枣品种改良研究进展

概述了枣品种选育成果和杂交育种基础等方面研究取得的主要进展。品种选育主要回顾了实生选种及其成果;杂交育种重点阐述了授粉生物学、授粉受精及胚胎发育、胚败育机理和胚培养等基础进展;同时对雄性不育种质鉴定,实生后代性状遗传规律,利用分子生物技术对实生后代进行杂种鉴别等进行了总结;提出了枣育种存在的主要问题,并对枣育种前景进行了展望。     

Development of novel chloroplast microsatellite markers for Dendrobium officinale, and cross-amplification in other Dendrobium species (Orchidaceae)

Nine pairs of polymorphic chloroplast microsatellite primers were developed for Dendrobium officinale Kimura et Migo, an endangered herb. Levels of polymorphism were tested across a total of 55 individuals from four natural populations (12–15 individuals per population). Allele numbers varied from two to four per locus, while the number of haplotypes ranged from four to six per population. Transferability of the nine polymorphic chloroplast microsatellite primers was checked on an additional set of 51 Dendrobium individuals (belonging to 17 different species). Three markers could be transferable to all the species tested, while the remaining six markers successfully cross-amplified in most species tested. Moreover, polymorphism of the nine chloroplast microsatellite primers was tested across Dendrobium moniliforme (L.) Sw. and Dendrobium loddigesii Rolfe. All of them were polymorphic in D. moniliforme, while seven of which were polymorphic in D. loddigesii. These polymorphic chloroplast microsatellite primers developed for D. officinale will be a useful tool for the study of genetic diversity, population genetic structure, evolution of D. officinale and establishment of effective conservation strategies.     

Genetic diversity in Apium graveolens and related species revealed by SRAP and SSR markers

Genetic diversity is essential to crop improvement. However, lack of molecular markers prevents the understanding of genetic diversity in celery and related species. In this study, SRAP and SSR markers was firstly used to evaluate genetic variation in 68 accessions of Apium graveolens and related species. A total of 888 bands were generated by 40 primer combinations of SRAP and 32 bands were produced by eight SSR markers. Of the 920 bands, 95.1% were polymorphic between A. graveolens and related species, and 49.2% were polymorphic within A. graveolens. Cluster and structure analysis could distinguish local celery, celery, and related species. These results suggested that both SRAP and SSR technologies can be efficiently used to characterize genetic variation and analyze genetic relationship in celery and related species.     

Development of novel EST-SSR markers for cucumber (Cucumis sativus) and their transferability to related species

We report on the development of novel simple sequence repeat (SSR) markers from publicly available Cucumis sativus expressed sequence tags (ESTs) and on their transferability among related species. In total, 533 di- to penta-type SSRs were identified from 6344 cucumber ESTs retrieved from GenBank. Identified SSRs mainly comprised of di- and tri-nucleotide repeats, of which AG and AAG motifs were much abundant. A total of 392 SSR-containing unigenes (non-redundant ESTs/consensus sequences) were suitable for primer design. From these, 35 primer pairs were designed as representative samples and 28 were usable markers. Twenty-six out of 28 usable markers revealed polymorphism among 21 cucumber accessions with 2–7 alleles detected (mean = 3.77) and their polymorphism information content (PIC) values ranged from 0.091 to 0.748 (mean = 0.388). The polymorphism observed herein partially arose from the null alleles which occurred at the multiple homoeoloci detected by the markers. Transferability of the 28 EST-SSR markers was investigated in four other cucurbits: melon, watermelon, pumpkin and gourd which showed frequency of 92.9%, 57.1%, 53.6% and 60.7%, respectively. The EST-SSR markers developed herein will complement the currently available genomic SSR markers and may be useful for genetic studies in cucumber and related species.     

Genetic diversity in local Tunisian pears (Pyrus communis L.) studied with SSR markers

Few records are available about local Tunisian pear cultivars characterized by low chilling requirements and adaptation to dry conditions. In this work, seven SSRs derived from apple were successfully transferred to 25 local Tunisian pear genotypes and 6 common varieties of Pyrus communis cultivated in Europe. The 7 SSRs used amplified a total of 36 fragments. All the microsatellites except one seem to amplify more than one locus in some of the genotypes studied. Only 12 different fingerprinting patterns could be distinguished among the 25 Tunisian cultivars studied indicating a high number of synonymies. The mean expected and observed heterozygosities in the 25 Tunisian cultivars analyzed averaged 0.71 indicating a high level of genetic diversity among the local Tunisian pear germplasm. These markers will be useful to optimize the conservation of this highly threatened germplasm.     

盐胁迫下枣叶片蛋白质组差异的分析

【目的】为了探明盐胁迫下枣蛋白表达的差异,【方法】以较耐盐碱的‘七月鲜’枣品种的扦插苗为材料,经过临界浓度(0.60%)的钠盐(NaCl)处理,取其叶片进行蛋白质双向电泳,经ImageMaster 2D分析,【结果】结果表明,处理与对照之间总蛋白的整体分布模式非常相似,在pH 3~10和MW50~90 kD内的蛋白点分布最多,处理与对照之间量变倍数大于1.5倍的差异点有26个,其中6个蛋白受胁迫上调,20个蛋白受胁迫下调。在上调的蛋白质点中,3个点受盐胁迫诱导增加了近4倍,2个蛋白质点相对丰度增加了2倍以上,表现出强烈的盐诱导特性。说明他们可能在枣的抗盐机制中发挥重要作用。在下调的蛋白质点中,2个点相对丰度降低至对照的5倍左右,表现出强烈的盐抑制特性,说明其可能是对盐胁迫比较敏感的2个蛋白质或多肽,并且在枣的抗盐性机制中也发挥比较重要的作用。【结论】在临界浓度钠盐胁迫下,枣叶片蛋白质表达有显著差异。     

Rose (Rosa hybrida L.) EST-derived microsatellite markers and their transferability to strawberry (Fragaria spp.)

The ‘Genome database for Rosaceae (GDR)’ provides a large collection of expressed sequence tags (ESTs) harboring simple sequence repeats (SSRs) from several Rosaceae genera, including Rosa (rose). Primer pairs flanking SSR were designed for 312 unique Rosa ESTs based on GDR database. Eight rose (Rosa hybrida L.) genotypes were tested for PCR amplification, and 287 (92%) of the primer pairs generated allele-specific PCR bands that were readily scored. From 183 (63.7%) primer pairs that evidenced polymorphic alleles among the eight rose cultivars, 20 pairs evidencing EST sequence homology to known gene functions and high levels of polymorphism were selected and utilized for DNA fingerprinting and genetic diversity assessments of 47 rose hybrids. A total of 202 polymorphic bands were scored and generated unique fingerprints for each rose hybrid. The Nei–Li genetic similarity coefficients among 1081 pair-wise comparisons of 47 cultivars exhibited a broad range of genetic variations from 0.30 (‘Grand King’ and ‘Carnival’) to 0.99 (‘First Red’ and ‘Red Champ’). UPGMA cluster analysis divided 47 hybrids into five major groups and two sub-groups. The cross-species transferability of 273 EST-SSR primer pairs was evaluated using four genotypes of the strawberry, a genus member of the Rosaceae family. PCRs on the DNA samples of strawberry were successful for 165 primer pairs; among these, 123 pairs amplified 243 polymorphic bands. As surrogates of the marker transfer, the phenetic relationship among the four strawberry genotypes was evaluated. Genetic similarity coefficients varied from 0.78 (‘Maehyang’ and ‘Janghyee’) to 0.64 (‘Janghyee’ and ‘Pragana’). The results of cluster analysis showed that the three octaploid strawberry cultivars were quite similar, whereas the diploid ‘Pragana’ was related distantly at the genomic DNA level. The EST-SSR markers developed in the present study can be efficiently utilized for genetic diversity studies in Rosaceae.     

Physico-chemical properties and antioxidant capacity of different jujube (Ziziphus jujuba Mill.) cultivars grown in loess plateau of China

The physico-chemical properties and antioxidant capacity of the five main jujube varieties: Junzao, Lingbaozao, Jinzao, Zanhuangzao and Lizao collected from loess plateau of China were determined. The analyzed components included fruit yield, moisture content, total mass per fruit, pH, titratable acidity (TA), reducing sugars, total sugars, total soluble solids (TSS), ascorbic acid, total phenolics content, total flavonoids content and several pure phenolic compounds. The output of the analyses showed higher amounts of ascorbic acid and phenolics in these jujube varieties than in some common fruits. The antioxidative capacity of the jujube extracts, evaluated with the reducing power, the β-carotene bleaching, the 2,2-diphenyl-1-picrylhydracyl (DPPH•), and the 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonicacid) (ABTS•⁺) scavenging methods, showed that the antioxidant activity of the extracts of Lingbaozao was excellent for free radical scavenging and a potent natural antioxidant of commercial value. Statistically significant differences were observed between jujube cultivars investigated with regards to the measured parameters except rutin content of fruit. These results demonstrated that the cultivar was the main factor which influences the physico-chemical properties and antioxidant activity of jujubes.     

Genetic diversity of Chinese natural bermudagrass (Cynodon dactylon) germplasm using ISSR markers

Bermudagrass (Cynodon dactylon L.) is an important warm-season turfgrass. Although it is widely distributed in China, studies on the genetic variation and relationship among the large-scale indigenous bermudagrass were relatively insufficient, especially at molecular level. The purpose of this study was to assess the molecular variation and relationship among one commercial cultivar ‘Tift3’ and 95 wild bermudagrass accessions collected from 11 provinces in China by ISSR marker technique. The results indicated that 29 ISSR primers generated a total of 248 bands among which 242 (97.6%) were polymorphic bands. The genetic similarity coefficients among accessions ranged from 0.51 to 0.97 with an average of 0.74. All accessions could be clustered into 11 groups with UPGMA method. Accessions from the same or adjacent regions generally were clustered into the same group or subgroups. A few accessions, however, were greatly different from the majority of all accessions. The results suggested that ISSR marker is an effective tool for the study of genetic variation in Chinese natural bermudagrass.     

Comparison of the use of morphological,protein and DNA markers in the genetic characterization of Iranian wild Prunus species

In this study, the genetic diversity of four Iranian wild Prunus species including Prunus eleagnifolia, Prunus hauskenchtii, Prunus scoparia and Prunus lycioides were investigated using morphological, protein and DNA markers. DNA markers included nuclear and chloroplast SSRs and self-incompatibility (S) allele amplification. At the morphological level, leaf width showed significant differences between the four wild Prunus species. Concerning fruit and kernel characters, their values are relatively similar indicating the high degree of homoplasy described in Prunus. Nuclear SSR markers have been the most abundant markers with a higher polymorphism in comparison with morphological, protein and chloroplast SSR markers. Results also indicated the high variability present in the S locus. On the other hand, the correlation between the clustering based on DNA markers and protein were in general low. Dendogram performed using nuclear and chloroplast SSR indicated a more diffuse clustering between the wild almond species probably due to the natural introgression of genes observed in these wild almond species. Data from the analysis of the total protein seems to be more accurate to establish taxonomy relationships in these very close wild species.     

Conversion of chromosome-specific RAPDs into SCAR-based anchor markers for onion linkage maps and its application to genetic analyses in other Allium species

Integration of previously developed Allium cepa linkage maps requires the availability of anchor markers for each of the eight chromosomes of shallot (A. cepa L. common group Aggregatum). To this end, eight RAPD markers originating from our previous research were converted into SCAR markers via cloning and sequencing of RAPD amplicons and designing of 24-mer oligonucleotide primers. Of the eight pairs of SCAR primers, seven resulted in the amplification of single bands of the original RAPDs, and the remaining primer set amplified an additional band. The results of Southern hybridization using RAPD amplicons from genomic DNA of Japanese bunching onion (Allium fistulosum L.)—shallot monosomic addition lines indicated that five SCAR markers were single shallot chromosome-specific markers and were not detected in genomic DNA of A. fistulosum. The eight SCAR primer pairs were applied to other Allium species and exhibited three types of amplification profiles, namely RAPD amplicons observed only in shallot, in shallot and Allium vavilovii, and in several Allium species. A mapping study using 65 F₂ plants generated by the selfing of one interspecific cross A. cepa × Allium roylei individual integrated the SCAR marker SAOE17₅₀₀ into chromosome 5 as expected. The results of the present study show that the eight SCAR primer sets specific to shallot can facilitate the mapping in A. cepa and can also serve as anchor points between maps of different Allium species.     

Assessment of genetic diversity of Latvian and Swedish sweet cherry (Prunus avium L.) genetic resources collections by using SSR (microsatellite) markers

Three previously described highly polymorphic SSR (microsatellite) primer pairs were tested on 126 sweet cherry (Prunus avium L.) accessions to adapt a fast, reliable method for preliminary screening of sweet cherry germplasm collections and to compare two sweet cherry germplasm collections: at the Latvia State Institute of Fruit-Growing, Dobele (LIFG-Dobele) and at the Division of Horticultural Genetics and Plant Breeding at Balsgård, Department of Crop Sciences, Swedish University of Agricultural Sciences (SLU-Balsgård). The SSR loci were highly polymorphic with 4–10 different alleles and 5–18 genotypes. Heterozygosity values ranged from 0.431 to 0.809, gene diversity (PIC) values ranged from 0.400 to 0.753, and the discriminating power of each locus varied from 0.631 to 0.894. The combined discriminating power of all loci was highly effective (0.996). Sixteen identical accession groups with the same allele profile were discovered in both collections. This study demonstrated that SSR fingerprinting with the three primer pairs tested, can be used for preliminary characterization of sweet cherry germplasm collections.     

Development of microsatellite markers in cultivated vanilla: Polymorphism and transferability to other vanilla species

The sources of natural vanilla are the cured fruits of two obligatorily hand-pollinated and clonally propagated orchids: ‘Bourbon/Mexican vanilla’ (Vanilla planifolia G. Jackson) and ‘Tahitian vanilla’ (Vanilla tahitensis J.W. Moore). In this paper we describe for the first time the isolation and characterization of 14 microsatellite loci from V. planifolia. These were monomorphic within cultivated accessions, as expected from the probable single clonal origin of this crop and previous genetic studies. These markers were transferable to V. tahitensis and 11 loci were polymorphic between these two closely related species. Furthermore, some of these markers were transferable and polymorphic across 15 other wild American, African and Asian species and revealed consistent relationships between species, together with a strong pattern of Old World versus New World differentiation in the genus. These microsatellites will be very useful for diversity, hybridization and phylogeographic studies in the genus Vanilla.     

ISSR variations in eggplant (Solanum melongena L.) and related Solanum species

Inter-simple sequence repeat (ISSR) analysis was performed in eight cultivars of eggplant (Solanum melongena) and 12 accessions in eight related Solanum species to evaluate the applicability of this analysis for assessing the phylogenetic relationships and identifying cultivars. A total of 552 polymorphic amplified bands were obtained from 34 of the 100 primers tested, and the percentage of polymorphisms was 99.1%. Cluster analysis based on the ISSR markers classified the Solanum species into seven groups: (i) S. melongena; (ii) S. aethiopicum and S. anguivi; (iii) S. incanum; (iv) S. violaceum and S. kurzii; (v) S. macrocarpon; (vi) S. virginianum and (vii) S. torvum. Combining the ISSR markers obtained by a few of the 34 primers was enough for distinguishing of the eight cultivars of eggplant. This ISSR analysis was demonstrated to be available for the phylogenetic study and the cultivar identification.     

Flower yield performance and stability of various Rosa damascena Mill. landraces under different ecological conditions

The flower yield stability of Damask rose as an important medicinal and aromatic plant at different environments has not been well documented. In order to evaluate flower yield and stability, 35 landraces of Damask rose were studied at 8 locations in Iran during 2007–2008. Analysis of variance revealed significant differences (p ≤ 0.01) among landraces (G), environments (E), locations (L) and for landrace × environment (GE) and landrace × location (GL) interactions. Both GE and GL interactions were mainly crossover, a large portion of which was accounted for by non-linear (unpredictable) component. The landraces of IS9, YZ2, WA1, IS7 and IS1 with 3120.63, 2941.63, 2894.62, 2769.15 and 2716.92 kg/ha respectively produced the highest flower yield among studied landraces. Kerman with average flower yield of 3635.46 kg/ha produced the highest yield among studied locations. According to the results, most of landraces that originated from temperate, warm temperate and arid regions produced higher flower yield than those from cool, cool temperate, semi-arid and humid regions. The landraces of YZ2, IS5, IS8, IS4, KZ1, AR1_, IS3 and BA1 were stable and YZ2, IS5, IS8, IS4, KZ1, AR1 IS6, IS3, BA1, IS10 and YZ1 were adaptable landraces for flower yield according to Eberhart and Russell (1966) model. The presence of some high flower yield and stable landraces such as YZ2 and IS5 suggests that a genotype can demonstrate high flower yield and stability for yield simultaneously. Thus, simultaneous selection for flower yield and stability using nonparametric methods could be possible. In addition, taking into consideration flower yield and stability potential, the landraces of YZ2, IS5, IS8, IS4 and KZ1 as general stable, adaptable, and high flower yield are recommended. Furthermore, the landraces of IS9 and WA1 as high flower yield and specific adaptable landraces can be recommended for temperate and arid areas and the landraces of IS7 and IS1 for semitemperate and cool areas.     

Assessment of genetic diversity and species relationships in eggplant (Solanum melongena L.) using STMS markers

Ninety six accessions including 92 of Solanum melongena and four related non-tuberous species (Solanum insanum, S. incanum, S. integrifolium and S. sysimbriifolium) were taken for the assessment of genetic diversity using 23 STMS primers. Eleven of the 23 primers tested showed polymorphism. The number of alleles per primer ranged from three to six with an average of 4.4. S. melongena had maximum average similarity with its closely related species, S. insanum (0.67) and minimum average similarity with the wild species, S. sysimbriifolium (0.50). The two weedy species S. incanum and S. integrifolium showed more average similarity value of 0.62 and 0.61, respectively with the cultivated S. melongena. S. insanum. S. incanum and S. integrifolium were relatively similar to each other with similarity index value of 0.61 (between S. insanum and S. incanum), 0.63 (between S. insanum and S. integrifolium) and 0.62 (between S. incanum and S. integrifolium). In contrast S. sysimbriifolium was most divergent with the similarity value of 0.49, 0.47 and 0.51 with S. insanum, S. incanum and S. integrifolium, respectively. The closely related species S. insanum and S. incanum, which clustered along with S. melongena accessions, being crossable with cultivated species, constitute important sources of genes that can be introgressed by backcross breeding. Molecular markers can be employed to identify the hybrids and also to monitor introgression of the useful genes.     

ISSR polymorphism in Indian wild orange (Citrus indica Tanaka,Rutaceae) and related wild species in North-east India

Inter simple sequence repeats (ISSR) polymorphism in Citrus indica Tanaka (Rutaceae), an endemic and threatened wild species, was examined along with three other closely related wild taxa (C. medica L., C. latipes (Swingle) Tanaka, and C. sp. ‘Memang athur’) by analyzing 53 representative accessions sampled from North-east India. Jaccard's similarity values among 53 accessions of Citrus ranged from 0.46 to 0.97 (average = 0.75). Genetic similarity values among all the 34 accessions of C. indica were found in the range of 0.82 to 0.97 with an average of 0.90. Heterozygosity (Ht = 0.123) and Shannon's information index (I = 0.188) values estimated for C. indica revealed significantly low level of genetic variation within the species. UPGMA dendrogram grouped all 53 accessions of Citrus into four major clusters: Cluster I – C. latipes; Cluster II – C. medica; Cluster III – ‘Memang athur’ and Cluster IV – C. indica. The dendrogram placed all the 34 accessions of C. indica in five sub-clusters under Cluster IV. The placement of C. indica accessions in various sub-clusters and groups in the dendrogram was based on molecular differentiation of individual accessions rather than their geographical origin. Very low genetic diversity and destruction of its natural habitat pose serious threat to C. indica even in the Citrus Gene Sanctuary in Nokrek Biosphere Reserve (NBR) in Meghalaya. Low genetic variability, heterozygosity and Shannon's information index in C. medica, C. latipes and ‘Memang athur’ are also concerns that need to be addressed for developing appropriate strategies to conserve the genetic diversity extant in these valuable genetic resources.     

Genome composition and genetic diversity of Musa germplasm from China revealed by PCR-RFLP and SSR markers

Banana (Musa spp.) is one of the most important crops in the world. In this study, 216 banana accessions, 184 from the National Banana Germplasm Collection of China (NBGCC) and 32 from the International Network for the Improvement of Banana and Plantain (INIBAP), were used to determine the genome composition of banana plants in these collections and to estimate their genetic diversity. The genome composition was examined using PCR-RFLP markers. The molecular data for all but one accession (ITC 1231) from INIBAP were in agreement with the initial records based on phenotypic characteristics. Microsatellite (SSR) markers were used to investigate the genetic variability and relationships among these banana accessions. Ten of the 47 primer pairs tested consistently produced reproducible and discrete fragments. We identified a total of 92 alleles, ranging from 5 to 15 per locus. The genetic similarity between the accessions ranged between 0.1 and 1, when estimated using Jaccard's coefficient. The UPGMA method based on genetic similarities, grouped the NBGCC accessions according to those containing the ‘A’ and ‘B’ genomes. However, this analysis could not separate all the accessions, especially the somatic mutations, using the primers in this study. These data indicated that limited genetic variation exists within these accessions and the collections of NBGCC should include a much wider range of banana plant material.