Adaptability and stability of corn inbred lines regarding resistance to gray leaf spot and northern leaf blight

Resistance of maize inbred lines to major leaf diseases should be characterized for the development of new hybrids in breeding programs. Thus, this study aimed to assess the severity of leaf diseases in maize inbredlines with different kernel hardnessand two sowingseasons. We assessed four inbred lines and one check hybrid with dent kernels and four inbred lines and a check hybrid with flint kernels. Treatments were conducted in two sowing seasons, one in October, and another in December 2013. The symptoms of gray leaf spot (Cercospora zeae-maydis), northern leaf blight (Exserohilum turcicum), and white leaf spot (a complex of Phaeosphaeria maydis and Pantoea ananatis) were assessed every 10 days from flowering. The area under the disease progress curve was also calculated. Severity level of the diseases was higher in inbred lines when compared to the check hybrds (AG8041 PRO and P30R50YH), regardless of kernel hardness. Dent-kernel inbred lines showed a higher severity of northern leaf blight symptoms when compared to flint-kernelones. It is worth mentioning that disease severity increased as sowing was delayed.

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Identification and characterization of maize lines resistant to leaf diseases

Semina Ciências Agrárias ◽

10.5433/1679-0359.2019v40n2p517 ◽

2019 ◽

Vol 40 (2) ◽

pp. 517

Author(s):

Kaian Albino Corazza Kaefer ◽

Adilson Ricken Schuelter ◽

Ivan Schuster ◽

Jonatas Marcolin ◽

Eliane Cristina Gruszka Vendruscolo

Keyword(s):

Genetic Diversity ◽

Leaf Spot ◽

Block Design ◽

Snp Markers ◽

Gray Leaf Spot ◽

Leaf Blight ◽

Yield Reduction ◽

Northern Leaf Blight ◽

Sources Of Resistance ◽

White Leaf

Among the maize leaf diseases, white leaf spot, northern leaf blight, gray leaf spot, and southern rust are recognized not only by the potential for grain yield reduction but also by the widespread occurrence in the producing regions of Brazil and the world. The aim of this study was to characterize common maize lines for resistance to white leaf spot, northern leaf blight, gray leaf spot, and southern rust and suggest crosses based on the genetic diversity detected in SNP markers. The experiment was conducted in a randomized block design with three replications in order to characterize 72 maize lines. Genotypic values were predicted using the REML/BLUP procedure. These 72 lines were genotyped with SNP markers using the 650K platform (Affymetrix®) for the assessment of the genetic diversity. Genetic diversity was quantified using the Tocher and UPGMA methods. The existence of genetic variability for disease resistance was detected among maize lines, which made possible to classify them into three large groups (I, II, and III). The maize lines CD 49 and CD50 showed a good performance and can be considered sources of resistance to diseases. Therefore, their use as gene donors in maize breeding programs is recommended. Considering the information of genetic distance together with high heritability for leaf diseases, backcrossing of parent genotypes with different resistance levels, such as those of the lines CD49 x CD69 and CD50 x CD16, may result in new gene combinations, as they are divergent and meet good performances.

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Field Characterization of Partial Resistance to Gray Leaf Spot in Elite Maize Germplasm

Phytopathology ◽

10.1094/phyto-12-19-0446-r ◽

2020 ◽

Vol 110 (10) ◽

pp. 1668-1679

Author(s):

James O. Nyanapah ◽

Patrick O. Ayiecho ◽

Julius O. Nyabundi ◽

Washington Otieno ◽

Peter S. Ojiambo

Keyword(s):

Disease Resistance ◽

Leaf Area ◽

Plant Development ◽

Leaf Spot ◽

Partial Resistance ◽

Inflection Point ◽

Inbred Lines ◽

Gray Leaf Spot ◽

Diseased Leaf ◽

Diseased Leaf Area

Forty-eight inbred lines of maize with varying levels of resistance to gray leaf spot (GLS) were artificially inoculated with Cercospora zeina and evaluated to characterize partial disease resistance in maize under field conditions from 2012 to 2014 across 12 environments in western Kenya. Eight measures of disease epidemic—that is, final percent diseased leaf area (FPDLA), standardized area under the disease progress curve (SAUDPC), weighted mean absolute rate of disease increase (ρ), disease severity scale (CDSG), percent diseased leaf area at the inflection point (PDLAIP), SAUDPC at the inflection point (SAUDPCIP), time from inoculation to transition of disease progress from the increasing to the decreasing phase of epidemic increase (TIP), and latent period (LP)—were examined. Inbred lines significantly (P < 0.05) affected all measures of disease epidemic except ρ. However, the proportion of the variation attributed to the analysis of variance model was most strongly associated with SAUDPC (R2 = 89.4%). Inbred lines were also most consistently ranked for disease resistance based on SAUDPC. Although SAUDPC was deemed the most useful variable for quantifying partial resistance in the test genotypes, the proportion of the variation in SAUDPC in each plot was most strongly (R2 = 93.9%) explained by disease ratings taken between the VT and R4 stages of plant development. Individual disease ratings at the R4 stage of plant development were nearly as effective as SAUDPC in discerning the differential reaction of test genotypes. Thus, GLS rankings of inbred lines based on disease ratings at these plant developmental stages should be useful in prebreeding nurseries and preliminary evaluation trials involving large germplasm populations.

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CO475 corn inbred line

Canadian Journal of Plant Science ◽

10.1139/cjps-2020-0057 ◽

2020 ◽

Author(s):

Aida Kebede ◽

Lana M Reid ◽

Constantin Voloaca ◽

Ron De Schiffart ◽

Jinhe Wu ◽

...

Keyword(s):

Inbred Line ◽

Leaf Blight ◽

Ear Rot ◽

Northern Leaf Blight ◽

Gibberella Ear Rot ◽

Days To Flowering ◽

Stalk Rot ◽

Intermediate Response ◽

Corn Inbred ◽

Moderate Resistance

CO475 is an early-medium maturity (75 days to flowering) mostly Iodent yellow semi-dent inbred which combines well with several testers in many different locations. It has moderate resistance to gibberella ear rot (both the inbred and in hybrid combinations) and intermediate response to smut, fusarium stalk rot, northern leaf blight, eyespot, rust, and goss’s wilt.

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Inheritance of Resistance to Gray Leaf Spot in Crosses Involving Selected Resistant Inbred Lines of Corn

Phytopathology ◽

10.1094/phyto.1998.88.9.972 ◽

1998 ◽

Vol 88 (9) ◽

pp. 972-982 ◽

Cited By ~ 21

Author(s):

S. T. Coates ◽

D. G. White

Keyword(s):

Leaf Area ◽

Leaf Spot ◽

Inbred Lines ◽

Gray Leaf Spot ◽

Inheritance Of Resistance ◽

Generation Mean Analysis ◽

Susceptible Parent ◽

Dominance Model ◽

Resistant Parent ◽

Naturally Occurring

Three populations derived from crosses of selected resistant inbreds (061, B37HtN, and DS:74:1071) with susceptible inbred FR1141 and a population derived from a cross of B37 × B37HtN were evaluated for gray leaf spot severity in 1992 and 1993 at Urbana, IL, and Andrews, NC. Populations included the susceptible parent (P1), the resistant parent (P2), F1 and F2 generations, backcrosses BCP1 and BCP2, and, when space and seed were available, one or more of the F3, BCP1S1, and BCP2S1 generations. Plants at Urbana were inoculated, and naturally occurring disease was relied upon at Andrews. Individual plants were rated by visually estimating the percent leaf area blighted (necrotic). Generation mean analysis of data combined over years or locations indicated that a simple additive-dominance model was able to explain the inheritance of resistance for all populations. Dominance effects were detected in all population evaluated. For the FR1141 × 061 and FR1141 × B37HtN populations, dominance was significant at early ratings, but not at late ratings. Results from generation mean analysis for individual years, locations, and rating were variable.

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Disease Severity and Yield of Sweet Corn Hybrids with Resistance to Northern Leaf Blight

Plant Disease ◽

10.1094/pdis.1998.82.1.57 ◽

1998 ◽

Vol 82 (1) ◽

pp. 57-63 ◽

Cited By ~ 14

Author(s):

J. K. Pataky ◽

R. N. Raid ◽

L. J. du Toit ◽

T. J. Schueneman

Keyword(s):

Disease Severity ◽

Partial Resistance ◽

Yield Loss ◽

Sweet Corn ◽

Correlation Coefficients ◽

Inbred Lines ◽

Leaf Blight ◽

Northern Leaf Blight ◽

Corn Hybrids ◽

Highly Correlated

Reactions of supersweet (sh2) sweet corn to northern leaf blight (NLB) and associated yields were evaluated in Belle Glade, Florida and Urbana, Illinois in yield-loss trials, hybrid evaluations, and evaluations of breeding materials. Hybrids differed significantly for NLB in all trials. Severity of NLB ranged from 0 to 66% on 35 sh2 hybrids in yield-loss trials, and from 0 to 60% on 80 sh2 hybrids in hybrid evaluations. NLB ratings ranged from 1 to 9 (approximately 0 to 80% severity) on 375 hybrids and 186 inbred lines in evaluations of breeding materials. Various methods of rating NLB and ratings from multiple dates were highly correlated, with correlation coefficients ranging from 0.76 to 0.98. Yield, measured as weight of ears and number of marketable ears from inoculated plots as a percentage of that from control plots, decreased as disease severity increased. Linear or quadratic regression models explained 31 to 70% of the variation in percent yield as a function of disease severity at harvest. The effects of NLB on yield were limited by NLB-resistance in several hybrids, including CCO 3268, Chieftain, Crisp N Sweet 710A, Day Star, Envy, Forever, GSS 1526, Jupiter, Midship, Prime Plus, Sch 5005, and SummerSweet 7630. Although high levels of partial resistance to NLB were prevalent among 375 new experimental sh2 hybrids and 186 sh2 inbred lines evaluated in 1995, use of the gene HtN may increase in the near future as breeders are incorporating this resistance into new inbreds and hybrids. Breeders and plant pathologists would be wise to continue improving partial resistance to NLB without using the gene HtN in genotypes with adequate levels of partial resistance, because the widespread use of the gene HtN will select for virulent races of Exserohilum turcicum which occur in Florida, or for races with new combinations of virulence.

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SWEET CORN INBREDS WITH PARTIAL RESISTANCE TO NORTHERN LEAF BLIGHT AND STEWART'S WILT

HortScience ◽

10.21273/hortsci.25.9.1067a ◽

1990 ◽

Vol 25 (9) ◽

pp. 1067a-1067 ◽

Cited By ~ 1

Author(s):

A. C. Meyer ◽

J. K Pataky ◽

J.A. Juvik

Keyword(s):

Partial Resistance ◽

Sweet Corn ◽

Leaf Blight ◽

Exserohilum Turcicum ◽

Northern Leaf Blight ◽

Dent Corn ◽

Erwinia Stewartii ◽

Stewart's Wilt ◽

Corn Inbred ◽

Moderately Resistant

Approximately 200 sweet corn inbred lines were screened for two years for resistance to northern leaf blight, caused by Exserohilum turcicum, and Stewart's wilt, caused by Erwinia stewartii. Inbreds with the best levels of partial resistance to races 1 and 2 of E. turcicum included IL11d, IL676a, IL677a, IL685d, IL766a, IL767a and IL797a. Inbreds with the best partial resistance to E. stewartii included IL126b, IL676a, IL767a, IL772a, IL774g, IL797a, IL798a and M6011. Several of these resistant and moderately resistant inbreds had common ancestors; however, inspection of pedigrees suggested that resistance was derived from Puerto Rican, Bolivian, and other tropical sources and/or dent corn. Thus, many of the sweet corn inbreds may carry different genes for resistance and can be used for the development of populations with improved resistance.

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Benefits of maize resistance breeding and chemical control against northern leaf blight in smallholder farms in South Africa

South African Journal of Science ◽

10.17159/sajs.2020/8286 ◽

2020 ◽

Vol 116 (11/12) ◽

Author(s):

Dave K. Berger ◽

Tumisang Mokgobu ◽

Katrien de Ridder ◽

Nanette Christie ◽

Theresa A.S. Aveling

Keyword(s):

South Africa ◽

Disease Resistance ◽

Leaf Spot ◽

Smallholder Farmers ◽

Resistance Breeding ◽

Leaf Blight ◽

Northern Leaf Blight ◽

Maize Hybrids ◽

Kwazulu Natal ◽

Disease Resistance Breeding

Maize underpins food security in South Africa. An annual production of more than 10 million tons is a combination of the output of large-scale commercial farms plus an estimated 250 000 ha cultivated by smallholder farmers. Maize leaves are a rich source of nutrients for fungal pathogens. Farmers must limit leaf blighting by fungi to prevent sugars captured by photosynthesis being ‘stolen’ instead of filling the grain. This study aimed to fill the knowledge gap on the prevalence and impact of fungal foliar diseases in local smallholder maize fields. A survey with 1124 plant observations from diverse maize hybrids was conducted over three seasons from 2015 to 2017 in five farming communities in KwaZulu-Natal Province (Hlanganani, Ntabamhlophe, KwaNxamalala) and Eastern Cape Province (Bizana, Tabankulu). Northern leaf blight (NLB), common rust, Phaeosphaeria leaf spot, and grey leaf spot had overall disease incidences of 75%, 77%, 68% and 56%, respectively, indicating high disease pressure in smallholder farming environments. NLB had the highest disease severity (LSD test, p<0.05). A yield trial focused on NLB in KwaZulu-Natal showed that this disease reduced yields in the three most susceptible maize hybrids by 36%, 71% and 72%, respectively. Eighteen other hybrids in this trial did not show significant yield reductions due to NLB, which illustrates the progress made by local maize breeders in disease resistance breeding. This work highlights the risk to smallholder farmers of planting disease-susceptible varieties, and makes recommendations on how to exploit the advances of hybrid maize disease resistance breeding to develop farmer-preferred varieties for smallholder production.

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Combining ability and GGE biplot analyses for resistance to northern leaf blight in tropical and subtropical elite maize inbred lines

Euphytica ◽

10.1007/s10681-012-0806-x ◽

2012 ◽

Vol 191 (2) ◽

pp. 245-257 ◽

Cited By ~ 10

Author(s):

Julia Sibiya ◽

Pangirayi Tongoona ◽

John Derera

Keyword(s):

Combining Ability ◽

Inbred Lines ◽

Leaf Blight ◽

Gge Biplot ◽

Northern Leaf Blight ◽

Maize Inbred Lines

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Increased Severity of Foliar Diseases of Sweet Corn Infected with Maize Dwarf Mosaic and Sugarcane Mosaic Viruses

Plant Disease ◽

10.1094/pdis-94-9-1093 ◽

2010 ◽

Vol 94 (9) ◽

pp. 1093-1099 ◽

Cited By ~ 11

Author(s):

M. D. Meyer ◽

J. K. Pataky

Keyword(s):

Virus Infection ◽

Mosaic Virus ◽

Leaf Spot ◽

Sweet Corn ◽

Viral Disease ◽

Gray Leaf Spot ◽

Leaf Blight ◽

Maize Dwarf Mosaic Virus ◽

Foliar Diseases ◽

Corn Leaf Blight

Maize dwarf mosaic (MDM), caused by Maize dwarf mosaic virus (MDMV) and Sugarcane mosaic virus (SCMV), is an economically important viral disease of sweet corn (Zea mays). MDM is known to increase the severity of fungal root rots and southern corn leaf blight (SCLB). The effect of infection with MDMV-A and SCMV on eight foliar diseases was evaluated on 32 sweet corn hybrids (27 MDM-susceptible hybrids and five MDM-resistant hybrids) in 2007, 2008, and 2009. Virus infection substantially increased the severity of five diseases, including: SCLB, northern corn leaf spot (NCLS), gray leaf spot (GLS), Diplodia leaf streak (DLS), and eyespot. Among MDM-susceptible hybrids, mean severity of SCLB, NCLS, GLS, DLS, and eyespot on virus-infected plants was typically double that of plants that were asymptomatic of viral infection. Three diseases were not substantially increased by MDM, including: common rust, northern corn leaf blight (NCLB), and Stewart's wilt. Virus infection appeared to affect the severity of diseases caused by necrotrophic foliar fungi that colonize mesophyll tissue. MDM did not appear to substantially affect the severity of diseases caused by pathogens that form haustoria or invade the vascular system. The extent to which SCLB severity is increased by MDM in terms of changes in level of host resistance also was determined. For MDM-susceptible hybrids, reactions to SCLB ranged from resistant to moderately susceptible in MDM-free treatments, but each of these hybrids was classified as moderately susceptible to susceptible when infected with MDMV-A and/or SCMV. The results of this experiment demonstrate the importance of breeding for MDM resistance, not only to control this important viral disease of sweet corn, but also to lower the potential for detrimental effects from several other foliar diseases that often are of minor importance on sweet corn in the absence of MDM.

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