Development of streak virus‐resistant maize populations through improved challenge and selection methods

Abstract

SUMMARY Tolerance to maize streak virus (MSV) was found and rapidly incorporated into high yielding maize populations for the tropics. Methods were developed for vector propagation and rapid accurate screening of many accessions for virus tolerance in large screenhouses. Tolerance was found in only two accessions and at low frequencies. Further refinements enabled field evaluation for virus tolerance to be combined with high agronomic performance. The tolerance found is simply inherited and was fixed rapidly in breeding. Non‐strain specific tolerance was sought by collecting vectors and different indigenous host grasses from a wide area. The tolerance developed was sufficiently high hardly to affect yield of infected plants. It provided epidemiological or field resistance by reducing disease incidence to insignificance under natural conditions. This tolerance and field resistance has proved effective in several countries of East, West and southern Africa. Varieties derived from this work are now being promoted in Nigeria, and they have potential application elsewhere in the lowland tropics.

Combining ability of grain yield and agronomic traits in diverse maize lines with maize streak virus resistance for Eastern Africa region

“…The plants were inoculated at the 3-leaf stage in the field by attaching a small plastic vial with three viruliferous leafhoppers onto distal portions of the youngest leaf. A rating scale of 1 (no symptoms) to 5 (severe streaking with chlorosis) based on the protocol described by Soto et al (1982) was used. MSV severity was rated on plot basis using the 1-5 scale with half points as follows: 1= no symptom on leaves; 1.5= very few streaks on leaves; 2= light streak on old leaves, gradually decreasing on young leaves; 2.5= light streaking on old and young leaves; 3= moderate streaks on old and young leaves; 3.5= moderate streaks on old and young leaves and slight stunting; 4= severe streaking on 60% of leaf area, plants stunted; 4.5= severe streaking on 75% of leaf area, plants severely stunted and 5= severe streaking on 75% or more of the leaf area, plants severely stunted, dying or dead.…”

“…Many studies suggest that the obvious strategy to reduce maize yield losses caused by MSV would be to develop MSV resistant and/or tolerant cultivars (van Rensburg, 1981;Soto et al, 1982;Shoyinka, 1988). The development of maize germplasm that is resistant to MSV has therefore been the goal of several breeding programs in Africa.…”

Serotyping and Strain Identification of Maize Streak Virus Isolates

“…Maize streak virus (MSV) occurs naturally in many plants of the Gramineae throughout Africa (Storey & McClean, 1930;Rose, 1978), Mauritius (Ricaud & F61ix, 1978), R6union (Soto et al, 1982), Vanuatu (Dollet et al, 1986) and possibly India (Seth et al, 1972). The host range of MSV includes maize, other cereals and sugarcane making it an economically important pathogen (Damsteegt, 1983).…”

Use of IPM in the control of multiple diseases in maize: Strategies for selection of host resistance

“…The MSV resistance in inbred TZ-Y was considered to be simply inherited (Soto et al, 1982), but Kim et al (1989) reported that resistance in inbred IB32 (Ibadan 32 -developed from TZ-Y) was quantitatively inherited through additive action of up to several genes. More recent studies of genetic control of MSV resistance in population CVR3-C3 have shown that multiple genetic systems for resistance to MSV may indeed exist (Rodier et al, 1995).…”