Studies on genetic divergence in potato

Summary Sixty-seven potato varieties/hybrids were grouped in 15 clusters on the basis of D² values. The clustering pattern was not influenced by the geographic diversity of the varieties. However, a segregation between varieties of the Tuberosum and Andigena type varieties was observed. The exotic potato varieties and also the Indian varieties bred from Tuberosums showed a poor divergence. In contrast, the divergence in the varieties developed from Tuberosum-Andigena crosses was much greater. The inter-cluster distance of such varieties, with respect to Tuberosum and Andigena clusters, appeared to be influenced by the cytoplasm they carried. The varieties with Tuberosum cytoplasm were closer to clusters having Tuberosum varieties and those with Andigena cytoplasm were closer to clusters having Andigena type varieties. The characters least influenced by the selection during the course of evolution of the present day varieties were found to be mainly responsible for adding divergence to the population. A breeding plan involving varieties from different clusters has been outlined.     

Molecular markers for cytoplasm in potato: male sterility and contribution of different plastid-mitochondrial configurations to starch production

Distinct parental cytoplasms were combined in symmetric tetraploid hybrids of potato by somatic cell fusion. This allowed, in the presence of nearly isogenic nuclear genomes, to estimate the contribution of mitochondrial (mt) and chloroplast (cp) genomes to starch content. Analysis of mt-cp configurations in the complete gene pool of german potato cultivars [2n=4x], in a reciprocal dihaploid population [2n=2x],in di-haploid fusion parents [2n=2x] and in their respective hybrids [2n=4x] made visible the effects of different cytoplasmic backgrounds and mitochondrial subgenomic rearrangements. Genotypes identified by markers as cytoplasm Wγ were associated with cytoplasmic male sterility. Evaluation of cytoplasmic types leads to the conclusion, that in starch content the ‘wild type’ cytoplasms Wα and Wγ have a significant advantage to other cytoplasmic types(Tβ, Wδ, Sε).This results from the experiments with a reciprocal population, 180 di-haploids, and from cultivar comparisons. In hybrids an interaction between starch content and different mt-cp combinations could be found. In general the highest field performance, measured in starch content and yield was associated with such cytoplasmic configurations which appeared to a high frequency within a population, when the segregation process was completed. This fact is explained by a selection advantage of clones with optimized organellar segregation already during in vitro phase. PCR markers for cytoplasm differentiation are actualized on a website, http://www.flg.tum.de/pbpz/mm/mt/hybrid.html This revised version was published online in July 2006 with corrections to the Cover Date.     

Molecular characterization of a β-conglycinin deficient soybean

Summary The soybean seed storage protein β-conglycinin has a low amino acid score, shows lower functional gelling properties compared with glycinin and contains a major allergen. The wild soybean (Glycine soja Sieb et Zucc.) QT2 lacks all the subunits of β-conglycinin, and this deficiency is controlled by a single dominant gene Scg-1 (suppressor of β-conglycinin). Scg-1 was introduced into a soybean cultivar Fukuyutaka from QT2 and this near-isogenic line was designated as QY7-25. Segregation analyses of the progeny derived from a cross between QY7-25 and the wild type did not show any significant changes caused by Scg-1 in the germination ratio and seed weight. Low amounts of mRNAs for the α ’, α and β subunits of β-conglycinin were detected by RT-PCR in QY7-25. We revealed that an α subunit mRNA expressed from a region which replaced with mutant line in the near-isogenic line QY7-25 by single nucleotide polymorphisms analysis. In addition, an abnormal splicing event in a cDNA clone for the β subunit isolated from immature seed of QY7-25 was observed. Southern analysis using the coding region of α ’ subunit gene as a probe revealed a polymorphism between QY7-25 and wild type and this genotypes co-segregate with the deficiency of β-conglycinin subunits. These results suggest that the β-conglycinin deficiency might be controlled by a claster region of β-conglycinin subunit genes. In the present study, no agronomical disadvantage in QY7-25 was observed, confirming that Scg-1 is a valuable gene for soybean breeding.     

Molecular diversity of Egyptian cotton (<Emphasis Type="Italic">Gossypium barbadense</Emphasis> L.) and its relation to varietal development

Twenty-eight Egyptian cotton (Gossypium barbadense L.) genotypes (varieties and hybrids) were used for analysis of genetic diversity using DNA based markers (ISSR, SSR, and EST) and to study varietal development of cotton. The ISSR markers gave the highest percentage of polymorphic bands as well as polymorphic information content compared with the other molecular markers (i.e. EST and SSR markers). Using clustering analysis, no general clustering according to the pedigree history of the genotypes was observed. Using principal coordinate analysis (PCOORDA), cotton genotypes were separated by the first three principal coordinates (PC1, PC2, and PC3) accounting for 11.5, 8.6, and 7.2% of the total genetic variance, respectively. The cotton genotypes were distributed into three parts based on the first PC, each part containing a group of varieties having a common ancestor. ‘Giza 12’ variety was the common ancestor for the varieties included in the first part and ‘Ashmouni’ variety was the common ancestor for the varieties included in the second part, while both ‘Sakha 3’ and ‘Sakha 4’ varieties were common ancestors for the varieties included in the third part. The results of the PCOORDA also showed better resolution of the genetic diversity than cluster analysis especially in the illustration of the varietal development of cotton. That means that principal coordinate analysis can be strongly used either alone or in combination with cluster analysis to discuss both genetic diversity and varietal development in the cotton genotypes.     

The role of cytoplasmatic diversification on some productivity traits of maize

The discovery of cytoplasmic male sterility directed scientists to focus their research on the role and influence of cytoplasmic factors on the heredity of some important agronomic traits, especially in hybrids. In this context, numerous cytolines have been created at the Agricultural Research and Development Station Turda (Romania) in order to assess if their genetic value could be due to cytoplasm diversification. Backcross was performed for ten generations in order to transfer the nucleus of the pollenator into the cytoplasm of the maternal genotype. This paper presents the results regarding yield and yield components of 100 hybrids, originated from crosses among isolines and four testers. The isolines, used as maternal genotypes, were created by transferring the nucleus of the elite inbred lines TC 209, TC 316, TC 243, TB 367 and D 105 onto the cytoplasm of T 248, TB 329, TC 177 and TC 221 inbred lines. The cytoplasms–nucleus interaction and the triple cytoplasm–nucleus–tester interaction, caused significant differentiation between the hybrids originated from cytoline maternal genotype in comparison to those from original inbred lines. Yield, thousand kernel weight, ear weight, grain weight/ear and the number of kernels/row were used for comparisons among all genotypes used into this research.     

Effect of parental genotypes and colchicine treatment on the androgenic response of wheat F1 hybrids

The effect of the parental genotypes and colchicine treatment on the androgenic response of wheat (Triticum aestivum L.) F1 hybrids was studied. For this, anthers from three F1 hybrids and their parents were cultured on W14 initiation medium and W14 supplemented with 0.03% colchicine. The number of responding anthers, microspore‐derived structures/100 anthers, green plants/embryos cultured, green plants/100 anthers and albino plants/100 anthers were recorded. It was observed that embryo formation and plant regeneration ability were genetically controlled and genotype dependent. In both treatments the variety Kavkaz had a significantly higher percentage of responding anthers, microspore‐derived structures and green plants/100 anthers than the other genotypes. On the other hand, the variety Myconos also demonstrated high microspore‐derived structure production and green plant regeneration when treated with colchicine. The good response observed in these two varieties indicates the importance of colchicine treatment only for certain genotypes. Green plant production capacity of the hybrids was intermediate to that of the parental varieties. As one parent with a high or even an intermediate response to anther culture could lead to the production of sufficient (for breeding purposes) green plants from the F₁ hybrids, it was concluded that screening the inbred lines for the response to anther culture with and without colchicine treatment could contribute to utilization of breeding material with a low response to anther culture via the proper hybrid combinations.     

The development of a co-dominant marker for the β-conglycinin α′ subunit in soybeans

The development of soybean varieties that lack the β-conglycinin α′ subunit is an attractive goal because the β-conglycinin α′ subunit exerts a negative influence on nutrition and tofu gelation, and is also a major allergen. We sought to develop a co-dominant DNA marker for the β-conglycinin α′ subunit (Cgy-1) gene for use in marker-assisted selection (MAS). We identified a deleted sequence responsible for the null allele of Cgy-1 in a soybean variety lacking the β-conglycinin α′ subunit known as ‘Keburi’. The deletion spanned 12,998 bp and included Cgy-1 and its incomplete tandem duplicate on chromosome 10. Based on the Cgy-1 sequence from both the Williams 82 soybean reference sequence and the Keburi variety, a set of three allele-specific primers was designed for multiplex PCR assay. These primers enabled allelic discrimination by the sizes of PCR products. This amplified two distinct DNA fragments of 913 and 649 bp in Williams 82 and Keburi, respectively. The practicality of the developed co-dominant marker for Cgy-1 was also confirmed by amplification in five other soybean varieties including three wild types and two mutants. The heterozygosity of the F₁ plants at the Cgy-1 locus was ascertained using our novel co-dominant marker. This PCR-based co-dominant marker is capable of detecting the presence or absence of β-conglycinin α′ subunit for soybean marker assisted breeding system.     

Genetic effects and genotype × environment interactions for cooking quality traits in Indica-japonica crosses of rice (Oryza sativa L.)

Indica-japonica hybridization is an important approach for developing superior performing hybrids in rice (Oryza sativa L.). In view of the scanty information available on cooking quality characters in indica-japonica crosses, an investigation was undertaken to estimate genetic and genotype × environment variance and covariance components of amylose content, gel consistency and alkali digestion value, and to determine the relative importance of direct genetic effects, maternal genetic effects and cytoplasmic effects in the genetic variations of the three quality characters. Two indica photo-sensitive genic male sterile (PGMS) lines and four japonica varieties were used as parents to make crosses. Genetic model with genotype × environment interactions for triploid endosperm was used for genetic studies of the three cooking quality characters. Variance component analysis revealed that genetic variations of the three characters were mainly attributable to direct additive and maternal additive effects, and the three traits had significant direct and maternal heritabilities. Genotype × environment interactions were mainly dominance × environment (including direct dominance × environment and maternal dominance × environment) and cytoplasm × environment interactions. Environment factors could only affect the expression extent of dominant genes, without changing their directions. Predicted values of genetic effects indicated that the parental lines, ‘VI-70’ and ‘H9304-1’, appeared to be best for amylose content, ‘T 1950’ and ‘Suxuan’ appeared to be best for gel consistency and alkali digestion value. This revised version was published online in August 2006 with corrections to the Cover Date.     

Phenotypic characterization and nuclear microsatellite analysis reveal genomic changes and rearrangements underlying androgenesis in tetraploid potatoes (Solanum tuberosum L.)

Two (di)haploids (2n = 2x = 24) and nine tetraploids (2n = 4x = 48) obtained from Solanum tuberosum through anther culture were characterized for nDNA variation, phenotypic variation and nuclear microsatellite polymorphism. Androgenic (di)haploids were also characterized for late blight resistance. The (di)haploid C-13 was derived from Indian tetraploid potato cv. Kufri Chipsona-2, while D4 from TPS (true potato seed) parental line JTH/C-107, which is an interspecific hybrid between Indian tetraploid cv. Kufri Jyoti and diploid (2n = 2x = 24) cultivated species S. phureja Juz. & Buk. IVP-35. C-13 and D4 (both male-fertile) could be distinguished from their corresponding tetraploid anther donors based on plant height, shoot number, terminal leaflet length and width, leaf ratio, anther length, pollen diameter and corolla width and radius. A complete reversal of flower color occurred in D4, and C-13 was highly resistant to late blight. Most interestingly, about 3–7% increase in nDNA content occurred in most of the anther-derived tetraploids. Both the androgenic (di)haploids and their anther donors had unique genotypes at the microsatellite loci POTM1-2, STM0015 and STM0019b. However, the nine anther-derived tetraploids shared the same allelic profiles with their anther donor JTH/C-107 at all the microsatellite loci, except at STM0019a where they were characterized by the absence of a standard donor allele (186-bp). A typical (di)haploid-specific allele was detected for the locus STWAX-2 where the standard donor alleles were replaced by a 230-bp allele in both C-13 and D4. The over-expression of microsatellite variation in D4 that also shows triallelic profiles at the microsatellite loci POTM1-2 and STM0015 can perhaps be attributed to its chimeric structure, which might have been formed through incomplete fusion of two different pro-embryos during the first steps of microspore division.     

Resistance to Meloidogyne incognita in Ethiopian Coffea arabica accessions

Polyacrylamide gel electrophoresis (PAGE) was used to study the polymorphism of esterases in Allium cepa L. and A. fistulosum L. Two varieties of each species, an A. fistulosum × A. cepa interspecific F₁ hybrid, and (A. fistulosum × A. cepa) hybrid derivatives were analyzed for determination of banding patterns upon staining with α- and β-napthyl acetate substrates of esterase. Complex band patterns were observed. In total, 10 bands were detected between A. cepa and A. fistulosum — five inA. cepa, six in A. fistulosum with only one band common to both species. With the exception of one band unique to A. fistulosum which appeared only when stained with α-substrate, extracts of both A. cepa and A. fistulosum leaf tissue exhibited the same bands when stained with both α- and β-substrates. Bands stained with the different systems are distinguished by color: α-substrate always appeared black, while bands stained to β-substrate are always red. Esterase bands were assigned into 5 presumptive loci of four zones of activity with according to the migration distance of the bands from the front, color of each band upon staining with α- and β-substrates, and segregation observed in crosses and hybrid derivatives. Esterase enzymes detected in this study appear to be monomeric. Polymorphisms were identified between A. cepa and A. fistulosum by esterase banding patterns. Esterase enzymes provide an additional marker in monitoring introgression of foreign germplasm in interspecific onion breeding. This revised version was published online in August 2006 with corrections to the Cover Date.     

Exploiting genotypic variability from low-altitude Brazilian Savannah-adapted <Emphasis Type="Italic">Chenopodium quinoa</Emphasis>

Saponin-free quinoa genotypes were evaluated in summer and autumn–winter sowings, for phenotypic traits and yield stability. They were obtained by single plant-progeny selection from hybrids, as part of the breeding efforts in adapting the crop to the Brazilian Savannah environments. The soils (Ferralsols) were limed and fertilized prior to cultivation. The experiment was sown in two dates: 20th December 2006 (summer), and 30th April 2007 (autumn–winter), at 15°39′ and 16°14′ S latitude, 47°27′ and 47°44′ W longitude, with altitudes of 976 and 1,110 m, respectively. The mean temperature and rainfall for the summer sowing were 23.0°C and 723 mm. In autumn–winter, under controlled irrigation, the mean temperature was 2.9°C lower than in summer, when plants were exposed to water logging spells. The treatments consisted of fourteen selected genotypes and the varieties Kancolla, BRS Piabiru and Q4.5, used as controls. Comparisons were based on plant height, biomass and grain yield, harvest index (HI) and 1,000 seed weight. The experimental design was a complete randomized bloc, with three replications. Analysis of variance was performed for each sowing and jointly. Statistical differences for the environments were evident only for grain size and plant height. The performance of selected genotypes in each sowing date and in the joint analysis, allows saying that populations Q0779, Q0780 and Q0782 are potentially useful in the acquisition of stable genotypes for the Brazilian Savannahs.     

Confirmation and characterization of interspecific hybrids of <Emphasis Type="Italic">Passiflora</Emphasis> L. (Passifloraceae) for ornamental use

Three new varieties of Passiflora hybrids were developed from crosses between P. sublanceolata J. M. MacDougal (ex P. palmeri var. sublanceolata Killip) versus P. foetida var. foetida L. Twenty putative hybrids were analyzed. Hybridizations were confirmed by RAPD and SSR markers. The RAPD primer UBC11 (5′-CCGGCCTTAC-3′) generated informative bands. The SSR primer A08FP1 amplified species-specific fragments and heterozygote status was observed with the two parent bands 240 and 280 bp. The molecular markers generated by primers were analyzed in terms of the presence or absence of specific informative bands. The morphological characterization of the hybrids enabled their differentiation into three groups, identified as: (1) Passiflora ‘Alva’, composed of five hybrid plants with white flowers, large corona, light purple filaments at base, white and purple/white banding to apex; (2) P. ‘Aninha’, composed of six hybrid plants with pale pink flowers, corona filaments reddish/purple at base, white, purple/white banding to apex; (3) P. ‘Priscilla’, composed of nine hybrid plants with white flowers, small corona, filaments dark purple at base, white and purple to apex. The genomic homology of parent plants was verified by cytogenetic analysis. Both parents were 2n = 22. Meiosis was regular in genitors and hybrids. Aneuploidy was observed at hybrid groups P. ‘Alva’ and P. ‘Priscilla’ (2n = 20). Other authors had already observed the same number of chromosomes for some P. foetida genotypes. Obtaining valuable interspecific hybrids opens up new perspectives to offer opportunities in agribusiness for producers and to arouse the interest of consumers into using passion flowers in the Brazilian ornamental plant market.     

Genetic effects of embryo and endosperm for four malting quality traits of barley

Seed of seven cultivars of two-rowed barley (Hordeum Vulgare L.) and F2 seed from a half-diallel set of crosses among the cultivars were malted in two years to obtain data on diastatic power (DP), alpha-amylase activity (αAA), beta- amylase activity (βAA) and malt nitrogen (N) content. Embryo and endosperm genetic effects on the traits were studied by using a genetic model including genotype × environment interaction for malting quality characters. Variation of the four malting quality traits was affected by gentic effects and environmental interaction. Performance of DP and βAA was mainly controlled not only by endosperm dominance effects but also by embryo genotype × environment interaction and endosperm dominance × environment interaction. Variation of αAA and malt N content was controlled by both embryo and endosperm genetic effects, but the embryo dominance and endosperm additive effects contributed a major part to the total genetic effects. Significant interaction variances (embryo additive × environment and dominance × environment and endosperm dominance × environment) were also observed for αAA and malt N content. Diastatic power was related positively to βAA. Malt N content was associated positively with DP, largely because of the relationship between malt N and βAA. No obvious phenotype association between DP and αAA was found. General narrow-sense heritabilities of αAA and malt N content were 26.1% and 27.8%, respectively. This revised version was published online in July 2006 with corrections to the Cover Date.     

盐胁迫对不同玉米品种幼苗渗透调节物质的影响

以辽宁玉米主栽品种丹玉103、京科301、丹玉99、丹玉201、金刚35、郑单958、瑞盛512、丹玉603、辽单145为试验材料,测定不同浓度盐溶液胁迫对各玉米品种幼苗脯氨酸、可溶性糖以及可溶性蛋白含量的影响。试验结果表明:随着盐胁迫浓度的增加,所有玉米品种幼苗的脯氨酸、可溶性糖含量均有所增加,可溶性蛋白含量均有所降低;上述9个玉米品种中,丹玉103、京科301、丹玉99属强耐盐品种;丹玉603、辽单145属中度耐盐品种;丹玉201、金刚35、郑单958、瑞盛512属弱耐盐品种。     

A simple and efficient cryopreservation of in vitro-grown shoot tips of `Troyer' citrange [Poncirus trifoliata (L.) Raf. × Citrus sinensis (L.) Osbeck.] by encapsulation-vitrification

Wheat of two strong high-protein and two weak low-protein cultivars from New Zealand and Australia were milled to commercial specifications. All millstreams were tested for α-amylase, β-amylase, falling number, protein, starch, damaged starch, amylose, amylopectin, pentosan and ash. The distribution of β-amylase in millstream flours was more variable among cultivars than α-amylase. Generally, both enzymes had lowest activity in sizing and early reduction flours. α-Amylase was very high in the bran, pollard and germ fractions, in which ash content was very high, whereas β-amylase was low in these fractions. These observations, together with the moderate correlation of α-amylase and poor correlation of β-amylase to ash content, suggest that most α-amylasein flour derives from contamination with bran, pollard and germ, whereas most β-amylase derives from the endosperm. Falling numbers varied between the cultivars, but variation amongst millstreams for each cultivar was low, except for cv. Frame, which had particularly high falling number values (834 and 1197) in second and third break flours. These two flours had some of the highest α-amylase levels and lowest starch levels. However, they also had very high protein content (22 and 26%) and very low starch damage (3.2 and 4.5%), which may contribute to the high falling numbers. When endogenous α-amylase in the flour with the highest falling number was supplemented with high levels of barleyα-amylase, the flour withstood the detrimental effects of α-amylasein baking (sticky crumb, poor crumb texture and loaf volume) better than flours of lower falling number, but did not withstand the effects ofα-amylase on falling number. This revised version was published online in August 2006 with corrections to the Cover Date.     

The distribution of normal and male-sterile cytoplasms in Chinese sugar-beet germplasm

Forty-two Chinese sugar-beet breeding lines were evaluated for the presence of normal and male-sterile (Owen) cytoplasms using polymorphisms in the chloroplast petG-psbE region as well as in the mitochondrial minisatellite loci. The polymorphisms detected allowed the distinction of three cytoplasm types over the whole sample, one being associated with Owen cytoplasm, a second with the maintainer inbred ‘TK-81mm-O’-type cytoplasm (termed normal-1 cytoplasm) and a third with another maintainer inbred ‘NK-310mm-O’-type cytoplasm (normal-2 cytoplasm). Western blot analysis was carried out to confirm that expression of the male-sterility-associated protein (preSATP6) occurred in plants with Owen cytoplasm but not in plants with either normal-1 or normal-2 cytoplasm. Of the 42 breeding lines examined, 14 had exclusively normal (normal-1 and/or normal-2) cytoplasm and 11 had only Owen cytoplasm. The remaining 17 lines possessed both normal and Owen cytoplasms, and noticeably, some of these 17 lines have been expected to become the source of superior maintainer lines. The results thus show that molecular identification of the cytoplasm is required to avoid wasting resources on account of attempting to develop the maintainer genotype from plants with Owen cytoplasm.     

Induction of fertile flowers in potato (Solanum tuberosum L.) by silver thiosulphate anionic complex

Summary The effect of gibberellic acid containing mixtures, silver thiosulphate and extended photoperiod on flowering induction in 16 non-flowering potato genotypes and on flowering enhancement in 14 normally potato flowering genotypes was studied in sub-tropical plains of India during short-day autumn crop season of 2000–2001 and 2001–2002. Extended photoperiod alone was not successful in induction of flowering. Silver thiosulphate in combination with extended photoperiod effectively induced flowering in 16 potato genotypes studied for flowering induction. Induced flowers of some genotypes were male fertile. Normal berry setting was observed on induced flowers and seeds obtained from such berries germinated normally. Gibberellic acid containing treatments were not very effective in flower induction as they induced some flowering only in few genotypes. In the normally flowering genotypes silver thiosulphate enhanced maximum flowering and duration of flowering to a great extent.     

Development of TGMS lines for developing two-line rice hybrids for the tropics

A breeding program was initiated at the International Rice Research Institute (IRRI) in 1990 to develop thermosensitive genic male sterile (TGMS) rice lines for developing two-line rice hybrids for the tropics. The TGMS trait was transferred from a temperate japonica TGMS mutant, Norin PL 12, to indica and tropical japonica rice varieties using the pedigree selection procedure. Six new TGMS rice lines adapted to tropical conditions were developed which showed complete pollen and spikelet sterility when maximum temperature was higher than 30 ^°C 1–2 week after panicle initiation. However, up to 85.5% spikelet fertility was observed when these lines were exposed to 26–29 ^°C during the critical stage. Using two of these TGMS lines, some heterotic rice hybrids showing 1–1.6 t/ha higher grain yield than the inbred check varieties were identified in unreplicated observational yield trial conducted at IRRI. Two of the six two-line hybrids yielded significantly higher than the check variety in a replicated preliminary yield trial. This revised version was published online in July 2006 with corrections to the Cover Date.     

Alteration of the genomic composition of Solanum nigrum (+) potato backcross derivatives by somatic hybridization: selection of fusion hybrids by DNA measurements and GISH

Fusion experiments were performed with a first (BC₁‐6738) and a second (BC₂‐9017) generation backcross hybrid of 6x Solarium nigrum (+) 2x potato somatic hybrids with potato cultivars. Because no progeny was obtained from the BC₂ genotypes, alternative approaches were sought to overcome the sexual crossing barrier. Five potato genotypes, one of which contains the hygromycin resistance gene, were used in the fusion experiments. All vigorous regenerants were used for the estimation of nuclear DNA content using flow cytometry. Plants with a DNA content higher than that of the BC₁‐6738 or BC₂ genotypes were considered potential somatic hybrids. Forty‐nine potential somatic hybrids resulted from fusion experiments with BC₁‐6738, from which 20 grew vigorously in the greenhouse and flowered. After pollination with several 4x potato cultivars, eight genotypes produced seeded berries and five genotypes gave seedless berries. In addition, 11 of these 13 somatic hybrids were selected for genomic in situ hybridization (GISH) analysis to determine their genomic composition. Nine had exactly or approximately the expected number of 36 S. nigrum and 60 potato chromosomes. In one genotype, only 22 instead of 36 S. nigrum chromosomes were found and one potato chromosome was possibly missing. Only five potential somatic hybrids were detected among the 79 regenerants from BC₂‐9017 (+) 2x potato fusion experiments that were analysed by flow cytometry. Two of these hybrids were rather vigorous and did flower, but pollinations with potato have not yet set any berries.     

基于SNP标记的爆裂玉米农家品种遗传多样性

为了评价广西爆裂玉米农家品种的遗传多样性,利用56K SNP芯片技术对中国广西45个爆裂玉米农家品种、中国2个爆裂玉米杂交种和6个南美爆裂玉米种质进行全基因组扫描,获得多态性标记14 338个,基因分型为6 种类型。其中A/G类型最多,为5 805个;A/T类型最少,为149个。1号染色体的多态性SNP位点最多,为2 302个;10号染色体最少,为848个。45个农家品种间平均遗传相似系数为0.62,变幅为0.41~0.99,总体遗传相似度高。聚类分析将参试品种划分为三大类群,相同来源的农家品种大多聚在一起;主成分分析显示大部分农家品种聚在一起,与杂交品种和南美品种之间没有交集,表明农家品种遗传相似性较高,与杂交品种和南美品种遗传差异较大。