Inheritance study and stable sources of maydis leaf blight(Cochliobolus heterostrophus)resistance in tropical maize germplasm

Abstract

Maydis leaf blight (MLB), a serious foliar fungal disease of maize, may cause up to 40% losses in yield. The present studies were undertaken to identify the stable sources of MLB resistance, its inheritance study, and testing of MLB resistance linked markers from diverse background in the Indian adapted tropical maize genotypes. A set of 112 inbred lines were screened under artificially created epiphytotics conditions at three hotspot locations. Analysis across multi-locations revealed significant effects of genotypes and environments, and non-significant effects due to genotypes × environment interaction on disease incidence. A total of 25 inbred lines with stable resistance were identified across multi-locations. Inheritance of resistance was studied in six F 1 s and two F 2 s of resistant and susceptible parents. The null hypothesis of segregation of resistance and susceptible for mono and digenic ratios in two F 2 populations was rejected by Chi-square test. The non-significant differences among the reciprocal crosses depicted the complete control of nuclear genome for MLB resistance. Partial dominance in F 1 s and normal distribution pattern in F 2 s of resistant and susceptible parents suggested polygenic nature of MLB resistance. Correlation studies in F 2 populations exhibited significant negative correlation between disease score and days to flowering. Five simple sequence repeats (SSRs) markers, found associated to MLB resistance in different studies were unable to differentiate amongst MLB resistance and susceptible parents in our study. This emphasizes the need of fine mapping for MLB resistance in Indian germplasm. The identified stable sources of resistance and information on inheritance study can be used further in strengthening of resistance breeding against MLB.

Gene effects from Bipolaris maydis incidence and severity on popcorn

“…Estimates of means of the squares from effects found SCA values to be higher than the GCA ones (Table 1); it indicated that the gene actions and genetic structure of the evaluated hybrids favored manifestation of non-additive gene effects. Studies indicate that genetic resistance to southern corn leaf blight in Corn is predominantly determined by additive effect genes (Kumar et al, 2016;Li et al, 2018). However, the existence of non-additive effects on B. maydis control has also been reported in the literature (Carson et al, 2004).…”

Evaluation of Maize Genotypes against Maydis Leaf Blight Caused by Bipolaris maydis (Nisikado and Miyake) Shoemaker under Artificial Epiphytotic Conditions

“…Seventeen newly developed QPM inbred lines were screened against maydis leaf blight and charcol rot by Kumar et al, (2013) Malik et al, 2015. Kumar et al, (2016 carried out inheritance study on 112 inbred maize lines and identified the stable source of MLB resistance, and MLB resistance linked markers from diverse background in the Indian adapted tropical maize genotypes.…”

A detached leaf assay to rapidly screen for resistance of maize to Bipolaris maydis, the causal agent of southern corn leaf blight

“…However, in tropical regions of SSA, maize production is frequently affected by southern corn leaf blight (SCLB), a foliar disease caused by the fungus Bipolaris maydis (Y. Nisik. and C. Miyake) Shoemaker (teleomorph: Cochliobolus heterostrophus Drechsler) (Kumar et al 2016). The disease can be catastrophic such as during the infamous 1970-1971 epidemic in the US caused by Race T (Bhandari et al 2017;Tatum 1971;Ullstrup 1972).…”