Showing papers by "José M. Jiménez-Gómez published in 2014"

The genome of the stress-tolerant wild tomato species Solanum pennellii

Abstract: Solanum pennellii is a wild tomato species endemic to Andean regions in South America, where it has evolved to thrive in arid habitats. Because of its extreme stress tolerance and unusual morphology, it is an important donor of germplasm for the cultivated tomato Solanum lycopersicum. Introgression lines (ILs) in which large genomic regions of S. lycopersicum are replaced with the corresponding segments from S. pennellii can show remarkably superior agronomic performance. Here we describe a high-quality genome assembly of the parents of the IL population. By anchoring the S. pennellii genome to the genetic map, we define candidate genes for stress tolerance and provide evidence that transposable elements had a role in the evolution of these traits. Our work paves a path toward further tomato improvement and for deciphering the mechanisms underlying the myriad other agronomic traits that can be improved with S. pennellii germplasm.

The relationship between flowering time and growth responses to drought in the Arabidopsis Landsberg erecta x Antwerp-1 population.

Abstract: Limited water availability is one of the most prominent abiotic constraints to plant survival and reproduction. Thus, plants have evolved different strategies to cope with water deficit, including modification of their growth and timing of developmental events such as flowering. In this work, we explore the link between flowering time and growth responses to moderate drought stress in Arabidopsis thaliana using natural variation for these traits found in the Landsberg erecta x Antwerp-1 recombinant inbred line population. We developed and phenotyped near isogenic lines containing different allelic combinations at three interacting quantitative trait loci (QTL) affecting both flowering time and growth in response to water deficit. We used these lines to confirm additive and epistatic effects of the three QTL and observed a strong association between late flowering and reduced sensitivity to drought. Analyses of growth responses to drought over time revealed that late flowering plants were able to recover their growth in the second half of their vegetative development. In contrast, early flowering, a common drought escape strategy that ensures plant survival under severe water deficit, was associated with strongly impaired plant fitness. The results presented here indicate that late flowering may be advantageous under continuous mild water deficit as it allows stress acclimatization over time.

Functional analysis of the Landsberg erecta allele of FRIGIDA

Abstract: Background: Most of the natural variation in flowering time in Arabidopsis thaliana can be attributed to allelic variation at the gene FRIGIDA (FRI, AT4G00650), which activates expression of the floral repressor FLOWERING LOCUS C (FLC, AT5G10140). Usually, late-flowering accessions carry functional FRI alleles (FRI-wt), whereas early flowering accessions contain non-functional alleles. The two most frequent alleles found in early flowering accessions are the ones present in the commonly used lab strains Columbia (FRI-Col) and Landsberg erecta (FRI-Ler), which contain a premature stop codon and a deletion of the start codon respectively. Results: Analysis of flowering time data from various Arabidopsis natural accessions indicated that the FRI-Ler allele retains some functionality. We generated transgenic lines carrying the FRI-Col or FRI-Ler allele in order to compare their effect on flowering time, vernalization response and FLC expression in the same genetic background. We characterize their modes of regulation through allele-specific expression and their relevance in nature through re-analysis of published datasets. We demonstrate that the FRI-Ler allele induces FLC expression, delays flowering time and confers sensitivity to vernalization in contrast to the true null FRI-Col allele. Nevertheless, the FRI-Ler allele revealed a weaker effect when compared to the fully functional FRI-wt allele, mainly due to reduced expression. Conclusions: The present study defines for the first time the existence of a new class of Arabidopsis accessions with an intermediate phenotype between slow and rapid cycling types. Although using available data from a common garden experiment we cannot observe fitness differences between accessions carrying the FRI-Ler or the FRI-Col allele, the phenotypic changes observed in the lab suggest that variation in these alleles could play a role in adaptation to specific natural environments.