NaCl胁迫对不同染色体倍性西瓜种子发芽特性的影响

用盐水浸种催芽方法,通过对蜜枚西瓜的二倍体、三倍体、四倍体在不同浓度NaCl胁迫下种子的发芽率、胚轴长度以及鲜重、发芽指数、活力指数等指标的测定,在30-90mmol／L低浓度下,倍性之间相对发芽率没有明显差异;在120 mmol／L以上浓度时,不同倍性之间差异明显,在150mmol／L NaCl胁迫下。其M4x、M3x、M2x相对发芽率分别为77.8％、63.4％、30.6％,180mmol／L时分别为37.8％、31.7％、0,在210mmol／L时,M4x和M3x仍然有种子萌发,耐盐性为M4x>M3x>M2x。     

麻黄愈伤组织诱导及其倍性鉴定

以草麻黄幼苗的幼茎和下胚轴为外植体,采用不同激素组合及浓度配比的MS培养基进行愈伤组织的诱导。结果表明:草麻黄幼茎愈伤组织诱导的最佳培养基为MS+1．1mg／L 2,4-D+0．2 mg／L KT。在MS+2 mg／L 6-BA +0．2 mg／L IAA的培养基上,下胚轴的诱导率高于幼茎。愈伤组织继代增殖的最佳培养基为MS+0．5mg／L 2,4-D +0．2 mg／L 6-BA,在其上继续生长,形成淡绿色、致密的愈伤组织,愈伤组织细胞主要为二倍体,也有少量的亚二倍体细胞和其它倍性细胞产生。     

烟草染色体倍性快速鉴定方法

摘要: 对两个杂交组合(G28 × NC2326和K326 × Coker176) F1烟草 (Nicotiana tabacum) 花药培养诱导出763个不同倍性植株。基于植株的花和种子结实率常规鉴定倍性水平比较，用气孔保卫细胞叶绿体数目预测植株倍性准确率达93.52%。表明采用气孔保卫细胞叶绿体计数法可以在苗期快速、准确地确定植株染色体倍性。同时, 在移栽前间接地鉴定、筛选出叶绿体数<14的单倍体苗，作进一步秋水仙碱加倍处理，以减少对单倍体材料的浪费，加快DH群体构建速度。     

Polygon of crossability between eleven species of Ipomoea: section Batatas (Convolvulaceae)

Summary Crossability within Ipomoea section Batatas is complex because of genetic, cytogenetic and physiological interactions. This complexity is responsible for the fact that knowledge about phylogenetic relationships within this section remains preliminary. Between 1988 and 1991, studies of planting, pollination and evaluation of progenies were carried out at the facilities of CIP in La Molina and San Ramon, Peru. Self-compatibility was found in nine diploid species. Self-incompatibility was found in diploid I. trifida, tetraploid I. tiliacea and both tetraploid and hexaploid I. batatas. Sexual compatibility is though to be related to a multiallelic sporophytic incompatibility system which is expressed in the stigmatic papillae. Altogether, 4,162 cross pollinations were made between 11 species and 76 interspecific combinations of 110 possible combinations in a diallel 11×11 design. From these 76 interspecific combinations only 38 survived, and in these crossability (= proportion between number of fruits harvested/pollinations made) ranged from 0.01 to 1.00 at La Molina. At San Ramon, 11 out of 17 cross combinations were successful, and in these crossability ranged from 0.01 to 0.71. Crossability appeared to be influenced by latitude which is related to flowering synchrony. The early death of seedlings is hypothesized to be related to a genomic imbalance between embryo and endosperm. Maternal effects were found in crosses between diploids and tetraploids which produced triploid and diploid offspring, and in crosses between hexaploids and diploids which gave rise to hexaploid offspring. This study shows that I. trifida and I. x leucantha may act as bridge species for gene flow from wild Ipomoea species to the genepool of the sweetpotato.     

Polyembryony in species of the genus Allium

Polyembryony has been detected in 26 Allium species during a series of germination tests. Additionally to those species already known for their polyembryonic tendency, high rates (up to 32%) of twin seedlings have been found in A. splendens and some other species. Genotype effects were obvious between several accessions within the species A. tuberosum. In A. tuberosum, enzymatic embryo sac isolation has been used for demonstration of polyembryonic development in early stages. Genotype and ploidy dependence of the polyembryonic process and ploidy alterations in plants derived from polyembryony are discussed. This revised version was published online in August 2006 with corrections to the Cover Date.     

Ploidy races in Actinidia chinensis

Summary Ploidy levels were examined in 26 accessions of Actinidia chinensis: 20 accessions were diploid (2n=2x=58) and 6 accessions were tetraploid (2n=4x=116). There was no evidence of variation in ploidy level within an accession. Our results are consistent with tetraploid A. chinensis coming from a restricted part of China.Interploid crosses within A. chinensis produced only low numbers of seedlings which were mainly triploid. Crossing hexaploid A. deliciosa with pollen of tetraploid A. chinensis produced a large family of plants and those checked were pentaploid.Counts on 83 genotypes of different ploidy levels (2x, 3x, 4x, and 5x) confirmed that the basic chromosome number in Actinidia is 29.     

The importance of Endosperm Balance Number in potato breeding and the evolution of tuber-bearing Solanum species

Summary Endosperm failure is considered the primary reason for the lack of success in intra-and interspecific crosses. The Endosperm Balance Number (EBN) hypothesis is a unifying concept for predicting endosperm function in intraspecific, interploidy, and interspecific crosses. In the EBN system, every species has an effective ploidy (EBN), which must be in a 2:1 maternal to paternal ratio in the endosperm for crosses to succeed. The knowledge of EBN is very useful in the transfer of genes from exotic germplasm, and in the development of new breeding schemes in potato. The paper describes the strategies for introducing 2x(1EBN), 2x(2EBN), 4x(2EBN) and 6x(4EBN) germplasm into the cultivated 4x(4EBN) potato gene pool. A new methodology for producing 4x(4EBN) and 2x(2EBN) chromosome addition lines is also discussed. EBN has evolutionary importance in the origin of tuber-bearing Solanums. The role of the EBN in the origin of diploid and polyploid potato species, and as a barrier for hybridization and speciation of sympatric species within the same ploidy level is demonstrated. The origin of 3x and 5x cultivated tuber-bearing Solanums may also be explained using the EBN concept. EBN has been reported to exist in other plant species: alfalfa, beans, blueberries, rice, soybeans, squashes, tomato, forage legumes, grasses, ornamentals and Datura stramonium. This indicates that EBN may have broad application and could be useful for germplasm transfer and breeding in other crop species.     

Towards breeding of triploid chamomile (Matricaria recutita L.) – Ploidy variation within German chamomile of various origins

German chamomile is an important medical plant with a long history of usage and a wide range of medical applications. Wild forms are diploid, whereas cultivated ones are diploid and tetraploid. Ploidy level variation within 15 origins (varieties, accessions, populations) of chamomile was investigated. Both naturally occurring triploids and those induced through directed crosses between diploid and tetraploid parents were identified and analysed, and these data could facilitate the exploitation of triploidy in chamomile as in other crop plants (fruit and ornamental plants).     

The hematology of diploid and triploid transgenic Atlantic salmon (Salmo salar)

This study examined the erythrocyte height/length, hematocrit, total blood hemoglobin concentration and mean cellular hemoglobin content of diploid and triploid transgenic and non-transgenic Atlantic salmon, to clarify the interaction between metabolic rate and hematology in these fish. Triploid erythrocytes were significantly longer and proportionately thinner than diploid erythrocytes for both genotypes. These morphological differences gave triploid erythrocytes an elliptical appearance with the width being ∼53% of the length, whereas diploid erythrocytes tended to be more rounded with the width being ∼62% of the length. As well, diploid and triploid transgenic erythrocytes were significantly shorter and thinner (P<0.0001) than their non-transgenic counterparts. Although not significant, observations using a Channelized Coulter Counter showed that transgenic erythrocytes tended to be higher in count and smaller in volume than non-transgenic erythrocytes of the same ploidy. Transgenics likely produce erythrocytes with higher surface area to volume ratio in response to their elevated metabolic rates. No other major hematological differences were observed between transgenics and non-transgenics of the same ploidy. This revised version was published online in August 2006 with corrections to the Cover Date.     

Geographic distribution and genetic resources of Dactylis in Galicia (northwest Spain)

Three Dactylis glomerata subspecies can occur in Galicia (Spain): subsp. glomerata, subsp. izcoi and subsp. marina. The second includes diploid and tetraploid populations adapted to acid soils. The third subspecies comprises natural tetraploid populations mainly on sea cliffs, with high digestibility. Dactylis taxonomy is difficult due to the existence of different ploidy levels and to free hybridization at the tetraploid level. This difficulty increases in Galicia, where there is a rich flora with relics and hybrids. The advance of human technology makes necessary the collection of natural Dactylis resources. In this paper, Dactylis distribution in Galicia is described. Tetraploid populations from subsp. izcoi have a wider ecological range than diploids (Galician diploid). These diploids and the subsp. marina are more widespread than formerly recognized. Morphologically, subsp. glomerata and izcoi are more similar than hitherto reported. It is suggested that the subspecies are adapted ecotypes which hybridize. They are useful genetic resources for pasciculture on acid soils and agroforestry.