Mapping the distribution of maize streak virus genotypes across the forest and transition zones of Ghana

Abstract

Throughout sub-Saharan Africa, maize streak virus strain A (MSV-A), the causal agent of maize streak disease (MSD), is an important biological constraint on maize production. In November/December 2010, an MSD survey was carried out in the forest and transition zones of Ghana in order to obtain MSV-A virulence sources for the development of MSD-resistant maize genotypes with agronomic properties suitable for these regions. In 79 well-distributed maize fields, the mean MSD incidence was 18.544 % and the symptom severity score was 2.956 (1 = no symptoms and 5 = extremely severe). We detected no correlation between these two variables. Phylogenetic analysis of cloned MSV-A isolates that were fully sequenced from samples collected in 51 of these fields, together with those sampled from various other parts of Africa, indicated that all of the Ghanaian isolates occurred within a broader cluster of West African isolates, all belonging to the highly virulent MSV-A1 subtype. Besides being the first report of a systematic MSV survey in Ghana, this study is the first to characterize the full-genome sequences of Ghanaian MSV isolates. The 51 genome sequences determined here will additionally be a valuable resource for the rational selection of representative MSV-A variant panels for MSD resistance screening.

Incidence and severity of maize streak disease: The influence of tillage, fertilizer application and maize variety

“…The plants were also scored for disease severity based on a scale of 1 to 5 adopted from Bosque-Perez and Alam (1992) with a modification by Oppong et al (2014a, b) (Table 1).…”

“…Severe streaking on more than 75% leafarea, plants severely stunted or dead Very severe infection Source: Bosque-Perez et al (1992) and Oppong et al (2014a, b).…”

Combining ability of tropical early maize (Zea mays L.) inbred lines for grain yield and resistance to maize streak virus disease

“…An evaluation trial was carried out at Wenchi (7.7333N; 2.1W), Ghana from October, 2015 to January, 2016. Wenchi is known to be a hot spot for MSV-A1 strain, the most virulent strain of MSV especially in the minor season (Oppong et al, 2015 The evaluation site lies in the heart of the Transition zone of Ghana, characterized by two seasons of rainfall with the major season starting from March and ending in July while the minor season begins from September and ends in November or December. The soil is sandy loam The experimental field was sprayed with rid-out (glyphosate, 360 g/l) at 5.0 l/ha before ploughing and harrowing were done.…”

“…It is a major foliar disease that affects maize throughout the sub-Saharan Africa (Pingali and Pandey, 2001) and its prevalence on farmers" fields has been reported in several regions of Ghana (Oppong et al, 2015). Amongst the diseases that cause economic damage to maize in the world, MSVD ranks third following northern leaf blight and grey leaf spot, besides it has remained the most severe viral disease of maize in Africa resulting in the loss of returns, which ranges from US $ 120 to 480 million yearly (Martin and Shepherd, 2009).…”

“…Oppong et al (2015) reported that MSV-A1 variant was predominant in the transition and forest zones of Ghana, and it exhibits an increased level of pathogenicity than the other MSV-A variants which are MSV-A2, MSV-A3, MSV-A4 and MSV-A6 (Martin et al, 2001). The incidence and severity of MSVD can be reduced by chemical control of leafhoppers and cultural practices such as crop rotation, irrigation, inter-cropping, application of appropriate fertilizer rate and plant density manipulation but the most economically sustainable option is provided by using disease resistant varieties (Martin and Shepherd, 2009).…”