Characterization of Southern African Isolates of Maize Streak Virus: Typing of Three Isolates by Restriction Mapping

Maize is an important food crop in Kenya and is susceptible to a wide range of diseases. A survey was conducted in 2012 in different agro-ecological zones (AEZ) of Kiambu, Embu and Nakuru counties to determine the distribution of northern leaf blight (NLB), common rust (CR), maize streak disease (MSD), gray leaf spot (GLS), head smut (HS) and common smut (CS). Data collected included prevalence, incidence and severity of each of the diseases. Maize leaf samples infected with MSD were also collected for molecular characterization of Maize streak virus (MSV). Northern leaf blight was reported in all counties surveyed with 100% disease prevalence. Kiambu had the highest incidence (100%) of CR whereas Embu had the highest prevalence (45%) of MSD. The incidences of GLS and HS were very low with averages of below 2.5%. The highest incidence of GLS was in Kiambu (5%). High altitude areas had higher incidences of NLB and GLS while CS and MSD were widespread in the three counties. Comparison of 797 nucleotides from the open reading frame (ORF) C2/C1 of MSV with other sequences from the GenBank showed sequence similarities of 99 to 100% with MSV-A strain. The study revealed that the major foliar diseases of maize are widespread in Kenya and therefore there is need to institute measures to manage these diseases and reduce associated losses. Also, the high percent sequence similarities of MSV indicate low variability which is good for breeders since developed resistant varieties can be adopted over a wider region.

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Biological and Genomic Sequence Characterization of Maize streak virus Isolates from Wheat

Phytopathology ◽

10.1094/phyto.2002.92.1.81 ◽

2002 ◽

Vol 92 (1) ◽

pp. 81-86 ◽

Cited By ~ 19

Author(s):

J. A. Willment ◽

D. P. Martin ◽

E. Van der Walt ◽

E. P. Rybicki

Keyword(s):

Genomic Sequence ◽

Phylogenetic Analyses ◽

Maize Streak Virus ◽

Streak Virus ◽

Genome Sequences ◽

Sequence Characterization ◽

Sequence Identity ◽

Maize Type ◽

Barley Genotypes

Maize streak virus (MSV) is best known as the causal agent of maize streak disease. However, only a genetically uniform subset of the viruses within this diverse species is actually capable of producing severe symptoms in maize. Whereas these “maize-type” viruses all share greater than 95% sequence identity, MSV strains isolated from grasses may share as little as 79% sequence identity with the maize-type viruses. Here, we present the complete genome sequences and biological characterization of two MSV isolates from wheat that share ≈89% sequence identity with the maize-type viruses. Clonal populations of these two isolates, named MSV-Tas and MSV-VW, were leafhopper-transmitted to Digitaria sanguinalis and a range of maize, wheat, and barley genotypes. Whereas the two viruses showed some differences in their pathogenicity in maize, they were both equally pathogenic in D. sanguinalis and the various wheat and barley genotypes tested. Phylogenetic analyses involving the genome sequences of MSV-Tas and MSV-VW, a new maize-type virus also fully sequenced in this study (MSV-VM), and all other available African streak virus sequences, indicated that MSV-Tas and MSV-VW are close relatives that together represent a distinct MSV strain. Sequence analyses revealed that MSV-VM has a recombinant genome containing MSV-Tas/VW-like sequences within its movement protein gene.

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