Short Communication: First report of outcrossing rates in camelina [<i>Camelina sativa</i> (L.) Crantz], a potential platform for bioindustrial oils

The development of transgenic oilseed Camelina sativa (2n = 40) and the potential for hybridization with its weedy relative Capsella bursa‐pastoris (2n = 36) necessitates a careful evaluation of the reproductive compatibility between the species. Here, we conducted over 1800 crosses (emasculation and manual pollination) to examine the ability of 10 Canadian C. bursa‐pastoris (♀) accessions to hybridize with five accessions of C. sativa (♂). Seven hybrids were confirmed among 586 putative hybrids screened with species‐specific markers, indicating a hybridization rate of 1.5 hybrids per 10 000 ovules pollinated. All seven hybrids had intermediate DNA content compared to their parents, were morphologically distinct, had low (1.9%) pollen fertility and failed to produce selfed or backcrossed seed. Given the abundance of C. bursa‐pastoris along field margins, hybrids will likely be generated in the wild, but they will be unable to establish lineages unless fertility is restored. The large number of crosses and the diversity captured by the use of multiple accessions resulted in strong statistical power and a high degree of confidence in the estimated hybridization rate.

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“…) and 0.09–0.28% (Walsh et al. ), respectively. This will likely contribute to prepollination barriers under natural conditions.…”

Section: Discussionmentioning

confidence: 98%

Sexual hybridization between Capsella bursa‐pastoris (L.) Medik (♀) and Camelina sativa (L.) Crantz (♂) (Brassicaceae)

et al. 2015

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“…Hybrid seeds with the DsRed trait were visually identified using fluorescence (330/570 nm). Putative hybrids were previously verified to contain the bar gene and putative nonhybrids screened for false negatives with a glufosinate application (Walsh et al, 2012). Sample sizes for seed screening were established with power analyses using binomial probabilities as described by Zar (1999) and reported by Jhala et al (2011).…”

Section: Methodsmentioning

confidence: 99%

“…Camelina is primarily self‐fertile (Francis and Warwick, 2009; Walsh et al, 2012; Groeneveld and Klein, 2013). The flowers are protogynous (stigma ripens before anthers) and exhibit perfect sexual reproduction, with stamens and pistil present within the same flower (Francis and Warwick, 2009).…”

mentioning

confidence: 99%

“…Selfing occurs as the flowers begin to close towards the evening, directing stamens towards the stigma where pollen is deposited (Schultze‐Motel, 1986; Tedin, 1922). Camelina PMGF measured at close proximity (up to 0.6 m) ranged from 0.09 to 0.28% when the pollen donor area was small (0.2 by 7.0 m) (Walsh et al, 2012). Although camelina is primarily self‐pollinating, Groeneveld and Klein (2013) reported insect visitation of up to 29 different species in field trials conducted in Germany.…”

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confidence: 99%

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Pollen‐mediated Gene Flow in Camelina sativa (L.) Crantz

Walsh

Hills²,

Martin

et al. 2015

Crop Science

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Camelina sativa (L.) Crantz is a biofuel crop with application on the Great Western Plains of North America that is being developed using genetic engineering. Before release of genetically engineered cultivars, the potential for pollen‐mediated gene flow (PMGF) needs to be assessed to determine if they can coexist with conventional cultivars without causing market harm. Medium‐scale field experiments (40‐m diameter) were conducted in 2011 and 2012 to quantify PMGF using a seed‐expressed florescent marker and bar gene that confers resistance to glufosinate [2‐amino‐4‐(hydroxymethylphosphinyl) butanoic acid] in Alberta, Canada. More than 17 million seeds were screened to quantify outcrossing. Pollen‐mediated gene flow best fit an exponential decay model in which the highest average PMGF (0.78%) occurred adjacent to the donor crop and rapidly declined to 0.09% by 20 m. Pollen‐mediated gene flow was leptokurtic, with a 50% reduction in gene flow 1.5 m from the pollen source. No directional trends were detected, suggesting wind dispersal was not influencing experimental results. The risk of PMGF at longer distances is minimal, but not zero, in this primarily self‐pollinating species.

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“…If wind pollination is more likely, small-plot experiments can be conducted either in greenhouses or outdoors. Donor plants can be surrounded with receptor plants, with or without the presence of a crop species (Murray et al 2002;Walsh et al 2012). If conducted in a greenhouse, fans can be used to move pollen or pollen source plants can be placed above receptor plants.…”

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confidence: 99%

Experimental Methods to Study Gene Flow

2015

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Herbicide resistance is an exceptional marker to quantify gene flow. Quantification of pollen-, seed-, and vegetative propagule-mediated gene flow provides key weed biology information. Pollen-mediated gene flow influences the genetic variance within a population, the frequency of multiple or polygenic herbicide resistance, and the evolutionary dynamics of a species. Seed-mediated gene flow predominates in self-pollinating species. Gene flow quantification may enable the estimation of herbicide resistance epicenter, the comparison of the relative importance of gene flow pathways, and prediction of future distribution of resistance traits. Gene flow studies using herbicide resistance also can provide insight into the rates and importance of hybridization.Approaches to studying gene flow must consider the biology, breeding system, and dispersal mechanism(s) of the species. We recommend a hypothesis-driven, tiered approach, adopted from an environmental risk assessment for genetically modified crops (Garcia-Alonso et al. 2006;Raybould 2006;Raybould and Cooper 2005;Wolt et al. 2010). General approaches to gene flow studies are outlined, primarily utilizing herbicide resistance as a marker system, but morphological and molecular markers may be required to assist with rapid identification or to identify/confirm hybrids.A well-constructed quantification of gene flow first organizes existing information on the nature of the resistance trait, the biology of the species (weed or crop), and the mode of inheritance (tier 0) (Figure 1). Data are then systematically acquired on frequency and distance of gene flow, moving from small-scale, controlled environments (tier 1) to more variable environments, at a larger scale and sample size (tiers 2 and 3). Information gathered in early tiers guides hypothesis development and experimental design for studies in subsequent tiers. The aim of this chapter is to guide the decision-making process and provide examples of appropriate experimental designs and analysis, recognizing that these may need to be modified on the basis of the species and ecological system. This chapter first outlines information required for problem identification (tier 0) and then describes the tiered approach for pollen-, seed-, and vegetative propagule-mediated gene flow. Models of pollen-and seed-mediated gene flow have been reviewed elsewhere (Beckie and Hall 2008;Nathan et al. 2011) and are not addressed here.Approaches to Study Gene Flow. Tier 0 Problem Identification. Problem identification is the first step in developing the hypothesis and designing experiments for gene flow quantification. Assemble available information, including reproductive biology, pollen vectors, related species with the potential to hybridize, the nature of inheritance of herbicide resistance, and pre-existing data on gene flow within (intra) and between (inter) species or genera. Information required for seed-or vegetative propagule-mediated gene flow includes dispersal mechanisms and vectors for dispersal. Next, identify informati...

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Short Communication: First report of outcrossing rates in camelina [Camelina sativa (L.) Crantz], a potential platform for bioindustrial oils

Cited by 37 publications

References 16 publications

Sexual hybridization between Capsella bursa‐pastoris (L.) Medik (♀) and Camelina sativa (L.) Crantz (♂) (Brassicaceae)

Sexual hybridization between Capsella bursa‐pastoris (L.) Medik (♀) and Camelina sativa (L.) Crantz (♂) (Brassicaceae)

Pollen‐mediated Gene Flow in Camelina sativa (L.) Crantz

Experimental Methods to Study Gene Flow

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