Quantification of critical factors affecting fitness of the sugary1 mutant in maize

Fitness of sugary1 (su1) is affected by some critical traits that depend on the genotypes and environments, while their effects have not been quantified with convincing statistical methods. The objective of this work was to identify and quantify the critical factors of su1 fitness with different genotypes and environments. We used two pairs of field corn inbreds that differentially affected su1 viability to develop F1, F2, BC1 and BC2. After selfing, Su1 and su1 kernels were evaluated under controlled environmental conditions and in field trials. Multiple regressions showed that dry weight of juvenile plant was affected by early vigour (plant size, colour and health) and emergence in cold conditions; ear weight by plant appearance, number of plants and chlorophyll content; number of ears by plant appearance, number of plants, chlorophyll content and female flowering; and kernel weight by ear weight, number of plants, row number and ear length. The main critical factors for su1 fitness were early vigour and emergence under cold conditions at initial stages, while several adult traits were related with final fitness.Research was supported by the Spanish Plan for Research and Development (project code AGL2007-64218/AGR and AGL2010-22254) and the Diputación Provincial de Pontevedra. A Djemel acknowledges his fellowship from the Spanish Council for Scientific Research (CSIC).MICINNDiputación Provincial de PontevedraCSICPeer 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 accessions 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.This research was supported by the Spanish Agency for International Cooperation and Development (AECID project A/023430/09), the École Nationale Supérieure Agronomique (ENSA) Algiers,Algeria,the Spanish Council for Scientific Research (CSIC) and the Algerian Ministry of high Education and scientific research (MESRS).Peer reviewe

HvFT1 (VrnH3) drives latitudinal adaptation in Spanish barleys

29 Pag., 5 Tabl., 4 Fig. The definitive version is available at: http://www.springer.com/life+sciences/plant+sciences/journal/122Flowering time is an important factor in the adaptation of barley varieties to environmental conditions and maximizing yield potential (Boyd et al. 2003; Cockram et al. 2007a; Cuesta-Marcos et al. 2009), by synchronizing the plant cycle to the prevailing environmental conditions. Flowering time is a complex trait that shows an almost continuous variation in cereals. The investigation of the genetic control of flowering time in barley has benefited from the comparative use of floral pathways in Arabidopsis thaliana (Cockram et al. 2007a) and rice, via the identification of candidate genes through orthology. The variation in flowering time is mainly due to variations in genes regulated by day length (photoperiod) or long exposures to low temperature (vernalization) (Laurie et al. 1995; Trevaskis et al. 2003; Dubcovsky et al. 2005). In barley, three genes are responsible for the vernalization requirement: VrnH1 (isolated by map-based cloning in diploid wheat, Yan et al. 2003), VrnH2 (identified by positional cloning, Yan et al. 2004) and VrnH3 (identified by homology to a known gene from Arabidopsis thaliana, Yan et al. 2006). VrnH1 is induced by vernalization and promotes the transition from vegetative to reproductive development. VrnH2 is a floral repressor that delays flowering until the plants are vernalized. The VrnH3 gene seems to be orthologous to the A. thaliana floral pathway integrator FT (FLOWERING LOCUS T) gene (Yan et al. 2006; Faure et al. 2007; Turck et al. 2008; Kikuchi et al. 2009). In A. thaliana, FT expression increases in the leaves when plants are exposed to inductive day length. In barley, expression of orthologous HvFT1 (synonymous to VrnH3) is induced by long day conditions and promotes flowering (Hemming et al. 2008). The winter growth habit of barley requires the presence of a recessive VrnH1 allele, together with an active VrnH2 allele (Cockram et al. 2007b; Hemming et al. 2009). Vernalization induces VrnH1 under both short and long days, which then represses VrnH2. Distelfeld et al. (2009) reported that the interactions among the three vernalization genes generate a feedback regulatory loop that once started, leads to an irreversible induction of flowering. The function of HvFT1 has started to be unraveled only recently. There is now mounting evidence supporting the role of the FT protein in Arabidopsis (and corresponding proteins in other species) as an important part of the florigen (Corbesier et al. 2007; Tamaki et al. 2007). Kikuchi et al. (2009) presented strong evidence suggesting that HvFT1 plays a central role in promoting flowering, integrating the photoperiod and vernalization pathways. HvFT1 expression seems to be regulated by the major photoperiod response genes: PpdH1 under LD conditions and PpdH2 under SD conditions. There are evidences on the adaptive role played by VrnH1, VrnH2 and PpdH1 during the expansion of the crop, facilitating its adaptation to new agroecological niches (Cockram et al. 2007a; Jones et al. 2008). Does VrnH3-HvFT1 also have an adaptive role? We know that the phenotypic effect of HvFT1 on flowering time can be very large (Yan et al. 2006), and therefore may be an important factor for the final determination of barley flowering time. Other open questions on this gene are: to what environmental cue does VrnH3 respond, temperature or photoperiod? What effect does it have on flowering time under natural conditions? To address these questions, we analyzed the polymorphism and the phenotypic effect of this gene on a collection of Spanish barley landraces and its variation at the sequence level, and validated its effect on a segregating population.This work was supported by the Spanish Ministry of Science and Innovation (Projects AGL2007-63625 and RTA01-088-C3) and by the European Regional Development Fund. A Djemel was supported by a fellowship from IAMZ-CIHEAM. S Yahiaoui and L Ponce were supported by fellowships from AECID-Spanish Ministry of Foreign Affairs and Cooperation.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

Estabilidad del mutante sugary1 en maíz dulce

157 páginas.- Memoria de tesis presentada para optar al grado de Doctor por la Universidad de Lleida[EN] We studied the effect of diverse maize genetic backgrounds on sugary1 fitness and to estimate the genetic effects on sugary1 fitness, the effect of the introgression of su1 in the genetic regulation of agronomic performance and to determine the most limiting factors for su1 fitness under natural and controlled conditions, and the genes or genomic regions affecting the genetic regulation of su1 viability. We used five successive selfing cycles in two separated mean generation designs in the field. The genetic regulation of su1 was examined in two RILs genotyped with 1106 SNPs and an F2 characterized with 295 SSRs. The su1 fitness depends on many genes with small effects on a variety of fitness-related traits throughout the genome that are significant or not depending on both genetic background and environmental conditions.[ES] Se pretende evaluar los efectos del fondo genético del maíz en la viabilidad de su1 y estimar los efectos genéticos que controlan esta viabilidad, determinar los efectos de la introducción de su1 en el valor agronómico y los caracteres limitantes para la viabilidad, e identificar regiones cromosómicas asociadas a la viabilidad de su1. Se han utilizado dos sistemas basados en medias de generaciones autofecundadas separadamente durante cinco años consecutivos y evaluados en campo y en condiciones controladas. La regulación genética de la viabilidad de su1 se ha estudiado en dos poblaciones de RIL genotipadas con 1106 SNP y una F2 con 295 SSR. La viabilidad del mutante su1 depende de múltiples genes con efectos menores distribuidos a lo largo de todo el genoma. Estos genes, que están fuertemente influidos por la naturaleza del fondo genético y por las condiciones ambientales, controlan varios caracteres ligados a la viabilidad del mutante sugary1.[FR] Els objectius són avaluar els efectes de fons genètics del blat de moro sobre la viabilitat de su1, estimar els factors genètics que afecten aquesta variabilitat, els efectes de la introducció de su1 en el valor agronòmic i, determinar els caràcters més limitants per a la seva viabilitat i identificar gens o regions cromosòmiques que afecten la regulació genètica de la viabilitat de su1. S'ha estudiat utilitzant dos sistemes basats en mesures de generacions auto-fecundades separadament durant cinc anys consecutius. La regulació genètica de la viabilitat de su1 s'ha estudiat en dues poblacions de RIL con 1106 SNP i una F2 caracteritzat amb 295 SSR. La viabilitat de su1 depèn de múltiples gens amb efectes menors distribuïts al llarg de tot el genoma. Aquests gens, que estan fortament influïts per la naturalesa del fons genètic i per les condicions ambientals, controlen diversos caràcters lligats a la viabilitat del mutant su1.Research was supported by the Spanish Plan I+D (AGL2007-64218/AGR, AGL2010- 22254) and the Excma. Diputación Provincial de Pontevedra.Peer reviewe

Efectos genéticos en la viabilidad del mutante sugary1 en maíz

2 páginas, 2 tablas.- Trabajo presentado al V Congreso de mejora genética de plantas celebrado en Madrid (España) en Julio del 2010.La viabilidad del mutante del maíz dulce (Zea mays L.) sugaryl (sul) está regulada genéticamente. En este trabajo se estudian los efectos genéticos que regulan la viabilidad del alelo sul mediante dos diseños de medias generacionales constituidos por dos parejas de líneas puras SulSul. Las generaciones se cruzaron con la línea sul P39 y se hicieron cuatro autofecundaciones. La reducción de la frecuencia de sul siguió una regresión lineal. La viabilidad de sul depende de la interacción gen x genotipo y está regulada principalmente por efectos dominantes cuyo signo depende del genotipo y por efectos aditivos semejantes.Este habajo ha sido financiado por el Plan Nacional de I+D (AGL 2007-64218). Abderrahmane Djemel agradece una beca JAE del CSIC.Peer reviewe

Genetic effects on fitness of the mutant sugary1 in wild-type maize

Knowing the genetic regulation of fitness is crucial for using mutants in breeding programmes, particularly when the mutant is deleterious in some genetic backgrounds, as it happens with the sweet corn mutant sugary1 (su1) in maize (Zea mays L.). The fitness and genetic effects of maize mutant su1 were monitored through five successive selfing generations in two separated mean-generation designs. The first involved two inbreds with similar genetic backgrounds, while unrelated inbreds were used for the second design. Parents, F1s, F2s, and backcrosses were crossed to P39 as the donor of su1 and the 12 crosses were successively self-pollinated for 5 years. The su1 frequency decreased linearly across selfing generations in both designs. Additive effects were significant for su1 seed viability. However, dominance effects were of higher magnitude than additive effects, even though the dominance effects were not significant. Genetic effects depended on genotypes and environments. Therefore, the fitness of su1 is under genetic control, with significant additive effects due to minor contributions of multiple genes. The fitness of su1 is strongly affected by maize genotypic background and environment. It is hypothesized that genotypes could have evolutionary potential for modulating the fitness of single mutations. © 2012 Cambridge University Press.This research was supported by the Spanish Plan I+D (AGL2007-64218/AGR, AGL2010-22254) and the Excma. Diputación Provincial de Pontevedra. A. Djemel acknowledges his fellowship from the Spanish Council for Scientific Research (CSIC).MICINNExcma. Diputación Provincial de PontevedraCSICPeer Reviewe

Maize (Zea mays L.) from the Saharan oasis: adaptation to temperate areas and agronomic performance

29 Pags., 6 Tabls. The definitive version is available at: http://www.springerlink.com/content/0925-9864/Saharan maize had been adapted to extreme conditions and could have developed resistance to different stresses. However, genebanks and breeding collections have poor representation from Saharan germplasm and, particularly, from Algeria. This is a preliminary approach to investigate the adaptation and agronomic performance of a representative sample of Saharan maize. We evaluated open-pollinated Saharan populations along with European and American cultivars during 2 years in humid and dry Spanish locations and in Algiers (Algeria). Saharan populations were able to grow in temperate environments, although results were not consistent over years and the genotype-by- environment interactions were very important. Some of the Algerian populations evaluated in 2010 showed promising yield and anthesis silking interval over environments, but none of the Algerian populations evaluated in 2009 were adequately adapted to Spanish conditions. These results suggest that there are wide ranges of variability within Saharan maize for adaptation to temperate conditions, and further evaluations of Saharan maize should identify potential base populations for breeding maize in either side of the Mediterranean Sea. However, this germplasm requires prebreeding for adaptation to temperate conditions in order to be adequate for breeding programs in temperate areas.This research was supported by the Agencia Española de Cooperación y Desarrollo (AECID), the Spanish Council for Scientific Research (CSIC), and the École Nationale Supérieure Agronomique, El Harrach-Algiers. A. Djemel has a JAE Pre contract from CSIC.Peer reviewe

Regulación genética de la viabilidad en los mutantes: El caso del gen sugary1 en maíz

Trabajo presentado en el VII Congreso de mejora genética de plantas, celebrado en Zaragoza (España) entre los días 16 y 18 de septiembre de 2014.- 2 páginas y 2 figuras.Varios mutantes del maíz (Zea mays L.) tienen importancia económica, como el mutante sugary1 (su1) localizado en el cromosoma 4. Este mutante puede ser letal o semiletal cuando se íntroduce en algunos genotipos silvestres. Revilla el al. (2010) mostraron que la viabilidad de su1 depende de la interacción donante Y receptor y está determinada por diversos caracteres a lo largo del crecimiento de la planta. Pero no se conoce la regulación genética de la viabilidad de su1 ni los efectos genéticos que produce su introducción en genotipos silvestres. Los objetivos de este trabajo fueron: 1) estimar los efectos genéticos que regulan la viabilidad de su1, 2) determinar las modificaciones en los efectos genéticos causadas por la introducción de su1 y 3) identificar regiones genéticas que afecten la regulación de la viabilidad de su1.Esta investigación ha sido financiada por el Plan Nacional de I+D+i (AGL20 10-22254).Peer reviewe

Genetic of the fitness of the sweet corn mutant sugary1

Resumen del póster presentado en Trento (Italia) del 18 al 21 de Marzo de 2010.Peer reviewe