- 8 had better resistance compared to other tested
genotypes.La s\ue9lection pour la r\ue9sistance est un \ue9l\ue9ment
majeur de la gestion int\ue9gr\ue9e des maladies bact\ue9riennes
courantes des haricots ( Phaseolus vulgaris L.). L\u2019utilisation
de souches moins virulentes ou de souches \ue0 virulence
att\ue9nu\ue9e peut conduire \ue0 la s\ue9lection de
g\ue9notypes r\ue9sistants \ue0 r\ue9ponse interm\ue9diaire,
lorsqu\u2019ils sont expos\ue9s \ue0 des souches plus virulentes
du pathog\ue8ne. L\u2019objectif de cette \ue9tude etait
d\u2019identifier et de caract\ue9riser les isolats ougandais de
pathog\ue8nes causant la maladie bact\ue9rienne commune pour la
virulence. Des bact\ue9ries ont \ue9t\ue9 isol\ue9es \ue0
partir d\u2019\ue9chantillons de feuilles pr\ue9lev\ue9s dans
les districts de Kabale, Masaka, Bukomansimbi, Mubende, Mbale,
Bulambuli et Apac, tous en Ouganda, au cours de la premi\ue8re saison
de 2016. Les bact\ue9ries ont \ue9t\ue9 test\ue9es pour leur
pathog\ue9nicit\ue9, ainsi que leur virulence \ue0 la fois pour
la reproduction et vari\ue9t\ue9s locales. L\u2019\ue9tude a
identifi\ue9 les trois isolats les plus virulents, \ue0 savoir
MBL020, KAB-3 et BUL-14, tous appartenant \ue0 Xathomonas citri pv
fuscans. Ces isolats sont tr\ue8s similaires \ue0 ceux
pr\ue9c\ue9demment identifi\ue9s en Ouganda (NCPB 670 et NCCPB
1402), il y a plus de 50 ans. L\u2019\ue9tude a en outre
r\ue9v\ue9l\ue9 que NAROBEAN1, NAROBEAN 2, NAROBEAN 4, VAX 3,
VAX5 et NE 2- 14-8 avaient une meilleure r\ue9sistance par rapport
aux autres g\ue9notypes test\ue9s
Pasting properties of high-quality cassava flour of some selected improved cassava varieties in Tanzania for baking
Open Access ArticlePartial substituting wheat with high-quality cassava flour (HQCF) in bread making would be economically beneficial in Tanzania. However, cassava varieties with the best pasting quality for this use are unknown. In addition, the appropriate time of harvesting the varieties to attain the best pasting quality is also unknown. This study, therefore, aimed at identifying the most appropriate cassava varieties and their appropriate harvesting time that could be used for production of HQCF for baking bread. Nine improved cassava varieties namely Kiroba, Mkuranga1, Pwani, Chereko, Mkumba, Hombolo, Orela, Kizimbani and Kipusa and two local varieties, Albert and Kibandameno were planted in 2020/2021 and 2021/2022 seasons at TARI-Ukiriguru using a split plot design. Harvesting was done at 10 and 12 months after planting (MAP). Pasting characteristics of the HQCF samples were determined at the International Centre of Tropical Agriculture, Dar es salaam, Tanzania using Perten Rapid Visco Analyzer (RVA) Tecmaster equipment, Model: N103802. The results indicated that KIPUSA had the lowest significant setback, while Hombolo had the highest significant setback both at 10 and 12 MAP suggesting that HQCF produced from KIPUSA should be considered for partial substitution of wheat in baking bread that is attractive to consumers
Genome‑wide association studies reveal novel loci for resistance to groundnut rosette disease in the African core groundnut collection
Groundnut is cultivated in several African countries where it is a major source of food, feed and income. One of the major constraints to groundnut production in Africa is groundnut rosette disease (GRD), which is caused by a complex of three agents: groundnut rosette assistor luteovirus, groundnut rosette umbravirus and its satellite RNA. Despite several years of breeding for GRD resistance, the genetics of the disease is not fully understood. The objective of the current study was to use the African core collection to establish the level of genetic variation in their response to GRD, and to map genomic regions responsible for the observed resistance. The African groundnut core genotypes were screened across two GRD hotspot locations in Uganda (Nakabango and Serere) for 3 seasons. The Area Under Disease Progress Curve combined with 7523 high quality SNPs were analyzed to establish marker-trait associations (MTAs). Genome-Wide Association Studies based on Enriched Compressed Mixed Linear Model detected 32 MTAs at Nakabango: 21 on chromosome A04, 10 on B04 and 1 on B08. Two of the significant markers were localised on the exons of a putative TIR-NBS-LRR disease resistance gene on chromosome A04. Our results suggest the likely involvement of major genes in the resistance to GRD but will need to be further validated with more comprehensive phenotypic and genotypic datasets. The markers identified in the current study will be developed into routine assays and validated for future genomics-assisted selection for GRD resistance in groundnut
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