QTL mapping for Mediterranean corn borer resistance in European flint germplasm using recombinant inbred lines

<p>Abstract</p> <p>Background</p> <p><it>Ostrinia nubilalis </it>(ECB) and <it>Sesamia nonagrioides </it>(MCB) are two maize stem borers which cause important losses in temperate maize production, but QTL analyses for corn borer resistance were mostly restricted to ECB resistance and maize materials genetically related (mapping populations derived from B73). Therefore, the objective of this work was to identify and characterize QTLs for MCB resistance and agronomic traits in a RILs population derived from European flint inbreds.</p> <p>Results</p> <p>Three QTLs were detected for stalk tunnel length at bins 1.02, 3.05 and 8.05 which explained 7.5% of the RILs genotypic variance. The QTL at bin 3.05 was co-located to a QTL related to plant height and grain humidity and the QTL at bin 8.05 was located near a QTL related to yield.</p> <p>Conclusions</p> <p>Our results, when compared with results from other authors, suggest the presence of genes involved in cell wall biosynthesis or fortification with effects on resistance to different corn borer species and digestibility for dairy cattle. Particularly, we proposed five candidate genes related to cell wall characteristics which could explain the QTL for stalk tunnelling in the region 3.05. However, the small proportion of genotypic variance explained by the QTLs suggest that there are also many other genes of small effect regulating MCB resistance and we conclude that MAS seems not promising for this trait. Two QTLs detected for stalk tunnelling overlap with QTLs for agronomic traits, indicating the presence of pleitropism or linkage between genes affecting resistance and agronomic traits.</p

Genetic variation and quantitative trait loci associated with developmental stability and the environmental correlation between traits in maize

11 páginas, 4 figuras, 5 tablas.There is limited experimental information about the genetic basis of micro-environmental variance (VE) (developmental stability) and environmental correlations. This study, by using a population of maize recombinant inbred lines (RIL) and simple sequence repeat (SSR) polymorphic markers, aims at the following: firstly, to quantify the genetic component of the VE or developmental stability for four traits in maize and the environmental correlation between these traits, and secondly, to identify quantitative trait loci (QTLs) that influence these quantities. We found that, when estimating variances and correlations and testing their homogeneity, estimates and tests are needed that are not highly dependent on normality assumptions. There was significant variation among the RILs in VE and in the environmental correlation for some of the traits, implying genetic heterogeneity in the VE and environmental correlations. The genetic coefficient of variation of the environmental variance (GCVVE) was estimated to be 20%, which is lower than estimates obtained for other species. A few genomic regions involved in the stability of one trait or two traits were detected, and these did not have an important influence on the mean of the trait. One region that could be associated with the environmental correlations between traits was also detected.The National Plan for Research and Development of Spain (project code AGL2006-13140) is acknowledged for financial support. B. Ordas acknowledges a contract from the Spanish National Research Council (I3P Program).Peer reviewe

Genetic diversity in Algerian maize (Zea mays L) landraces using SSR markers

In the Sahara, maize (Zea mays L) has been adapted to extreme environmental conditions during the last five centuries; therefore, this germplasm has a potential value as source of tolerance to stress. No previous report of the genetic diversity of Saharan maize has been published so far. The objective of this study was to determine the genetic diversity of a collection of Saharan maize. Fifteen accessions representing the geographic diversity of Algeria were characterized with 18 SSR. Most loci (93%) were polymorphic; the total amount of alleles was 87 and the average of alleles per locus was 5.8. The total genetic diversity (He) was 0.57, being 69% intra-accessions and 31% inter-accession. Eight of the alleles were accession-specific and belonged to six populations. Genetic distance among the 15 accessions resulted in the definition of three main clusters related to the geographic origin. Maize germplasm from the Algerian Sahara can be classified at least in three groups and the most variable acces¬sions are in the southern oasis. Some accessions were highly variable and can be sources of favorable alleles for breeding for tolerance to extreme stress conditions

Genetic diversity of the floury race of maize Avati Morotî from the Guaraní tribe in Paraguay

Avati Morotî is a race of floury maize widely used by the Guarani people in South America, whose variability and potential value for breeding has been neglected so far. The objective of this research was to explore the genetic variability within the main Paraguayan race Avati Morotî. We studied the genetic variability available in the 20 accessions of Paraguayan Avati Morotî included in the South American core collection made by CIMMYT. Thirty individuals per accession were genotyped with 30 SSR (simple sequence repeat); we determined genetic diversity and made a cluster analysis in order to define genetic relationships among accessions. Mean of polymorphic loci (0.96), alleles per locus (3.57), alleles per polymorphic locus (3.65), expected (0.48) and observed (0.43) heterozygosity, and coefficient of consanguinity (0.12) revealed that Avati Morotî contains a genetic diversity comparable to the most variable maize races of maize. The cluster analysis classified the 20 populations in eight groups, five of them with a single accession, and a large group representing a central pool of germplasm. These results indicate that there is a large variability available in this race, and encourage the collection of more samples of Avati Morotî, particularly in marginal areas that were scarcely sampled

Evaluación de la heterosis en dos poblaciones sintéticas de maíz después de tres ciclos de selección recurrente interpoblacional

Se muestra la respuesta de la heterosis entre dos poblaciones de maíz mejoradas por selección recurrente recíproca y tres líneas puras. Se evalúan rendimiento y encamado de planta, y los resultados avanzan en la propuesta de nuevos patrones heteróticos en maíz

Data from Mayer et.al 2017 TAG

This data package accompanies the following publication:<br><br>Mayer et al. 2017 (Theoretical and Applied Genetics)<br>Is there an optimum level of diversity in utilization of genetic resources?<div>doi:10.1007/s00122-017-2959-4<br><br>It contains a copy of the data files used in this paper as well as further accompanying files (see README.txt).<br></div

Additional file 2: Figure S1. of A comprehensive study of the genomic differentiation between temperate Dent and Flint maize

Metrics of the selection screens for 136 temperate inbred lines along the ten maize chromosomes based on genotyping data. (PDF 4242 kb

Additional file 7: Table S9. of A comprehensive study of the genomic differentiation between temperate Dent and Flint maize

Gene-wise level of differentiation of allele frequencies between landraces and Dent (left) and Flint (right) elite lines based on genotyping data. (XLSX 27 kb