A Molecular Genetic Linkage Map of Eucommia ulmoides and Quantitative Trait Loci (QTL) Analysis for Growth Traits

SUMMARYCassava (Manihot esculenta Crantz) is an economically important root crop in Thailand, which is ranked the world's top cassava exporting country. Production of cassava can be hampered by several pathogens and pests. Cassava anthracnose disease (CAD) is an important disease caused by the fungus Colletotrichum gloeosporioides f. sp. manihotis. The pathogen causes severe stem damage resulting in yield reductions and lack of stem cuttings available for planting. Molecular studies of cassava response to CAD will provide useful information for cassava breeders to develop new varieties with resistance to the disease. The current study aimed to identify quantitative trait loci (QTL) and DNA markers associated with resistance to CAD. A total of 200 lines of two F1 mapping populations were generated by reciprocal crosses between the varieties Huabong60 and Hanatee. The F1 samples were genotyped based on simple sequence repeat (SSR) and expressed sequence tag-SSR markers and a genetic linkage map was constructed using the JoinMap®/version3·0 program. The results showed that the map consisted of 512 marker loci distributed on 24 linkage groups with a map length of 1771·9 centimorgan (cM) and a mean interval between markers of 5·7 cM. The genetic linkage map was integrated with phenotypic data for the response to CAD infection generated by a detached leaf assay test. A total of three QTL underlying the trait were identified on three linkage groups using the MapQTL®/version4·0 program. Those DNA markers linked to the QTL that showed high statistically significant values with the CAD resistance trait were identified for gene annotation analysis and 23 candidate resistance genes to CAD infection were identified.

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A genetic linkage map of tetraploid orchardgrass (Dactylis glomerata L.) and quantitative trait loci for heading date

Genome ◽

10.1139/g2012-026 ◽

2012 ◽

Vol 55 (5) ◽

pp. 360-369 ◽

Cited By ~ 17

Author(s):

Wengang Xie ◽

Joseph G. Robins ◽

B. Shaun Bushman

Keyword(s):

Quantitative Trait Loci ◽

Linkage Map ◽

Quantitative Trait ◽

Genetic Linkage ◽

Genetic Linkage Map ◽

Heading Date ◽

Dactylis Glomerata ◽

Linkage Groups ◽

Trait Loci ◽

Dactylis Glomerata L

Orchardgrass ( Dactylis glomerata L.), or cocksfoot, is indigenous to Eurasia and northern Africa, but has been naturalized on nearly every continent and is one of the top perennial forage grasses grown worldwide. To improve the understanding of genetic architecture of orchardgrass and provide a template for heading date candidate gene search in this species, the goals of the present study were to construct a tetraploid orchardgrass genetic linkage map and identify quantitative trait loci associated with heading date. A combination of SSR markers derived from an orchardgrass EST library and AFLP markers were used to genotype an F1 population of 284 individuals derived from a very late heading Dactylis glomerata subsp. himalayensis parent and an early to mid-heading Dactylis glomerata subsp. aschersoniana parent. Two parental maps were constructed with 28 cosegregation groups and seven consensus linkage groups each, and homologous linkage groups were tied together by 38 bridging markers. Linkage group lengths varied from 98 to 187 cM, with an average distance between markers of 5.5 cM. All but two mapped SSR markers had homologies to physically mapped rice (Oryza sativa L.) genes, and six of the seven orchardgrass linkage groups were assigned based on this putative synteny with rice. Quantitative trait loci were detected for heading date on linkage groups 2, 5, and 6 in both parental maps, explaining between 12% and 24% of the variation.

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Construction of a high-density genetic linkage map and mapping of quantitative trait loci for growth-related traits in silver carp (Hypophthalmichthys molitrix)

Scientific Reports ◽

10.1038/s41598-019-53469-8 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 2

Author(s):

Xinhua Wang ◽

Haiyang Liu ◽

Meixia Pang ◽

Beide Fu ◽

Xiaomu Yu ◽

...

Keyword(s):

Quantitative Trait Loci ◽

Linkage Map ◽

Quantitative Trait ◽

Genetic Linkage ◽

Genetic Linkage Map ◽

Growth Traits ◽

Silver Carp ◽

High Density ◽

Potential Candidate ◽

Hypophthalmichthys Molitrix

AbstractHigh-density genetic map and quantitative trait loci (QTL) mapping are powerful tools for identifying genomic regions that may be responsible for such polygenic trait as growth. A high-density genetic linkage map was constructed by sequencing 198 individuals in a F1 family of silver carp (Hypophthalmichthys molitrix) in this study. This genetic map spans a length of 2,721.07 cM with 3,134 SNPs distributed on 24 linkage groups (LGs). Comparative genomic mapping presented a high level of syntenic relationship between silver carp and zebrafish. We detected one major and nineteen suggestive QTL for 4 growth-related traits (body length, body height, head length and body weight) at 6, 12 and 18 months post hatch (mph), explaining 10.2~19.5% of phenotypic variation. All six QTL for growth traits of 12 mph generally overlapped with QTL for 6 mph, while the majority of QTL for 18 mph were identified on two additional LGs, which may reveal a different genetic modulation during early and late muscle growth stages. Four potential candidate genes were identified from the QTL regions by homology searching of marker sequences against zebrafish genome. Hepcidin, a potential candidate gene identified from a QTL interval on LG16, was significantly associated with growth traits in the analyses of both phenotype-SNP association and mRNA expression between small-size and large-size groups of silver carp. These results provide a basis for elucidating the genetic mechanisms for growth and body formation in silver carp, a world aquaculture fish.

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