Moncada, Spain
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Asins M.J.,IVIA | Bolarin M.C.,CSIC - Center of Edafology and Applied Biology of the Segura | Perez-Alfocea F.,CSIC - Center of Edafology and Applied Biology of the Segura | Estan M.T.,CSIC - Center of Edafology and Applied Biology of the Segura | And 6 more authors.
Theoretical and Applied Genetics | Year: 2010

Grafting desirable crop varieties on stress-tolerant rootstocks provides an opportunity to increase crop salt tolerance. Here, a commercial hybrid tomato variety was grafted on two populations of recombinant inbred lines developed from a salt-sensitive genotype of Solanum lycopersicum var. cerasiforme, as female parent, and two salt-tolerant lines, as male parents, from S. pimpinellifolium, the P population, and S. cheesmaniae, the C population, to identify an easy screening method for identifying rootstocks conferring salt tolerance in terms of fruit yield. Potential physiological components of salt tolerance were assessed in the scion: leaf biomass, [Na+], nutrition, water relations and xylem ABA concentration. A significant correlation between scion fruit yield and scion leaf fresh weight, water potential or the ABA concentration was found in the C population under salinity, but the only detected QTL did not support this relationship. The rootstocks of the P population clearly affected seven traits related to the sodium, phosphorous and copper concentrations and water content of the scion leaf, showing heritability estimates around 0. 4 or higher. According to heritability estimates in the P population, up to five QTLs were detected per trait. QTLs contributing over 15% to the total variance were found for P and Cu concentrations and water content of the scion leaf, and the proportion of fresh root weight. Correlation and QTL analysis suggests that rootstock-mediated improvement of fruit yield in the P population under salinity is mainly explained by the rootstock's ability to minimise perturbations in scion water status. © 2010 Springer-Verlag.

Owens R.A.,U.S. Department of Agriculture | Sano T.,Hirosaki University | Duran-Vila N.,IVIA
Methods in Molecular Biology | Year: 2012

When Diener discovered Potato spindle tuber viroid in 1971 (Diener, Virology 45:411-428, 1971), only a limited number of techniques were available for plant virus detection and purification. Biological assays using indicator hosts showing characteristic symptoms of infection and able to support high levels of viroid replication played a critical role in viroid detection and characterization. Polyacrylamide gel electrophoresis (PAGE) was the first molecular technique to be used for the rapid (2-3 days) identification of viroid-infected plants. Because it is the only diagnostic method that is sequence-independent, PAGE under denaturing conditions continues to play a key role in the identification of new viroids. Starting in the early 1980s, dot blot hybridization began to replace PAGE for routine viroid diagnosis. The first diagnostic protocols based on reverse transcription-polymerase chain reaction (RT-PCR) appeared approximately 10 years later, and much effort has subsequently been devoted to simplifying the sample preparation procedure and identifying group-specific primer pairs. This chapter describes four simple, easy-to-follow protocols-two involving PAGE and two others based on enzymatic amplification of viroid cDNAs-that currently play key roles in viroid discovery and characterization. © 2012 Springer Science+Business Media, LLC.

Asins M.J.,IVIA | Raga V.,IVIA | Roca D.,IVIA | Belver A.,CSIC - Experimental Station of El Zaidín | Carbonell E.A.,IVIA
Theoretical and Applied Genetics | Year: 2015

Key message: Rootstock HKT1 genotype affected fruit [Na+] and non-commercial fruit yield; QTL analysis of rootstock-mediated scion nutrition is a powerful forward genetic approach to identify wild genes for rootstock breeding.Abstract: The present study approaches the QTL dissection of rootstock effects on a commercial hybrid variety grafted on a population of RILs derived from Solanum pimpinellifolium, genotyped for 4370 segregating SNPs from the SolCAP tomato panel and grown under moderate salinity. Results are compared to those previously obtained under high salinity. The most likely functional candidate genes controlling the scion [Na+] were rootstock HKT1;1 and HKT1;2 as it was previously reported for non-grafted genotypes. The higher fruit [Na+] found when rootstock genotype was homozygote for SpHKT1 supports the thesis that scion HKT1 is loading Na+ into the phloem sap in leaves and unloading it in sink organs. A significant increment of small, mostly seedless, fruits was found associated with SlHKT1 homozygous rootstocks. Just grafting increased the incidence of blossom end rot and delayed fruit maturation but there were rootstock RILs that increased commercial fruit yield under moderate salinity. The heritability and number of QTLs involved were lower and different than those found under high salinity. Four large contributing (>17 %) rootstock QTLs, controlling the leaf concentrations of B, K, Mg and Mo were detected whose 2 Mbp physical intervals contained B, K, Mg and Mo transporter-coding genes, respectively. Since a minimum of 3 QTLs (two of them coincident with leaf K and Ca QTLs) were also found governing rootstock-mediated soluble-solids content of the fruit under moderate salinity, grafting desirable crop varieties on stress-tolerant rootstocks tenders an opportunity to increase both salt tolerance and quality. © 2015, Springer-Verlag Berlin Heidelberg.

Bernet G.P.,IVIA | Fernandez-Ribacoba J.,IVIA | Carbonell E.A.,IVIA | Asins M.J.,IVIA
Molecular Breeding | Year: 2010

Citrus genetic resources are rich but underutilized in breeding because their complex reproductive biology and the scarceness of inheritance studies on agronomic traits. Here, we investigated the genomic distribution of segregation distortion regions, the inheritance of organelle DNA and colinearity between scion citrus linkage maps by using a reciprocal cross design. The parents were Fortune, a hybrid mandarin from C. clementina, and Chandler, a hybrid pummelo from C. grandis that largely differ in fruit size, taste and colour. The inheritance of organelle DNA was studied in 201 hybrids by using four organelle DNA markers, and the linkage maps were based on 174 of those hybrids. Around ten percent of the seedlings derived from the pummelo as female parent showed the same organelle markers as those of the mandarin, indicating a possible exception to their expected maternal inheritance in citrus. Most segregation distortion affects just the allele frequencies, generally representing differences in pollen fertilization success, as a likely consequence of the presence of gametal factors affecting the functionality of gametes and pollen-pistil interactions. The large extension of colinearity found when comparing the C. grandis and C. clementina linkage maps to those previously reported for rootstock species (C. aurantium and P. trifoliata), will be helpful to infer the position of orthologous genes and QTLs in citrus species and for a more useful genetic characterization of citrus germplasm collections. © Springer Science+Business Media B.V. 2010.

Some crops do not adapt to winter disinfestation because low temperatures reduce the evaporation capacity of fumigants and its spatial distribution can't be done with the desired uniformity, and remaining phytotoxic residues need more time to be eliminated. The most problematic case in Spanish farming is on strawberry mother plants crop in highland nurseries, where disinfestation before plantation is done with soil temperatures about 10°C during application. Main problems are soil fungi and the presence of weeds in springtime and summer with the mother plants still developing. In a first season were studied three new formulations of 1,3- dichloropropene 55.2% + chloropicrin 30.3% at 50 g/m 2 furnished by Agroquimicos de Levante SA., (Agrocelhone NE); methyl bromide 50% + chloropicrin 50% at 40 g/m 2 and a non disinfested check. Application has been done by shank injection, as is usually done, on mid March and crop started beginning of May. On a second season the best adjuvant was compared added or not to a set of standard mixtures of 1,3-D 36.7% and Chloropicrin 52.8%; 1,3-D 55.2% and Chloropicrin 30.3% formulated for shank injection and with emulsifiers and compared to methyl bromide. On a third season, 100 plants per plot, produced in our second season mother plant experiment, were transplanted in a commercial field at Lucena (Huelva) in order to monitor the yield, vigour and healthy state along a standard crop. The first season results showed that there are no significant differences with respect to weed control among treatments except for the check. In check treatment weeds seize the whole plot and finally plants together with weeds were eliminated. Runner production was improved by the new formulation up to the level of methyl bromide. The new formulation showed a better control of weeds than the standard mixture. On the second season, emulsifiable formulation and special formulations gave better control of weeds. On the third season no differences among treatments were found on yield and healthiness even with the check, but diameter of rhizomes on MB and especial formulations with adjuvant were significantly higher than standard formulations.

Davino S.,University of Palermo | Willemsen A.,Polytechnic University of Valencia | Panno S.,University of Palermo | Davino M.,University of Catania | And 4 more authors.
PLoS ONE | Year: 2013

Citrus tristeza virus (CTV) outbreaks were detected in Sicily island, Italy for the first time in 2002. To gain insight into the evolutionary forces driving the emergence and phylogeography of these CTV populations, we determined and analyzed the nucleotide sequences of the p20 gene from 108 CTV isolates collected from 2002 to 2009. Bayesian phylogenetic analysis revealed that mild and severe CTV isolates belonging to five different clades (lineages) were introduced in Sicily in 2002. Phylogeographic analysis showed that four lineages co-circulated in the main citrus growing area located in Eastern Sicily. However, only one lineage (composed of mild isolates) spread to distant areas of Sicily and was detected after 2007. No correlation was found between genetic variation and citrus host, indicating that citrus cultivars did not exert differential selective pressures on the virus. The genetic variation of CTV was not structured according to geographical location or sampling time, likely due to the multiple introduction events and a complex migration pattern with intense co- and re-circulation of different lineages in the same area. The phylogenetic structure, statistical tests of neutrality and comparison of synonymous and nonsynonymous substitution rates suggest that weak negative selection and genetic drift following a rapid expansion may be the main causes of the CTV variability observed today in Sicily. Nonetheless, three adjacent amino acids at the p20 N-terminal region were found to be under positive selection, likely resulting from adaptation events. © 2013 Davino et al.

PubMed | INAT, CIRAD - Agricultural Research for Development and IVIA
Type: | Journal: Journal of plant physiology | Year: 2016

For grafted plants, salt stress tolerance of the aerial plant part is poorly documented. Thus, we developed a simple, fast and inexpensive method to identify tolerant genotypes. Twigs of 14 mandarin accessions that we previously analyzed as seedlings were cut in solution to prevent embolism and were then evaluated in salt stress condition for a week. Physiological parameters such as gas exchanges, leaf Cl(-) and Na(+), as well as the presence of H2O2 and the activity of enzymes involved in ROS synthesis and detoxification processes were analyzed. One accession known to be tolerant as rootstock was shown to be sensitive with limited Cl(-) translocation from the solution to the shoot while sensitive accessions when grown as seedlings presented limited wilting symptoms and accumulated large leaf Cl(-) content. A model is proposed to explain the different strategies of the plant to cope with high toxic ion content. This method allows separation of the root compartment, where ion exclusion mechanisms may exist and have an impact on the salt stress tolerance of the whole plant.

PubMed | IVIA
Type: Journal Article | Journal: TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik | Year: 2013

Besides QTL location and the estimation of gene effects, QTL analysis based on genetic markers could be used to comprehensively investigate quantitative trait-related phenomena such as pleiotropy, gene interactions, heterosis, and genotype-by-environment interaction (G x E). Given that the G x E interaction is of great relevance in tree improvement, the objective of the research presented here was to study the effect of years on QTL detection for 15 quantitative traits by means of isozymatic markers in a large progeny group of an intervarietal cross of almond. At least 17 putative QTLs were detected, 3 of which had alleles with opposite effects to those predicted from the parental genotypes. Only 3 QTLs behaved homogeneously over the years. Three possible causes are discussed in relation to this lack of stability: the power of the test statistic being used, the low contribution of the QTL to the genetic variation of the trait, and a differential gene expression dependent on the year (G x E). Most cases showing lack of stability involved traits whose heritability estimates change drastically from year to year and/or whose correlation coefficients between years are low, suggesting the presence of G x E as the most likely cause. A marker-assisted selection scheme to improve late flowering and short flowering duration is suggested for an early and wide screening of the progeny.

PubMed | IVIA
Type: Journal Article | Journal: TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik | Year: 2013

A statistical model for doubled haploids and backcrosses based on the interval-mapping methodology has been used to carry out power studies to investigate the effects of different experimental designs, heritabilities of the quantitative trait, and types of gene action, using two test statistics, the F of Fisher-Snedecor and the LOD score. The doubled haploid experimental design is more powerful than backcrosses while keeping actual type I errors similar to nominal ones. For the doubled haploid design, individual QTLs, showing heritabilities as low as 5% were detected in about 90% of the cases using only 250 individuals. The power to detect a given QTL is related to its contribution to the heritability of the trait. For a given nominal type I error, tests using F values are more powerful than with LOD scores. It seems that more conservative levels should be used for the LOD score in order to increase the power and obtain type I errors similar to nominal ones.

PubMed | IVIA
Type: Journal Article | Journal: TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik | Year: 2013

Salt tolerance defined in terms of fruit yield under different NaCl concentrations (171.1 and 325.1 mM) is analyzed in 11 lines belonging to: Lycopersicon esculentum, L. cheesmanii, L. chmielewski, L. peruvianum and L. pimpinellifolium. Four L. pimpinellifolium lines and two L. cheesmanii lines tolerated the 171.1mM treatment; the latter species even tolerates 325.1 mM of NaCl. Changes in gene expression induced by salt treatment were also investigated by studying anther and leaf zymograms for L. esculentum and one salt-tolerant L. pimpinellifolium line, and leaf proteinograms for all lines. Changes in leaf PRX and MDH enzymatic systems were detected, mainly in the salt-sensitive genotype (L. esculentum). Four saltrelated peptides from 14 500 to 40 000 daltons were found. A polyclonal antibody raised against one of these peptides (number 2), also binds another peptide, named 2, of much higher molecular weight, present both in control and salt-tolerant L. cheesmanii lines at the end of 171.1 mM treatment. The xero-halophyte shrub Atriplex halimus also showed a likely 2-homologous peptide with this treatment, while its counterpart C3 species A. triangularis did not.

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