Submitted to: Genome
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/4/1998
Publication Date: N/A
Citation: Interpretive Summary: Corn is an important staple food for large regions of sub-Saharan Africa. A major virus disease of corn in Africa, caused by maize streak virus, limits production and causes financial hardship for many marginal African farmers. In this paper, we report on the identification and genetic mapping of a major gene for resistance to maize streak virus. This is the first report of the genetic map position for any gene for resistance to maize streak virus. This single gene controls the majority of the resistance found in the maize streak resistant corn variety Tzi4. These results form the basis for using molecular methods to aid in converting susceptible African corn varieties to maize streak resistance.
Technical Abstract: Maize streak, incited by maize streak geminivirus (MSV), is a major disease limiting maize production over widespread areas of Africa. To understand the genetic basis of tolerance to MSV, recombinant inbred lines (RILs), derived from the cross of the MSV tolerant inbred Tzi4 with the MSV susceptible inbred Hi34, were evaluated for MSV tolerance. Experiments were conducted using controlled leafhopper infestation in one glasshouse experiment at Namulonge, Uganda, and two field experiments at CIMMYT, Harare, Zimbabwe. There was a significant association of MSV tolerance with RFLP markers on the short arm of chromosome 1. By single factor analysis of variance, the portion of the phenotypic variance explained by genotype class (R2) for the association between npi262 and the area under disease progress curve measure of MSV tolerance was as high as 76% in field experiments. Interval mapping analyses identified the chromosome 1 region bracketed by bnl12.06a and npi262 as explaining the largest proportion of the variation in MSV tolerance. After classification of symptom responses from the final field ratings into resistant and susceptible classes, qualitative analysis of data fit a chi- square test to the 1:1 Mendelian. Multipoint linkage analysis placed this gene, designated msv1, at a genetic distance of 3 cM distal to npi262. Identification of the tightly linked molecular marker locus npi262 should greatly aid ongoing conversion of susceptible African varieties to maize streak resistance.