Differential Dynamic Changes of Reduced Trait Model for Analyzing the Plastic Response to Drought Phases: A Case Study in Spring Wheat

Current limited water availability due to climate changes results in severe drought stress and desiccation in plants. Phenotyping drought tolerance remains challenging. In particular, our knowledge about the discriminating power of traits for capturing a plastic phenotype in high-throughput settings is scant. The study is designed to investigate the differential performance and broad-sense heritability of a battery set of morphological, physiological, and cellular traits to understand the adaptive phenotypic response to drought in spring wheat during the tillering stage. The potential of peroxisome abundance to predict the adaptive response under severe drought was assessed using a high-throughput technique for peroxisome quantification in plants. The research dissected the dynamic changes of some phenological traits during three successive phases of drought using two contrasting genotypes of adaptability to drought. The research demonstrates 5 main findings: (1) a reduction of the overall dimension of the phenological traits for robust phenotyping of the adaptive performance under drought; (2) the abundance of peroxisomes in response to drought correlate negatively with grain yield; (3) the efficiency of ROS homeostasis through peroxisome proliferation which seems to be genetically programmed; and (4) the dynamics of ROS homeostasis seems to be timing dependent mechanism, the tolerant genotype response is earlier than the susceptible genotype. This work will contribute to the identification of robust plastic phenotypic tools and the understanding of the mechanisms for adaptive behavior under drought conditions.Summary statementThis study presents the estimated broad-sense heritability of 24 phenological traits under drought compared with non-stressed conditions. The results demonstrated a reduced model of the overall dimension of the phenological traits for phenotyping drought tolerant response including a novel trait (peroxisome abundance). Also, it displays that the adaptive mechanism through peroxisomes proliferation that is a genetic-dependent manner and related to the stress phase, since tolerant plants can sense the stress and maintain the cellular balance earlier than the sensitive plants

Quantitative Trait Loci Associated with Milling and Baking Quality in a Soft X Hard Wheat Cross

Interclass hybridization between soft and hard wheat (Triticum aestivum L.) results in new genetic combinations of potential value

Large deletions in the CBF gene cluster at the Fr-B2 locus are associated with reduced frost tolerance in wheat.

Wheat plants which are exposed to periods of low temperatures (cold acclimation) exhibit increased survival rates when they are subsequently exposed to freezing temperatures. This process is associated with large-scale changes in the transcriptome which are modulated by a set of tandemly duplicated C-repeat Binding Factor (CBF) transcription factors located at the Frost Resistance-2 (Fr-2) locus. While Arabidopsis has three tandemly duplicated CBF genes, the CBF family in wheat has undergone an expansion and at least 15 CBF genes have been identified, 11 of which are present at the Fr-2 loci on homeologous group 5 chromosomes. We report here the discovery of three large deletions which eliminate 6, 9, and all 11 CBF genes from the Fr-B2 locus in tetraploid and hexaploid wheat. In wild emmer wheat, the Fr-B2 deletions were found only among the accessions from the southern sub-populations. Among cultivated wheats, the Fr-B2 deletions were more common among varieties with a spring growth habit than among those with a winter growth habit. Replicated freezing tolerance experiments showed that both the deletion of nine CBF genes in tetraploid wheat and the complete Fr-B2 deletion in hexaploid wheat were associated with significant reductions in survival after exposure to freezing temperatures. Our results suggest that selection for the wild-type Fr-B2 allele may be beneficial for breeders selecting for varieties with improved frost tolerance

Large deletions in the CBF gene cluster at the Fr-B2 locus are associated with reduced frost tolerance in wheat

Wheat plants which are exposed to periods of low temperatures (cold acclimation) exhibit increased survival rates when they are subsequently exposed to freezing temperatures. This process is associated with large-scale changes in the transcriptome which are modulated by a set of tandemly duplicated CBF ( C-repeat Binding Factor ) transcription factors located at the Fr-2 ( Frost Resistance-2 ) locus. While Arabidopsis has three tandemly duplicated CBF genes, the CBF family in wheat has undergone an expansion and at least 15 CBF genes have been identified, eleven of which are present at the Fr-2 loci on homoeologous group 5 chromosomes. We report here the discovery of three large deletions which eliminate six, nine, and all eleven CBF genes from the Fr-B2 locus in tetraploid and hexaploid wheat. In wild emmer wheat, the Fr-B2 deletions were found only among the accessions from the southern sub-populations. Among cultivated wheats, the Fr-B2 deletions were more common among varieties with a spring growth habit than among those with a winter growth habit. Replicated freezing tolerance experiments showed that both the deletion of nine CBF genes in tetraploid wheat and the complete Fr-B2 deletion in hexaploid wheat are associated with significant reductions in survival after exposure to freezing temperatures. Our results suggest that selection for the wild type Fr-B2 allele may be beneficial for breeders selecting for varieties with improved frost tolerance