Importance of the onion leaf twister disease in Ghana and the effect of Trichoderma asperellium on the mycelial growth and sporulation of the causal agent

Abstract Studies were carried out to determine the disease incidence and severity of the onion leaf twister disease in the Eastern Region of Ghana to confirm the aetiology of the disease in the country. Field survey was carried out in two districts of the Eastern Region and the disease incidence and severity were measured. The causal agent was isolated on media and identified using morphological characteristics, and polymerase chain reaction with the species specific primer CgInt combined with ITS4 primer. The effect of Trichoderma asperellium on the mycelial growth and sporulation of the causal agent of the disease were determined. The results showed that the disease incidence was 43.6 per cent and 62.5 per cent in the Kwahu South and Fanteakwa districts, respectively, with severity of 0.8 and 2.7 respectively, on a scale of 1 – 5. The causal agent was confirmed as Colletotrichum gloeosporioides. The bio-agent, T. asperellium was able to significantly suppress the mycelial growth and sporulation of the pathogen infecting the onions

Linking science and farmers' innovative capacity: diagnostic studies from Ghana and Benin

The article is an introduction to a series of articles about diagnostic studies carried out by eight PhD students in Ghana and Benin. These studies form a prelude to their experimental action research with groups of farmers to develop technologies that work in local conditions and are acceptable to farmers. A last article reports on a comparison of these eight studies by the ninth PhD student in the Convergence of Sciences (CoS) project. In this introductory article, it is argued that the need to ground agricultural research in the needs and circumstances of farmers is as strong as the need to ground research in the international scientific discourse. It explores the reasons why the West African context requires careful diagnostic studies to be able to design agricultural research that is of any use. It introduces preanalytical choice as an overriding concept to explain why choices that reduce the degrees of freedom have to be made explicitly on the basis of criteria. Such criteria are suggested for the quality of preanalytical choices, and the paper ends by examining the way the CoS project made some of its choice

INTROGRESSION OF DROUGHT TOLERANCE ROOT TRAITS INTO KENYAN COMMERCIAL CHICKPEA VARIETIES USING MARKER ASSISTED BACKCROSSING

Roots play critical roles in enhancing drought tolerance, more so under terminal drought conditions. The objective of this study was to introgress drought tolerant root traits into Kenyan chickpea varieties through marker assisted backcrossing (MABC). Eight simple sequence repeat (SSR) markers, linked to quantitative trait loci (QTL) for root traits, were used to screen parents at ICRISAT in India, and 1144 single nucleotide polymorphic (SNPs) markers at Legume Genomics Centre in the United Kingdom. Crosses were made between two selected varieties, ICCV 92944 (Chania Desi II) and ICCV 00108 (LDT 068); and ICC 4958, QTL donor parent. Polymorphic SSR and SNP markers were used to select offspring with root QTL at F1, BC1F1, and BC2F1, and later advanced to BC2F3. BC2F3 families were evaluated for root traits at Egerton University in Kenya in a pot experiment under rain shelter. The BC2F3 families were significantly (P<0.05) different for root dry weight (RDW), shoot dry weight (SDW), total plant dry weight (PDW), and root to shoot dry weight (R/S) ratio (R/S) for Chania Desi II x ICC 4958; while R/S was significantly different for LDT 068 x ICC 4958. Root length density (RLD) and RDW were positively and significantly (P<0.05) correlated with most of the traits, indicating its usefulness in the indirect selection of these traits. The utilisation of MABC is an effective and efficient method of introgressing complex root traits into commercial lines, expected to improve yields under drought. There is need for deployment of marker-assisted breeding in difficult to phenotypically select traits.Les racines jouent un r\uf4le essentiel dans l\u2019am\ue9lioration de la tol\ue9rance \ue0 la s\ue9cheresse, plus encore en cas de s\ue9cheresse terminale. L\u2019objectif de cette \ue9tude \ue9tait d\u2019introduire des traits de racine tol\ue9rants \ue0 la s\ue9cheresse dans des vari\ue9t\ue9s Kenyannes de chickpea par r\ue9trocroisement assist\ue9 par marqueurs (MABC). Huit marqueurs de r\ue9p\ue9tition de s\ue9quence simple (SSR), li\ue9s \ue0 des locus de traits quantitatifs (QTL) pour les traits racinaires, ont \ue9t\ue9 utilis\ue9s pour s\ue9lectionner les parents \ue0 l\u2019ICRISAT en Inde, et 1144 marqueurs polymorphes \ue0 un seul nucl\ue9otide (SNP) au Legume Genomics Center au Royaume-Uni. Des croisements ont \ue9t\ue9 r\ue9alis\ue9s entre deux vari\ue9t\ue9s s\ue9lectionn\ue9es, ICCV 92944 (Chania Desi II) et ICCV 00108 (LDT 068) ; et ICC 4958, parent donneur QTL. Des marqueurs SSR et SNP polymorphes ont \ue9t\ue9 utilis\ue9s pour s\ue9lectionner la prog\ue9niture avec un QTL racine \ue0 F1, BC1F1 et BC2F1, puis avanc\ue9 \ue0 BC2F3. Les familles BC2F3 ont \ue9t\ue9 \ue9valu\ue9es pour les traits racinaires \ue0 l\u2019Universit\ue9 d\u2019Egerton au Kenya dans une exp\ue9rience en pot sous abri contre la pluie. Les familles BC2F3 \ue9taient significativement diff\ue9rentes (P<0,05) pour le poids sec des racines (RDW), le poids sec des pousses (SDW), le poids sec total de la plante (PDW) et le rapport poids sec des racines sur les pousses (R/S) (R/S ) pour Chania Desi II x ICC 4958\ua0; tandis que R/S \ue9tait significativement diff\ue9rent pour LDT 068 x ICC 4958. La densit\ue9 de longueur des racines (RLD) et RDW \ue9taient corr\ue9l\ue9es positivement et significativement (P < 0,05) avec la plupart des traits, indiquant son utilit\ue9 dans la s\ue9lection indirecte de ces traits. L\u2019utilisation de MABC est une m\ue9thode efficace et efficiente d\u2019introgression de traits racinaires complexes dans des lign\ue9es commerciales, cens\ue9e am\ue9liorer les rendements en p\ue9riode de s\ue9cheresse. Il est n\ue9cessaire de d\ue9ployer la s\ue9lection assist\ue9e par marqueurs dans les caract\ue8res difficiles \ue0 s\ue9lectionner ph\ue9notypiquement

Mapping chromosomal regions associated with anther indehiscence with exerted stigmas in CRI-48 and Jasmine 85 cross of rice (Oryza sativa L)

Anther indehiscence in certain wide crosses combines male sterility with stigma exertion, a phenomenon that is desirable for hybrid rice seed production. This study sought to identify chromosomal region(s) that combine anther indehiscence with exerted stigmas. A mapping population consisting of 189 BC1F1 plants was derived from a cross between CRI-48 and Jasmine 85 and backcrossing the resulting F1 to Jasmine 85. Contrary to the three complementary genes mode of inheritance reported earlier, a single locus (AI6-1) was mapped on chromosome 6 at 27.4 cM for anther indehiscence with exerted stigmas through a mixed model-based composite interval mapping (MCIM). This locus was flanked by two single nucleotide polymorphism (SNP) markers, K_ID6002884 and K_ID6003341 within a range of 23.1–28.9 cM. The allele at the locus was contributed by the CRI-48 parent which has Oryza glaberrima ancestry. This locus is suggested to control anther indehiscence and stigma exertion through pleiotropic gene action or cluster of genes

Exploring genetic variability, heritability, and trait correlations in gari and eba quality from diverse cassava varieties in Nigeria.

Open Access ArticleBACKGROUND Gari (especially in Nigeria) is an important West African food product made from cassava. It is an affordable, precooked, dry, easy to prepare and store food product. Eba is a stiff dough produced by reconstituting gari in hot water. Gari and eba quality is an important driver of varietal acceptance by farmers, processors, and consumers. RESULTS This study characterized the genetic variability, heritability, and correlations among quality-related traits of fresh roots, gari, and eba. Thirty-three diverse genotypes, including landraces and released and advanced breeding genotypes, were used in this study. In total, 40 traits categorized into fresh root quality, colour, functional, and texture properties trait groups were assessed. We observed broad phenotypic variability among the genotypes used in this study. Dry matter content had a positive (P < 0.05) correlation with gari%, bulk density and a negative correlation with eba hardness and gumminess. Broad-sense heritability across all environments varied considerably among the different trait groups: 62% to 79% for fresh root quality, 0% to 96% for colour, 0% to 79% for functional and 0% to 57% for texture properties. CONCLUSIONS The stable broad-sense heritability found for gari%, gari and eba colour, bulk density, swelling index, and hardness measured using instrumental texture profile analysis coupled with sufficient variability in the population indicate good potential for genetic improvement of these traits through recurrent selection. Also, it is possible to genetically improve gari%, bulk density, and swelling power by simultaneously improving the dry matter content of fresh roots

Participatory rural appraisal of the impact of drought and farmers’ preferences for cowpea [Vigna unguiculata (L.) walp] in Kano State, Nigeria

Drought is the most important constraint threatening food security in the world because change in temperature and rainfall has drastic effect on agricultural productivity. A more sustainable approach to improving farmers’ adoption of new crop varieties and new technologies is to include farmers in the developmental processes. This study aimed at analyzing the impact of drought on cowpea production, control strategies and to identify farmers’ preferred traits of breeding priorities of cowpea. A participatory rural appraisal (PRA) was conducted in cowpea growing regions of four local government areas of Kano State, Nigeria with total of 150 individuals for semi-structured survey and 80 individuals for focus group discussion (FGD). Results of this study indicate that 80% of cowpea farmers interviewed had experienced drought stress during growing season and that about 75% of the grain yield were lost whenever drought stress occurred during the growing season. About 55% of the respondents use irrigation as a control strategy, 93% manipulate planting and harvesting times and 95% planted improved cowpea varieties. Grain yield reduction between 51% and 75% was recorded by the farmers in the event of drought corresponding to reduction in the realizable income. Drought, pests and diseases and non-availability of drought tolerant varieties were major constraints to production. Quality traits such as large seeds and short cooking time were equally preferred as drought and pest tolerance when choosing cowpea varieties. These findings are relevant in breeding for drought tolerant varieties which combine farmers’ preferences for choosing new varieties. Keywords: Cowpea production, drought tolerance, preferred traits, PRA, and sustainabilit

Subcellular location and expression of tobacco Necrosis necrovirus p7a protein

A putative movement protein (p7a) of tobacco necrosis Necrovirus, strain D (TNV-D), produced in Escherichia coli using an expression vector, was used to raise an antiserum. Immunoblot analysis using this antiserum showed that the p7a protein was detectable only in the combined cell wall and cell membrane fraction prepared from TNV-D infected Phaseolus vulgaris leaves. The p7a protein was detectable 1 day after inoculation and reached a maximum 3 days later, before declining, whereas coat protein was not detectable until 3 days after inoculation and continued to increase in concentration for a further 2 days before declining. Differences in the detectable amounts of both proteins may reflect their differential stability in extracts from necrotic tissue and/or the transient expression of the putative movement protein early in the replication cycle of TNV-D.Peer reviewe

The tobacco necrosis virus p7a protein is a nucleic acid-binding protein

The two centrally located open reading frames (ORFs) of necroviruses may, by analogy with the similarly located and related ORFs of carmoviruses, be expected to have a function in virus movement in plants. In the case of tobacco necrosis virus (TNV) strain D these proteins both have a molecular mass of approximately 7 kDa and are thus known as p7a and p7b. We over-expressed p7a in Escherichia coli, separated it from bacterial proteins and renatured it on gels, and showed that p7a was able to bind single-stranded RNA and single-stranded DNA, but was unable to bind double-stranded DNA. These protein-nucleic acid complexes were stable at moderately high salt concentrations. Protein p7b could not be expressed in a number of bacterial systems. We speculate that in TNV, unlike some other viruses which encode a single movement protein with separate functional domains for RNA binding and plasmodesmatal targeting, p7a and p7b may respectively provide these functions on separate proteins.Peer reviewe