Publications by authors named "Rosa Ana Malvar"

18 Publications

  • Page 1 of 1

Elucidating the multifunctional role of the cell wall components in the maize exploitation.

BMC Plant Biol 2021 Jun 2;21(1):251. Epub 2021 Jun 2.

Facultad, de Biología, Departamento de Biología Vegetal Y Ciencias del Suelo, Universidad de Vigo, As Lagoas Marcosende, 36310, Vigo, Spain.

Background: Besides the use of maize grain as food and feed, maize stover can be a profitable by-product for cellulosic ethanol production, whereas the whole plant can be used for silage production. However, yield is reduced by pest damages, stem corn borers being one of the most important yield constraints. Overall, cell wall composition is key in determining the quality of maize biomass, as well as pest resistance. This study aims to evaluate the composition of the four cell wall fractions (cellulose, hemicellulose, lignin and hydroxycinnamates) in diverse maize genotypes and to understand how this composition influences the resistance to pests, ethanol capacity and digestibility.

Results: The following results can be highlighted: (i) pests' resistant materials may show cell walls with low p-coumaric acid and low hemicellulose content; (ii) inbred lines showing cell walls with high cellulose content and high diferulate cross-linking may present higher performance for ethanol production; (iii) and inbreds with enhanced digestibility may have cell walls poor in neutral detergent fibre and diferulates, combined with a lignin polymer composition richer in G subunits.

Conclusions: Results evidence that there is no maize cell wall ideotype among the tested for optimal performance for various uses, and maize plants should be specifically bred for each particular application.
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http://dx.doi.org/10.1186/s12870-021-03040-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8170779PMC
June 2021

Maize Resistance to Stem Borers Can Be Modulated by Systemic Maize Responses to Long-Term Stem Tunneling.

Front Plant Sci 2020 11;11:627468. Epub 2021 Mar 11.

Misión Biológica de Galicia (CSIC), El Palacio-Salcedo, Pontevedra, Spain.

Limited attention has been paid to maize ( L.) resistance induced by corn borer damage, although evidence shows that induced defenses have lower resource allocation costs than constitutive defenses. Maize responses to short- and long-term feeding by the Mediterranean corn borer (MCB, ) have been previously studied, but the suggested differences between responses could be due to experimental differences. Therefore, in the current study, a direct comparison between short- and long-term responses has been made. The objectives were (i) to determine changes in the level of antibiosis of the stems induced by feeding of larvae for 2days (short-term feeding) and 9days (long-term feeding), (ii) to characterize the metabolome of the stems' short- and long-term responses to borer feeding, and (iii) to look for metabolic pathways that could modulate plant resistance to MCB. Defenses were progressively induced in the resistant inbred, and constitutive defenses were broken down in the susceptible inbred. Results suggest that the different resistance levels of the two inbreds to stem tunneling by MCB could depend on their ability to establish a systemic response. Based on these results, a high throughput look for specific metabolites implicated in systemic induced resistance to maize stem borers is recommended; the current focus on constitutive defense metabolites has not been successful in finding molecules that would be valuable tools for pest control.
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http://dx.doi.org/10.3389/fpls.2020.627468DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7991579PMC
March 2021

Genomics of Maize Resistance to Fusarium Ear Rot and Fumonisin Contamination.

Toxins (Basel) 2020 06 30;12(7). Epub 2020 Jun 30.

Misión Biológica de Galicia (CSIC), Apdo. 28, 36080 Pontevedra, Spain.

Food contamination with mycotoxins is a worldwide concern, because these toxins produced by several fungal species have detrimental effects on animal and/or human health. In maize, fumonisins are among the toxins with the highest threatening potential because they are mainly produced by , which is distributed worldwide. Plant breeding has emerged as an effective and environmentally safe method to reduce fumonisin levels in maize kernels, but although phenotypic selection has proved effective for improving resistance to fumonisin contamination, further resources should be mobilized to meet farmers' needs. Selection based on molecular markers linked to quantitative trait loci (QTL) for resistance to fumonisin contamination or/and genotype values obtained using prediction models with markers distributed across the whole genome could speed up breeding progress. Therefore, in the current paper, previously identified genomic regions, genes, and/or pathways implicated in resistance to fumonisin accumulation will be reviewed. Studies done until now have provide many markers to be used by breeders, but to get further insight on plant mechanisms to defend against fungal infection and to limit fumonisin contamination, the genes behind those QTLs should be identified.
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http://dx.doi.org/10.3390/toxins12070431DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7404995PMC
June 2020

Mapping of resistance to corn borers in a MAGIC population of maize.

BMC Plant Biol 2019 Oct 17;19(1):431. Epub 2019 Oct 17.

Misión Biológica de Galicia, Spanish National Research Council (CSIC), Apartado 28, 36080, Pontevedra, Spain.

Background: Corn borers constitute an important pest of maize around the world; in particular Sesamia nonagrioides Lefèbvre, named Mediterranean corn borer (MCB), causes important losses in Southern Europe. Methods of selection can be combined with transgenic approaches to increase the efficiency and durability of the resistance to corn borers. Previous studies of the genetic factors involved in resistance to MCB have been carried out using bi-parental populations that have low resolution or using association inbred panels that have a low power to detect rare alleles. We developed a Multi-parent Advanced Generation InterCrosses (MAGIC) population to map with high resolution the genetic determinants of resistance to MCB.

Results: We detected multiple single nucleotide polymorphisms (SNPs) of low effect associated with resistance to stalk tunneling by MCB. We dissected a wide region related to stalk tunneling in multiple studies into three smaller regions (at ~ 150, ~ 155, and ~ 165 Mb in chromosome 6) that closely overlap with regions associated with cell wall composition. We also detected regions associated with kernel resistance and agronomic traits, although the co-localization of significant regions between traits was very low. This indicates that it is possible the concurrent improvement of resistance and agronomic traits.

Conclusions: We developed a mapping population which allowed a finer dissection of the genetics of maize resistance to corn borers and a solid nomination of candidate genes based on functional information. The population, given its large variability, was also adequate to map multiple traits and study the relationship between them.
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http://dx.doi.org/10.1186/s12870-019-2052-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6796440PMC
October 2019

Effect of Long-Term Feeding by Borers on the Antibiotic Properties of Corn Stems.

J Econ Entomol 2019 05;112(3):1439-1446

Universidad de Vigo, Facultad de Biología, Dpto. Biología Vegetal y Ciencias del Suelo, Unidad Asociada BVE1-UVIGO y Misión Biológica de Galicia (CSIC), Campus As Lagoas Marcosende, Vigo, Spain.

Plant long-term response against chewing insects could become stronger than initial reactions and even turn into systemic. The objectives of the present study were 1) to evaluate whether the long-running attack to the stem by corn borers can improve the stem antibiotic properties; 2) to check whether hydroxycinnamic acids could be involved in this antibiotic response; 3) and to check whether elicitation by Sesamia nonagrioides Lef. (Lepidoptera: Noctuidae) regurgitant could activate long-term plant responses. In this sense, we observed that long-term feeding by S. nonagrioides larvae induced genotype-dependent changes in stem antibiosis and phenolic profiles, but the hydroxycinnamate content does not have a significant role in the systemic defense induced by the attack. In addition, response to long-term feeding by larvae could not be fully mimicked by elicitation using S. nonagrioides regurgitant alone. For the first time, it has been demonstrated that 'long-term' attack to the stem by corn borers can increase the stem antibiotic properties, and this has to be considered attending to breeding strategies.
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http://dx.doi.org/10.1093/jee/toz035DOI Listing
May 2019

Fine analysis of a genomic region involved in resistance to Mediterranean corn borer.

BMC Plant Biol 2018 Aug 15;18(1):169. Epub 2018 Aug 15.

Misión Biológica de Galicia, Spanish National Research Council (CSIC), Apartado 28, 36080, Pontevedra, Spain.

Background: Sesamia nonagrioides Lefebvere (Mediterranean corn borer, MCB) is the main pest of maize in the Mediterranean area. QTL for MCB stalk tunneling and grain yield under high MCB infestation had been located at bin 8.03-8.05 (4-21 cM and 10-30 cM respectively) in a previous analysis of the EP42 x EP39 RILs mapping population. The objective of the present work was to study with higher resolution those QTL, and validating and estimating with higher precision their locations and effects. To achieve this objective, we developed a set of 38 heterogeneous inbred families (HIFs) which were near-homozygous in the genome, except in the region under study. The HIFs were evaluated in multiple environments under artificial infestation with MCB and genotyped with SNPs.

Results: The QTL for grain yield under high infestation was confirmed with higher precision and improved reliability at 112.6-116.9 Mb. On the contrary, the location of the QTL for stalk tunneling was not validated probably due to the fixation of some genomic regions during the development of the HIFs. Our study confirmed that the co-localization of the QTL for stalk tunneling and grain yield in the previous study was due to linked genes, not to pleiotropic effects. So, the QTL for grain yield can be used for improving grain yield without undesirable effect on stalk tunneling.

Conclusions: The HIF analysis is useful for validating QTL and for conducting deeper studies in traits related to corn borer resistance.
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http://dx.doi.org/10.1186/s12870-018-1385-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6094900PMC
August 2018

Association mapping for cold tolerance in two large maize inbred panels.

BMC Plant Biol 2016 06 6;16(1):127. Epub 2016 Jun 6.

Misión Biológica de Galicia, Spanish National Research Council (CSIC), PO Box 2836080, Pontevedra, Spain.

Background: Breeding for cold tolerance in maize promises to allow increasing growth area and production in temperate zones. The objective of this research was to conduct genome-wide association analyses (GWAS) in temperate maize inbred lines and to find strategies for pyramiding genes for cold tolerance. Two panels of 306 dent and 292 European flint maize inbred lines were evaluated per se and in testcrosses under cold and control conditions in a growth chamber. We recorded indirect measures for cold tolerance as the traits number of days from sowing to emergence, relative leaf chlorophyll content or quantum efficiency of photosystem II. Association mapping for identifying genes associated to cold tolerance in both panels was based on genotyping with 49,585 genome-wide single nucleotide polymorphism (SNP) markers.

Results: We found 275 significant associations, most of them in the inbreds evaluated per se, in the flint panel, and under control conditions. A few candidate genes coincided between the current research and previous reports. A total of 47 flint inbreds harbored the favorable alleles for six significant quantitative trait loci (QTL) detected for inbreds per se evaluated under cold conditions, four of them had also the favorable alleles for the main QTL detected from the testcrosses. Only four dent inbreds (EZ47, F924, NK807 and PHJ40) harbored the favorable alleles for three main QTL detected from the evaluation of the dent inbreds per se under cold conditions. There were more QTL in the flint panel and most of the QTL were associated with days to emergence and ΦPSII.

Conclusions: These results open new possibilities to genetically improve cold tolerance either with genome-wide selection or with marker assisted selection.
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http://dx.doi.org/10.1186/s12870-016-0816-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4895824PMC
June 2016

Hydroxycinnamate Synthesis and Association with Mediterranean Corn Borer Resistance.

J Agric Food Chem 2016 Jan 12;64(3):539-51. Epub 2016 Jan 12.

Misión Biológica de Galicia (CSIC) , Apartado 28, 36080 Pontevedra, Spain.

Previous results suggest a relationship between maize hydroxycinnamate concentration in the pith tissues and resistance to stem tunneling by Mediterranean corn borer (MCB, Sesamia nonagrioides Lef.) larvae. This study performs a more precise experiment, mapping an F2 derived from the cross between two inbreds with contrasting levels for hydroxycinnamates EP125 × PB130. We aimed to co-localize genomic regions involved in hydroxycinnamate synthesis and resistance to MCB and to highlight the particular route for each hydroxycinnamate component in relation to the better known phenylpropanoid pathway. Seven quantitative trait loci (QTLs) for p-coumarate, two QTLs for ferulate, and seven QTLs for total diferulates explained 81.7, 26.9, and 57.8% of the genotypic variance, respectively. In relation to borer resistance, alleles for increased hydroxycinnamate content (affecting one or more hydroxycinnamate compounds) could be associated with favorable effects on stem resistance to MCB, particularly the putative role of p-coumarate in borer resistance.
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http://dx.doi.org/10.1021/acs.jafc.5b04862DOI Listing
January 2016

Identification of QTL for resistance to Mediterranean corn borer in a maize tropical line to improve temperate germplasm.

BMC Plant Biol 2015 Nov 4;15:265. Epub 2015 Nov 4.

Misión Biológica de Galicia, Spanish National Research Council (CSIC), P.O. Box 28, 36080, Pontevedra, Spain.

Background: A QTL mapping study for maize resistance to the Mediterranean corn borer (MCB) was performed with a RIL population derived from the cross B73 × CML103. To develop commercial inbreds of maize resistant to the MCB for use in Europe, it would be useful to transfer resistance from tropical germplasm like the subtropical inbred CML103 to temperate lines. The inbred B73 was chosen as representative of the Stiff Stock heterotic group, a major heterotic group used in hybrid grown in both North American and Europe. The objectives were to study the architecture of genetic factors for resistance to MCB and to check the feasibility of using marker-assisted selection (MAS) for transferring those genetic factors.

Results: Eight quantitative trait loci (QTL) were declared significant for resistance traits and eight QTL were located for agronomic traits. Alleles from CML103 at QTL significant for tunnel length could reduce tunnel length made for MCB in inbred B73 in more than 8 cm; favorable alleles for yield were also found in CML103 and no genetic correlation coefficient between tunnel length and yield was detected.

Conclusions: MAS for transferring resistance genes to corn borer attack from CML103 to B73 could be successful based on cross validation results and a negative effect on yield would not be expected.
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http://dx.doi.org/10.1186/s12870-015-0652-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4632334PMC
November 2015

Genome-wide association study reveals a set of genes associated with resistance to the Mediterranean corn borer (Sesamia nonagrioides L.) in a maize diversity panel.

BMC Plant Biol 2015 Feb 5;15:35. Epub 2015 Feb 5.

Misión Biológica de Galicia, Spanish National Research Council (CSIC), P.O. Box 28, 36080, Pontevedra, Spain.

Background: Corn borers are the primary maize pest; their feeding on the pith results in stem damage and yield losses. In this study, we performed a genome-wide association study (GWAS) to identify SNPs associated with resistance to Mediterranean corn borer in a maize diversity panel using a set of more than 240,000 SNPs.

Results: Twenty five SNPs were significantly associated with three resistance traits: 10 were significantly associated with tunnel length, 4 with stem damage, and 11 with kernel resistance. Allelic variation at each significant SNP was associated with from 6 to 9% of the phenotypic variance. A set of genes containing or physically close to these SNPs are proposed as candidate genes for borer resistance, supported by their involvement in plant defense-related mechanisms in previously published evidence. The linkage disequilibrium decayed (r(2) < 0.10) rapidly within short distance, suggesting high resolution of GWAS associations.

Conclusions: Most of the candidate genes found in this study are part of signaling pathways, others act as regulator of expression under biotic stress condition, and a few genes are encoding enzymes with antibiotic effect against insects such as the cystatin1 gene and the defensin proteins. These findings contribute to the understanding the complex relationship between plant-insect interactions.
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http://dx.doi.org/10.1186/s12870-014-0403-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4340109PMC
February 2015

Critical environmental and genotypic factors for Fusarium verticillioides infection, fungal growth and fumonisin contamination in maize grown in northwestern Spain.

Int J Food Microbiol 2014 May 19;177:63-71. Epub 2014 Feb 19.

Misión Biológica de Galicia (CSIC), Apdo. 28, 36080 Pontevedra, Spain.

In northwestern Spain, where weather is rainy and mild throughout the year, Fusarium verticillioides is the most prevalent fungus in kernels and a significant risk of fumonisin contamination has been exposed. In this study, detailed information about environmental and maize genotypic factors affecting F. verticillioides infection, fungal growth and fumonisin content in maize kernels was obtained in order to establish control points to reduce fumonisin contamination. Evaluations were conducted in a total of 36 environments and factorial regression analyses were performed to determine the contribution of each factor to variability among environments, genotypes, and genotype × environment interactions for F. verticillioides infection, fungal growth and fumonisin content. Flowering and kernel drying were the most critical periods throughout the growing season for F. verticillioides infection and fumonisin contamination. Around flowering, wetter and cooler conditions limited F. verticillioides infection and growth, and high temperatures increased fumonisin contents. During kernel drying, increased damaged kernels favored fungal growth, and higher ear damage by corn borers and hard rainfall favored fumonisin accumulation. Later planting dates and especially earlier harvest dates reduced the risk of fumonisin contamination, possibly due to reduced incidence of insects and accumulation of rainfall during the kernel drying period. The use of maize varieties resistant to Sitotroga cerealella, with good husk coverage and non-excessive pericarp thickness could also be useful to reduce fumonisin contamination of maize kernels.
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http://dx.doi.org/10.1016/j.ijfoodmicro.2014.02.004DOI Listing
May 2014

Is it possible to control fumonisin contamination in maize kernels by using genotypes resistant to the Mediterranean corn borer?

J Econ Entomol 2013 Oct;106(5):2241-6

Misión Biológica de Galicia, Spanish Council for Scientific Research (CSIC), Apartado 28, E-36080 Pontevedra, Spain.

Insect activity has long been associated with Fusarium infection. The objectives of the current study were 1) to estimate the impact of Mediterranean corn borer, Sesamia nonagrioides Lefèbvre, damage on fumonisin contamination in the maize kernel by comparing fumonisin contamination under infestation and protected conditions, and 2) to measure the potential use of genotypes resistant to this borer as controlling factors of fumonisin contamination. Genotypes with increased kernel damage by borers tended to increase fumonisin accumulation under infestation conditions. In particular environments, other factors influenced fumonisin contamination more than damage by borers. When ear damage by borers is significant, maize resistance to ear damage could contribute to the reduction of fumonisin contamination in the kernels. Genotype such as EP42 x EP77 that combines low ear damage by borers and low fumonisin level across environments is a good choice to control fumonisin contamination. The use of an applicable methodology to identify Mediterranean corn borer-resistant genotypes to ear attack under artificial infestations might be a promising approach.
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http://dx.doi.org/10.1603/ec13084DOI Listing
October 2013

Is the basal area of maize internodes involved in borer resistance?

BMC Plant Biol 2011 Oct 14;11:137. Epub 2011 Oct 14.

Misión Biológica de Galicia, Spanish National Research Council (CSIC), Apartado 28, 36080 Pontevedra, Spain.

Background: To elucidate the role of the length of the internode basal ring (LIBR) in resistance to the Mediterranean corn borer (MCB), we carried out a divergent selection program to modify the LIBR using two maize synthetic varieties (EPS20 and EPS21), each with a different genetic background. We investigated the biochemical mechanisms underlying the relationship between the LIBR and borer resistance. Selection to lengthen or shorten the LIBR was achieved for each synthetic variety. The resulting plants were analyzed to determine their LIBR response, growth, yield, and borer resistance.

Results: In the synthetic variety EPS20 (Reid germplasm), reduction of the LIBR improved resistance against the MCB. The LIBR selection was also effective in the synthetic variety EPS21 (non-Reid germplasm), although there was no relationship detected between the LIBR and MCB resistance. The LIBR did not show correlations with agronomic traits such as plant height and yield. Compared with upper sections, the internode basal ring area contained lower concentrations of cell wall components such as acid detergent fiber (ADF), acid detergent lignin (ADL), and diferulates. In addition, some residual 2,4-dihydroxy-7-methoxy-(2H)-1,4-benzoxazin-3-(4H)-one (DIMBOA), a natural antibiotic compound, was detected in the basal area at 30 days after silking.

Conclusion: We analyzed maize selections to determine whether the basal area of maize internodes is involved in borer resistance. The structural reinforcement of the cell walls was the most significant trait in the relationship between the LIBR and borer resistance. Lower contents of ADF and ADL in the rind of the basal section facilitated the entry of larvae in this area in both synthetic varieties, while lower concentrations of diferulates in the pith basal section of EPS20 facilitated larval feeding inside the stem. The higher concentrations of DIMBOA may have contributed to the lack of correlation between the LIBR and borer resistance in EPS21. This novel trait could be useful in maize breeding programs to improve borer resistance.
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http://dx.doi.org/10.1186/1471-2229-11-137DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3206430PMC
October 2011

Inducible maize defense mechanisms against the corn borer Sesamia nonagrioides: a transcriptome and biochemical approach.

Mol Plant Microbe Interact 2012 Jan;25(1):61-8

Spanish Council for Scientific Research, Pontevedra, Spain.

In spite of multiple studies elucidating individual defense mechanisms against stalk borer feeding, little information is available about the plant response to these members of Lepidoptera. Four maize inbred lines were cultivated in a greenhouse and challenged with larvae of the corn borer Sesamia nonagrioides. Transcriptome and biochemical analyses were performed to elucidate the maize response mechanisms to this insect. General plant defense mechanisms were activated, including the jasmonic acid biosynthetic pathway, proteinase inhibitors, and four defense-related transcription factors. Interestingly, gene ontology analysis shows that maize plants undergo cell-wall reorganization after being attacked. These results were confirmed through biochemical analyses showing that the concentration of some cell-wall-related compounds significantly changed after plant infestation in a genotype-dependent way. In conclusion, maize plants respond to the attack of the corn borer S. nonagrioides through cell-wall fortification, activating genes involved in cell-wall organization, which finally is reflected in a higher concentration of some cell-wall components, especially in resistant genotypes.
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http://dx.doi.org/10.1094/MPMI-06-11-0154DOI Listing
January 2012

Role of hydroxycinnamic acids in the infection of maize silks by Fusarium graminearum Schwabe.

Mol Plant Microbe Interact 2011 Sep;24(9):1020-6

Spanish Council for Scientific Research, Pontevedra, Spain.

In the current study, the hydroxycinnamic acids in silks of diverse maize inbred lines differing in Fusarium resistance were determined at several times after inoculation with Fusarium graminearum or sterile water as control. The main objective was to determine the possible relationship between the hydroxycinnamic acid changes in silks and ear rot resistance. Several changes in the cell-wall-bound hydroxycinnamic acid concentrations were observed after inoculation with F. graminearum, although these changes were not directly correlated with genotypic resistance to this fungus. Ester-bound ferulic acid decreased, probably due to degradation of hemicellulose by hydrolytic enzymes produced by Fusarium spp., while p-coumaric acid and diferulates showed slight increases that, in conjunction, did not result in delayed F. graminearum progression through the silks. It is important to note that the decrease of ferulic acid in the F. graminearum treatment was faster in susceptible than in resistant genotypes, suggesting a differential hemicellulose degradation in silk tissues. Therefore, the ability of the maize genotypes to slow down that process through hemicellulose structural features or xylanase inhibitors needs to be addressed in future studies.
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http://dx.doi.org/10.1094/MPMI-03-11-0079DOI Listing
September 2011

Yield and fruit quality of four sweet corn hybrids (Zea mays) under conventional and integrated fertilization with vermicompost.

J Sci Food Agric 2011 May 15;91(7):1244-53. Epub 2011 Feb 15.

Departamento de Ecología y Biología Animal, Universidad de Vigo, Campus Lagoas-Marcosende, Vigo E-36310, Spain.

Background: Vermicompost has been proposed as a valuable fertilizer for sustainable agriculture. The effects of vermicompost on yield and quality of sweet corn were evaluated in this study. In two field trials, sweet corn plants were grown under (i) a conventional fertilization regime with inorganic fertilizer, and integrated fertilization regimes in which 75% of the nutrients were supplied by the inorganic fertilizer and 25% of the nutrients were supplied by either (ii) rabbit manure, or (iii) vermicompost. All three types of fertilization regime were supplied at two doses. Two pairs of nearly isogenic sweet corn hybrids homozygous for sugary1 and shrunken2 mutants were included in the trials to explore fertilizer × genotype interactions. Growth, yield and ear quality of the plants were evaluated in relation to the three fertilization regimes.

Results: In general, the integrated regimes yielded the same productivity levels as the conventional treatment. Moreover, both vermicompost and manure produced significant increases in plant growth and marketable yield, and also affected the chemical composition and quality of the marketable ear. Nevertheless, most of the observed effects of the organic fertilizers were genotype-dependent.

Conclusion: The results confirm that the use of organic fertilizers such as vermicompost has a positive effect on crop yield and quality. Nevertheless, these effects were not general, indicating the complexity of the organic amendment-plant interactions and the importance of controlling genetic variation when studying the effects of vermicompost on plant growth.
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http://dx.doi.org/10.1002/jsfa.4306DOI Listing
May 2011

Corn borer (Lepidoptera: Noctuidae and Crambidae) resistance of main races of maize from North America.

J Econ Entomol 2007 Feb;100(1):209-14

Misión Biológica de Galicia, Consejo Superior de Investigaciones Cientificas, Apartado 28, 36080 Pontevedra, Spain.

Resistance to corn borers, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae) and Sesamia nonagrioides (Lefebvre) (Lepidoptera: Noctuidae) in maize, Zea mays L., populations is partial, and more resistant populations are needed. The objective of this research was to compare resistance to corn borers of the main maize races from North America. Twenty open-pollinated maize populations belonging to the races Southern Dent, Corn Belt Dent, and Northern Flint, and three check populations, were evaluated under artificial infestation with S. nonagrioides and O. nubilalis. None of the populations had complete resistance. Northern Flint had the lowest yield under corn borer infestation, whereas Southern Dent had the highest yield but also the largest damage. Corn Belt Dent had a shorter growing cycle and similar yield of infected plants than Southern Dent. The checks had intermediate yield and resistance and were not significantly different from Corn Belt Dent for any trait. The Southern Dent populations Tennessee Red Cob and White Dent (PI221885 and PI311232) could be used as sources of tolerance to corn borers, although they are not expected to provide great gains compared with the levels of tolerance already present in some Corn Belt Dent and European Flint populations and would require adaptation to short growing cycle. The Corn Belt Dent synthetic BS17 had the highest yield and general agronomic performance under corn borer infestation, along with Rustler and Silver King, and the European Flint composite EPS13.
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February 2007

Maize (Zea mays L.) genetic factors for preventing fumonisin contamination.

J Agric Food Chem 2006 Aug;54(16):6113-7

Misión Biológica de Galicia, Spanish Council for Scientific Research, Pontevedra.

Fusarium moniliforme and Fusarium proliferatum are the most frequently isolated fungi from maize (Zea mays L.) in Spain. Both Fusarium species produce toxins potentially dangerous for animals and humans, the fumonisins being the most significant of those toxins. White maize is preferred for human consumption, and extra care should be taken to avoid kernel mycotoxin contamination. The objectives of this study were to identify and quantify kernel infection by Fusarium spp. and contamination by fumonisin on white maize hybrids, to search for white maize sources of resistance to infection by Fusarium spp. and mycotoxin contamination, and to preliminarily study the genetics involved in such resistances. Ten F(1) single crosses derived from a diallel mating design among five white maize inbreds were evaluated in a randomized complete block design with three replications in 2002 at two locations. Fusarium verticilloides and F. proliferatum were detected on kernels of white maize hybrids cultivated in northwestern Spain. No differences in fungal infection were found among maize genotypes, but differences in fumonisin contamination were significant and could be related, in part, to differences in husk tightness. Among the genotypes studied, general combining ability (GCA) effects were the most important for resistance to fumonisin contamination. Inbreds EP10 and EC22 showed the most favorable GCA effects for husk tightness and fumonisin content, and the cross between them, EP10 x EC22, had the most favorable specific combining ability (SCA) effect for husk tightness. Inbreds EP10 and EC22 showed favorable GCA effects for fumonisin contamination and husk tightness, and the cross EP10 x EC22 was the only one with an average fumonisin level below 1 mug/g. Although this should be confirmed with more extensive studies, white maize inbreds developed from white maize landraces could be sources of resistance to fumonisin contamination.
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http://dx.doi.org/10.1021/jf0611163DOI Listing
August 2006