Importance of Landraces in Cereal Breeding for Stress Tolerance.

The renewed focus on cereal landraces is a response to some negative consequences of modern agriculture and conventional breeding which led to a reduction of genetic diversity. Cereal landraces are still cultivated on marginal lands due to their adaptability to unfavourable conditions, constituting an important source of genetic diversity usable in modern plant breeding to improve the adaptation to abiotic or biotic stresses, yield performance and quality traits in limiting environments. Traditional agricultural production systems have played an important role in the evolution and conservation of wide variability in gene pools within species. Today, on-farm and ex situ conservation in gene bank collections, together with data sharing among researchers and breeders, will greatly benefit cereal improvement. Many efforts are usually made to collect, organize and phenotypically and genotypically analyse cereal landrace collections, which also utilize genomic approaches. Their use in breeding programs based on genomic selection, and the discovery of beneficial untapped QTL/genes/alleles which could be introgressed into modern varieties by MAS, pyramiding or biotechnological tools, increase the potential for their better deployment and exploitation in breeding for a more sustainable agricultural production, particularly enhancing adaptation and productivity in stress-prone environments to cope with current climate changes.

Regulation and Evolution of NLR Genes: A Close Interconnection for Plant Immunity.

NLR (NOD-like receptor) genes belong to one of the largest gene families in plants. Their role in plants' resistance to pathogens has been clearly described for many members of this gene family, and dysregulation or overexpression of some of these genes has been shown to induce an autoimmunity state that strongly affects plant growth and yield. For this reason, these genes have to be tightly regulated in their expression and activity, and several regulatory mechanisms are described here that tune their gene expression and protein levels. This gene family is subjected to rapid evolution, and to maintain diversity at NLRs, a plethora of genetic mechanisms have been identified as sources of variation. Interestingly, regulation of gene expression and evolution of this gene family are two strictly interconnected aspects. Indeed, some examples have been reported in which mechanisms of gene expression regulation have roles in promotion of the evolution of this gene family. Moreover, co-evolution of the NLR gene family and other gene families devoted to their control has been recently demonstrated, as in the case of miRNAs.

Molecular Approaches to Genetically Improve the Accumulation of Health-Promoting Secondary Metabolites in Staple Crops-A Case Study: The Lipoxygenase-B1 Genes and Regulation of the Carotenoid Content in Pasta Products.

Secondary metabolites, also known as phytochemicals, represent a large subset of plant molecules that include compounds with health-promoting effects. Indeed, a number of epidemiological studies have shown that, when taken regularly and in adequate amounts, these molecules can have long-term beneficial effects on human health, through reduction of the incidence of degenerative diseases, such as cardiovascular diseases, obesity, diabetes, and cancer. As the dietary intake of these phytochemicals is often inadequate, various strategies are in use to improve their content in staple crops, and the end-products thereof. One of the most effective strategies is crop improvement through genetic approaches, as this is the only way to generate new cultivars in which the high accumulation of a given phytochemical is stably fixed. Efforts to genetically improve quality traits are rapidly evolving, from classical breeding to molecular-assisted approaches; these require sound understanding of the molecular bases underlying the traits, to identify the genes/alleles that control them. This can be achieved through global analysis of the metabolic pathway responsible for phytochemical accumulation, to identify the link between phytochemical content and the activities of key enzymes that regulate the metabolic pathway, and between the key enzymes and their encoding genes/alleles. Once these have been identified, they can be used as markers for selection of new improved genotypes through biotechnological approaches. This review provides an overview of the major health-promoting properties shown to be associated with the dietary intake of phytochemicals, and describes how molecular approaches provide means for improving the health quality of edible crops. Finally, a case study is illustrated, of the identification in durum wheat of the Lipoxygenase-B1 genes that control the final carotenoid content in semolina-based foods, such as pasta products.

Recombinant Lipases and Phospholipases and Their Use as Biocatalysts for Industrial Applications.

Lipases and phospholipases are interfacial enzymes that hydrolyze hydrophobic ester linkages of triacylglycerols and phospholipids, respectively. In addition to their role as esterases, these enzymes catalyze a plethora of other reactions; indeed, lipases also catalyze esterification, transesterification and interesterification reactions, and phospholipases also show acyltransferase, transacylase and transphosphatidylation activities. Thus, lipases and phospholipases represent versatile biocatalysts that are widely used in various industrial applications, such as for biodiesels, food, nutraceuticals, oil degumming and detergents; minor applications also include bioremediation, agriculture, cosmetics, leather and paper industries. These enzymes are ubiquitous in most living organisms, across animals, plants, yeasts, fungi and bacteria. For their greater availability and their ease of production, microbial lipases and phospholipases are preferred to those derived from animals and plants. Nevertheless, traditional purification strategies from microbe cultures have a number of disadvantages, which include non-reproducibility and low yields. Moreover, native microbial enzymes are not always suitable for biocatalytic processes. The development of molecular techniques for the production of recombinant heterologous proteins in a host system has overcome these constraints, as this allows high-level protein expression and production of new redesigned enzymes with improved catalytic properties. These can meet the requirements of specific industrial process better than the native enzymes. The purpose of this review is to give an overview of the structural and functional features of lipases and phospholipases, to describe the recent advances in optimization of the production of recombinant lipases and phospholipases, and to summarize the information available relating to their major applications in industrial processes.

Different stress responsive strategies to drought and heat in two durum wheat cultivars with contrasting water use efficiency.

BACKGROUND: Durum wheat often faces water scarcity and high temperatures, two events that usually occur simultaneously in the fields. Here we report on the stress responsive strategy of two durum wheat cultivars, characterized by different water use efficiency, subjected to drought, heat and a combination of both stresses. RESULTS: The cv Ofanto (lower water use efficiency) activated a large set of well-known drought-related genes after drought treatment, while Cappelli (higher water use efficiency) showed the constitutive expression of several genes induced by drought in Ofanto and a modulation of a limited number of genes in response to stress. At molecular level the two cvs differed for the activation of molecular messengers, genes involved in the regulation of chromatin condensation, nuclear speckles and stomatal closure. Noteworthy, the heat response in Cappelli involved also the up-regulation of genes belonging to fatty acid ß-oxidation pathway, glyoxylate cycle and senescence, suggesting an early activation of senescence in this cv. A gene of unknown function having the greatest expression difference between the two cultivars was selected and used for expression QTL analysis, the corresponding QTL was mapped on chromosome 6B. CONCLUSION: Ofanto and Cappelli are characterized by two opposite stress-responsive strategies. In Ofanto the combination of drought and heat stress led to an increased number of modulated genes, exceeding the simple cumulative effects of the two single stresses, whereas in Cappelli the same treatment triggered a number of differentially expressed genes lower than those altered in response to heat stress alone. This work provides clear evidences that the genetic system based on Cappelli and Ofanto represents an ideal tool for the genetic dissection of the molecular response to drought and other abiotic stresses.