Analysis of loquat germplasm (Eriobotrya japonica Lindl) by RAPD molecular markers

The loquat’s adaptation to Spain has proved very successful. In the Valencia area, the crop has met with very good environmental conditions for its development. Many new cultivars have been selected by growers and a European loquat germplasm collection has been established in Valencia at IVIA. An efficient sampling as well as implementation of germplasm resources requires the accurate identification of plant material. Molecular markers offer an effective tool for cultivar fingerprinting, estimation of genetic similarity and relationships. In this study, as a tool for germplasm management, RAPD markers were tested. Thirty-six primers were used to screen 33 cultivars. Twenty-three primers proved polymorphic. These primers generated 29 polymorphic amplification fragments that were selected as markers. Twenty-two cultivars out of 33 were identified by unique combinations of RAPD markers. Four different combinations were shared by two or more cultivars each. Cluster analysis based on the similarity matrix obtained from Nei’s coefficient among cultivars showed groupings that agreed according to geographical and genetic origin. RAPD technology was useful in distinguishing those cultivars obtained through hybridization but could not be used to distinguish those obtained by selection of mutations. This revised version was published online in August 2006 with corrections to the Cover Date.     

水杨酸处理对三倍体西瓜种子萌发及其质膜透性的影响

摘　 要: 为解决三倍体西瓜种子的萌发问题,以三倍体西瓜种子为材料,研究了不同浓度的水杨酸（SA）引发处理对三倍体西瓜种子萌发及其种子浸出液电导率的影响。结果表明: 在SA浓度为0.01-1.0mmol﹒L-1范围内浸种处理可明显促进三倍体西瓜种子的萌发,其发芽势、发芽率、发芽指数、活力指数呈增长趋势,其中0.1 mmol﹒L-1的SA处理24h效果极为显著。而当SA浓度高于1.0 mmol﹒L-1时则对种子的萌发起抑制作用,其各项萌发指标均随SA浓度的增加而明显下降。SA浸种后三倍体西瓜种子浸出液电导率的变化同种子萌发的趋势相似,较低浓度SA可显著降低种子浸出液的电导率,此后随SA浓度的升高其呈明显下降趋势。     

Water Deficit during the Reproductive Period of Grass Pea (Lathyrus sativus L.) Reduced Grain Yield but Maintained Seed Size

The grain legume grass pea (Lathyrus sativus L.) is adapted to drought‐prone environments, but the extent and mechanisms of its tolerance are not well understood. In a pot experiment, water deficit was imposed on plants by withholding water from first flowering until predawn leaf water potential (LWP_pd) was ?3.12 MPa. Water deficit reduced dry matter, seed yield, harvest index and water use efficiency by 60 %, 87 %, 67 % and 75 %, respectively, when compared with the controls. Flower production stopped when LWP_pd fell to ?1.8 MPa. At LWP_pd?1.5 MPa, only 25 % of flowers resulted in filled pods (compared with 95 % filled pods in the control) with the rest aborted as flowers (48 %) or pods (27 %). Filled pods had more aborted ovules than controls, resulting in 29 % less seeds per pod. Water deficit reduced pollen viability, germination and the number of pollen tubes reaching the ovary by 13 %, 25 % and 31 %, respectively. Emergence from seeds produced from water‐deficient plants was 21 % less than controls, but seedling shoot dry mass was 18 % higher, in accordance with the 19 % higher seed mass. The sensitivity of flowering to drought limited pod numbers but enabled plants to retain existing pods and develop near‐normal seeds with low β‐N‐oxalyl‐l ‐α‐β‐diaminopropionic acid toxin concentrations. This trait is useful for farming systems reliant on harvested seed for the next crop and in cases where seed size influences the value of the product.     

Pollen and pistil morphology, in vitro pollen grain germination and crossing success of Lens cultivars and species

Morphological and in vitro germination characteristics of pollen altogether with pistil and style length were analysed, so as to carry out a morphological comparison between different lentil (Lens culinaris Medik.) cultivars and wild species, as well as to correlate the morphological and functional statistics with data regarding crossing success. Pollen length and width in the different genotypes were found to have a positive and highly significant correlation with pistil and style length and in vitro pollen tube length. A cluster analysis detected two different plant groups, namely, (i) large‐seeded L. culinaris (macrosperma), and (ii) a second group formed by two subgroups, a first subgroup with L. ervoides standing alone and a second subgroup including small‐seeded L. culinaris (microsperma) and the wild L. culinaris ssp. orientalis, L. odemensis, L. nigricans. A high and significant correlation was detected between crossing success and phenotypic similarity (r > 0.98; P < 0.05), therefore implying that phenotypic similarity, based on pollen morphology and in vitro pollen length together with pistil and style length, is a good predictor of hybridization success.     

植物生长调节物质对黄金梨花粉萌发和花粉管生长的影响

目的:研究不同质量浓度的6-BA、NAA、2,4-D、多效唑等4种植物生长调节物质对黄金梨花粉萌发和花粉管生长的影响。方法:配制含有不同浓度的生长调节物质的花粉液体培养基,对采集的黄金梨花粉进行培养,研究不同浓度植物生长调节物质对花粉萌发和花粉管生长的影响。结果:在所使用的植物生长调节物质的浓度范围内:(1)较低浓度的6-BA和2,4-D能促进花粉萌发和花粉管生长,但超过一定浓度时起抑制作用;(2)NAA和多效唑均对花粉萌发和花粉管的生长表现出抑制作用。结论:6-BA和2,4-D促进黄金梨花粉萌发与花粉管生长的最适宜浓度分别为10mg/L和5mg/L。     

The crossing of common wheat (Triticum aestivum L.) with cultivated rye (Secale cereale L.). I. crossability,pollen grain germination and pollen tube growth

Summary The crossing of common wheat (Triticum aestivum L.) with rye (Secale cereale L.), and especially the action of the crossability genes of wheat, was studied using the readily crossable wheat cv Chinese Spring (genotype kr ₁ kr ₁ kr ₂ kr ₂ >), the poorly crossable wheat cv Hope (genotype Kr ₁ Kr ₁ Kr ₂ Kr ₂ ), as well as the disomic substitution line of chromosome 5B of Hope into Chinese Spring (CS/Hope 5B, genotype Kr ₁ Kr ₁ kr ₂ kr ₂ ). By comparing crossability and actual fertilization, the poor crossability with rye of both cv Hope and the CS/Hope 5B substitution line was shown to result from absence of fertilization. Studies of pollen grain germination and pollen tube growth showed that the dominant alleles of the crossability genes manifested themselves through retardation and eventually inhibition of pollen tube growth at the style base and in the ovary wall. In Hope the growth of all pollen tubes was inhibited, whereas in CS/Hope 5B rarely fertilization was achieved. The recessive alleles of the crossability genes do not seem to have an influence on the growth of rye pollen tubes in wheat pistils.     

Compatibility and incompatibility in witloof-chicory (Cichorium intybus L.). 1. The influence of temperature and plant age on pollen germination and seed production

Summary For the production of inbred lines and F₁ hybrids in witloof-chicory information is wanted on characteristics such as the incompatibility system. These characteristics can only be studied properly if the influence of temperature and physiological status of the plant on pollen germination and seed production is known. Investigations were carried out with 9 self-incompatible (SI) and 6 self-compatible (SC) clones in glasshouses of the IVT phytotron at constant temperatures of 10, 14, 17, 20, 23 and 26°C. In general, in vivo pollen germination percentages were rather low after self pollination with an optimum for germination around 17–20°C. No seeds were formed at the lowest temperature (10°C) while seed production for SC clones was usually (rather) good at higher temperatures. At 26°C seed production in some clones decreased. Both pollen germination and seed production decreased at the end of the flowering period. There was a rather positive relationship at e.g. 17 and 20°C between pollen germination after selfing and seed production. When no pollen germination was observed, no seed formation occurred. When pollen grains did germinate, seed development would not necessarily occur in all cases. So this relationship only enables negative mass selection for SC.     

Establishment of reliable methods of in vitro pollen germination and pollen preservation of Brassica rapa (syn. B. campestris)

A simple and reliable method for evaluating the viability of Brassica pollen was established in which the in vitro germination rate of pollen was adopted as the index of the viability of pollen grains. Pollen grains were preincubated in an atmosphere in which the relative humidity (RH) was fixed to 52% or 66% at 20 °C for 5 hours. They were cultured for 16 hours at 25 °C in a liquid Kwack's medium (1964) supplemented with 20% sucrose, and the pH was adjusted to 8.0. They were then observed under a microscope and the number of germinating and unchanged pollen grains were counted. The germination rate of pollen was improved and stabilized by preincubation and the use of a high pH medium. More than 90% of the freshly harvested pollen grains of Brassica rapa (syn. B. campestris) germinated constantly in these conditions Undehisced anthers were collected from flowers at anthesis and dehydrated by incubation at 20 °C for 16–24 hours in an atmosphere where the RH was fixed to 15% or 32%. They were put into a plastic vial and preserved in a freezer at -20 °C. The germination percentage of the preserved pollen was scored at intervals during preservation. The germination rate of the pollen grains preserved at -20°C for 1 year was higher than 50% and the pollen proved to be efficient for seed set. Most of the seeds germinated normally. This revised version was published online in August 2006 with corrections to the Cover Date.     

Seed protein variation for identification of common buckwheat (Fagopyrum esculentum Moench) cultivars

Summary Total seed proteins of 24 common buckwheat cultivars and cultivated populations within a molecular weight range of 30 to 54 kDa were analysed by SDS-PAGE. Single seed analysis of six cultivars identified a total of 18 alternative protein bands with different mobilities. Differences of individual protein band frequencies extracted from single seeds among six buckwheat cultivars varied distinctively, indicating high intravarietal polymorphism. The relation between frequencies of protein bands revealed by single seed analysis and their appearance on the bulk seed analyses was demonstrated. Regarding to band mobility rate and relative band intensity among 24 bulk samples analysed, 14 had distinctive electrophoregrams while the other 10 were ranged into four distinct groups. Analysis of endosperm and cotyledon proteins showed that proteins stored in these main seed parts are tissue specific. The observed electrophoretic polymorphism related to proteins stored in the cotyledons while there was no apparent variability with endosperm proteins.     

The site of action of the crossability genes (Kr 1, Kr 2) between Triticum and Secale. I. Pollen germination,pollen tube growth,and number of pollen tubes

Summary Seven genotypes of common wheat (Triticum aestivum L.) were crossed with rye (Secale cereale L.) in order to find the site or sites of action of the crossability genes, Kr ₁ and Kr ₂, of wheat. The data obtained, by fluorescence microscopy, were compared to the controls (wheat x wheat). The results indicate that the crossability genes have little effect on pollen germination and on the time taken for the pollen tubes to reach the microphyle, irrespective of their crossabilities with rye. The number of pollen tubes reaching the microphyle is, however, affected by the Kr-genes, as high crossable genotypes have more pollen tubes than the low crossable ones. There was a high correlation between the mean number of pollen tubes at the micropyle with seed set, which also reflects the crossability. The Kr-genes seem to manifest themselves in the retardation and inhibition of pollen tube growth between the style base and the top of the embryo sac, where the effect is most distinct in the low crossable genotypes.     

Effects of gamma irradiation on in vitro pollen germination of different Cucumis species

Summary Pollen grains of 14 Cucumis accessions were irradiated with 0, 1, 2, 3 or 4 kGy acute gamma rays and germinated in vitro directly afterwards. Pollen germination was significantly reduced by increasing irradiation dose for all species, except C. melo var. agrestis. Pollen tube growth was generally reduced likewise. Pollen of two C. anguria subspecies was most sensitive to irradiation. Sensitivity of the pollen with respect to pollen tube growth in relation to irradiation dose was inversely related to total DNA amount per nucleus. In vitro germination was not related to DNA amount per nucleus. Results show that the examined Cucumis species, especially C. melo var. agrestis, are sufficiently resistant to irradiation to be used as donor species for in vivo egg cell transformation of the cucumber.     

外源生长调节物质对阔叶杨桐种子萌发的影响

试验研究了厚皮香科植物阔叶杨桐种子在3种外源生长调节物质GA、IAA和6-BA浸种处理下的萌发特性。结果表明,阔叶杨桐种子为休眠性种子,不同外源生长调节物质对种子萌发影响不同,与对照相比,50 mg/L和100 mg/L的GA浸种提高了种子的萌发率,而150 mg/L的GA处理抑制种子的正常萌发;低浓度的IAA(<100 mg/L)浸种处理促进种子的萌发,高浓度IAA浸种降低种子的萌发率;种子萌发对不同浓度6-BA的响应趋势与IAA相似,综合分析认为,低浓度的外源生长调节物质浸种处理可以在一定程度上解除种子的休眠,提高种子的萌发率,其中50 mg/L的6-BA浸种处理12 h效果最佳。     

Analysis of pollen tube growth in situ to investigate self-incompatibility in the wild potato Solanum commersonii

Summary Pollen tube growth was investigated in a diallelic crossing design with seven genotypes of the diploid wild potato species Solanum commersonii, accession O/S UR-9, CIP 762459. Pollen tube growth in the style was recorded using a combined quantitative and qualitative evaluation scale. Clear-cut differences in pollen tube growth behavior in compatible and in partially or completely incompatible crosses were detected. Diallelic crossing of the seven randomly chosen genotypes, intercrossing within two progeny families, and backcrossing of two progeny populations to the parents revealed the existence of a one-locus gametophytic system of stylar incompatibility. The S-allele status of all genotypes investigated was determined.     

Occurrence of 2n and jumbo pollen in the Brazilian ginseng (Pfaffia glomerata and P. tuberosa)

An analysis of microsporogenesis was carried out in four populations of Pfaffia tuberosa (2n=4x=68) and in ten populations of P. glomerata(2n=2x=34). Monads, dyads and triads were reported at high frequency in all populations of P. tuberosa. In P. glomerata, on the other hand, only four populations presented monads, and at low frequency. Dyads and triads were observed in both species, albeit at a higher frequency in P. tuberosa populations. Certain abnormalities of spindles in the second division, such as sequential and tripolar spindles, led to triad formation by the rejoining of two chromosome sets. The precise causes of monad and dyad formation have not been found during meiosis, although evidence exists that dyads originated by omission of second meiosis and monads by omission of both meiotic divisions. This revised version was published online in July 2006 with corrections to the Cover Date.     

重金属Cu污染对苏丹草种子发芽及幼苗生长的影响

为了探讨苏丹草在重金属Cu污染土壤植被修复中的应用,以苏丹草种子为材料,研究了不同浓度铜(Cu)溶液对苏丹草种子发芽及幼苗生长的影响。结果表明：Cu胁迫浓度低于10 mg/L时,对苏丹草种子的发芽率、发芽势、发芽指数和5 mm胚芽鞘的伸长具有促进作用,随Cu浓度升高,促进作用变为抑制效应;Cu胁迫浓度对幼苗高度、根长、鲜重和干重均存在抑制作用,且浓度越高对幼苗生长抑制越明显;Cu对苏丹草幼苗地上部分的抑制作用大于对根系的抑制。重金属Cu对苏丹草种子萌发和幼苗生长存在抑制效应,植被修复中应测定土壤Cu含量后决定播种及种子用量。     

Interspecific compatibility barriers,development of interspecific hybrids through embryo rescue and lineage of Trifolium alexandrinum (Egyptian clover)—important tropical forage legume

Genetic improvement of Trifolium alexandrinum L. is hampered because of narrow genetic base and lack of interspecies compatibility information. The study was envisaged to understand the interspecies incompatibility and the affinity between T. alexandrinum and 22 species of the genus representing different sections and to develop interspecific crosses. Development of interspecific hybrids with T. resupinatum, T. lappaceum, T. subterraneum, T. vesiculosum and T. echinatum, through embryo rescue, revealed their affinity with T. alexandrinum. Failure of pollen germination or restricted pollen tube growth showed its distant relatedness with T. clypeatum, T. balansae, T. purpureum, T. leucanthum, T. hirtum, T. pilulare and T. hybridum. Pollen tubes reached up to ovule among the crosses with T. alpestre, T. repens and T. nigrescens, whereas it travelled up to ovary among the crosses with T. angustifolium, T. grandiflorum and T. dasyurum indicating need of manipulation to overcome barrier. Thus, incompatibility of T. alexandrinum with many Trifolium species could be overcome through embryo rescue with intensive crossing. Egyptian clover ecotype ‘Fahli’ was more compatible with other species than ‘Mescavi’.     

Inheritance of Seed Dormancy in Lisianthus (Eustoma grandiflorum)

The genetics of chill-related seed dormancy, exhibited by a lisianthus (Eustoma grandiflorum) genotype native to North America, was investigated. Less than 1 % of the seeds germinated by direct hydration at 20°C, while full germination (98%) was attained by chilling imbibed seeds, for at least 11 days, at 3°C, before transferring them to 20°C. The inheritance of seed dormancy was analyzed in F₁, BC₁, and F₂, populations, derived from mating between a normal non-chill-requiring genotype (P₁) and the above chill-requiring genotype (P₂). F₁ seeds, of both reciprocals, and BC₁ (P₁) seeds were all non-dormant. The proportion of seed dormancy in F₂ and BC, (P₂) was 0.06 and 0.68, respectively. The inheritance model proposed includes six diallelic loci with cumulative effects, in which the presence of at least nine ‘dormancy-conferring’ alleles is necessary for inducing phenotypic seed dormancy. Possible implications of inherent seed dormancy on the utilization of native lisianthus germplasm for breeding are discussed.     

In vitro pollen germination and tube growth of tomato (Lycopersicon esculentum Mill.) and its relation with plant growth

Summary In vitro pollen germination at 10°C, 14°C and 22°C of four groups of two pure line tomato varieties was compared with their plant growth at 19°C D/10°C N under controlled environmental conditions. Generally, pollen germination was slow at 10°C but after 6 h the percentage of germination was similar to that at 22°C. Maximum germination was obtained at 14°C already after 4 h. The longest pollen tubes occurred at 22°C. The two varieties within each group differed significantly from each other for percentage of pollen germination. For one group, this difference was greater at 10°C than at 22°C. The varieties in two groups also differed significantly for pollen tube growth. These differences in pollen tube growth rate were greater at 22°C than at 10°C. There was no clear relationship between pollen germination, pollen tube growth and plant growth in any of the four pairs of varieties. The results are discussed with regard to the possibility of pollen selection at low temperature in order to improve the efficiency of breeding for growth at low temperature.     

Incompatible pollen tube growth and protein composition in styles of Japanese pear following high temperature treatments

Summary Immersing the excised-prepollinated styles of self-incompatible Japanese pear, Pyrus serotina Rehd., into distilled water at 45°C for 1.5–2.5 min promoted the growth of self-pollen tubes; both the number of styles penetrating the pollen tubes through styles to cut ends and of pollen tubes protruding from cut ends were increased. The subsequent growth of the protruded pollen tubes on agar media was also enhanced by the treatments. Treatments at 40°C did not promote the growth of self-pollen tubes and those at 50°C led the styles to necrosis. In the stylar proteins analyzed by isoelectricfocusing polyacrylamide gel electrophoresis, several changes in banding pattern were found following the heat treatment; one of the bands was a glycoprotein that increases in quantity in developing styles as self-incompatibility of the style becomes stronger (Hiratsuka et al., 1986). This protein band was stained more weakly by Coomassie Brilliant Blue-G250 dye. Antigenic substances in the styles examined by immunodiffusion seemed not to be denatured by high temperature treatments.Abbreviations IEF-PAGE isoelectricfocusing polyacrylamide gel electrophoresis - CBB Coomassie Brilliant Blue     

重金属铅胁迫对绿豆种子萌发及幼苗生长的抑制效应

为初步探明重金属对作物种子萌发和幼苗生长的抑制效应,以不同浓度(10.0、20.0、50.0、100.0、200.0 mg·kg-1)重金属铅溶液培养绿豆种子(蒸馏水培养作对照),观察其对绿豆种子萌发、幼苗生长和种子活力的影响.结果表明,受试绿豆种子的发芽率、发芽势以及根长、芽长和幼苗鲜重等指标均随铅离子(Pb2+)浓...