Functional analysis of Triticum durum type 1 metallothionein gene (dMT) in response to varying levels of cadmium

The effect of varying levels of cadmium and correlated changes on the expression level of a type 1 metallothionein gene (dMT) were investigated in Triticum durum cv. Balçalı-85. Increasing the cadmium concentration resulted in a decrease in the dry weights of roots and shoots, and the effect was stronger in roots. Roots also showed a higher capacity to accumulate cadmium. Southern blot analyses revealed that the dMT gene, delineated by two exons and a non-coding intron region, exists at a single locus in the T. durum genome. Changes in dMT gene expression during cadmium exposure were monitored by two approaches. Northern blot analyses showed that the transcript level in roots increased upon treatment with increasing cadmium, which was quantified by qRT-PCR as 4.5 fold of the base level at 10 µM Cd. These results show a positive correlation between cadmium exposure and expression of dMT gene in durum wheat, and will provide a basis for studies on the role of type 1 metallothioneins in cadmium response. © 2017, Indian Society for Plant Physiology

Use of a large-scale Triticeae expressed sequence tag resource to reveal gene expression profiles in hexaploid wheat (Triticum aestivum L.).

The US Wheat Genome Project, funded by the National Science Foundation, developed the first large public Triticeae expressed sequence tag (EST) resource. Altogether, 116,272 ESTs were produced, comprising 100,674 5' ESTs and 15 598 3' ESTs. These ESTs were derived from 42 cDNA libraries, which were created from hexaploid bread wheat (Triticum aestivum L.) and its close relatives, including diploid wheat (T. monococcum L. and Aegilops speltoides L.), tetraploid wheat (T. turgidum L.), and rye (Secale cereale L.), using tissues collected from various stages of plant growth and development and under diverse regimes of abiotic and biotic stress treatments. ESTs were assembled into 18,876 contigs and 23,034 singletons, or 41,910 wheat unigenes. Over 90% of the contigs contained fewer than 10 EST members, implying that the ESTs represented a diverse selection of genes and that genes expressed at low and moderate to high levels were well sampled. Statistical methods were used to study the correlation of gene expression patterns, based on the ESTs clustered in the 1536 contigs that contained at least 10 5' EST members and thus representing the most abundant genes expressed in wheat. Analysis further identified genes in wheat that were significantly upregulated (p < 0.05) in tissues under various abiotic stresses when compared with control tissues. Though the function annotation cannot be assigned for many of these genes, it is likely that they play a role associated with the stress response. This study predicted the possible functionality for 4% of total wheat unigenes, which leaves the remaining 96% with their functional roles and expression patterns largely unknown. Nonetheless, the EST data generated in this project provide a diverse and rich source for gene discovery in wheat

Gene structure and expression pattern analysis of three monodehydroascorbate reductase (Mdhar) genes in Physcomitrella patens: Implications for the evolution of the MDHAR family in plants

The original publication can be found at www.springerlink.comThe ascorbate–glutathione pathway plays a major role in the detoxification of reactive oxygen species (ROS) in vascular plants. One of the key enzymes in this pathway is monodehydroascorbate reductase (MDHAR), a FAD enzyme that catalyses the reduction of the monodehydroascorbate radical. To elucidate the evolution and functional role of MDHAR we identified and characterised MDHARs from the moss Physcomitrella patens. Expressed sequence tag (EST) databases containing approximately 100.000 ESTs from Physcomitrella were searched and three isoforms of monodehydroascorbate reductase (PpMDHAR1, PpMDHAR2 and PpMDHAR3) were identified. In vascular plants MDHAR is found in the cytosol, chloroplast, mitochondria and peroxisome. Surprisingly, all three PpMDHARs resembled the cytosolic isoforms from vascular plants lacking the NH ₂-terminal or COOH-terminal extension found in organelle targeted MDHARs. The number and position of introns was also conserved between PpMDHARs and cytosolic MDHARs from vascular plants. Phylogenetic analysis revealed that cytosolic MDHARs are monophyletic in origin and the ancestral gene evolved before the divergence of bryophytes more than 400 million years ago. Transcript analyses showed that expression of PpMdhar1 and PpMdhar3 was increased up to 5-fold under salt stress, osmotic stress or upon exposure to abscisic acid. In contrast, PpMdhar transcription levels were unchanged upon chilling, UV-B exposure or oxidative stress. The conservation of cytosolic MDHAR in the land-plant lineage and the transcriptional upregulation under water deficiency suggest that the evolution of cytosolic MDHAR played an essential role in stress protection for land plants when they inhabited the dry terrestrial environment.Christina Lunde, Ute Baumann, Neil J. Shirley, Damian P. Drew and Geoffrey B. Finche

A Toolbox for Triticeae Genomics

International audienceIn the last two decades, progress in cereal genomics has been remarkable, enabling a better understanding of the structure and function of the cereal genomes. However, significant advances mainly concerned rice and maize, whereas for the Triticeae species, namely wheat, barley and rye, the development of genomic tools and resources has long been hampered by the size and the complexity of their genomes. Recently, new technologies have allowed the development of a toolbox for Triticeae genomics comparable to what is available for rice and maize. Triticeae scientists and breeders can now benefit from a wide range of tools, including molecular markers, genetic maps, EST sequences, microrarrays, BAC libraries and transformation systems that can be applied to structural, functional, evolutionary and comparative genomic studies of the Triticeae genomes

Genomics of tolerance to abiotic stress in the Triticeae

Genomics platforms offer unprecedented opportunities to identify, select and in some cases clone the genes and the quantitative trait loci (QTLs) that govern the tolerance of Triticeae to abiotic stresses and, consequently, grain yield. Transcriptome profiling and the other \u201comics\u201d platforms provide further information to unravel gene functions and validate the role of candidate genes. This review provides a synopsis of the main results on the studies that have investigated the genomics of Triticeae crops under conditions of abiotic constraints. With their rich biodiversity and high functional plasticity in response to environmental stresses, Triticeae crops provide an ideal ground for taking full advantage of the opportunities offered by genomics approaches. Ultimately, the practical impact of the knowledge and materials generated through genomics-based approaches will depend on their integration and exploitation within the extant breeding programs