Genome of wild olive and the evolution of oil biosynthesis.

Here we present the genome sequence and annotation of the wild olive tree (Olea europaea var. sylvestris), called oleaster, which is considered an ancestor of cultivated olive trees. More than 50,000 protein-coding genes were predicted, a majority of which could be anchored to 23 pseudochromosomes obtained through a newly constructed genetic map. The oleaster genome contains signatures of two Oleaceae lineage-specific paleopolyploidy events, dated at ∼28 and ∼59 Mya. These events contributed to the expansion and neofunctionalization of genes and gene families that play important roles in oil biosynthesis. The functional divergence of oil biosynthesis pathway genes, such as FAD2, SACPD, EAR, and ACPTE, following duplication, has been responsible for the differential accumulation of oleic and linoleic acids produced in olive compared with sesame, a closely related oil crop. Duplicated oleaster FAD2 genes are regulated by an siRNA derived from a transposable element-rich region, leading to suppressed levels of FAD2 gene expression. Additionally, neofunctionalization of members of the SACPD gene family has led to increased expression of SACPD2, 3, 5, and 7, consequently resulting in an increased desaturation of steric acid. Taken together, decreased FAD2 expression and increased SACPD expression likely explain the accumulation of exceptionally high levels of oleic acid in olive. The oleaster genome thus provides important insights into the evolution of oil biosynthesis and will be a valuable resource for oil crop genomics.

Molecular and ecological investigations on the wild populations of Glycyrrhiza L. taxa distributed in the East Mediterranean Area of Turkey.

This paper covers studies on the molecular and ecological aspects of G. glabra var. glandulifera, G. flavescens ssp. flavescens and G. echinata collected from Hatay (Turkey); with the aim to better understand their genetic variation and ecological requirements for possible conservation programs. The material including total genomic DNA was extracted by the CTAB, and for PCR reaction, a total of 14 SSR primers developed for Medicago truncatula were used. PCR amplifications were performed in a Multigen® Thermal Cycler. Soil samples were analysed for their texture, pH, total soluble salts, calcium carbonate, total N content, total phosphorus and organic matter content. In order to see the association between genetic, ecological and geographical data, a similarity matrix was generated. Genetic similarity distances between genotypes were correlated with those of Eucledian distances obtained from ecological and geographical data. Analysis of molecular variance (AMOVA) was performed using GenAlEx 6.5 software to determine variation among and within genetic variations. The genetic analysis showed that the highest expected heterozygosity values were obtained from G. glabra while the lowest were obtained from G. echinata. In general heterozygosity values were low, especially for G. echinata. Therefore, variation appears to be lower within each species than among three species. The physical and chemical analysis of soil and plant samples indicates that mineral accumulation in plants is substantially affected by the soil characteristics. There is a need for identification of better strategies for the improvement of varieties, especially for small farmers managing marginal soils. More studies should be conducted in order to safeguard these taxa, especially G. glabra var. glandulifera which is collected intensively due to its economic value, the same is true for endemic taxon G. flavescens ssp. flavescens.

Genome-wide identification of salinity responsive HSP70s in common bean.

The present study is aimed to identify and characterize HSP70 (PvHSP70) genes in two different common bean cultivars under salt stress. For this purpose various in silico methods such as RNAseq data and qRT-PCR analysis were used. A total of 24 candidate PvHSP70 gene were identified. Except for chromosome 4 and 7, these candidate PvHSP70 genes were distributed on the remaining chromosomes. While the lowest number of PvHSP70 genes was determined on chromosomes 1, 3, 5, 7, 9, 10 and 11 (one HSP70 gene), the highest number of PvHSP70s was on chromosomes 6 and 8 (seven HSP70 genes each). Three genes; PvHSP70-5, -9, and -10 were found to have no-introns. In addition, four tandemly and six segmentally duplicated gene couples were detected. A total of 13 PvHSP70 genes were targeted by miRNAs of 44 plant species and the most targeted genes were PvHSP70-5 and -23. The expression profile of PvHSP70 genes based on publicly available RNA-seq data was identified and salt treated leaf tissue was found to have more gene expression levels compared to the root. qRT-PCR analysis showed that the transcript concentrations of upregulated PvHSP70 genes in leaves of Zulbiye (sensitive) were mostly higher than those of Yakutiye (resistant). The present study revealed that PvHSP70 genes might play an important role in salt stress response for common bean cultivars and variability between cultivars also suggests that these genes could be used as functional markers for salt tolerance in common bean.

Transcriptome analysis of wheat inoculated with Fusarium graminearum.

Plants are frequently exposed to microorganisms like fungi, bacteria, and viruses that cause biotic stresses. Fusarium head blight (FHB) is an economically risky wheat disease, which occurs upon Fusarium graminearum (Fg) infection. Moderately susceptible (cv. "Mizrak 98") and susceptible (cv. "Gun 91") winter type bread wheat cultivars were subjected to transcriptional profiling after exposure to Fg infection. To examine the early response to the pathogen in wheat, we measured gene expression alterations in mock and pathogen inoculated root crown of moderately susceptible (MS) and susceptible cultivars at 12 hours after inoculation (hai) using 12X135K microarray chip. The transcriptome analyses revealed that out of 39,179 transcripts, 3668 genes in microarray were significantly regulated at least in one time comparison. The majority of differentially regulated transcripts were associated with disease response and the gene expression mechanism. When the cultivars were compared, a number of transcripts and expression alterations varied within the cultivars. Especially membrane related transcripts were detected as differentially expressed. Moreover, diverse transcription factors showed significant fold change values among the cultivars. This study presented new insights to understand the early response of selected cultivars to the Fg at 12 hai. Through the KEGG analysis, we observed that the most altered transcripts were associated with starch and sucrose metabolism and gluconeogenesis pathways.

Genome-wide fungal stress responsive miRNA expression in wheat.

MicroRNAs (miRNAs) are small non-coding class of RNAs. They were identified in many plants with their diverse regulatory roles in several cellular and metabolic processes. A number of miRNAs were involved in biotic and abiotic stress responses. Here, fungal stress responsive wheat miRNAs were analyzed by using miRNA-microarray strategy. Two different fungi (Fusarium culmorum and Bipolaris sorokiniana) were inoculated on resistant and sensitive wheat cultivars. A total of 87 differentially regulated miRNAs were detected in the 8 × 15 K array including all of the available plant miRNAs. Using bioinformatics tools, the target transcripts of responsive miRNAs were predicted, and related biological processes and mechanisms were assessed. A number of the miRNAs such as miR2592s, miR869.1, miR169b were highly differentially regulated showing more than 200-fold change upon fungal-inoculation. Some of the miRNAs were identified as fungal-inoculation responsive for the first time. The analyses showed that some of the differentially regulated miRNAs targeted resistance-related genes such as LRR, glucuronosyl transferase, peroxidase and Pto kinase. The comparison of the two miRNA-microarray analyses indicated that fungal-responsive wheat miRNAs were differentially regulated in pathogen- and cultivar-specific manners.

High-density mapping and comparative analysis of agronomically important traits on wheat chromosome 3A.

Bread wheat chromosome 3A has been shown to contain genes/QTLs controlling grain yield and other agronomic traits. The objectives of this study were to generate high-density physical and genetic-linkage maps of wheat homoeologous group 3 chromosomes and reveal the physical locations of genes/QTLs controlling yield and its component traits, as well as agronomic traits, to obtain a precise estimate of recombination for the corresponding regions and to enrich the QTL-containing regions with markers. Physical mapping was accomplished by 179 DNA markers mostly representing expressed genes using 41 single-break deletion lines. Polymorphism survey of cultivars Cheyenne (CNN) and Wichita (WI), and a substitution line of CNN carrying chromosome 3A from WI [CNN(WI3A)], with 142 RFLP probes and 55 SSR markers revealed that the extent of polymorphism is different among various group 3 chromosomal regions as well as among the homoeologs. A genetic-linkage map for chromosome 3A was developed by mapping 17 QTLs for seven agronomic traits relative to 26 RFLP and 15 SSR chromosome 3A-specific markers on 95 single-chromosome recombinant inbred lines. Comparison of the physical maps with the 3A genetic-linkage map localized the QTLs to gene-containing regions and accounted for only about 36% of the chromosome. Two chromosomal regions containing 9 of the 17 QTLs encompassed less than 10% of chromosome 3A but accounted for almost all of the arm recombination. To identify rice chromosomal regions corresponding to the particular QTL-containing wheat regions, 650 physically mapped wheat group 3 sequences were compared with rice genomic sequences. At an E value of E < or = 10(-5), 82% of the wheat group 3 sequences identified rice homologs, of which 54% were on rice chromosome 1. The rice chromosome 1 region collinear with the two wheat regions that contained 9 QTLs was about 6.5 Mb.

Analysis of recombination and gene distribution in the 2L1.0 region of wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.).

Both wheat and barley belong to tribe Triticeae and are closely related. High-density detailed comparison of physical and genetic linkage maps revealed that wheat genes are present in physically small gene-rich regions (GRRs). One of the largest GRRs is located around fraction length 1.0 of the long arm of wheat homoeologous group 2 chromosomes termed the "2L1.0 region." The main objective of this study was to analyze the structural and functional organization of the 2L1.0 region in barley in comparison to wheat. Using the 29 physically mapped RFLP markers for the region, wheat and barley consensus genetic linkage maps of the 2L1.0 region were generated by combining information from 18 wheat and 7 barley genetic linkage maps. Comparative analysis using these consensus maps and other available wheat and barley mapping resources identified 227 DNA markers and ESTs for the region. The region accounted for 58% of the genes and 68% of the arm's recombination in wheat. However, the corresponding region in barley accounted for about 42% of the genes and 81% of the recombination. The kb/cM ratio for the region was 122 in barley compared to 244 in wheat. Distribution of genes and recombination varied between the two species even though the gene order and density were similar.

Demarcating the gene-rich regions of the wheat genome.

By physically mapping 3025 loci including 252 phenotypically characterized genes and 17 quantitative trait loci (QTLs) relative to 334 deletion breakpoints, we localized the gene-containing fraction to 29% of the wheat genome present as 18 major and 30 minor gene-rich regions (GRRs). The GRRs varied both in gene number and density. The five largest GRRs physically spanning <3% of the genome contained 26% of the wheat genes. Approximate size of the GRRs ranged from 3 to 71 Mb. Recombination mainly occurred in the GRRs. Various GRRs varied as much as 128-fold for gene density and 140-fold for recombination rates. Except for a general suppression in 25-40% of the chromosomal region around centromeres, no correlation of recombination was observed with the gene density, the size, or chromosomal location of GRRs. More than 30% of the wheat genes are in recombination-poor regions thus are inaccessible to map-based cloning.

Identification of wheat chromosomal regions containing expressed resistance genes.

The objectives of this study were to isolate and physically localize expressed resistance (R) genes on wheat chromosomes. Irrespective of the host or pest type, most of the 46 cloned R genes from 12 plant species share a strong sequence similarity, especially for protein domains and motifs. By utilizing this structural similarity to perform modified RNA fingerprinting and data mining, we identified 184 putative expressed R genes of wheat. These include 87 NB/LRR types, 16 receptor-like kinases, and 13 Pto-like kinases. The remaining were seven Hm1 and two Hs1(pro-1) homologs, 17 pathogenicity related, and 42 unique NB/kinases. About 76% of the expressed R-gene candidates were rare transcripts, including 42 novel sequences. Physical mapping of 121 candidate R-gene sequences using 339 deletion lines localized 310 loci to 26 chromosomal regions encompassing approximately 16% of the wheat genome. Five major R-gene clusters that spanned only approximately 3% of the wheat genome but contained approximately 47% of the candidate R genes were observed. Comparative mapping localized 91% (82 of 90) of the phenotypically characterized R genes to 18 regions where 118 of the R-gene sequences mapped.