The chromosome region including the earliness per se locus Eps-Am1 affects the duration of early developmental phases and spikelet number in diploid wheat

Earliness per se genes are those that regulate flowering time independently of vernalization and photoperiod, and are important for the fine tuning of flowering time and for the wide adaptation of wheat to different environments. The earliness per se locus Eps-Am1 was recently mapped within a 0.8 cM interval on chromosome 1AmL of diploid wheat Triticum monococcum L., and it was shown that its effect was modulated by temperature. In this study, this precise mapping information was used to characterize the effect of the Eps-Am1 region on both duration of different developmental phases and spikelet number. Near isogenic lines (NILs) carrying the Eps-Am1-l allele from the cultivated accession DV92 had significantly longer vegetative and spike development phases (P <0.0001) than NILs carrying the Eps-Am1-e allele from the wild accession G3116. These differences were paralleled by a significant increase in the number of spikelets per spike, in both greenhouse and field experiments (P <0.0001). Significant interactions between temperature and Eps-Am1 alleles were detected for heading time (P <0.0001) but not for spikelet number (P=0.67). Experiments using NILs homozygous for chromosomes with recombination events within the 0.8 cM Eps-Am1 region showed that the differences in number of spikelets per spike were linked to the differences in heading time controlled by the Eps-Am1 locus. These results indicate that the differences in these two traits are either pleiotropic effects of a single gene or the effect of closely linked genes. A similar effect on spikelet number was detected in the distal region of chromosome 1AL in common wheat (T. aestivum L.)

Control of flowering time and spike development in cereals: the earliness per se Eps-1 region in wheat, rice, and Brachypodium

The earliness per se gene Eps-Am1 from diploid wheat Triticum monococcum affects heading time, spike development, and spikelet number. In this study, the Eps1 orthologous regions from rice, Aegilops tauschii, and Brachypodium distachyon were compared as part of current efforts to clone this gene. A single Brachypodium BAC clone spanned the Eps-Am1 region, but a gap was detected in the A. tauschii physical map. Sequencing of the Brachypodium and A. tauschii BAC clones revealed three genes shared by the three species, which showed higher identity between wheat and Brachypodium than between them and rice. However, most of the structural changes were detected in the wheat lineage. These included an inversion encompassing the wg241-VatpC region and the presence of six unique genes. In contrast, only one unique gene (and one pseudogene) was found in Brachypodium and none in rice. Three genes were present in both Brachypodium and wheat but were absent in rice. Two of these genes, Mot1 and FtsH4, were completely linked to the earliness per se phenotype in the T. monococcum high-density genetic map and are candidates for Eps-Am1. Both genes were expressed in apices and developing spikes, as expected for Eps-Am1 candidates. The predicted MOT1 protein showed amino acid differences between the parental T. monococcum lines, but its effect is difficult to predict. Future steps to clone the Eps-Am1 gene include the generation of mot1 and ftsh4 mutants and the completion of the T. monococcum physical map to test for the presence of additional candidate genes

Effect of three environments on the efficiency of indirect selection in Eragrostis curvula (lovegrass) genotypes

A significant genotype environment interaction can limit gains in selecting superior genotypes since the best genotype in one locality may not be the best one in another locality. The efficiency of indirect selection is related to the heritability of the trait and to the genetic correlation between localities.Since a major objective of Eragrostis curvula (lovegrass) breeding programmes in Argentina is to select superior genotypes from new cultivar introductions, research on the relative effectiveness of direct and indirect selection is necessary in order to identify localities under which the efficiency of indirect selection could be maximized.To do this, experiments using a set of 18 hybrids were carried out in three localities from the semi-arid region of Argentina. Aerial biomass yield, leaf length, crown diameter, panicle number and panicle length were measured and an analysis of variance and covariance were performed. The high genetic correlation obtained suggests that the genetic mechanisms involved in the expression of these traits would be the same, or at least very similar, in Rı´o Cuarto, Villa Mercedes and Bahı´a Blanca environments where the hybrids showed a stable performance. In general, the heritability obtained was higher in Villa Mercedes and BahÍa Blanca than in Rıo Cuarto. For a given selection intensity the expected correlated response in Villa Mercedes and BahÍa Blanca to indirect selection was compared with the expected gain with direct response to selection in Rıo Cuarto. For dry matter yield, indirect selection in Bahı´a Blanca did not differ from selection done inRı´o Cuarto (x3%). However, for performance in Villa Mercedes indirect selection was shown to be less efficient (x29%). For the other traits considered, indirect selection was variable and less efficient,ranging from x18 to x34%. The stimated decrease in efficiency of selection for all the traits considered in the Locality of RÍo Cuarto was higher than in the other localities, suggesting that this place was not a good choice for carrying out indirect selection. Conversely, genetic progress would be faster if selection was carried out in Villa Mercedes, because the evaluations provide higher and more accurate estimates of the heritabilities than in the other localities.Fil: Di Renzo, Miguel Angel. Universidad Nacional de Río Cuarto. Facultad de Agronomía y Veterinaria; ArgentinaFil: Ibañez, M. A.. Universidad Nacional de Río Cuarto. Facultad de Agronomía y Veterinaria; ArgentinaFil: Bonamico, Natalia Cecilia. Universidad Nacional de Río Cuarto. Facultad de Agronomía y Veterinaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Faricelli, M. E.. Universidad Nacional de Río Cuarto. Facultad de Agronomía y Veterinaria; ArgentinaFil: Poverene, María Mónica. Universidad Nacional del Sur. Departamento de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; ArgentinaFil: Echenique, Carmen Viviana. Universidad Nacional del Sur. Departamento de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentin