Inheritance of resistance against northern leaf blight of maize using conventional breeding methods

Abstract

Maize (Zea mays L.) is one of the important cereal crops along with wheat and rice worldwide. The purpose of this study was to use classical genetic approaches to assess the resistance of various maize parents and hybrids to the northern corn leaf blight (NCLB) disease in two different locations in Egypt. Eight parents, 28 F1, and 2 check hybrids were evaluated. The analysis of variance showed high significant variations between maize parents and their hybrids for the studied parameters and NCLB disease, besides there are significant variations between both locations. Results of maize parents showed that Sids 63, Giza 602, and Giza 628 cultivars exhibited the highest values and were resistant to NCLB in both locations comparing with Nubaria 39 and Gemmiza 18 that were susceptible to NCLB disease. Concerning the maize hybrids, analysis of variance and mean squares of growth characters in both locations indicated high significant variations between the maize hybrids including the check hybrids. When combined between the two locations for current parameters against NCLB, the data pointed that the Sakha location values for maize hybrids were much closed to the combining data in parents and the hybrids detected high resistance to this disease comparing with Nubaria location. All tested maize lines (38 lines), including parents and hybrids were classified as follows, two lines were rated as 1 (highly resistant), three were rated as 2 (resistant), sixteen were rated as 3 (moderate resistant), eight were rated 4 (moderately susceptible) and nine were rated 5 (susceptible). The data explaining that the crossing between high resistant maize cultivars produced high levels of resistance to NCLB disease. Therefore, our results verified that classical breeding could efficiently increase the resistance levels of maize germplasm against NCLB disease by developing new cultivars with superior performance in terms of grain yield, disease resistance and grain quality.

Keywords: Breeding; Growth characters; Hybrid; Maize; Northern leaf blight disease.

Fig. 1

Different northern leaf blight disease symptoms which detected in this current study, (1–4) healthy or control plants and (5–16) infected plants.

Fig. 2

Cluster analysis for maize hybrids showed the different levels of resistance against northern leaf blight disease based on morphological characters and resistant parents.

Fig. 3

Heat map representing the different categories of maize parents and their hybrids to different levels of resistance against northern leaf blight disease based on morphological characters. The color scale at the left of the heat map represents the expression level (parents group compared with their hybrids and two cheek lines groups), where the colors light green (highly resistant and resistant), dark green (Moderately resistant), black (Moderately susceptible), red (Susceptible) indicate upregulated, down-regulated and unaltered expression, respectively.