Symbiotic germination of three species of epiphytic orchids susceptible to genetic erosion, from Soconusco (Chiapas, Mexico)

Orchids are known to establish complex relationships with endophytic fungi throughout their life cycle, and particularly during germination of their reserves-deprived seeds. Characterizing generalist or specialist interactions between orchids and associated fungi is key to supporting orchid conservation efforts. Here, endophytic fungi associated with roots of epiphytic orchids were studied in two montane Andean forests in Southern Ecuador. Orchid root samples were collected from ten ~500 m2 plots distributed between two neighboring forests. Endophytic fungi associated with these roots were then isolated, cultured, and identified by sequencing of rDNA markers. In total, 52 pure isolates were recovered from the roots of 10 orchid species. These isolates were classified into nine taxonomic groups except for one isolate that remained unclassified. Most fungal isolates were found in roots of up to two different orchid species; however, Coprinellus radians was found in the roots of all sampled orchids. The potential of C. radians to promote germination of orchid seeds was tested in a separate assay using seeds from two orchid species different than those found in the experimental forest plots. Of the two C. radians isolates tested, one improved germination in the two orchids evaluated to a level about half of that observed in seeds germinated in nutrient-rich medium (Phytamax) and above the null germination observed in plates without the fungus. Together, these results revealed a generalist relationship between C. radians and all the studied epiphytic orchids and the potential role of this fungus as a promoter of orchid seed germination. Key Words: Agaricales, Epidendrum, symbiotic germination

Download Full-text

Faculty Opinions recommendation of Climate-induced range contraction drives genetic erosion in an alpine mammal.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.717959702.793462926 ◽

2012 ◽

Author(s):

Joel Kingsolver ◽

Lauren Buckley

Keyword(s):

Genetic Erosion ◽

Range Contraction

Download Full-text

Are there populations suffering genetic erosion that would benefit from augmented gene flow?

10.1093/oso/9780198783398.003.0011 ◽

2017 ◽

Author(s):

Richard Frankham ◽

Jonathan D. Ballou ◽

Katherine Ralls ◽

Mark D. B. Eldridge ◽

Michele R. Dudash ◽

...

Keyword(s):

Gene Flow ◽

Genetic Erosion ◽

Genetic Rescue ◽

Isolated Populations

Having identified small geographically and genetically isolated populations, we need to determine whether they are suffering genetic erosion, and if so, whether there are any other populations to which they could be crossed. We should next ask whether crossing is expected to be harmful or beneficial, and if beneficial, whether the benefits would be large enough to justify a genetic rescue attempt. Here, we address these questions based on the principles established in the preceding chapters.

Download Full-text

Genetic Diversity of Landraces and Improved Varieties of Rice (Oryza sativa L.) in Taiwan

Rice ◽

10.1186/s12284-020-00445-w ◽

2020 ◽

Vol 13 (1) ◽

Author(s):

Ai-ling Hour ◽

Wei-hsun Hsieh ◽

Su-huang Chang ◽

Yong-pei Wu ◽

Han-shiuan Chin ◽

...

Keyword(s):

Genetic Diversity ◽

Genetic Variation ◽

Indigenous Peoples ◽

Oryza Sativa L ◽

Crop Improvement ◽

Genetic Erosion ◽

Germplasm Conservation ◽

Gene Pools ◽

Improved Varieties ◽

Breeding Goals

Abstract Background Rice, the most important crop in Asia, has been cultivated in Taiwan for more than 5000 years. The landraces preserved by indigenous peoples and brought by immigrants from China hundreds of years ago exhibit large variation in morphology, implying that they comprise rich genetic resources. Breeding goals according to the preferences of farmers, consumers and government policies also alter gene pools and genetic diversity of improved varieties. To unveil how genetic diversity is affected by natural, farmers’, and breeders’ selections is crucial for germplasm conservation and crop improvement. Results A diversity panel of 148 rice accessions, including 47 cultivars and 59 landraces from Taiwan and 42 accessions from other countries, were genotyped by using 75 molecular markers that revealed an average of 12.7 alleles per locus with mean polymorphism information content of 0.72. These accessions could be grouped into five subpopulations corresponding to wild rice, japonica landraces, indica landraces, indica cultivars, and japonica cultivars. The genetic diversity within subpopulations was: wild rices > landraces > cultivars; and indica rice > japonica rice. Despite having less variation among cultivars, japonica landraces had greater genetic variation than indica landraces because the majority of Taiwanese japonica landraces preserved by indigenous peoples were classified as tropical japonica. Two major clusters of indica landraces were formed by phylogenetic analysis, in accordance with immigration from two origins. Genetic erosion had occurred in later japonica varieties due to a narrow selection of germplasm being incorporated into breeding programs for premium grain quality. Genetic differentiation between early and late cultivars was significant in japonica (FST = 0.3751) but not in indica (FST = 0.0045), indicating effects of different breeding goals on modern germplasm. Indigenous landraces with unique intermediate and admixed genetic backgrounds were untapped, representing valuable resources for rice breeding. Conclusions The genetic diversity of improved rice varieties has been substantially shaped by breeding goals, leading to differentiation between indica and japonica cultivars. Taiwanese landraces with different origins possess various and unique genetic backgrounds. Taiwanese rice germplasm provides diverse genetic variation for association mapping to unveil useful genes and is a precious genetic reservoir for rice improvement.

Download Full-text

The Diversity of Root-Associated Endophytic Fungi from Four Epiphytic Orchids in China

Diversity ◽

10.3390/d13050197 ◽

2021 ◽

Vol 13 (5) ◽

pp. 197

Author(s):

Tao Wang ◽

Miao Chi ◽

Ling Guo ◽

Donghuan Liu ◽

Yu Yang ◽

...

Keyword(s):

Endophytic Fungi ◽

Southern China ◽

Culture Method ◽

Amplicon Sequencing ◽

Community Diversity ◽

Mycorrhizal Symbiosis ◽

Epiphytic Orchids ◽

Culture Independent ◽

Almost All

Root-associated endophytic fungi (RAF) are found asymptomatically in almost all plant groups. However, little is known about the compositions and potential functions of RAF communities associated with most Orchidaceae species. In this study, the diversity of RAF was examined in four wild epiphytic orchids, Acampe rigida, Doritis pulcherrima, Renanthera coccinea, and Robiquetia succisa, that occur in southern China. A culture-independent method involving Illumina amplicon sequencing, and an in vitro culture method, were used to identify culturable fungi. The RAF community diversity differed among the orchid roots, and some fungal taxa were clearly concentrated in a certain orchid species, with more OTUs being detected. By investigating mycorrhizal associations, the results showed that 28 (about 0.8%) of the 3527 operational taxonomic units (OTUs) could be assigned as OMF, while the OTUs of non-mycorrhizal fungal were about 99.2%. Among the OMFs, Ceratobasidiaceae OTUs were the most abundant with different richness, followed by Thelephoraceae. In addition, five Ceratobasidium sp. strains were isolated from D. pulcherrima, R. succisa, and R. coccinea roots with high separation rates. These culturable Ceratobasidium strains will provide materials for host orchid conservation and for studying the mechanisms underlying mycorrhizal symbiosis.

Download Full-text

Genetic Diversity and Population Structure of Serbian Barley (Hordeum vulgare L.) Collection during a 40-Year Long Breeding Period

Agronomy ◽

10.3390/agronomy11010118 ◽

2021 ◽

Vol 11 (1) ◽

pp. 118

Author(s):

Ljiljana Brbaklić ◽

Dragana Trkulja ◽

Sanja Mikić ◽

Milan Mirosavljević ◽

Vojislava Momčilović ◽

...

Keyword(s):

Genetic Diversity ◽

Population Structure ◽

Hordeum Vulgare ◽

Crop Improvement ◽

Genetic Erosion ◽

Breeding Period ◽

Phenotypic Variance ◽

Hordeum Vulgare L ◽

Phenotypic Data ◽

Breeding Material

Determination of genetic diversity and population structure of breeding material is an important prerequisite for discovering novel and valuable alleles aimed at crop improvement. This study’s main objective was to characterize genetic diversity and population structure of a collection representing a 40-year long historical period of barley (Hordeum vulgare L.) breeding, using microsatellites, pedigree, and phenotypic data. The set of 90 barley genotypes was phenotyped during three growing seasons and genotyped with 338 polymorphic alleles. The indicators of genetic diversity showed differentiation changes throughout the breeding periods. The population structure discriminated the breeding material into three distinctive groups. The principal coordinate analysis grouped the genotypes according to their growth habit and row type. An analysis of phenotypic variance (ANOVA) showed that almost all investigated traits varied significantly between row types, seasons, and breeding periods. A positive effect on yield progress during the 40-year long breeding period could be partly attributed to breeding for shorter plants, which reduced lodging and thus provided higher yield stability. The breeding material revealed a considerable diversity level based on microsatellite and phenotypic data without a tendency of genetic erosion throughout the breeding history and implied dynamic changes in genetic backgrounds, providing a great gene pool suitable for further barley improvement.

Download Full-text

AFLP and PBA polymorphisms in an endangered medicinal plant, Rhazya stricta, in Pakistan

Plant Genetic Resources ◽

10.1017/s147926211300052x ◽

2013 ◽

Vol 12 (2) ◽

pp. 199-206 ◽

Cited By ~ 1

Author(s):

Syed Abdullah Gilani ◽

Ryoko Hirano ◽

Yoshiharu Fujii ◽

Kazuo N. Watanabe

Keyword(s):

Habitat Fragmentation ◽

Genetic Differentiation ◽

Medicinal Plant ◽

Genetic Erosion ◽

Human Pressure ◽

Rhazya Stricta ◽

Endangered Medicinal Plant ◽

Genomic Markers ◽

High Gene ◽

Commercial Harvesting

Rhazya stricta is an endangered medicinal plant that is under severe human pressure as a result of commercial harvesting. As a model of habitat fragmentation, we selected the Kohat Plateau in the Pakistani Himalaya, where populations are fragmented, with less than 100 individuals per population. We hypothesized that the populations may be threatened by rapid habitat fragmentation and by unsustainable utilization of the plant. We analysed P450-based analogue functional genomic markers and amplified fragment length polymorphism markers from six populations of R. stricta on the Kohat Plateau, and examined their variations both within and among the populations. Both the marker groups revealed lower genetic differentiation among the populations and higher genetic differentiation within the populations as a result of high gene flow. The results confirmed that habitat fragmentation is being caused by severe human pressure, and although signs of genetic erosion are not yet visible, they seem likely to become visible in the future. Therefore, the conservation of R. stricta populations is necessary.

Download Full-text

Ecological relevance of the endophytic fungal diversity in velamen roots of tropical epiphytic orchids.

Czech Mycology ◽

10.33585/cmy.73107 ◽

2021 ◽

Vol 73 (1) ◽

pp. 91-108

Author(s):

Azhanthanilkunnathil Sankunny Deepthi ◽

Joseph George Ray

Keyword(s):

Fungal Diversity ◽

Epiphytic Orchids ◽

Ecological Relevance

Download Full-text

Impacts of habitat fragmentation on genetic diversity in a tropical forest butterfly on Borneo

Journal of Tropical Ecology ◽

10.1017/s0266467407004543 ◽

2007 ◽

Vol 23 (6) ◽

pp. 623-634 ◽

Cited By ~ 21

Author(s):

Suzan Benedick ◽

Thomas A. White ◽

Jeremy B. Searle ◽

Keith C. Hamer ◽

Nazirah Mustaffa ◽

...

Keyword(s):

Genetic Diversity ◽

Time Delay ◽

Habitat Fragmentation ◽

Forest Fragmentation ◽

Haplotype Diversity ◽

Genetic Erosion ◽

Forest Sites ◽

Increased Risk ◽

Forest Remnants ◽

Mtdna Diversity

Many areas of rain forest now exist as habitat fragments, and understanding the impacts of fragmentation is important for determining the viability of populations within forest remnants. We investigated impacts of forest fragmentation on genetic diversity in the butterfly Mycalesis orseis (Satyrinae) in Sabah (Malaysian Borneo). We investigated mtDNA diversity in 90 individuals from ten forest sites typical of the sizes of forest remnants that currently exist in the region. Nucleotide diversity declined with increasing isolation of remnants, but there was no effect of remnant size or population size, and haplotype diversity was similar among sites. Thus, approximately 50 y after forest fragmentation, few changes in genetic diversity were apparent and remnants apparently supported genetically viable populations of this butterfly. Many studies have shown that responses of species to habitat fragmentation usually follow a time delay, and so we developed a Monte Carlo simulation model to investigate changes in genetic diversity over time in small remnants. Model output indicated a substantial time delay (> 100 y) between fragmentation and genetic erosion, suggesting that, in the smallest study remnants, an increased risk of extinction from reduced genetic diversity is likely in the longer term.

Download Full-text