In two arid/semiarid regions, we studied diversity of algae in lakes and pools with salinity ranging from 0.1‰ up to 39‰ In plankton and periphyton of 34 lakes in northern Kazakhstan, we found 252 species belonging to 113 genera of 8 algal divisions. In 24 pools with experimental salinity ranges in the Negev desert of Israel, we recorded 86 species from 47 genera of 6 algal divisions. The dominant groups of both arid regions are represented by widespread species of diatoms, green algae, and cyanobacteria in similar proportions. Alkaliphiles among the indicators of acidification and betamesosaprobionts among the indicators of saprobity prominently prevail in both regions. The indices of saprobity in lakes (1.48–2.7) and in pools (0.75–2.18) reflect a low-trophic loading. Oligohalobes-indifferents are most common in both arid regions. Cluster analysis based on data containing 420 species revealed 9 clusters, of which the highly diverse communities of low mineralized lakes and pools and the low diversity communities of highly-mineralized lakes and pools are separated at the highest dissimilarity level. CCA analysis revealed correlation of the algal species diversity preferences with salinity level in lakes in Kazakhstan and in pools of Israel, which are more impacted by arid factors. These results point to mineralization being the most important variable defining the diversity levels irrespective of the type and location of reservoirs in the arid regions.
Authors:C. Li, X. Ma, A. Wang, E. Nevo, and G. Chen
The aerial surface of land plants is protected by a cuticle against abiotic and biotic stresses. A better understanding of the determinants of cuticle formation and function has the potential to contribute to the breeding of more drought tolerant and disease resistant crop varieties. Two doubled haploid (DH) mapping populations, Steptoe × Morex populations and OWB-dominant × recessive populations were exploited to genetically position homologs of a set of known cuticle-associated genes. These genes were also placed on a consensus map, BinMap2005, which includes 27 eceriferum (cer) loci. Of the 49 known cuticle-associated genes, 21 identified a homolog in barley, and of these, 14 were mapped. There was a complete linkage between HvCER6 and cer-zg, suggesting the possibility that HvCER6 is the candidate gene of CER-ZG. Positioning known cuticle-associated genes on a consensus map containing cuticle mutant loci may guide the selection of candidate genes for cuticle mutants, and thus facilitate the isolation of cuticle-associated genes in barley.
Triticum dicoccoides, wild emmer wheat, is the direct progenitor of cultivated wheats, has the same genome formula as durum wheat, and has contributed two genomes to bread wheat. It harbors many useful genes, more than can be used for wheat improvement. These genes are associated with many agronomic traits, abiotic stress tolerances, biotic stress resistances, grain protein content and micronutrient mineral concentrations. In this review, we summarized the achievements regarding gene discovery, i.e. gene identification, mapping and cloning in wild emmer wheat. These genes, controlling important agronomic traits, disease resistance, drought tolerance, high protein content and micronutrient mineral content, should be very useful for improvement of wheat production and food nutrition. However, the majority of genetic resources in wild emmer remain untapped, demonstrating the need for further exploration and utilization for wheat breeding programs. The large number of molecular markers, genomics tools and efficient cloning techniques available for wheat will greatly accelerate the application of wild emmer germplasm to wheat improvement and ensure sustainability of global wheat production.