Genetic variation and covariation for growth, parasite resistance and heat tolerance in tropical cattle

AbstractHeat stress greatly limits the productivity of wheat in many regions. Knowledge on the degree of genetic diversity of wheat varieties along with their selective traits will facilitate the development of high yielding, stress-tolerant wheat cultivar. The objective of this study were to determine genetic variation in morpho-physiological traits associated with heat tolerance in 30 diverse wheat genotypes and to examine genetic diversity and relationship among the genotypes varying heat tolerance using molecular markers. Phenotypic data of 15 traits were evaluated for heat tolerance under non-stress and stress conditions for two consecutive years. A positive and significant correlation among cell membrane stability, canopy temperature depression, biomass, susceptibility index and grain yield was shown. Genetic diversity assessed by 41 polymorphic simple sequence repeat (SSR) markers was compared with diversity evaluated for 15 phenotypic traits averaged over stress and non-stress field conditions. The mean polymorphic information content for SSR value was 0.38 with range of 0.12–0.75. Based on morpho-physiological traits and genotypic data, three groups were obtained based on their tolerance (HHT, MHT and LHT) levels. Analysis of molecular variance explained 91.7% of the total variation could be due to variance within the heat tolerance genotypes. Genetic diversity among HHT was higher than LHT genotypes and HHT genotypes were distributed among all cluster implied that genetic basis of heat tolerance in these genotypes was different thereby enabling the wheat breeders to combine these diverse sources of genetic variation to improve heat tolerance in wheat breeding programme.

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Genetic Variation for Heat Tolerance During the Reproductive Phase in Brassica rapa

Journal of Agronomy and Crop Science ◽

10.1111/jac.12034 ◽

2013 ◽

Vol 199 (6) ◽

pp. 424-435 ◽

Cited By ~ 16

Author(s):

Annisa ◽

S. Chen ◽

N. C. Turner ◽

W. A. Cowling

Keyword(s):

Genetic Variation ◽

Brassica Rapa ◽

Heat Tolerance ◽

Reproductive Phase

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Neutral versus adaptive genetic variation in parasite resistance: importance of major histocompatibility complex supertypes in a free-ranging primate

Heredity ◽

10.1038/sj.hdy.6800993 ◽

2007 ◽

Vol 99 (3) ◽

pp. 265-277 ◽

Cited By ~ 120

Author(s):

N Schwensow ◽

J Fietz ◽

K H Dausmann ◽

S Sommer

Keyword(s):

Genetic Variation ◽

Major Histocompatibility Complex ◽

Major Histocompatibility ◽

Parasite Resistance ◽

Adaptive Genetic Variation ◽

Histocompatibility Complex ◽

Free Ranging

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Genetic Variation for Heat Tolerance in Primitive Cultivated Subspecies ofTriticum turgidumL.

Journal of Crop Improvement ◽

10.1080/15427528.2015.1060915 ◽

2015 ◽

Vol 29 (5) ◽

pp. 565-580 ◽

Cited By ~ 2

Author(s):

Jianming Fu ◽

Robert L. Bowden ◽

P. V. Vara Prasad ◽

Amir M.H. Ibrahim

Keyword(s):

Genetic Variation ◽

Heat Tolerance

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Resistance to nematode parasites in Merino sheep: sources of genetic variation

Australian Journal of Agricultural Research ◽

10.1071/ar9960895 ◽

1996 ◽

Vol 47 (6) ◽

pp. 895 ◽

Cited By ~ 35

Author(s):

SJ Eady ◽

RR Woolaston ◽

SI Mortimer ◽

RP Lewer ◽

HW Raadsma ◽

...

Keyword(s):

Genetic Variation ◽

Total Variation ◽

Weighted Average ◽

Parasite Resistance ◽

Artificial Infection ◽

Merino Sheep ◽

Nematode Parasites ◽

Management Group ◽

Wide Range ◽

Faecal Egg Count

Merino sheep representing a range of bloodlines in resource flocks located across Australia were tested for resistance to gastro-intestinal nematodes. These flocks included the JB Pye Flock (Camden, NSW), Katanning Base Flock (Katanning, WA), Turretfield Merino Resource Flock (Rosedale, SA), CSIRO Finewool Flock (Armidale, NSW), and the Trangie D Flock (Trangie, NSW). Faecal egg count (FEC) was used to measure relative resistance of sheep to nematode parasites after either natural or artificial infection with Haemonchus contortus and Trichostrongylus colubriformis. Differences in FEC 0' 33 between strains and between and within bloodlines were examined and the heritability of this trait was estimated. A low proportion of the total variation in parasite resistance could be attributed to strain and bloodline effects (1 and 3.5%, respectively) after either natural or artificial infection. The major source of genetic variation was found within bloodlines (22.2% of total variation), with individual sires showing a wide range in parasite resistance. Paternal half-sib heritability estimates for FEC 0' 33 were significant (P < 0.05) in 9 of the 11 analyses and ranged from 0.07 to 0.42, with a weighted average of 0.22. The influence of the environmental effects of sex, age of dam, birth-rearing rank, and day of birth were also investigated, and were found to be only occasionally significant, accounting for a small proportion (0.3-2.2%) of variation. Management group effects both prior to and at the time of measurement were often significant, and accounted for 2.2-19.4% of variation in FEC. Correction of FEC for effects other than management group would seem to add little to precision of selection. These results have demonstrated that significant genetic variation for nematode parasite resistance exists within a wide range of Merino bloodlines, and within-flock selection of resistant sires appears to be an effective method of improving this trait in Merino sheep.

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Genetic variation in parasite resistance of Atlantic salmon to amoebic gill disease over multiple infections

Aquaculture ◽

10.1016/j.aquaculture.2012.08.026 ◽

2012 ◽

Vol 364-365 ◽

pp. 165-172 ◽

Cited By ~ 33

Author(s):

Peter D. Kube ◽

Richard S. Taylor ◽

Nicholas G. Elliott

Keyword(s):

Genetic Variation ◽

Atlantic Salmon ◽

Multiple Infections ◽

Parasite Resistance ◽

Gill Disease

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Genomic and transcriptomic signals of thermal tolerance in heat-tolerant corals (Platygyra daedalea) of the Arabian/Persian Gulf

10.1101/185579 ◽

2017 ◽

Author(s):

Nathan L. Kirk ◽

Emily J. Howells ◽

David Abrego ◽

John A. Burt ◽

Eli Meyer

Keyword(s):

Genetic Variation ◽

Heat Tolerance ◽

Stress Responses ◽

Thermal Tolerance ◽

Large Fraction ◽

Coral Host ◽

Adaptive Responses ◽

Transcriptional Responses ◽

Functional Basis ◽

Heat Tolerant

AbstractScleractinian corals occur in tropical regions near their upper thermal limits, and are severely threatened by rising ocean temperatures. Ocean warming leads to loss of symbiotic algae (Symbiodinium), reduced fitness for the coral host, and degradation of the reef. However, several recent studies have shown that natural populations of corals harbor genetic variation in thermal tolerance that may support adaptive responses to warming. Here we’ve extended these approaches to study heat tolerance of corals in the Persian/Arabian Gulf, where heat-tolerant local populations have adapted to warm summer temperatures (>36°C). To evaluate whether selection has depleted genetic variation in thermal tolerance, estimate the potential for future adaptive responses, and understand the functional basis for these corals’ unusual heat tolerance, we measured thermal tolerance using controlled crosses in the Gulf coral Platygyra daedalea. We found that heat tolerance is highly heritable in this population (0.487-0.748), suggesting substantial potential for adaptive responses to selection for thermal tolerance. To identify genetic markers associated with this variation, we conducted genomewide SNP genotyping in parental corals and tested for relationships between paternal genotype and thermal tolerance of the offspring. We found that multilocus SNP genotypes explained a large fraction of variation in thermal tolerance in these crosses (69%). To investigate the functional basis of these differences in thermal tolerance, we profiled transcriptional responses in tolerant and susceptible families, revealing substantial sire effects on transcriptional responses to thermal stress. We also studied sequence variation in these expressed sequences, identifying alleles and functional groups associated with thermal tolerance. Our findings demonstrate that corals in these populations harbor extensive genetic variation in thermal tolerance, and these heat-tolerant phenotypes differ in both gene sequences and transcriptional stress responses from their susceptible counterparts.

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Genetic variation in heat tolerance of the coral Platygyra daedalea offers the potential for adaptation to ocean warming

10.1101/2020.10.13.337089 ◽

2020 ◽

Author(s):

Holland Elder ◽

Virginia Weis ◽

Jose Montalvo-Proano ◽

Veronique J.L Mocellin ◽

Andrew H. Baird ◽

...

Keyword(s):

Genetic Variation ◽

Heat Stress ◽

Heat Tolerance ◽

Nucleotide Polymorphisms ◽

Narrow Sense Heritability ◽

Coding Regions ◽

Genomic Tools ◽

Coral Reef Ecosystems ◽

Few Data ◽

Genomic Regions

AbstractReef-building corals are foundational species in coral reef ecosystems and are threatened by many stressors including rising ocean temperatures. In 2015/16 and 2016/17, corals around the world experienced consecutive bleaching events and most coral populations are projected to experience temperatures above their current bleaching thresholds annually by 2050. Adaptation to higher temperatures is therefore necessary if corals are to persist in a warming future. While many aspects of heat stress have been well studied, few data are available for predicting the capacity for adaptive cross-generational responses in corals. To address this knowledge gap, we quantified the heritability and genetic variation associated with heat tolerance in Platygyra daedalea from the Great Barrier Reef (GBR). We tracked the survival of replicate quantitative genetic crosses (or families) of coral larvae from six parents in a heat stress selection experiment. We also identified allelic shifts in heat-selected survivors versus paired, non-selected controls of the same coral crosses. We estimated narrow sense heritability to be 0.66 and detected a total of 1,069 single nucleotide polymorphisms (SNPs) associated with heat tolerance. An overlap of 148 unique SNPs shared between experimental crosses indicates that specific genomic regions are responsible for heat tolerance of P. daedalea and some of these SNPs fall in coding regions. These findings suggest that this P. daedalea population has the genetic prerequisites for adaptation to increasing temperatures. This study also provides knowledge for the development of high throughput genomic tools to screen for variation within and across populations to harness or enhance adaptation through assisted gene flow and assisted migration.

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