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

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.

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

1998 ◽  
Vol 88 (9) ◽  
pp. 972-982 ◽  
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.

scholarly journals Evaluation efficiency of severity of angular leaf spot in common bean based on diseased and healthy leaf area

2013 ◽  
Vol 13 (3) ◽  
pp. 178-185
Author(s):  
Rafael Augusto da Costa Parrella ◽  
João Bosco dos Santos ◽  
Nádia Nardely Lacerda Durães Parrella ◽  
Diego Velásquez Faleiro e Silva
Keyword(s):  
Common Bean ◽  
Leaf Area ◽  
Leaf Spot ◽  
Chemical Control ◽  
Angular Leaf Spot ◽  
Diseased Leaf ◽  
Healthy Leaf ◽  
Progress Curve ◽  
Diseased Leaf Area ◽  
Dry And Rainy Seasons

This study compared severity of angular leaf spot in common bean lines, based on the healthy and diseased leaf area, and the graded scale. We used 12 common bean lines in the dry and rainy seasons. Two contiguous experiments were conducted in each season, with and without chemical control of the pathogen. We evaluated the percentage of the healthy and diseased leaf area; severity based on a graded scale and the area under the disease progress curve; and yield. The diseased or healthy leaf area is efficient to evaluate the severity of angular leaf spot with a sample of 20 to 30 leaflets per plot. For all traits, the results of central and border areas did not differ, indicating that the evaluation of border rows is unnecessary and, finally, the severity assessment of the upper plant half can discriminate the lines more efficiently.

scholarly journals The Influence of Silicon on Components of Resistance to Blast in Susceptible, Partially Resistant, and Resistant Cultivars of Rice

2001 ◽  
Vol 91 (1) ◽  
pp. 63-69 ◽  
Author(s):  
K. W. Seebold ◽  
T. A. Kucharek ◽  
L. E. Datnoff ◽  
F. J. Correa-Victoria ◽  
M. A. Marchetti
Keyword(s):  
Leaf Area ◽  
Incubation Period ◽  
Calcium Silicate ◽  
Magnaporthe Grisea ◽  
Upland Rice ◽  
Lesion Size ◽  
Diseased Leaf ◽  
Infection Efficiency ◽  
Components Of Resistance ◽  
Diseased Leaf Area

The application of silicon (Si) fertilizers reduces the severity of blast, caused by Magnaporthe grisea, in irrigated and upland rice; however, little research has been conducted to examine the epidemiological and etiological components of this reduction. Four cultivars of rice with differential susceptibilities to race IB-49 of M. grisea were fertilized with three rates of a calcium silicate fertilizer and inoculated with the pathogen to test the effects of Si on the following components of resistance to blast: incubation period, latent period, infection efficiency, lesion size, rate of lesion expansion, sporulation per lesion, and diseased leaf area. For each cultivar, the incubation period was lengthened by increased rates of Si, and the numbers of sporulating lesions, lesion size, rate of lesion expansion, diseased leaf area, and number of spores per lesion were reduced. Lesion size and sporulation per lesion were lowered by 30 to 45%, and the number of sporulating lesions per leaf and diseased leaf area were significantly reduced at the highest rate of Si. The net effect of Si on these components of resistance is an overall reduction in the production of conidia on plants infected with M. grisea, thereby slowing the epidemic rate of blast.

scholarly journals Severity of leaf diseases in maize inbred lines with different kernel hardness in two sowing seasons

2018 ◽  
Vol 39 (1) ◽  
pp. 29
Author(s):  
Cecília Aparecida Spada ◽  
Marcos Ventura Faria ◽  
Marcelo Cruz Mendes ◽  
Welton Luiz Zaluski ◽  
Emanuel Gava ◽  
...  
Keyword(s):  
Leaf Spot ◽  
Inbred Lines ◽  
Gray Leaf Spot ◽  
Leaf Blight ◽  
Kernel Hardness ◽  
Northern Leaf Blight ◽  
Maize Inbred Lines ◽  
Progress Curve ◽  
White Leaf ◽  
Cercospora Zeae Maydis

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.

scholarly journals The Pi40 Gene for Durable Resistance to Rice Blast and Molecular Analysis of Pi40-Advanced Backcross Breeding Lines

2009 ◽  
Vol 99 (3) ◽  
pp. 243-250 ◽  
Author(s):  
J. P. Suh ◽  
J. H. Roh ◽  
Y. C. Cho ◽  
S. S. Han ◽  
Y. G. Kim ◽  
...  
Keyword(s):  
Leaf Area ◽  
Resistance Genes ◽  
Rice Blast ◽  
Blast Resistance ◽  
Recurrent Parent ◽  
Diseased Leaf ◽  
Breeding Lines ◽  
Advanced Backcross ◽  
Diseased Leaf Area ◽  
Backcross Breeding

Rice blast severely reduces production in both irrigated and water-stressed upland ecosystems of tropical and temperate countries. Nearly 50 blast resistance genes have been identified and some of those are incorporated into several rice cultivars. However, most of the resistance genes break down in a few years because of their race specificity and the rapid change in pathogenicity of the blast fungus (Magnaporthe grisea). The objective of this study was to analyze advanced backcross breeding lines (ABL) possessing the gene Pi40 for durable rice blast resistance. In all, 4 resistant genotypes, 4 japonica cultivars, and 10 monogenic differential rice genotypes with some known resistance genes were bioassayed in the greenhouse using seven sequential plantings and 29 virulent M. grisea isolates of Korea. The genotypes with the Pi40 gene had <3% diseased leaf area, which was significantly below the disease threshold level of 40% considered for durable blast resistance. Moreover, the genotypes with the Pi40 gene expressed compatibility with only two to three virulent M. grisea isolates supporting durability of resistance, in contrast to susceptible cultivars with >50% diseased leaf area and 10 compatible isolates. Of the 10 known resistance genes tested, Piz-t, Piz-5, and Pi9 showed differential reactions to the pathogen isolates in seven plantings. Genotyping of the ABL with 260 simple sequence repeat (SSR) markers revealed rapid conversion toward recurrent parent genotypes with fewer donor chromosomal segments (5.3 to 14.5%). Our study based on a sequential testing and background selection of breeding lines with the resistance gene Pi40 provided valuable information for durable blast resistance breeding in rice.

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

2018 ◽  
Vol 18 (2) ◽  
pp. 148-154 ◽  
Author(s):  
Belisa Cristina Saito ◽  
Leonardo Queiroz Silva ◽  
João Antonio da Costa Andrade ◽  
Major M Goodman
Keyword(s):  
Leaf Spot ◽  
Inbred Lines ◽  
Gray Leaf Spot ◽  
Leaf Blight ◽  
Northern Leaf Blight ◽  
Corn Inbred

scholarly journals Distinct Mechanisms Govern the Dosage-Dependent and Developmentally Regulated Resistance Conferred by the Maize Hm2 Gene

2008 ◽  
Vol 21 (1) ◽  
pp. 79-86 ◽  
Author(s):  
Satya Chintamanani ◽  
Dilbag S. Multani ◽  
Holly Ruess ◽  
Gurmukh S. Johal
Keyword(s):  
Disease Resistance ◽  
Resistance Gene ◽  
Plant Development ◽  
Leaf Spot ◽  
Disease Resistance Gene ◽  
Developmentally Regulated ◽  
Cochliobolus Carbonum ◽  
Resistance Phenotype ◽  
Race 1 ◽  
Over Time

The maize Hm2 gene provides protection against the leaf spot and ear mold disease caused by Cochliobolus carbonum race 1 (CCR1). In this regard, it is similar to Hm1, the better-known disease resistance gene of the maize–CCR1 pathosystem. However, in contrast to Hm1, which provides completely dominant resistance at all stages of plant development, Hm2-conferred resistance is only partially dominant and becomes fully effective only at maturity. To investigate why Hm2 behaves in this manner, we cloned it on the basis of its homology to Hm1. As expected, Hm2 is a duplicate of Hm1, although the protein it encodes is grossly truncated compared with HM1. The efficacy of Hm2 in conferring resistance improves gradually over time, changing from having little or no impact in seedling tissues to providing complete immunity at anthesis. The developmentally specified phenotype of Hm2 is not dictated transcriptionally, because the expression level of the gene, whether occurring constitutively or undergoing substantial and transient induction in response to infection, does not change with plant age. In contrast, however, the Hm2 transcript is much more abundant in plants homozygous for this gene compared with plants that contain only one copy of the gene, suggesting a transcriptional basis for the dosage-dependent nature of Hm2. Thus, different mechanisms seem to underlie the developmentally programmed versus the partially dominant resistance phenotype of Hm2.

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