Estimation of Outcrossing in Basil

Nation, Renee G.; Janick, Jules; Simon, James E.

doi:10.21273/hortsci.27.11.1221

Cited by 19 publications

(7 citation statements)

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“…Ocimum spp. demonstrate relatively high rates of outcrossing in the presence of pollinators [ 9 ], while readily self-pollinating in their absence. The flexibility of this reproductive system has been exploited by natural and artificial selection, likely serving as a catalyst for morphological and volatile diversification of Ocimum spp.…”

Section: Introductionmentioning

confidence: 99%

“…For instance, karyological investigation of O. basilicum and O. basilicum x O. americanum F 1 hybrids found no evidence of tetravalent and little trivalent formation (4-8% of pollen mother cells) demonstrating high levels of preferential pairing within sub-genomes [ 11 ]. Relatively high levels of inter-specific hybridization [ 9 ] suggest allopolyploid formation to be more likely than autopolyploidy [ 16 ]. This hypothesis is also supported by genotype data from simple sequence repeat (SSR) and single nucleotide polymorphism (SNP) markers in the O. basilicum MRI x SB22 F 2 mapping family demonstrated that disomic segregation providing molecular evidence for an allotetraploid (AABB) O. basilicum [ 17 ].…”

Section: Introductionmentioning

confidence: 99%

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Population structure, genetic diversity and downy mildew resistance among Ocimum species germplasm

et al. 2018

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BackgroundThe basil (Ocimum spp.) genus maintains a rich diversity of phenotypes and aromatic volatiles through natural and artificial outcrossing. Characterization of population structure and genetic diversity among a representative sample of this genus is severely lacking. Absence of such information has slowed breeding efforts and the development of sweet basil (Ocimum basilicum L.) with resistance to the worldwide downy mildew epidemic, caused by the obligate oomycete Peronospora belbahrii. In an effort to improve classification of relationships 20 EST-SSR markers with species-level transferability were developed and used to resolve relationships among a diverse panel of 180 Ocimum spp. accessions with varying response to downy mildew.ResultsResults obtained from nested Bayesian model-based clustering, analysis of molecular variance and unweighted pair group method using arithmetic average (UPGMA) analyses were synergized to provide an updated phylogeny of the Ocimum genus. Three (major) and seven (sub) population (cluster) models were identified and well-supported (P < 0.001) by PhiPT (ΦPT) values of 0.433 and 0.344, respectively. Allelic frequency among clusters supported previously developed hypotheses of allopolyploid genome structure. Evidence of cryptic population structure was demonstrated for the k1 O. basilicum cluster suggesting prevalence of gene flow. UPGMA analysis provided best resolution for the 36-accession, DM resistant k3 cluster with consistently strong bootstrap support. Although the k3 cluster is a rich source of DM resistance introgression of resistance into the commercially important k1 accessions is impeded by reproductive barriers as demonstrated by multiple sterile F1 hybrids. The k2 cluster located between k1 and k3, represents a source of transferrable tolerance evidenced by fertile backcross progeny. The 90-accession k1 cluster was largely susceptible to downy mildew with accession ‘MRI’ representing the only source of DM resistance.ConclusionsHigh levels of genetic diversity support the observed phenotypic diversity among Ocimum spp. accessions. EST-SSRs provided a robust evaluation of molecular diversity and can be used for additional studies to increase resolution of genetic relationships in the Ocimum genus. Elucidation of population structure and genetic relationships among Ocimum spp. germplasm provide the foundation for improved DM resistance breeding strategies and more rapid response to future disease outbreaks.Electronic supplementary materialThe online version of this article (10.1186/s12870-018-1284-7) contains supplementary material, which is available to authorized users.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Population structure, genetic diversity and downy mildew resistance among Ocimum species germplasm

et al. 2018

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“…Ocimum basilicum is an outcrossing [ 32 ] tetraploid [ 18 , 33 ] that has demonstrated disomic inheritance for multiple traits [ 34 , 35 ], suggesting a diploidized polyploid genome. This allopolyploid hypothesis is supported by cytological evidence that demonstrated preferential pairing of O .…”

Section: Introductionmentioning

confidence: 99%

A first linkage map and downy mildew resistance QTL discovery for sweet basil (Ocimum basilicum) facilitated by double digestion restriction site associated DNA sequencing (ddRADseq)

et al. 2017

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Limited understanding of sweet basil (Ocimum basilicum L.) genetics and genome structure has reduced efficiency of breeding strategies. This is evidenced by the rapid, worldwide dissemination of basil downy mildew (Peronospora belbahrii) in the absence of resistant cultivars. In an effort to improve available genetic resources, expressed sequence tag simple sequence repeat (EST-SSR) and single nucleotide polymorphism (SNP) markers were developed and used to genotype the MRI x SB22 F2 mapping population, which segregates for response to downy mildew. SNP markers were generated from genomic sequences derived from double digestion restriction site associated DNA sequencing (ddRADseq). Disomic segregation was observed in both SNP and EST-SSR markers providing evidence of an O. basilicum allotetraploid genome structure and allowing for subsequent analysis of the mapping population as a diploid intercross. A dense linkage map was constructed using 42 EST-SSR and 1,847 SNP markers spanning 3,030.9 cM. Multiple quantitative trait loci (QTL) model (MQM) analysis identified three QTL that explained 37–55% of phenotypic variance associated with downy mildew response across three environments. A single major QTL, dm11.1 explained 21–28% of phenotypic variance and demonstrated dominant gene action. Two minor QTL dm9.1 and dm14.1 explained 5–16% and 4–18% of phenotypic variance, respectively. Evidence is provided for an additive effect between the two minor QTL and the major QTL dm11.1 increasing downy mildew susceptibility. Results indicate that ddRADseq-facilitated SNP and SSR marker genotyping is an effective approach for mapping the sweet basil genome.

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“…Although basil flower is hermaphrodite, there may be cross-pollination between different types or varieties, mainly by the activity of bees (Sobti and Pushpangadan 1982). Cross-pollination can vary between 32 and 66% (Krishnan 1981, Nation et al 1992. Its essential oil can be extracted from the leaves and from apices with inflorescences.…”

Section: Introductionmentioning

confidence: 99%

'Norine', a cinnamon-linalool hybrid cultivar of basil

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et al. 2015

Crop Breed. Appl. Biotechnol.

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Norine' is a hybrid cultivar of basil, adapted to the Northeastern Brazil, which is derived from the cultivars 'Cinnamon' and 'Maria Bonita'. It has essential oil content of 2.91% and yield of 2.37 mL plant-1. The main chemical compounds of the essential oil are (E)-methyl cinnamate (41.93 %) and linalool (34.92 %). 'Norine' is characterized by presenting upright growth habit, rounded crown, mean height of 55 cm, mean crown diameter of 59 cm, mean leaf length of 8.4 cm, and mean leaf width of 4.5 cm

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Estimation of Outcrossing in Basil

Cited by 19 publications

References 10 publications

Population structure, genetic diversity and downy mildew resistance among Ocimum species germplasm

Population structure, genetic diversity and downy mildew resistance among Ocimum species germplasm

A first linkage map and downy mildew resistance QTL discovery for sweet basil (Ocimum basilicum) facilitated by double digestion restriction site associated DNA sequencing (ddRADseq)

'Norine', a cinnamon-linalool hybrid cultivar of basil

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