Genetic diversity in local cultivars of garden pea (Pisum sativum L.) conserved ‘on farm’ and in historical collections

During a national Swedish collection mission of vegetable varieties conserved ‘on farm’ more than 70 pea accessions were obtained, many of which had been grown locally for more than 100 years. In spite of a likely origin in the multitude of obsolete commercial pea varieties available on the Swedish seed market in the nineteenth century, the rediscovered local cultivars have lost their original names and cultivar identity while being maintained ‘on farm’. To analyze genetic diversity in the repatriated material, 20 accessions were genotyped with twelve SSR markers and compared with 15 obsolete cultivars kept in genebanks and 13 cultivars preserved as non-viable seeds collected in 1877–1918. Most of the local cultivars were genetically distinct from each other, and in only a few cases could a possible origin in a tested obsolete cultivar be suggested. These results reflect the wide diversity of pea cultivars present in Sweden during the nineteenth century. Both between and within accession genetic diversity was larger among the historical samples of obsolete cultivars compared to local cultivars and cultivars preserved in genebanks, indicating genetic erosion over time both in genebanks and during conservation ‘on farm’. The constraints on identifying and verifying historical cultivars using genetic markers are discussed.     

Genetic diversity of storage protein genes in common wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) cultivars from China and its comparison with genetic diversity of cultivars from other countries

Contemporary trends and perspectives of Chinese winter wheat breeding programs were explored using multiple alleles of gliadin (Gli) and glutenin (Glu)-coding loci as genetic markers. To estimate genetic diversity and specific features of Chinese cultivars, the allele frequencies and genetic diversity H in Chinese wheat pool were calculated and compared to those of cultivars from 11 regions of the world. Among all these cultivars the Chinese ones exhibited the highest allelic diversity of the Gli loci while showing relatively low genetic variability for the Glu loci. Most (96%) of the cultivars examined had unique Gli allele compositions, which enabled to differentiate these cultivars with high precision. Cluster analysis of the genetic distances among the wheats from different regions showed that the Chinese cultivars were close to Italian and Russian ones, sharing with them the common Gli alleles. Clustering of modern cultivars and that of cultivars bred 10–15 years ago was essentially the same. All cultivars from all of the countries examined were classified into three groups according to their quality based on their Glu allele compositions. The Chinese cultivars showed a moderate quality score of 7.0, which conforms to the quality evaluation based on SDS sedimentation. This quality proved to be insufficiently high as compared to cultivars from other countries. However, the genetic diversity estimation suggests that Chinese cultivars have a potential for quality improvement.     

Identification and relationships of accessions grown in the grapevine (<Emphasis Type="Italic">Vitis vinifera</Emphasis> L.) Germplasm Bank of Castilla y Léon (Spain) and the varieties authorized in the VQPRD areas of the region by SSR-marker analysis

A total of sixty-five accessions from the Spanish region of Castilla y León including those authorized in the VQPRD areas were characterized for six SSR loci. All the samples but one unknown were identified by comparison to other databases. Thirty synonymous samples and three cases of homonymy were found out, confirming in most cases ampelographic expectations. Five unique genotypes belonging to local varieties in risk of extinction were detected. Several parameters were calculated to assess the usefulness of the chosen loci in this work. A dendrogram representing the genetic similarities among the accessions was constructed using the neighbor-joining method to investigate possible parentage relationships in the sample, and to explain them from an historical and cultural point of view.     

Genetic diversity and relationships between wild and cultivated olives (<Emphasis Type="Italic">Olea europaea</Emphasis> L.) in Sardinia as assessed by SSR markers

The genetic relationships within and between wild and cultivated olives were examined and clarified in an isolated and restricted area, such as the Mediterranean island of Sardinia. Wild (21 individuals) and cultivated olive trees (22 local cultivars from a germplasm collection and 35 ancient trees) were genotyped by means of 13 SSR loci. Five cases of synonymy were observed and nine distinct genotypes were identified in the collection. Five novel genotypes were also detected among the ancient trees. Differences on the allelic composition and heterozygosity levels were found between wild and cultivated trees. Model-based clustering method classified the olive trees into two major gene pools: (a) wild genotypes and (b) local cultivars from the collection and from heritage olives. Regarding the cultivated plant material, we observed that: (a) most of the Sardinian cultivars shared the same allelic profiles with the ancient cultivated trees and (b) the majority of these cultivars and all the novel genotypes were not related to any other cultivars included in this study. These findings as well as the detection of unique alleles and a certain wild genetic background at some cultivars revealed by the Bayesian analysis may indicate their autochthonous origin. The synonymy cases found between local cultivars and Italian mainland cultivars indicate interchange of genetic material among these growing areas, suggesting thus a possible allochthonous origin. The information obtained can assist in the management of an olive collection and sheds some light on the survival of true oleasters and the origin of Sardinian cultivars.     

Recovery,identification and relationships by microsatellite analysis of ancient grapevine cultivars from Castilla-La Mancha: the largest wine growing region in the world

A total of 374 grapevine accessions collected during prospecting works in different wine regions of Castilla-La Mancha in the period 2004–2011, in addition to 55 accessions belonging to national and international cultivars, conserved in the grapevine variety collection of Castilla-La Mancha were studied. For genetic characterization of all accessions, 26 nuclear and 5 chloroplast microsatellite markers were analyzed, yielding 158 different genetic profiles. Of the profiles, 44 were recorded as “new genotypes”, not previously described in the literature consulted. Some of them belonged to traditional cultivars cited as being present in the region in the early twentieth century, such as Churriago, Mizancho, Tortozona Tinta, Maquias and Zurieles and whose head was lost, while others were nameless cultivars hidden in ancient vineyards and unknown to science. The 26 microsatellite loci used reflected a high discrimination power (99.998 %) and a low probability that two randomly chosen individuals had identical genotypes, the probability of identity (1.02 × 10^?22) was comparable to those reported for other grapevine germplasms. Four chlorotypes, A, B, C and D, were defined among the studied cultivars, most of the cultivars (53 %) carried chlorotype A, followed by chlorotypes D (28 %), C (11 %) and B (7 %). Moreover, the 158 single genotypes were analyzed for possible parent-offspring relationships. A total of nine putative parentages not previously published were obtained, and another seven were confirmed.     

Intra-varietal genetic diversity of the grapevine (<Emphasis Type="Italic">Vitis vinifera</Emphasis> L.) cultivar ‘Nero d’Avola’ as revealed by microsatellite markers

The Sicilian grape cultivar ‘Nero d’Avola’ is among the oldest and most cultivated in the island, taking part in the production of several red wines exported worldwide, including DOC wines (Etna Rosso and Cerasuolo di Vittoria). Due to the ancient origin and repeated clonally propagation of the cultivar, phenotypic variability has been observed. Clone identification in this important cultivar has so far relied on phenotypic and chemical traits analyses, often affected by environmental conditions. Genetic markers, such as microsatellites, are particularly useful for cultivar identification, parentage testing, pedigree reconstruction and population structure studies. In the present paper, microsatellites were used to analyze the intra-varietal genetic diversity among 118 plants of ‘Nero d’Avola’, collected in 30 vineyards displaced in different areas of Sicily. Out of 22 microsatellites, 11 showed polymorphism among samples and 15 different phylogenetic groups were identified. Results show that ‘Nero d’Avola’ actually comprises different genetic profiles, although most of clones share a common origin.     

Single-locus EST-SSR markers for characterization of population genetic diversity and structure across ploidy levels in switchgrass (<Emphasis Type="Italic">Panicum virgatum</Emphasis> L.)

Polyploidy, ploidal variation between populations, and aneuploidy within some populations complicate population genetic analyses in switchgrass. We report 21 genic-simple sequence repeat marker loci with single-locus disomic segregation in tetraploids and apparently tetrasomic inheritance in octoploids, thus allowing population genetic analyses across ploidy levels. Based on 472 individuals sampled over four tetraploid and eight octoploid cultivars, six to 55 alleles were detected per locus with an average of 24.1. Genetic diversity was greater in octoploids than tetraploids, as expected from polysomic inheritance. One tetraploid cultivar displayed comparable diversity to the least diverse octoploid cultivars, suggesting breeding history or population history in the native stands of origin may have also affected within-cultivar diversity. Amplicon number at each locus and population relationships suggest autopolyploid origin of octoploids within upland tetraploids with significant cultivar differentiation. However, model-based Bayesian clustering of individuals indicated that closely related octoploid cultivars are difficult to identify, possibly due to slowed differentiation by polysomic inheritance. The analysis of the sampling effect indicated addition of loci is more effective for cultivar identification than more individuals sampled per cultivar. Discriminating power of loci tended to correlate with their variability. The eight loci with greatest discriminatory power within tetraploids were equally successful as 20 loci at identifying the four tetraploid cultivars. The set of markers reported in this study are useful for characterization of switchgrass germplasm and identifying population structure for association studies.     

Genetic diversity within a range of cultivars and landraces of flax (Linum usitatissimum L.) as revealed by RAPDs

Analysis of the extent and distribution of genetic diversity incrop plants is essential for optimizing sampling and breedingstrategies. We used random amplified polymorphic DNA (RAPD)markers to assess genetic diversity and relationships in 22 Canadiancultivars, 29 selected world cultivars and 10 landraces of flax(Linum usitatissimum L.). RAPDvariation was generally low and more variation was detected among,than within, the investigated flax accessions. Based on 53 variableRAPD loci observed for the 61 accessions, the landraces had a lowerproportion of fixed recessive RAPD loci (0.427) (i.e.,more genetic variation) than all of the flax cultivars examined(0.492). The linseed cultivars had a lower proportion ofrecessive loci (0.469) than the fiber flax cultivars(0.529). Canadian linseed cultivars had a lower proportionof recessive loci (0.465) than the selected world flaxcultivars (0.512). A trend was also observed that the rateof loss in genetic variation in Canadian flax breeding programs overthe last fifty years was approximately two variable loci per 100 lociper 10 years. Clustering analyses based on similarity estimatesshowed that the fiber cultivars were more related (or similar toeach other) and were classified as a homogeneous group. All ofthe linseed cultivars were clustered in diverse groups with the ninelandrace accessions. Implications of these findings for flax breedingand germplasm management are discussed.     

The major Italian landraces of lentil (<Emphasis Type="Italic">Lens culinaris</Emphasis> Medik.): Their molecular diversity and possible origin

The eleven most known landraces from central and southern Italy were analysed using ISSR markers on 15 randomly chosen individuals for each landrace, with the aim of assessing genetic variation within and among landraces and possibly ascertaining their origin and genetic relationships. A total of 164 loci were observed, 128 of which (78.05%) were polymorphic. Gene diversity over all landraces was I = 0.3759. The highest within-landrace diversity was observed in samples from the Apennine ridge and for one Sicilian landrace; on the other hand, samples from the small Sicily islands were less variable. Principal Component Analysis and AMOVA allowed the discrimination of groups of landraces with higher similarity. Analyses indicate that the small Sicily islands landraces are very closely related to one another and seem to be derived from the peninsular material; moreover, they help disclose relationships among geographically close landraces. The knowledge so acquired can, therefore, contribute to elaborate strategies for increasing the economical value of élite landraces and to protect producers from frauds.     

Studying the extent of genetic diversity among Gossypium arboreum L. genotypes/cultivars using DNA fingerprinting

Genetic diversity is an area of concern for sustaining crop yield. Information on genetic relatedness/diversity among Gossypium arboreum L. cultivars/genotypes is scanty. We have used random amplified polymorphic DNA (RAPD) analysis to assess the genetic divergence/relationship among 30 genotypes/cultivars of G. arboreum. Of 45 primers surveyed, 63% were polymorphic. Out of the total number of loci amplified, 36% were polymorphic. The calculated genetic similarity between the cultivars/genotypes was in the range of 47.05–98.73%. Two genotypes, HK-244 and Entry-17, were the most distantly related. The average genetic relatedness among all the genotypes was 80.46%. However, most of the cultivated varieties showed a close genetic relationship, indicating a narrow genetic base in comparison to the non-cultivated germplasm. The calculated coefficients were used to construct a dendrogram using the unweighted pair group of arithmetic means (UPGMA) algorithm, which grouped the genotypes/cultivars into two major and three smaller clusters. The study is the first comprehensive analysis of the genetic diversity of G. arboreum germplasm and identifies cultivars that will be useful in extending the genetic diversity of cultivated varieties and future genome mapping projects.     

不同生态区骨干谷子品种表型鉴定与遗传分析

骨干谷子品种对谷子产业发展发挥了重要的作用,为了解其优异性状遗传基础及利用价值,选用来源于不同生态区的12个骨干谷子品种,进行表型鉴定和遗传差异分析。结果表明,12个来源于不同生态区的骨干品种在株高、穗长、穗粗、穗下节间长、单穗重、生育期以及黄色素含量等方面差异较大。79对SSR多态性标记共检测到258个多态性变异位点,平均3.265 8个;SSR标记多态性(PIC)的变幅为0.141 1~0.711 6,平均为0.510 1;其中PIC>0.5的SSR标记有50对,占多态性标记的63.3%。12份材料的遗传距离变幅为0.140 2~0.801 1,平均为0.473 7;来自华北夏谷区的豫谷1号和沧谷4号遗传距离最近,而沧谷4号和来自内蒙高原的地方品种金香玉距离最远;总体而言,华北夏谷区品种和西北早熟春谷区品种遗传距离相对较大。相似性系数为0.594时,12个品种可聚为两类,华北夏谷区的豫谷1号、矮88、冀谷19号、沧谷4号和济谷12聚为一类,来自西北春谷早熟区、晚熟区和东北春谷区的7个品种聚为一类,聚类分析结果和品种的生态类型具有较高的一致性。群体结构分析和聚类分析的结果相似,华北夏谷区品种和春谷区品种之间存在基因交流。总之,不同生态区来源品种间遗传差异较大,同一生态区来源品种遗传差异较小;华北夏谷区骨干品种之间遗传差异较春谷区品种遗传差异相对较小;华北夏谷区品种和西北早熟春谷区品种间遗传差异较大,丰富华北夏谷区遗传变异,应加强与西北早熟春谷区品种之间的交流。本研究结果为优异谷子品种培育及种质资源利用提供了一定依据。     

Twelve-year investigation of copper soil concentrations shows that vineyards are at risk

During the period 2004–2015, the upper soil layer (0–20?cm) was sampled in eight agricultural production areas in Slovenia. Overall, 53, 249, 169, 139, and 413 samples were respectively taken from vegetable fields, arable cropland, hop fields, orchards, and vineyards. Copper was measured in the aqua-regia extracts of these samples using flame atomic absorption spectrometry. The minimum, maximum, average, and median concentrations were calculated for five land uses and for all eight production areas in Slovenia. Sample portions below and/or above the limit, warning, and critical concentrations of 60, 100, and 300?mg/kg, respectively, were calculated as well. The results were compared for different land uses and production areas and showed that the copper concentrations in the vegetable, arable crop, and hop fields and orchards did not exceed the critical concentration. In addition, the copper concentrations in the vineyards exceeded the critical concentration but the maximum copper concentration (508?mg/kg) was still lower than the concentrations reported from other vine-growing Mediterranean countries. Also, the copper concentrations in hop fields exhibited an increasing trend in the Celje (and Maribor) area(s).     

大蒜种质遗传多样性的SSR分析

为了探索中国大蒜种质个体的SSR位点的分布情况,为品种鉴定、保存及遗传改良提供分子生物学依据,利用6对SSR引物对40个大蒜(Allium sativumL.)品种进行聚类分析、主成分分析及遗传多样性评价。共检测到21个多态性位点,平均每对引物可扩增出约3.5条多态性片段,多态性百分率为56.76%;SSR引物组合平均有效等位基因数、Nei基因多样度和Shannon信息指数分别为1.5551、0.3414和0.5188。聚类分析显示,6对SSR引物可把40份大蒜种质资源从0.59相似系数水平上3个类群。第一类群包含28份种质,在相似系数为0.73的水平上进一步又被分成了3个亚类;第二亚类仅包含2份种质;第三亚类包含10份种质,在0.68的相似系数水平上分成了2个亚类。主成分分析和UPGMA的结果基本一致。不同地理来源的大蒜种质的Shannon-Weaver多样性指数的变幅为0.0576~0.4179,说明大蒜种质遗传多样性丰富。本研究利用SSR分子标记技术较准确地解析大蒜不同材料间的亲缘关系及遗传多样性,为中国大蒜SSR分子标记提供基础资料。     

Use of Microsatellite Polymorphisms to Develop an Identification Key for Tunisian Apricots

Microsatellite polymorphisms in 54 apricot landrace cultivars were identified by using 26 Prunus microsatellite primers. Samples of apricot cultivars were collected in eight growing regions in Tunisia ranging from the north to the south of the country and from the sub-humid to the saharian areas. The primers revealed 103 alleles and 155 different genotypes among the 54 apricot accessions. The most polymorphic microsatellite loci were used to develop an identification key. Five microsatellite primers and the 28 resulting alleles were sufficient to discriminate among all 54 cultivars. These results are discussed in the context of cultivar nomenclature, geographic origins, and the comprehensive fingerprinting of Tunisian apricot collections.     

Isozyme analysis of genetic diversity in wild Sicilian populations of Brassica sect. Brassica in view of genetic resources management

In Sicily and in the small surrounding islands the section Brassica of the genus Brassica comprises five species, B. insularis Moris, B. incana Ten., B. macrocarpa Guss., B. rupestris Raf. and B. villosa Biv. These taxa represent a genetic resource as relatives of kale crops but some populations are endangered or threatened, thus isozyme analyses were performed to assess the genetic diversity degree at population and species levels in order to assist the design of conservation management programs.Eleven loci from five enzyme systems (aconitase, leucine aminopeptidase, 6-phosphogluconate dehydrogenase, phosphoglucoisomerase phosphoglucomutase) were analyzed in sixteen natural population (fifteen from Sicily, one from Calabria). Mean within-population genetic diversity was moderate (P = 41%, A = 1.54, H = 0.16). In some cases a great number of heterozygous individuals were detected, in other cases fixation index (F) deviated significantly from Hardy-Weinberg genotypic expectations.A total of 37 alleles was recognized, six of which resulted exclusive to single populations. The among-population component of the total genetic diversity (Gst mean values) for each species was 0.30–0.37, indicating genetic differentiation among populations.Among B. villosa and B. rupestris populations genetic distance values resulted rather low and they resulted high with B. incana and B. macrocarpa populations.The results are discussed with regard to the distribution of the genetic diversity level and the genetic resources management.     

基于SSR标记的我国主栽日本栗品种(系)遗传结构分析和指纹图谱构建

为解析我国主栽日本栗品种资源的遗传多样性并构建其指纹图谱,本研究通过毛细管电泳和高质量的17个SSR分子标记对日本栗品种资源进行位点检测。结果显示,日本栗与茅栗具有较近的种间亲缘关系。在59份日本栗品种(系)中共检测到131个等位位点,每个标记平均有7.706个等位位点;多态信息含量(PIC)变幅为0.375~0.815,平均值为0.605;供试日本栗品种表现出高的遗传多样性。系统发育树、群体结构和主坐标分析结果一致,支持中国境内的部分日本栗品种(系)独立形成一个分支,且大多品种为杂交资源。此外,本研究根据多位点匹配分析确定了CmSI0922、CmSI00702和CmSI0658为核心引物,并利用这3个核心引物构建了59份日本栗品种(系)的指纹图谱。综上所述,相比其他栗属植物,日本栗分布范围较狭窄,但其具有丰富的遗传多样性,且品种资源间存在广泛的基因流。本研究成功构建了59份日本栗品种(系)资源的具有唯一对应关系的指纹图谱,为栗属植物的资源鉴定和保护利用提供了有力支撑。     

Genetic Diversity Among Brazilian Cultivars and Landraces of Tomato Lycopersicon Esculentum Mill. Revealed by RAPD Markers

Random amplified polymorphic DNA markers (RAPD) were used to estimate the variability of 35 tomato accessions (Lycopersicon esculentum Mill.). A total of 257 reproducibly scorable bands were obtained from 20 primers, 78.6% of which were polymorphic. The percentage distribution of RAPD markers shows a bimodal distribution, and the frequency of rare alleles is similar in commercial and landrace accessions. Genetic distances among accessions were calculated and a dendrogram showing the genetic relationships among them was constructed allowing for the separation of four groups. Twenty out of 23 Brazilian landraces fell within one group, whereas commercial cultivars were distributed in the four groups. AMOVA analysis of RAPD data showed that, despite the high within Brazilian landraces and commercial cultivars variation, these two groups are significantly different, indicating that landraces can be a source of variation for breeding programs.     

Investigation of the genetic structure of some common bean (Phaseolus vulgaris L.) commercial varieties and genotypes used as a genitor with SSR and SNP markers

Common bean is a species belonging to the Phaseolus genus of the Leguminosae family. It has economic importance due to being rich in protein, vitamin A and C, and minerals. Being one of the most cultivated species of legumes, the determination of genetic diversity in bean genotypes or populations has an important role in terms of our genetic resources. The objective of this study was to evaluate the genetic structure of 94 genotypes which were cultivated in different parts of the world and our country with SSR and SNP markers. 10 SSR loci and 73 SNP primers were used for the determination of genetic structure in commercial cultivars and breeding lines. All of the SSR and SNP loci used in the study were found to be polymorphic. A total of 89 alleles were identified for 10 SSR loci. Mean number of alleles per locus (Na?=?8.9), effective allele number (Ne?=?3.731), Shannon information index (I?=?1.468), observed heterozygosity (Ho?=?0.023), and expected heterozygosity (He?=?0.654) were calculated based on SSR analysis. According to the results of Bayesian-based STRUCTURE analysis using SSR and SNP data, 94 bean genotypes were genetically divided into three main clusters. According to genetic distance based UPGMA dendrogram obtained from SNP analysis, 94 bean genotypes were divided into 2 main clusters corresponding Mesoamerican and Andean gene pools. The obtained results provide important information about the genetic structures of the studied bean cultivars and breeding lines. With the obtained results, it will be possible to develop breeding programs to develop new cultivars by using our gene resources.

     

Genetic diversity and intra-specific phylogeny of Triticum turgidum L. subsp. dicoccon (Schrank) Thell. revealed by RFLPs and SSRs

Today, emmer wheat, T. turgidum subsp. dicoccon, widely grown in the past is a candidate crop for sustainable agriculture in Italy. As part of a research project aimed at the enhanced use of the hulled wheat germplasm, molecular characterization was carried out to understand the genetic structure of the crop and to identify accessions of interest. A collection of 194 accessions was analyzed with 15 microsatellite loci (SSRs), while only a sample of 38 accessions was tested with 19 RFLP probes. The marker loci were selected on the basis of their independent genomic distribution. Genetic distances and allelic frequencies were calculated for each marker class. The genetic relationships were visualized with dendrograms. RFLP loci were, on average, less polymorphic than SSRs. An average Dice's genetic distance of 0.22 for RFLPs vs 0.38 for SSRs was detected, while an expected average heterozygosity per locus of 0.23 for RFLPs vs 0.26 for SSRs was also estimated. With a least number of 10 loci per marker class it was possible to identify each genotype. The most diverse accessions had different geographic origins. Germplasms from Italy and Ethiopia appear to belong to a more primitive genepool, given that a group of accessions from these countries were genetically differentiated from a Russian-Iranian group.     

An assessment of the genetic diversity within a collection of<Emphasis Type="Italic">Saccharum spontaneum</Emphasis> L. with RAPD-PCR

A local collection of 33Saccharum spontaneum L. clones and two sugarcane cultivars (LCP 82-89 and LCP 85-384) were assessed for genetic variability using random amplified polymorphic DNA (RAPD)-PCR. A total of 157 polymorphic RAPD-PCR bands were scored with 17 primers. The number of RAPD-PCR products per primer ranged from four to 16. The data were analyzed with two multivariate analysis software programs, NTSYSpc and DNAMAN®. Although these two programs yielded similar results, a bootstrapped phylogenetic tree could only be generated with the DNAMAN® software. A substantial degree of genetic diversity was found within the localS. spontaneum collection. Pairwise genetic homology coefficients ranged from 65% (SES, 196/Tainan 2n = 96) to 88.5% (IND 81-80/IND 81-144). LCP 82-89 and LCP 85-384 shared a greater similarity (82%) than either was to any clone ofS. spontaneum (ranging from 60.5 to 75.2%). The 33S. spontaneum clones were assigned to eight groups independent of their geographic origin or morphology, while the two sugarcane cultivars were assigned to the ninth group. All but two pairs ofS. spontaneum clones could be distinguished by a single RAPD primer OPBB-02. The use of a second primer, either OPBE-04 or Primer 262, separated allS. spontaneum clones. One amplification product from the RAPD primer OPA-11, OPA-11-336, proved to be cultivar-specific and has been adopted for use in our breeding program. Information from this study would help conserve the genetic diversity ofS. spontaneum. Disclaimer: Product names and trademarks are mentioned to report on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA does not imply the approval of the product to the exclusion of others that may also be suitable. The experiments reported comply with the current laws of the USA.