Inheritance of resistance to Mal de Río Cuarto (MRC) disease in Zea mays (L.)

Abstract

No genetic estimates for resistance to Mal de Rı! o Cuarto (MRC) disease in Zea mays (L.) are currently available in the literature. Therefore, the objectives of this investigation were (i) to estimate the variance and heritability of partial resistance to MRC disease and of other agronomic traits from maize families and (ii) to examine associations among MRC disease severity values across different environments and between MRC and other agronomic traits. These estimations, obtained in an endemic area, could contribute to the design of efficient enhancement programmes and evaluation activity for the improvement of MRC resistance. The research was conducted by testing 227 F $ derived-lines from a cross between a susceptible dent line, Mo17, and a partially resistant flint line, BLS14, for MRC disease at two Rı! o Cuarto locations in each of 2 years. The resistance of the lines, measured with a disease severity index (DSI), was normally distributed across environments. Genotypic variances were highly significant on all scoring environments. Estimates of genotypeenvironment interaction were also significant, suggesting that certain genotypes have little stability over different environments. For disease severity index all estimates demonstrated moderate heritabilities ranging from 0n44 to 0n56 and were similar when based on individual environments or across environment. Confidence interval widths ranged from 34n88 to 50n30 % as large as the heritability point estimate. The correlations between environments were small enough to indicate that families did not rank similarly in individual environments for MRC resistance. Disease severity index correlated significantly (P 0n01) with plant height, leaf surface, leaf border, leaf length and tassel type. Heritability estimates for plant height and tassel type were 0n48 and 0n38 respectively and for the various leaf traits heritability values were very low. On the basis of the substantial genotypeenvironment interaction and the little association between DSI values in the different environments, selection for an increased resistance to MRC disease would require evaluation of germplasm across multiple years and locations. Tassel type would be a useful predictor of DSI and can be used effectively to improve screening procedures.

Identification of significant single nucleotide polymorphisms for resistance to maize rough dwarf disease in elite maize (Zea mays L.) inbred lines

“…In the present study, the response to MRDD was extremely diverse in the studied population, and the heritability for MRDD resistance was moderately low (H 2 = 47.15 %), which was consistent with results obtained by Di Renzo et al (2002) and Shi et al (2012a). The inheritance of quantitative traits (known as having low heritability) classically involves multiple genes with a small effect that are sensitive to environmental changes (Xing and Zhang 2010).…”

Microsatellite markers linked to QTL for resistance to Mal de Río Cuarto disease in Zea mays L.

“…A disease severity index (DSI) was calculated for each plot (Grau et al 1982) and used for phenotyping F 3 derived-lines. The details of the field testing are described in Di Renzo et al (2002).…”

“…The heritability can be used as an upper limit for the amount of phenotypic variation (R 2 ) that can be explained in the QTL model (Knapp et al 1990). The heritability in disease severity index estimated across environments ranged from 44 to 56 % (Di Renzo et al 2002). The genetic variation explained by the model with two QTL (Q 2 ) calculated as Q 2 =R 2 /h 2 ranged from 82 to 65 %, respectively.…”

“…Genetic resistance, as a component of integrated management, remains the least expensive and environmentally most sustainable control strategy although it is likely that field resistance results from a combination of physiological resistance and escape mechanisms. No genetic estimates for resistance to MRC disease in maize are currently available in the literature although recent work showed that when disease is analysed in the field, MRC resistance proves to be a partially heritable trait (Di Renzo et al 2002). All estimates demonstrated moderate heritabilities (h 2 ) ranging from 0 .…”

Taking Advantage of Organelle Genomes in Plant Breeding: An Integrated Approach

“…Un panel de mapeo por asociación debe abarcar la máxima diversidad fenotípica y molecular que pueda ser estimada de manera confiable en un ambiente común (Flint-Garcia et al, 2005). El uso de germoplasma con caracteres favorables es el procedimiento más económico y ambientalmente sustentable para lograr incrementos y estabilidad en la producción de maíz (Di Renzo et al, 2002). En la práctica, los programas de mejoramiento de clima templado intercambian germoplasma con programas de mejoramiento subtropical o de mediana altitud (Wu et al, 2016).…”