Recurrent Selection for Resistance to Exserohilum turcicum in Eight Subtropical Maize Populations

Abstract

There are few reports on the progress achieved through recurrent selection for quantitative resistance to diseases in tropical or subtropical maize (Zea mays L.) populations. The objective of this study was to evaluate the progress achieved after four cycles of full‐sib S1 recurrent selection in eight subtropical populations from the International Maize and Wheat Improvement Center (CIMMYT). Selection was primarily for improving polygenic resistance to the northern corn leaf blight (NCLB) induced by Exserohilum turcicum (Pass.) Leonard & Suggs, and the common rust (Puccinia sorghi Schw.). Evaluations were made under three environments (high, medium, and no disease pressure) represented by two locations each. A very rapid increase in resistance was obtained for both diseases (19 and 6% cycle−1 for NCLB and rust, respectively) without changing the maturity of the populations or reducing grain yield potential as measured by planting under relatively disease‐free conditions. Under disease pressure, yield was found to be associated with resistance to NCLB (r = 0.52**; significant at P = 0.01), reduced stalk lodging (r = −0.51**), and greater number of ears per plant (r = 0.60**). Results suggest high heritability values for polygenic resistance to NCLB. It was also demonstrated that the full‐sib S1 recurrent selection methodology employed was highly effective in achieving the initial breeding objectives in all the populations involved.

Inheritance of Tolerance of Maize Inbreds to Exserohilum turcicum in North Korea

“…Under the quantitatively resistance model, recurrent selection would be the most appropriate breeding method for improving tolerance. Indeed, several studies have documented significant gains from recurrent selection for NCLB resistance (Brewbaker et al, 2011;Campaña and Pataky 2005;Carson 2006;Ceballos et al, 1991;Jenkins et al, 1954;Pataky 1994) with 15 to 20% reduction in susceptibility per generation (Campaña and Pataky 2005;Carson 2006;Ceballos et al, 1991).…”

Selection Mapping of Loci for Quantitative Disease Resistance in a Diverse Maize Population

“…Plant materials and DNA extractions: In this study we examined Pool 30, which was one of eight maize populations (referred to by CIMMYT as gene pools) improved by full-sib S 1 recurrent selection by Ceballos et al (1991). Each cycle of selection was composed of two generations: (1) in one environment individuals were selected from within families and full-sib mated to individuals selected from other families and (2) in a second environment individuals were selected from within full-sib families (produced in step 1) and selfed to produce S 1 families (Figure 1).…”

“…This pattern was consistent with the hypothesis that a large number of loci contribute to NLB resistance. On the other hand, several studies using recurrent selection to increase NLB resistance have documented strong selection responses, with $15-20% reduction in susceptibility per generation (Ceballos et al 1991;Campaña and Pataky 2005;Carson 2006), which has been interpreted as indicative of an oligogenic mode of inheritance (Ceballos et al 1991). We hypothesized that SM could reveal the loci that account for the strong selection response and allow the discovery of superior alleles at these loci.…”

“…It is an endemic disease in the United States, and a resurgence in incidence has been noted over recent years (G. Bergstrom, personal communication). Well-documented maize populations that had undergone recurrent selection for NLB were available from the International Center for Maize and Wheat Improvement (CIMMYT) (Ceballos et al 1991). Because the founder populations used for selection were reported to be highly diverse and showed strong phenotypic responses to selection (Ceballos et al 1991), we hypothesized that the materials would be suitable for SM.…”

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

“…On-going efforts to breed for resistance in sub-Saharan Africa primarily have been undertaken by national programs, private sector, and international agricultural research centers. Maize breeding programs at the International Institute for Tropical Agriculture (IITA) and the Centro Internacional de Mehoriamento de Mais y Trigo (CIMMYT, the International Center for the Improvement of Maize and Wheat) have resulted in the improvement of numerous populations and inbred lines (Kim et al, 1989;Ceballos et al, 1991). Much progress has been made in the development of genetic resistance for many maize diseases: however, large areas are still planted with farmers' varieties that lack resistance to economic pathogens (Paliwal, 2000;Renfro, 1985).…”