Repeatability of adaptation in sunflowers reveals that genomic regions harbouring inversions also drive adaptation in species lacking an inversion.

Local adaptation commonly involves alleles of large effect, which experience fitness advantages when in positive linkage disequilibrium (LD). Because segregating inversions suppress recombination and facilitate the maintenance of LD between locally adapted loci, they are also commonly found to be associated with adaptive divergence. However, it is unclear what fraction of an adaptive response can be attributed to inversions and alleles of large effect, and whether the loci within an inversion could still drive adaptation in the absence of its recombination-suppressing effect. Here, we use genome-wide association studies to explore patterns of local adaptation in three species of sunflower: Helianthus annuus, Helianthus argophyllus, and Helianthus petiolaris, which each harbour a large number of species-specific inversions. We find evidence of significant genome-wide repeatability in signatures of association to phenotypes and environments, which are particularly enriched within regions of the genome harbouring an inversion in one species. This shows that while inversions may facilitate local adaptation, at least some of the loci can still harbour mutations that make substantial contributions without the benefit of recombination suppression in species lacking a segregating inversion. While a large number of genomic regions show evidence of repeated adaptation, most of the strongest signatures of association still tend to be species-specific, indicating substantial genotypic redundancy for local adaptation in these species.

In plants, like in humans, DNA is arranged into sections known as genes that are in turn organised into structures called chromosomes. Mutations that modify the activity of these genes can help plant species to adapt to a new environment or to extreme conditions such as drought. However, successful adaptation often requires changes in many different genes. If these sets of genes are located close to each other on the same chromosome, any mutations will likely be passed onto the next generation together. If the genes are located further away, or even on different chromosomes, they may instead be inherited separately so that the next generation does not benefit as much from the adaptation. A chromosome inversion ­ when a segment of chromosome breaks off and reattaches the other way around ­ can increase the likelihood that sets of mutations on the same chromosome will be inherited together. Many previous studies have found that chromosome inversions tend to drive the ability of species to adapt to different environments by keeping together mutations that affect the same characteristics. However, it is not clear how inversions affect the repeatability of the adaptation, that is, if another group of closely related plants faced the same challenge in their environment would they evolve in the same way, or would they evolve a new response? To address this question, Soudi, Jahani et al. used a genetics approach known as a genome wide association study to explore how three closely related species of sunflower have adapted to their respective environments. Two of the species grow in various environments across the centre and west of the USA that are often hot and dry, whereas the third species is restricted to the more humid coastal plain of Texas, USA. The experiments found that a few key genes had changed in all three sunflower species. However, each species also had mutations in a larger set of unique genes that were not changed in the other species. Regions of chromosomes harbouring inversions in one of the species tended to have more of the key genes within them, compared to other genomic regions. This was also true for species that did not have inversions in those regions. This demonstrates that genes in regions affected by chromosome inversions can still help plants adapt to changes in the environment even in the absence of inversions. Sunflowers are widely grown for their edible oily seeds. In the future, some of the key genes identified in this work may be useful candidates for plant breeding to improve the resilience of sunflowers to drought, high temperatures and other environmental challenges.

The genomics of linkage drag in inbred lines of sunflower.

Crop wild relatives represent valuable sources of alleles for crop improvement, including adaptation to climate change and emerging diseases. However, introgressions from wild relatives might have deleterious effects on desirable traits, including yield, due to linkage drag. Here, we analyzed the genomic and phenotypic impacts of wild introgressions in inbred lines of cultivated sunflower to estimate the impacts of linkage drag. First, we generated reference sequences for seven cultivated and one wild sunflower genotype, as well as improved assemblies for two additional cultivars. Next, relying on previously generated sequences from wild donor species, we identified introgressions in the cultivated reference sequences, as well as the sequence and structural variants they contain. We then used a ridge-regression best linear unbiased prediction (BLUP) model to test the effects of the introgressions on phenotypic traits in the cultivated sunflower association mapping population. We found that introgression has introduced substantial sequence and structural variation into the cultivated sunflower gene pool, including >3,000 new genes. While introgressions reduced genetic load at protein-coding sequences, they mostly had negative impacts on yield and quality traits. Introgressions found at high frequency in the cultivated gene pool had larger effects than low-frequency introgressions, suggesting that the former likely were targeted by artificial selection. Also, introgressions from more distantly related species were more likely to be maladaptive than those from the wild progenitor of cultivated sunflower. Thus, breeding efforts should focus, as far as possible, on closely related and fully compatible wild relatives.

Genome-Wide Association Mapping in Sunflower (Helianthus annuus) Reveals Common Loci and Putative Candidate Genes for Resistance to Diaporthe gulyae and D. helianthi Causing Phomopsis Stem Canker.

Diaporthe gulyae and D. helianthi cause Phomopsis stem canker of sunflower (Helianthus annuus L.) in the United States. Because Phomopsis stem canker did not gain importance until the disease epidemic in 2010, limited studies were conducted to understand the genetic basis of sunflower resistance to D. gulyae and D. helianthi. The objectives of this study were to evaluate the United States Department of Agriculture cultivated accessions for resistance to D. gulyae and D. helianthi as well as to utilize genome-wide association studies (GWAS) to identify quantitative trait loci (QTLs) and putative candidate genes underlying those loci common to both organisms. For each fungus, 213 accessions were screened in a complete randomized design in the greenhouse and the experiment was repeated once. Six plants per accession were inoculated with a single isolate of D. gulyae or D. helianthi at four to six true leaves using the mycelium-contact inoculation method. At 15 days (D. gulyae) and 30 days (D. helianthi) postinoculation, accessions were evaluated for disease severity and compared with the susceptible confection inbred PI 552934. GWAS identified 28 QTLs common to the two fungi, and 24 genes overlapped close to these QTLs. Additionally, it was observed that the resistance QTLs derived mainly from landraces rather than from wild species. Seventeen putative candidate genes associated with resistance to D. gulyae or D. helianthi were identified that may be related to plant-pathogen interactions. These findings advanced our understanding of the genetic basis of resistance to D. gulyae and D. helianthi and will help develop resources for genomics-assisted breeding.

Role of curcumin on miR-26a and its effect on DNMT1, DNMT3b, and MEG3 expression in A549 lung cancer cell.

CONTEXT: Most of the patients diagnosed with non-small cell lung cancer (NSCLC) are in their advanced stages and as a result might not be cured in spite of the advances in aimed therapy. In the recent years, the role of noncoding RNAs (ncRNAs) has been expanded to cancer as potential targets for RNA-based epigenetic therapies. Curcumin, as an active ingredient, is associated with epigenetic alterations, and it might modulate the expression of tumor suppressor and oncogenic microRNAs. MATERIALS AND METHODS: In this study, we investigated the RNA-based epigenetic effects of curcumin on NSCLC, and the effect of curcumin on A549 cell viability was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The expression of miR-26a, MEG3, DNA methyltransferase 1 (DNMT1), and DNMT3 beta (DNMT3b) was assessed by quantitative polymerase chain reaction. STATISTICAL ANALYSIS USED: Data analysis was done using Prism®6 software (GraphPad Software, Inc., La Jolla, CA, USA), and statistical analysis was performed using t-test between control and vitality samples. RESULTS: The results showed a significant increase (P < 0.05) of miR-26a expression which in turn was associated with a significant decrease (P < 0.05) in expression of DNMTs and subsequently a significant increase in MEG3 expression (P < 0.05) in A549 cell line after adding curcumin in the media. CONCLUSION: Considering all the data together, we could speculate the role of curcumin in ceasing the progression of cancer in its early stages and might be considered a potential drug for the treatment of NSCLC-derived lung cancer by establishing a meaningful relationship between epigenetic mechanisms and ncRNAs.

Expression complementation of gene presence/absence polymorphisms in hybrids contributes importantly to heterosis in sunflower.

INTRODUCTION: Numerous crops have transitioned to hybrid seed production to increase yields and yield stability through heterosis. However, the molecular mechanisms underlying heterosis and its stability across environments are not yet fully understood. OBJECTIVES: This study aimed to (1) elucidate the genetic and molecular mechanisms underlying heterosis in sunflower, and (2) determine how heterosis is maintained under different environments. METHODS: Genome-wide association (GWA) analyses were employed to assess the effects of presence/absence variants (PAVs) and stop codons on 16 traits phenotyped in the sunflower association mapping population at three locations. To link the GWA results to transcriptomic variation, we sequenced the transcriptomes of two sunflower cultivars and their F1 hybrid (INEDI) under both control and drought conditions and analyzed patterns of gene expression and alternative splicing. RESULTS: Thousands of PAVs were found to affect phenotypic variation using a relaxed significance threshold, and at most such loci the "absence" allele reduced values of heterotic traits, but not those of non-heterotic traits. This pattern was strengthened for PAVs that showed expression complementation in INEDI. Stop codons were much rarer than PAVs and less likely to reduce heterotic trait values. Hybrid expression patterns were enriched for the GO category, sensitivity to stimulus, but all genotypes responded to drought similarily - by up-regulating water stress response pathways and down-regulating metabolic pathways. Changes in alternative splicing were strongly negatively correlated with expression variation, implying that alternative splicing in this system largely acts to reinforce expression responses. CONCLUSION: Our results imply that complementation of expression of PAVs in hybrids is a major contributor to heterosis in sunflower, consistent with the dominance model of heterosis. This mechanism can account for yield stability across different environments. Moreover, given the much larger numbers of PAVs in plant vs. animal genomes, it also offers an explanation for the stronger heterotic responses seen in the former.

Genetic basis and dual adaptive role of floral pigmentation in sunflowers.

Variation in floral displays, both between and within species, has been long known to be shaped by the mutualistic interactions that plants establish with their pollinators. However, increasing evidence suggests that abiotic selection pressures influence floral diversity as well. Here, we analyse the genetic and environmental factors that underlie patterns of floral pigmentation in wild sunflowers. While sunflower inflorescences appear invariably yellow to the human eye, they display extreme diversity for patterns of ultraviolet pigmentation, which are visible to most pollinators. We show that this diversity is largely controlled by cis-regulatory variation affecting a single MYB transcription factor, HaMYB111, through accumulation of ultraviolet (UV)-absorbing flavonol glycosides in ligules (the 'petals' of sunflower inflorescences). Different patterns of ultraviolet pigments in flowers are strongly correlated with pollinator preferences. Furthermore, variation for floral ultraviolet patterns is associated with environmental variables, especially relative humidity, across populations of wild sunflowers. Ligules with larger ultraviolet patterns, which are found in drier environments, show increased resistance to desiccation, suggesting a role in reducing water loss. The dual role of floral UV patterns in pollinator attraction and abiotic response reveals the complex adaptive balance underlying the evolution of floral traits.

Flowers are an important part of how many plants reproduce. Their distinctive colours, shapes and patterns attract specific pollinators, but they can also help to protect the plant from predators and environmental stresses. Many flowers contain pigments that absorb ultraviolet (UV) light to display distinct UV patterns ­ although invisible to the human eye, most pollinators are able to see them. For example, when seen in UV, sunflowers feature a 'bullseye' with a dark centre surrounded by a reflective outer ring. The sizes and thicknesses of these rings vary a lot within and between flower species, and so far, it has been unclear what causes this variation and how it affects the plants. To find out more, Todesco et al. studied the UV patterns in various wild sunflowers across North America by considering the ecology and molecular biology of different plants. This revealed great variation between the UV patterns of the different sunflower populations. Moreover, Todesco et al. found that a gene called HaMYB111 is responsible for the diverse UV patterns in the sunflowers. This gene controls how plants make chemicals called flavonols that absorb UV light. Flavonols also help to protect plants from damage caused by droughts and extreme temperatures. Todesco et al. showed that plants with larger bullseyes had more flavonols, attracted more pollinators, and were better at conserving water. Accordingly, these plants were found in drier locations. This study suggests that, at least in sunflowers, UV patterns help both to attract pollinators and to control water loss. These insights could help to improve pollination ­ and consequently yield ­ in cultivated plants, and to develop plants with better resistance to extreme weather. This work also highlights the importance of combining biology on small and large scales to understand complex processes, such as adaptation and evolution.

Massive haplotypes underlie ecotypic differentiation in sunflowers.

Species often include multiple ecotypes that are adapted to different environments1. However, it is unclear how ecotypes arise and how their distinctive combinations of adaptive alleles are maintained despite hybridization with non-adapted populations2-4. Here, by resequencing 1,506 wild sunflowers from 3 species (Helianthus annuus, Helianthus petiolaris and Helianthus argophyllus), we identify 37 large (1-100 Mbp in size), non-recombining haplotype blocks that are associated with numerous ecologically relevant traits, as well as soil and climate characteristics. Limited recombination in these haplotype blocks keeps adaptive alleles together, and these regions differentiate sunflower ecotypes. For example, haplotype blocks control a 77-day difference in flowering between ecotypes of the silverleaf sunflower H. argophyllus (probably through deletion of a homologue of FLOWERING LOCUS T (FT)), and are associated with seed size, flowering time and soil fertility in dune-adapted sunflowers. These haplotypes are highly divergent, frequently associated with structural variants and often appear to represent introgressions from other-possibly now-extinct-congeners. These results highlight a pervasive role of structural variation in ecotypic adaptation.

Correlation Between Tympanosclerosis and Helicobacter pylori.

BACKGROUND: Tympanosclerosis is a condition caused by calcification of tissues in the middle ear mucosa that sometimes results hearing loss. Helicobacter pylori is one of the pathological and etiologic factors in the development of tympanosclerosis. OBJECTIVES: The purpose of this study was to show the role of H. pylori in the different aspects of chronic suppurative otitis media using the polymerase chain reaction (PCR) technique. PATIENTS AND METHODS: This case-control and cross-sectional study was performed on all patients with chronic otitis media, candidates for surgical operations, in 2013. They were allocated into the case group with tympanosclerosis and the control group without tympanosclerosis. During the surgical operation, biopsy was done from middle ear and the samples were studied to see if they contained H. pylori using the PCR method. RESULTS: From a total of 19 patients with tympanosclerosis , 16 cases (84.2%) were H. pylori positive, while in the control group 15 (45.4%) cases out of the 37 cases were H. pylori positive, which showed a significant difference (P = 0.002). Age and gender of the patients, ear dryness and perforation size were not correlated with the presence or absence of H. pylori. CONCLUSIONS: There is a significant correlation between tympanosclerosis and H. pylori (P = 0.002). This correlation can single out H. pylori as a pathological factor in the development of tympanosclerosis; however, further studies are needed to prove this correlation.

Determining the Role of Helicobacter pylori in Chronic Sinus Infections Using the Polymerase Chain Reaction.

BACKGROUND: Helicobacter pylori are becoming increasingly recognized as a possible pathological cause of chronic rhinosinusitis (CRS). OBJECTIVES: Considering the prevalence of CRS and its impact on quality of life, we decided to determine the role of H. pylori in chronic sinus infections by using the PCR technique. PATIENTS AND METHODS: In a case-control analytical epidemiologic survey, the study population was selected by consecutive sampling from patients with CRS undergoing endoscopic sinus surgery during years 2010 - 2012. Patients were divided into two groups. The study group consisted of patients with CRS and the control group consisted of patients with nasal obstruction caused by concha bullosa, without inflammation or infection of the sinuses. Sampling was performed during surgery from the infected tissue and from the middle turbinate mucosa. Eventually, bacterial DNA was extracted and used for the PCR test, in order to isolate H. pylori. RESULTS: Nine patients (18%) with CRS had H. pylori isolated from their samples whereas in the control group, H. pylori were only found in two patients (4%); this difference was statistically significant (P = 0.025). The indicator wasn't statistically significant between males and females. There was no statistical correlation in relative frequency of H. pylori for different age groups (P > 0.05). CONCLUSIONS: There was a significant correlation between CRS and presence of H. pylori in sinonasal mucosa. This relationship may reflect the role of H. pylori as one of the pathogenic factors in the development of CRS. However, further studies are required to confirm this role.

Identification and validation of functional markers in a global rice collection by association mapping.

Recent results indicate that marker-assisted selection is an effective approach to reduce the cost and to improve the efficacy and accuracy of selection in plant breeding. This study was conducted to identify and validate molecular markers linked to important breeding traits by association mapping. The association was evaluated between 81 molecular markers (STS, SSR, Indel, CAPS, and PCR-based SNP) and 15 morphological traits in a global panel of 100 rice (Oryza sativa) accessions. The population structure analysis identified three main subpopulations. Obvious kinship relationships were also detected between the rice accessions. Association analysis was performed based on the mixed linear model by considering population structure and family relatedness. In addition, the false discovery rate method was used to correct the multiple testing. A total of 47 marker-trait associations were identified, including 22 markers for 14 traits. Among all, the polymorphism at the loci DDR-GL was highly associated with grain characters (grain length, grain width, and length/width ratio). In addition, marker RM3148 was responsible for five important traits simultaneously. Results demonstrated that such informative markers can be very useful for rice breeding programs using marker-assisted selection. Moreover, the diverse populations of rice accessions are a valuable resource for association mapping of morphological traits.