scholarly journals Analysis of wild plant pathogen populations reveals a signal of adaptation in genes evolving for survival in agriculture in the beet rust pathogen (Uromyces beticola)

2021 ◽  
Author(s):  
Mark McMullan ◽  
Lawrence Percival-Alwyn ◽  
Kevin Sawford ◽  
Gemy Kaithakottil ◽  
Michelle Grey ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Plant Pathogen ◽  
Genetic Resistance ◽  
Fungal Genome ◽  
Wild Plant ◽  
Sources Of Resistance ◽  
Agricultural Plant ◽  
Crop Resistance ◽  
In The Wild ◽  
Pathogen Populations

Improvements in crop resistance to pathogens can reduce yield losses and address global malnourishment today. Gene-for-gene -type interactions can identify new sources of resistance but genetic resistance is often short lived. Ultimately an understanding of how pathogens rapidly adapt will allow us to both increase resistance gene durability and more effectively target chemical treatments. Until recently all agricultural pathogens were living on wild hosts. To understand crop pathogen evolution, we compared genetic diversity in agricultural and wild populations. Wild reservoirs may be the source of emergent pathogen lineages, but here we outline a strategy for comparison of wild and agricultural pathogen populations to highlight genes adapting to agriculture. To address this, we have selected and developed the beet rust system (Beta vulgaris, Uromyces beticola, respectively) as our wild-agricultural model. Our hypothesis is that pathogen adaptation to agricultural crops will be evident as divergence in comparisons of wild and agricultural plant pathogen populations. We sampled isolates in both the wild and agriculture, sequenced and assembled and annotated a large fungal genome and analysed genetic diversity in 42 re-sequenced rust isolates. We found population differentiation between isolates in the wild compared to a predominantly agricultural group. Fungal effector genes are co-evolving with host resistance and are important for successful colonisation. We predicted (and found) that these exhibit a greater signal of diversification and adaptation and more importantly displayed increased wild agricultural divergence. Finding a signal of adaptation in these genes highlights this as an important strategy to identify genes which are key to pathogen success, that analysis of agricultural isolates alone cannot.

scholarly journals Microsatellite analysis reveals low genetic diversity in managed populations of the critically endangered gharial (Gavialis gangeticus) in India

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Surya Prasad Sharma ◽  
Mirza Ghazanfarullah Ghazi ◽  
Suyash Katdare ◽  
Niladri Dasgupta ◽  
Samrat Mondol ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Indian Subcontinent ◽  
Population Decline ◽  
Mitochondrial Control Region ◽  
Critically Endangered ◽  
Term Survival ◽  
Low Level ◽  
Genetic Status ◽  
In The Wild ◽  
Gavialis Gangeticus

AbstractThe gharial (Gavialis gangeticus) is a critically endangered crocodylian, endemic to the Indian subcontinent. The species has experienced severe population decline during the twentieth century owing to habitat loss, poaching, and mortalities in passive fishing. Its extant populations have largely recovered through translocation programmes initiated in 1975. Understanding the genetic status of these populations is crucial for evaluating the effectiveness of the ongoing conservation efforts. This study assessed the genetic diversity, population structure, and evidence of genetic bottlenecks of the two managed populations inhabiting the Chambal and Girwa Rivers, which hold nearly 80% of the global gharial populations. We used seven polymorphic nuclear microsatellite loci and a 520 bp partial fragment of the mitochondrial control region (CR). The overall mean allelic richness (Ar) was 2.80 ± 0.40, and the observed (Ho) and expected (He) heterozygosities were 0.40 ± 0.05 and 0.39 ± 0.05, respectively. We observed low levels of genetic differentiation between populations (FST = 0.039, P < 0.05; G’ST = 0.058, P < 0.05 Jost’s D = 0.016, P < 0.05). The bottleneck analysis using the M ratio (Chambal = 0.31 ± 0.06; Girwa = 0.41 ± 0.12) suggested the presence of a genetic bottleneck in both populations. The mitochondrial CR also showed a low level of variation, with two haplotypes observed in the Girwa population. This study highlights the low level of genetic diversity in the two largest managed gharial populations in the wild. Hence, it is recommended to assess the genetic status of extant wild and captive gharial populations for planning future translocation programmes to ensure long-term survival in the wild.

scholarly journals Evaluation of a Diverse, Worldwide Collection of Wild, Cultivated, and Landrace Pepper (Capsicum annuum) for Resistance to Phytophthora Fruit Rot, Genetic Diversity, and Population Structure

2015 ◽  
Vol 105 (1) ◽  
pp. 110-118 ◽  
Author(s):  
R. P. Naegele ◽  
A. J. Tomlinson ◽  
M. K. Hausbeck
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Phytophthora Capsici ◽  
The United States ◽  
Fruit Rot ◽  
Sources Of Resistance ◽  
Plant Introductions ◽  
Genetic Clusters ◽  
Commercial Breeding ◽  
Moderately Resistant

Pepper is the third most important solanaceous crop in the United States and fourth most important worldwide. To identify sources of resistance for commercial breeding, 170 pepper genotypes from five continents and 45 countries were evaluated for Phytophthora fruit rot resistance using two isolates of Phytophthora capsici. Genetic diversity and population structure were assessed on a subset of 157 genotypes using 23 polymorphic simple sequence repeats. Partial resistance and isolate-specific interactions were identified in the population at both 3 and 5 days postinoculation (dpi). Plant introductions (PIs) 640833 and 566811 were the most resistant lines evaluated at 5 dpi to isolates 12889 and OP97, with mean lesion areas less than Criollo de Morelos. Genetic diversity was moderate (0.44) in the population. The program STRUCTURE inferred four genetic clusters with moderate to very great differentiation among clusters. Most lines evaluated were susceptible or moderately susceptible at 5 dpi, and no lines evaluated were completely resistant to Phytophthora fruit rot. Significant population structure was detected when pepper varieties were grouped by predefined categories of disease resistance, continent, and country of origin. Moderately resistant or resistant PIs to both isolates of P. capsici at 5 dpi were in genetic clusters one and two.

Genetic diversity among potato species as revealed by phenotypic resistances and SSR markers

2013 ◽  
Vol 11 (2) ◽  
pp. 131-139 ◽  
Author(s):  
D. Carputo ◽  
D. Alioto ◽  
R. Aversano ◽  
R. Garramone ◽  
V. Miraglia ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Ssr Markers ◽  
Sources Of Resistance ◽  
Wild Potato Species ◽  
Resistance Response ◽  
Potato Species ◽  
Average Value ◽  
Ssr Analysis ◽  
Efficient Breeding ◽  
Resistant Genotypes

The evolutionary diversity of wild potato species makes them excellent materials for improving the narrow genetic basis of the cultivated potato Solanum tuberosum. Understanding their genetic diversity is important not only to choose the best parents for breeding, but also to design proper crossing schemes and selection strategies. The objectives of this study were to determine the resistance response to Ralstonia solanacearum, Potato virus Y and low temperatures of 21 clones of 12 potato species, and to determine their genetic diversity through simple sequence repeat (SSR) markers. Sources of resistance have been found for all the investigated traits, with high resistance variability not only between but also within species. Combined resistances were also identified, with positive implications for efficient breeding. SSR analysis allowed the detection of 12 loci and 46 alleles across all genotypes, with an average value of 3.8 alleles per locus. Both unique and rare alleles useful for marker-assisted selection were found. SSR-based cluster analysis revealed that resistant genotypes were distributed among all clusters, suggesting that genetically different resistant genotypes were identified. The information obtained in this study is discussed from a breeding perspective.

scholarly journals Genotypic diversity among brazilian isolates of Macrophomina phaseolina revealed by RAPD

2003 ◽  
Vol 28 (3) ◽  
pp. 279-285 ◽  
Author(s):  
Álvaro M. R. Almeida ◽  
Ricardo V. Abdelnoor ◽  
Carlos A. Arrabal Arias ◽  
Valdemar P. Carvalho ◽  
David S. Jacoud Filho ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Crop Rotation ◽  
Genetic Resistance ◽  
Its Region ◽  
Genotypic Diversity ◽  
Macrophomina Phaseolina ◽  
Tropical Regions ◽  
Single Root ◽  
Average Similarity ◽  
Upgma Cluster Analysis

Macrophomina phaseolina has been considered one of the most prevalent soybean (Glycine max) pathogens in Brazil. No genetic resistance has been determined in soybean and very little is known about the genetic diversity of this pathogen in tropical and sub-tropical regions. Fifty-five isolates from soybean roots were collected in different regions and analyzed through RAPD for genetic diversity. The UPGMA cluster analysis for 74 loci scored permitted identification of three divergent groups with an average similarity of 99%, 92% and 88%, respectively. The three groups corresponded to 5.45%, 59.95% and 34.6%, respectively of all isolates used. A single plant had three different haplotypes, while 10.9% of the analyzed plants had two different haplotypes. In another study the genetic similarity was evaluated among isolates from different hosts [soybean, sorghum (Sorghum bicolor), sunflower (Helianthus annuus), cowpea (Vigna unguiculata), corn (Zea mays) and wheat (Triticum aestivum)] as well as two soil samples from native areas. Results showed that more divergent isolates originated from areas with a single crop. Isolates from areas with crop rotation were less divergent, showing high similarity values and consequently formed the largest group. Amplification of the ITS region using primers ITS1 and ITS4 produced only one DNA fragment of 620 bp. None of the isolates were differentiated through PCR-RFLP. Our results demonstrated genetic variability among Brazilian isolates of M. phaseolina and showed that one single root can harbor more than one haplotype. Moreover, cultivation with crop rotation tends to induce less specialization of the pathogen isolates. Knowledge of this variation may be useful in screening soybean genotypes for resistance to charcoal rot.

scholarly journals Evidence for the partial dominance of viability genes contributing to inbreeding depression in Mimulus guttatus.

Genetics ◽  
1994 ◽  
Vol 136 (1) ◽  
pp. 323-331
Author(s):  
Y B Fu ◽  
K Ritland
Keyword(s):  
Inbreeding Depression ◽  
Wild Plant ◽  
Mimulus Guttatus ◽  
Selfed Progeny ◽  
Partial Dominance ◽  
Complete Dominance ◽  
Model Free ◽  
Segregation Ratios ◽  
Marker Loci ◽  
In The Wild

Abstract The relative importance of different modes of gene expression of viability genes contributing to inbreeding depression was investigated in the wild plant, Mimulus guttatus. Viability genes were identified by self-fertilizing 31 outbred plants, each heterozygous for three to nine unlinked allozyme markers, and analyzing segregation ratios of selfed progeny at maturity for deviations from 1:2:1 ratios. In this study, 24 linkages of viability genes to marker loci were detected. To infer the nature of gene action for these viability genes, a "model-free" graphical method was developed that examines the "space" of segregation ratios allowed by each of seven selection models (i.e., overdominance, complete recessivity, partial recessivity, additivity, partial dominance, complete dominance and underdominance). Using this method, we found that, of 24 linkages detected, 18 were consistent with either partial dominance, complete dominance or underdominance. Six were consistent with either partial recessivity, complete recessivity or overdominance. This finding indicates that, in these chromosomal segments identified by allozyme markers, partial dominance plays the predominant role in inbreeding depression. This is inconsistent with either the dominance or overdominance hypotheses proposed to account for inbreeding depression.

scholarly journals DNA BARCODING USING COI GENE SEQUENCES OF WILD BETTA FIGHTING FISH FROM INDONESIA: PHYLOGENY, STATUS AND DIVERSITY

2020 ◽  
Vol 26 (2) ◽  
pp. 97
Author(s):  
Melta R. Fahmi ◽  
Eni Kusrini ◽  
Erma P. Hayuningtiyas ◽  
Shofihar Sinansari ◽  
Rudhy Gustiano
Keyword(s):  
Genetic Diversity ◽  
Genetic Distance ◽  
Dna Sequences ◽  
Phylogenetic Relationships ◽  
Gene Sequence ◽  
Ornamental Fish ◽  
Coi Gene ◽  
Tree Construction ◽  
In The Wild ◽  
Blast Program

The wild betta fish is a potential ornamental fish export commodity normally caught by traders or hobbyists in the wild. However, the population of wild betta in nature has declined and become a threat for their sustainability. This research was conducted to analyze the genetic diversity, phylogenetic relationships, and molecular identification through DNA COI gene sequence of Indonesian wild betta fish. A total of 92 wild betta fish specimens were collected in this study. Amplification of COI genes was carried out using Fish F1, Fish R1, Fish F2, and Fish R2 primers. The genetic diversity and phylogenetic relationships were analyzed using MEGA version 5 software program. Species identification of the specimen was conducted using BLAST program with 98-100% similarity value of the DNA sequences to indicate the same species. Phylogenetic tree construction showed seven monophyletic clades and showed that Betta smaragdina was the ancestral species of genus Betta in Indonesian waters. Genetic distance among species ranged from 0.02 to 0.30, whereas intra-species genetic distance ranged from 0 to 6.54.

Techniques and key issues in collecting crop wild relatives

2021 ◽  
pp. 155-184
Author(s):  
Michael Way ◽  
Keyword(s):  
Genetic Diversity ◽  
Best Practice ◽  
Seed Quality ◽  
Crop Wild Relatives ◽  
Wild Relatives ◽  
Wild Plant ◽  
Genetic Sampling ◽  
Key Issues ◽  
Essential Resource ◽  
Seed Collections

The genetic diversity found in populations of crop wild relatives is an essential resource for future crop breeding, but populations are at risk of loss before germplasm has been fully conserved in genebanks. This chapter describes best practice for targeting and identifying species, and review knowledge about the variation in wild plant populations to guide the timing of collecting and approaches for genetic sampling. Indicators are presented for seed quality, ripeness and dispersal. Techniques for collection of seed, herbarium vouchers and associated data are reviewed with examples drawn from the Adapting Agriculture to Climate Change (Crop Wild Relative) project. Further research is needed to find optimal approaches for handling of seed to ensure high longevity of seed collections, and improved tools are needed to guide sampling of genetic diversity of crop wild relatives.

scholarly journals Identification and characterization of maize lines resistant to leaf diseases

2019 ◽  
Vol 40 (2) ◽  
pp. 517
Author(s):  
Kaian Albino Corazza Kaefer ◽  
Adilson Ricken Schuelter ◽  
Ivan Schuster ◽  
Jonatas Marcolin ◽  
Eliane Cristina Gruszka Vendruscolo
Keyword(s):  
Genetic Diversity ◽  
Leaf Spot ◽  
Block Design ◽  
Snp Markers ◽  
Gray Leaf Spot ◽  
Leaf Blight ◽  
Yield Reduction ◽  
Northern Leaf Blight ◽  
Sources Of Resistance ◽  
White Leaf

Among the maize leaf diseases, white leaf spot, northern leaf blight, gray leaf spot, and southern rust are recognized not only by the potential for grain yield reduction but also by the widespread occurrence in the producing regions of Brazil and the world. The aim of this study was to characterize common maize lines for resistance to white leaf spot, northern leaf blight, gray leaf spot, and southern rust and suggest crosses based on the genetic diversity detected in SNP markers. The experiment was conducted in a randomized block design with three replications in order to characterize 72 maize lines. Genotypic values were predicted using the REML/BLUP procedure. These 72 lines were genotyped with SNP markers using the 650K platform (Affymetrix®) for the assessment of the genetic diversity. Genetic diversity was quantified using the Tocher and UPGMA methods. The existence of genetic variability for disease resistance was detected among maize lines, which made possible to classify them into three large groups (I, II, and III). The maize lines CD 49 and CD50 showed a good performance and can be considered sources of resistance to diseases. Therefore, their use as gene donors in maize breeding programs is recommended. Considering the information of genetic distance together with high heritability for leaf diseases, backcrossing of parent genotypes with different resistance levels, such as those of the lines CD49 x CD69 and CD50 x CD16, may result in new gene combinations, as they are divergent and meet good performances.

scholarly journals Assessing Genetic Resistance in Wheat to Black Point Caused by Six Fungal Species in the Yellow and Huai Wheat Area of China

Plant Disease ◽  
2020 ◽  
Vol 104 (12) ◽  
pp. 3131-3134
Author(s):  
Qiaoyun Li ◽  
Mengyu Li ◽  
Yumei Jiang ◽  
Siyu Wang ◽  
Kaige Xu ◽  
...  
Keyword(s):  
Disease Incidence ◽  
Genetic Resistance ◽  
Bipolaris Sorokiniana ◽  
Triticum Aestivum L ◽  
Fungal Species ◽  
Field Conditions ◽  
Sources Of Resistance ◽  
Black Point ◽  
Environmentally Sustainable ◽  
Resistant Cultivars

The most effective and environmentally sustainable method for controlling black point disease of wheat (Triticum aestivum L.) is to plant resistant cultivars. To identify sources of resistance to black point, 165 selected cultivars/lines were inoculated with isolates of six fungal species (Bipolaris sorokiniana, Alternaria alternata, Fusarium equiseti, Exserohilum rostratum, Epicoccum sorghinum, and Curvularia spicifera) known to cause black point in wheat using spore suspensions under controlled field conditions in 2016 and 2017. Inoculation of the isolates significantly increased the incidence of black point in the cultivars/lines compared with those grown under natural field conditions (NFC). The disease incidence of plants inoculated with B. sorokiniana and E. rostratum was 15.5% and 18.8% in 2016, and 20.4% and 23.0% in 2017, whereas those under NFC were 5.7% (2016) and 1.5% (2017), respectively. Furthermore, disease symptoms varied with pathogen. Among the 165 cultivars/lines tested, 3.6%, 50.9%, 60.0%, 1.8%, 47.3%, and 58.8% were resistant to B. sorokiniana, A. alternata, F. equiseti, E. rostratum, E. sorghinum, and C. spicifera, respectively. In addition, we identified one line (‘SN530070’) resistant to black point caused by all six pathogens. This is the first study to assess resistance to wheat black point caused by six fungal species under controlled conditions. The black point-resistant cultivars/lines could be useful in breeding and also in research on the mechanisms of resistance to black point.

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