Genetic diversity and population structure in Jatropha (Jatropha curcas L.) based on molecular markers

Genetic Resources and Crop Evolution - Jatropha (Jatropha curcas L.) is an oleaginous potential, howetever, some studies report that there is low genetic diversity in Brazilian genotypes....     

微卫星标记分析广西水牛遗传多样性

为研究广西沼泽型水牛(Bubalus bubalis)核基因组的多态性,采用23对荧光标记微卫星引物,对随机抽取的60个广西本地水牛样本进行了PCR检测。结果表明,23对引物中,有19对可以获得特异性产物且存在多态,平均有效等位基因数为4.0189,基因座ILSTS086含有13个等位基因;各微卫星基因座的平均杂合度变化范围为0.1852~0.4722,ILSTS019基因座平均杂合度最高(0.4722),而ILSTS017平均杂合度最低(0.1852);群体基因平均多态信息含量(PIC)为0.6639,19个标记中有18个PIC大于0.5,属高度多态位点。     

Genetic diversity of diploid Japanese strawberry species based on microsatellite markers

The United States Department of Agriculture (USDA)—Agricultural Research Service (ARS)—National Clonal Germplasm Repository (NCGR) in Corvallis, Oregon, is a genebank that preserves strawberry genetic resources. Representatives of two Japanese diploid species, Fragaria iinumae Makino and F. nipponica Makino were collected for conservation by the NCGR during an expedition to Hokkaido, Japan. Fragaria iinumae may be a genome contributor to the cultivated octoploid strawberries. The objective of this study was to evaluate the genetic diversity of these two species by using simple sequence repeat (SSR) markers. Twenty of 82 Fragaria-derived SSRs, polymorphic among and within the two species, were selected for genetic analysis of 137 accessions. Genetic diversity, based on the proportion of shared alleles between the two species, in F. nipponica (0.4542) and F. iinumae (0.1808) was significantly different. Three wild interspecific hybrids were identified from intermediate memberships in the two diploid species groups revealed by using the clustering program, Structure. Principal coordinate analysis followed by non-parametric modal clustering (PCO-MC) grouped accessions into two clusters representing the two diploid species. Further clustering within the species groups generated with the program, STRUCTURAMA^TM, resulted in seven subclusters in F. iinumae and three in F. nipponica, which may represent breeding populations appropriate for clonal conservation. Long-term preservation of the species populations and the limited number of hybrids on the island is discussed relative to their geographical distribution and the geological history of Hokkaido Island.     

Genetic diversity of Musa diploid and triploid accessions from the Brazilian banana breeding program estimated by microsatellite markers

Banana (Musa spp.) is one of the most consumed fruits worldwide. Production is based mainly on triploid cultivars, and most genetic improvement programs aim to generate tetraploid hybrids obtained from the crossing of established triploid cultivars with a diploid parent genotype, improved or wild, exhibiting the trait of interest, normally resistance to biotic factors. Microsatellites were used to investigate the genetic variability and relationships between 58 Musa genotypes, including 49 diploids and nine triploid cultivars maintained at the Musa germplasm collection of the Brazilian dessert banana breeding program. Thirty-three primer pairs developed for banana were tested, and nine amplified reproducible and discrete fragments, producing a total of 115 alleles. The average number of alleles amplified per primer was 12.8, ranging from 10 to 15. The diploid genotypes presented the largest genetic variability, demonstrated by the large number of alleles detected, and the low similarity between the clones. The phenetic analysis clustered the triploid cultivars in a separated group, with the exception of the Nanica and Gros Michel cultivars, which showed high similarity with the diploid cultivar Mambee Thu. It was not possible to separate the wild diploid genotypes from the cultivated ones, indicating a common origin of these genotypes. A high proportion of duplicated alleles and/or loci was observed for diploid and triploid genotypes. The information gathered about the similarity between diploid and triploid accessions will help to define potential crosses to maximize the recovery of the typical fruit qualities required in Brazil (AAB, Pome and Silk dessert banana).     

麻疯树对镉胁迫的生理耐性及富集特征研究

研究了不同Cd浓度（0、10、25、50、100、200mg.kg-1）对麻疯树的生理指标和Cd积累特征的影响。结果表明,在土壤中的Cd≤50mg.kg-1时,麻疯树的生长未受到明显影响（P〉0.05）,当Cd≥100mg.kg-1时,其生长受到明显抑制（P〈0.05）;同时,麻疯树叶中叶绿素含量随土壤中Cd浓度的增加而下降,而其体内Cd含量则呈增加趋势,且表现根〉茎〉叶的富集特征;麻疯树叶中的SOD、POD活性随Cd浓度的增加呈先升高后降低趋势,而CAT活性仅在Cd为200mg.kg-1时显著增加,麻疯树叶中的MDA、脯氨酸、可溶性糖和可溶性蛋白、酸溶性巯基和谷胱甘肽含量随Cd浓度的增大呈增加趋势,这可在一定程度上缓解金属Cd对麻疯树的毒害。因此,麻疯树在重金属镉污染土壤修复方面具有一定的应用潜能。     

Cultivation of Jatropha curcas L. leads to pronounced mycorrhizal community differences

Plantations of Jatropha curcas for biodiesel production in tropical and sub-tropical regions are currently booming. Although Jatropha species are well known for synthesizing a range of toxicants, the effects of J. curcas monoculture on the symbiotic status of staple crops and trees have hardly been investigated. We transferred to the greenhouse soil samples collected from 3 J. curcas plantations established 1, 2 and 15 years ago in Senegal, together with soil samples from the corresponding adjacent fallow plots. We tested whether the modification of the original chemical and microbial soil properties induced by the development of J. curcas could alter the growth of common local crops (millet, cowpea) and of a local tree (Acacia seyal), all grown in pots. We also investigated effects at the scale of the root mycorrhizal community by determining root colonization patterns (frequency, intensity) and taxonomic diversity (18S rDNA sequencing). Pronounced compositional shifts in root mycorrhizal communities were almost systematically observed between Glomeraceae and Gigasporaceae, or in some cases within Glomeraceae. Biomass and N–P shoot contents were often higher in J. curcas-grown soils. In conclusion, the altered composition of the soil mycorrhizal communities in response to the development of J. curcas did not have detrimental effects on local staple crops. The functional consequences of such modified mycorrhizal assemblages should now be further investigated under more stressful conditions.     

生物能源植物小桐子功能基因及基因组研究进展

为缓解能源需求与原油价格不断上涨以及有限的化石燃料储备之间的矛盾,人们得寻找更加生态、可持续再生的替代能源。利用能源植物生产生物柴油与生物酒精类燃料已成为发展的方向。其中,大戟科的小桐子以其强抗逆性、高含油量等特点而受到了广泛的关注。本文综述了能源植物小桐子油脂含量与质量、生物代谢以及抗逆性等方面的相关功能基因、细胞学染色体核型、核基因组以及叶绿体基因组的研究进展,以期为能源植物小桐子的遗传改良提供参考。     

Genetic diversity in Ethiopian hexaploid and tetraploid wheat germplasm assessed by microsatellite markers

The genetic diversity of a subset of the Ethiopian genebank collection maintained at the IPK Gatersleben was investigated applying 22 wheat microsatellites (WMS). The material consisted of 135 accessions belonging to the species T. aestivum L. (69 accessions), T. aethiopicum Jacubz. (54 accessions) and T. durum Desf. (12 accessions), obtained from different collection missions. In total 286 alleles were detected, ranging from 4 to 26 per WMS. For the three species T. aestivum, T. aethiopicum and T. durum on average 9.9, 7.9 and 7.9 alleles per locus, respectively, were observed. The average PIC values per locus were highly comparable for the three species analysed. Considering the genomes it was shown that the largest numbers of alleles per locus occurred in the B genome (18.4 alleles per locus) compared to A (10.1 alleles per locus) and D (8.2 alleles per locus) genomes. Genetic dissimilarity values between accessions were used to produce a dendrogram. All accessions could be distinguished, clustering in two large groups. Whereas T. aestivum formed a separate cluster, no clear discrimination between the two tetraploid species T. durum and T. aethiopicum was observed.     

Genetic diversity of some accessions of Cucurbita maxima from Spain using RAPD and SBAP markers

Increasing the knowledge of the molecular diversity of a crop is essential for extending its genetic base, identifying cultivars and selecting parental varieties for breeding programs. In this sense, Cucurbita maxima Duch. is poorly characterised. Nineteen accessions of this species and 8 related Cucurbita accessions were included in a genetic diversity analysis. For this purpose, Random Amplified Polymorphic DNA markers (RAPDs), which analyse neutral variability, and Sequence-Based Amplified Polymorphism (SBAPs), which preferentially amplify coding regions of the genome, were used. While the UPGMA cluster and the principal coordinates analysis obtained using RAPDs did not group the different accessions according either to fruit morphological criteria or to passport data (origin and agro-climatic conditions), the principal coordinates analysis obtained using SBAPs grouped the different pumpkin accessions fundamentally according to the type of use (human consumption, animal fodder or ornamental). This passport trait is reported to be associated with agronomic breeding characters of interest. The usefulness of both types of markers for discriminating accessions of breeding interest is discussed.     

不同年龄麻疯树林地土壤微生物多样性研究

为了探明麻疯树林地土壤微生物类群的生态分布情况,研究了1～10年1,1～20年,21～30年的不同年龄麻疯树林地土壤细菌、真菌及放线菌的数量和类群组成。结果表明:3种林地土壤微生物的数量和种类组成有明显差异,随着林龄的增加微生物数量和种类呈递减趋势;不同土层的微生物数量变化也有所不同,但3种林地都有一个共同特点,即26～30 cm范围内的微生物总数最少;细菌在不同年龄麻疯树林地的各个土层中均有分布,数量明显高于放线菌和真菌;在林地内共分离出土壤真菌20属,其中,假丝酵母属为3个不同年龄麻疯树林地土壤中的优势菌属。     

麻疯树生物柴油发展适宜性、能量生产潜力与环境影响评估

为对西南5省麻疯树生物柴油产业的发展提供依据,该文对西南5省适宜麻疯树种植的宜能边际土地资源潜力、适宜性等级等进行研究,并对该区发展麻疯树生物柴油的能量生产、温室气体减排潜力进行分析。利用多因子综合分析法对麻疯树适宜种植的边际土地资源进行识别及适宜性评价,获得麻疯树适宜种植的边际土地资源空间分布、适宜性等级和总量;利用生命周期分析法,对不同适宜性等级的边际土地资源生产麻疯树生物柴油的生命周期净能量、温室气体减排能力进行研究;利用上述研究结果,对生命周期模型进行扩展,获得西南5省规模化种植麻疯树的总净能量生产能力、温室气体减排潜力。研究结果表明,西南5省适宜与较适宜麻疯树发展的土地资源分别为199.45和557.28万hm2;如果这些土地资源全部被利用,则该区麻疯树生物柴油净能量年最大总生产潜力为15099.194万GJ,总温室气体年减排潜力为1591.655万t。该文研究结果可为制定生物能源产业政策提供参考。     

Genetic diversity and origin of cultivated potatoes based on plastid microsatellite polymorphism

The origin of cultivated potatoes has remaining questions. In this study, 237 accessions of all cultivated species and 155 accessions of wild species closely related to cultivated potatoes, including their putative ancestors, were analyzed using 15 plastid microsatellites (SSRs) to investigate genetic diversity and their relationships with the wild species. We here used polymorphic plastid SSRs we developed from potato plastid genome sequences as well as already known plastid SSR markers. All 15 loci were polymorphic and identified a total of 127 haplotypes. Dramatic decreases in levels of genetic diversity were revealed in landraces in comparison with wild ancestor species. The plastid SSR results showed a decrease in haplotype number and diversity from Peru to both north and south. Phylogenetic analysis revealed two distinct groups. One of them, group A, contained the majority of accessions of cultivated species of the Solanum tuberosum Andigenum group including all accessions of cultivated diploid and triploid cytotypes of this group (S. chaucha, S. phureja, and S. stenotomum by a former taxonomic system) and most of tetraploid accessions of the S. tuberosum Andigenum group (S. tuberosum subsp. andigenum), and the majority of accessions of wild ancestors from the northern members of the S. brevicaule complex. Another group B comprised most of the wild species accessions and almost exclusively hybrid cultivated species which have introgressed plastid genomes from the other wild gene pools. Lack of clustering of traditional cultivated species (as used above) support a revised group classification of S. tuberosum.     

Cytoplasmic diversity of Brassica napus L., Brassica oleracea L. and Brassica rapa L. as determined by chloroplast microsatellite markers

Cytoplasmic genomes in most angiosperms are known to be maternally inherited. Oilseed rape (Brassica napus L.) as a natural amphidiploid species hence may carry the B. oleracea L. or the B. rapa L. cytoplasm, depending on the cross direction. The presence of either the B. oleracea or the B. rapa cytoplasm in oilseed rape has been reported to affect agronomically important traits. However, to date little is known about the cytoplasmic composition and genetic diversity of current winter oilseed rape cultivars and breeding material. The aim of this study was to assess the usefulness of 40 previously published chloroplast cpSSR markers from Brassica species and Arabidopsis thaliana (L.) Heynh. for distinguishing the cytoplasms of 49 different genotypes of B. napus and its diploid ancestor species. Results showed that only 14 out of the 40 tested primer combinations were suitable to distinguish the cytoplasms of a test set of 8 Brassica genotypes. With the 14 primer pairs 64 different cpSSR alleles were identified in the set of 49 genotypes. Cluster analysis indicated distinct groups for the cytoplasms of B. napus, B. rapa, and B. oleracea. However, an unambiguous identification and classification of the cytoplasm types was not possible in all cases with the available polymorphic set of cpSSR primer pairs.     

Genetic diversity and population structure analysis of Grass pea (Lathyrus sativus L.) accessions collected from North-Western Ethiopia using SSR markers

Genetic Resources and Crop Evolution - Grass pea (Lathyrus sativus L.) is a legume crop known to be an excellent source of protein, tolerant to drought, waterlogging, and salinity. The crop is used...     

Genetic variability of Coffea arabica L. accessions from Ethiopia evaluated with RAPDs

The genetic diversity of 50 wild and semi-wild accessions of the Coffea arabica L. germplasm collection, gathered by the FAO and ORSTOM missions to Ethiopia, and maintained in Colombia by CENICAFE, was evaluated with RAPD markers. The evaluation was carried out in two phases: In phase one, the polymorphism of 8 Ethiopian accessions of different geographic origin, plus the cultivated variety 'Caturra' was assessed with the RAPD technique with forty-two 10-mer oligonucleotides. In phase two, 51 accessions were assessed with a set of 5 polymorphic primers that reproduced, with a correlation of 95%, the groups generated by the 24 polymorphic primers found in phase one. Principal Coordinate Analysis of molecular data revealed that a closely related group consisting of 86% of the Ethiopian C. arabica accessions evaluated are significantly different from the Caturra variety and could be used in a genetic breeding initiative to increase the variability of cultivated varieties. The results also indicate that a larger polymorphism is present in the Colombian replica of FAO Ethiopian coffee germplasm collection than previously reported.     

Genetic diversity in Sorghum bicolor(L.) Moench accessions from different ecogeographical regions in Malawi assessed with RAPDs

Genetic variation within and among several Sorghum populations from different agroecological zones in Malawi were investigated using random amplified polymorphic markers (RAPDs). DNA samples from individual plants were analyzed using 35 oligonucleotides of random sequence. Twenty five of these primers allowed amplifications of random polymorphic (RAPD) loci. Overall, 52% of the scored loci were polymorphic. Every accession was genetically distinct. The analysis of molecular variance revealed that the within-region (among accessions) variations accounted for 96.43% of the total molecular variance. Observed variations in allelic frequency was not related to agroecological differences. The degree of band sharing was used to evaluate genetic distance between accessions and to construct a phylogenetic tree. Further analysis revealed that the sorghum accessions analyzed were genetically close despite considerable phenotypic diversity within and among them. It is suggested that all the sorghum landraces currently available in Malawi should be conserved both ex situ and in situ to maintain the current level of genetic diversity.     

不同水量交替灌溉对小桐子生长调控与水分利用的影响

为研究不同水量交替灌溉对小桐子生长调控与水分利用的影响。采用4种水分处理模式(灌水定额分别为T1处理:10mm;T2处理:20mm;T3处理:30mm;T4处理:10和30mm,均不断的对2种灌水定额进行轮回交替)。结果表明:T1处理能在灌水定额为10mm,灌水周期为7d的环境下存活,表现出极强的抗干旱胁迫能力,其原因不仅是通过停止生长和叶片脱落适应干旱环境,而且最主要的原因是通过木质部有类似海绵状的物质能储存较多的乳白色的液体而继续存活。在节水21.6%前提下,与T3处理相比,T4处理的平均外皮层厚度显著增加了24%,叶片、叶柄、主杆、冠层和整株的单位干物质质量的贮存水能力分别显著增加28.3%、28.8%、13.7%、17%和12.3%,平均蒸散量和蒸腾量分别显著降低36.8%和20.4%,而根系和总干物质质量分别增加21.3%和1.3%,因此,总水分利用效率显著提高30.2%。可见,采用灌水定额为10和30mm交替灌溉的T4处理增强了贮存水调节能力,提高了小桐子的根系和总干物质质量,而降低了蒸腾量和蒸散量,从而使得水分利用效率显著提高。