中国粮食作物的野生近缘植物及其保存概况

中国的主要粮食作物约有20种,它们的多数都有野生近缘植物.目前,中国保存的粮食作物野生近缘植物资源约1.5万份,分别保存在国家作物种质资源库和种质圃内.     

Phenotypic variation of life‐history traits in native,invasive, and landrace populations of Brassica tournefortii

Varying environments can result in different patterns of adaptive phenotypes. By performing a common greenhouse experiment, we identified phenotypic differentiation on phenology, leaf morphology, branch architecture, size, and reproduction, among native, invasive, and landrace ranges of Brassica tournefortii. We first compared trait means and fitness functions among ranges, then we analyzed how trait means and selection strength of populations respond to varying aridity. Most traits varied such that landrace > invasive > native. Excluding reproduction, which was positively selected, most trait PCs experienced nonlinear selection in the native range but frequently shifted to directional selection in invasive and/or landrace ranges. The absence of strong clines for trait means in landrace and invasive populations suggest that agricultural practices and novel environments in source locations affected adaptive potential. Selection strength on faster reproductive phenology (negative directional) and leaf margin trait (disruptive) PCs coincided with increasing moisture. In native populations, higher aridity was associated with more days to reproduction, but landrace and invasive populations show stable mean time to reproduction with increasing moisture. A stable adaptive trait can increase range expansion in the invasive range, but stability can be beneficial for future harvest of B. tournefortii seed crops in the face of climate change.     

Genomic analysis unveils reduced genetic variability but increased proportion of heterozygotic genotypes of the intensively managed mezcal agave,Agave angustifolia

Premise

The central Oaxaca Basin has a century-long history of agave cultivation and is hypothesized to be the region of origin of other cultivated crops. Widely cultivated for mezcal production, the perennial crop known as “espadín” is putatively derived from wild Agave angustifolia. Nevertheless, little is known about its genetic relationship to the wild A. angustifolia or how the decades-long clonal propagation has affected its genetics.

Methods

Using restriction-site-associated DNA sequencing and over 8000 single-nucleotide polymorphisms, we studied aspects of the population genomics of wild and cultivated A. angustifolia in Puebla and Oaxaca, Mexico. We assessed patterns of genetic diversity, inbreeding, distribution of genetic variation, and differentiation among and within wild populations and plantations.

Results

Genetic differentiation between wild and cultivated plants was strong, and both gene pools harbored multiple unique alleles. Nevertheless, we found several cultivated individuals with high genetic affinity with wild samples. Higher heterozygosity was observed in the cultivated individuals, while in total, they harbored considerably fewer alleles and presented higher linkage disequilibrium compared to the wild plants. Independently of geographic distance among sampled plantations, the genetic relatedness of the cultivated plants was high, suggesting a common origin and prevalent role of clonal propagation.

Conclusions

The considerable heterozygosity found in espadín is contained within a network of highly related individuals, displaying high linkage disequilibrium generated by decades of clonal propagation and possibly by the accumulation of somatic mutations. Wild A. angustifolia, on the other hand, represents a significant genetic diversity reservoir that should be carefully studied and conserved.

     

Brassica rapa Domestication: Untangling Wild and Feral Forms and Convergence of Crop Morphotypes

The study of domestication contributes to our knowledge of evolution and crop genetic resources. Human selection has shaped wild Brassica rapa into diverse turnip, leafy, and oilseed crops. Despite its worldwide economic importance and potential as a model for understanding diversification under domestication, insights into the number of domestication events and initial crop(s) domesticated in B. rapa have been limited due to a lack of clarity about the wild or feral status of conspecific noncrop relatives. To address this gap and reconstruct the domestication history of B. rapa, we analyzed 68,468 genotyping-by-sequencing-derived single nucleotide polymorphisms for 416 samples in the largest diversity panel of domesticated and weedy B. rapa to date. To further understand the center of origin, we modeled the potential range of wild B. rapa during the mid-Holocene. Our analyses of genetic diversity across B. rapa morphotypes suggest that noncrop samples from the Caucasus, Siberia, and Italy may be truly wild, whereas those occurring in the Americas and much of Europe are feral. Clustering, tree-based analyses, and parameterized demographic inference further indicate that turnips were likely the first crop type domesticated, from which leafy types in East Asia and Europe were selected from distinct lineages. These findings clarify the domestication history and nature of wild crop genetic resources for B. rapa, which provides the first step toward investigating cases of possible parallel selection, the domestication and feralization syndrome, and novel germplasm for Brassica crop improvement.     

Bioclimatic evaluation of geographical range in Fragaria (Rosaceae): consequences of variation in breeding system,ploidy and species age

The evaluation of the intrinsic and extrinsic forces that determine geographical range sizes and niche breadth is key to the understanding of species distributions and for informing the conservation of biodiversity. Fragaria (Rosaceae) contains the economically important cultivated strawberry (Fragaria × ananassa subsp. ananassa) and numerous wild species. Using georeferenced species records and global bioclimatic data, we describe the bioclimatic niches for 21 Fragaria spp. and investigate the relationship between their niches and geographical range size, breeding system, ploidy and time since divergence. We found no evidence of phylogenetic signal for bioclimatic niches. There was also no relationship between ploidy and geographical or bioclimatic range area, but geographical range area was significantly greater for species that were capable of self‐fertilization. In addition, we found a significant decelerating relationship between species age and geographical range area. Overall, our results suggest that Fragaria spp., although similar in morphology and life history, show high levels of divergence in bioclimatic niches and significant over‐dispersion along some bioclimatic gradients, suggesting evolutionary lability in physiology and climate tolerance. As a consequence, wild species will remain a valuable resource for cultivated strawberry sustainability, especially under changing future climate. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 176 , 99–114.     

中国近缘野生大麦的RAPD分析与进化途径探讨

采用ＲＡＰＤ技术对１２份中国近缘野生大麦和栽培大麦（Ｈｏｒｄｅｕｍ ｖｕｌｇａｒｅ Ｌ．）、１份多年生短芒大麦草（Ｈ．ｂｒｅｖｉｓｕｂｕｌａｔｕｍ（Ｔｒｉｎ．）Ｌｉｎｋ）进行了分析。６３个随机引物中有３６个能产生２８５个稳定的扩增产物,其中２１９个产物具多态性。将每个扩增产物看作一个独立的性状,按其有无列出二元数据矩阵,计算单匹配系数（Ｍ）,Ｎｅｉ氏相似性系数（Ｓ）。ＰＨＹＬＩＰ ３．５ｃ软件包聚     

RAPD Analysis and the Probable Evolutionary Route of Wild Relatives of Barley from China

he genetic relationships among 12 wild relatives and cultivar of barley ( Hordeum vulgare L.) as well as 1 perennial wild barley grass (H. brevisubulatum (Trin.) Link) from China were investigated by RAPD analysis. 36 out of 63 arbitrary primers produced 285 distinctive bands in total, 219 of which were polymorphic. Clearly resolved bands were treated as independent characters and scored for their presence or absence in a binary data matrix. Simple matching coefficients and Nei's similarity coefficients were calculated respectively. Dendrograms were generated by using the PHYLIP 3.5c software. The results revealed that the cultivated barley and their wild relatives from China were clustered into one group, among which, the two-rowed wild relatives of barley ( H. vulgare L. ssp. spontaneum (Koch) Hsü) and the six-rowed wild forms (H. vulgare L. ssp. agriocrithon (Aberg) Hsü) were respectively clustered into different subgroups. It was considered that wild relatives of barley from China were subspecies of H.vulgare. And it was proposed that the cultivated barley was originally evolved from the two-rowed wild barley. The retrogressive two-rowed wild barley and the bottle-shaped wild forms (H. vulgare L. ssp. agriocrithon var. lagunculiforme Bakht Hsü) were the intermediate types in the evolutionary route from the two-rowed wild barley to the six-rowed wild forms and eventually evolved to the cultivated barley.     

The prevalence and spatial distribution of viruses in natural populations of Brassica oleracea

We report a survey of four viruses (beet western yellows luteovirus (BWYV), cauliflower mosaic caulimovirus (CaMV), turnip mosaic potyvirus (TuMV), turnip yellow mosaic tymovirus (TYMV)) in five natural populations of Brassica oleracea in Dorset (UK). All four viruses were common; 43% of plants were infected with BWYV, 60% with CaMV, 43% with TuMV and 18% with TYMV. For each virus there were significant differences in the proportion of infected plants among populations, which were not completely explained by differences in the age of plants. Multiple virus infections were prevalent, with 54% of plants having two or more virus types. There were statistically significant associations between pairs of viruses. The CaMV was positively associated with the other three viruses, and BWYV was also positively associated with TuMV. There was no detectable association between BWYV and TYMV, whereas TuMV and TYMV were negatively associated. We suggest these associations result from BWYV, CaMV and TuMV having aphid vectors in common, as aphids are attracted to plants that already have a virus infection. Infected plants were distributed randomly or were very weakly aggregated within populations. The implications of widespread multiple virus infections in natural plant populations are discussed with respect to the release of transgenic plants expressing virus-derived genes.     

Fitness of hybrids between rapeseed (Brassica napus) and wild Brassica rapa in natural habitats

Fitness of hybrids between genetically modified (GM) crops and wild relatives influences the likelihood of ecological harm. We measured fitness components in spontaneous (non-GM) rapeseed x Brassica rapa hybrids in natural populations. The F1 hybrids yielded 46.9% seed output of B. rapa, were 16.9% as effective as males on B. rapa and exhibited increased self-pollination. Assuming 100% GM rapeseed cultivation, we conservatively predict < 7000 second-generation transgenic hybrids annually in the United Kingdom (i.e. approximately 20% of F1 hybrids). Conversely, whilst reduced hybrid fitness improves feasibility of bio-containment, stage projection matrices suggests broad scope for some transgenes to offset this effect by enhancing fitness.     

Evolutionary origins of taro (Colocasia esculenta) in Southeast Asia

As an ancient clonal root and leaf crop, taro (Colocasia esculenta, Araceae) is highly polymorphic with uncertain genetic and geographic origins. We explored chloroplast DNA diversity in cultivated and wild taros, and closely related wild taxa, and found cultivated taro to be polyphyletic, with tropical and temperate clades that appear to originate in Southeast Asia sensu lato. A third clade was found exclusively in wild populations from Southeast Asia to Australia and Papua New Guinea. Our findings do not support the hypothesis of taro domestication in Papua New Guinea, despite archaeological evidence for early use or cultivation there, and the presence of apparently natural wild populations in the region (Australia and Papua New Guinea).     

Evolutionary history of the scorpionfly Dicerapanorpa magna (Mecoptera,Panorpidae)

Climate changes can have fundamental impacts on the distributional patterns of montane species, and range shifts frequently lead to allopatric divergence followed by the establishment of secondary contact zones. Many European and North American organisms have retreated to southern refugia during glacial periods and colonized northward during postglacial periods, but little is known about the evolutionary response of cold‐adapted insects to Pleistocene climate changes in eastern Asia. The scorpionfly Dicerapanorpa magna (Chou), with cold temperate habitat preference and weak dispersal ability, provides a good model system to explore how climate changes have influenced the distribution and divergence of cold‐adapted insects in eastern Asia. This study reconstructed the demographic dynamics and evolutionary history of D. magna with phylogeographic approaches, and predicted the species’ suitable areas under the Last Glacial Maximum (LGM) and current scenarios with the ecological niche modelling analysis. The mitochondrial cytochrome c oxidase subunit I resolved three phylogenetic lineages in D. magna dating back to Pleistocene, corresponding well with the geographically isolated Qinling, Bashan and Minshan Mountains. The ecological niche modelling recovered the suitable habitats for D. magna were the Qinling and Bashan Mountains under LGM and current conditions. The three lineages of D. magna might be in a process of incipient speciation, and likely derived their current distribution from separate glacial origins, followed by vicariance and divergence.     

Ecological specialization promotes diversity and diversification in the Eastern Mediterranean genus Ricotia (Brassicaceae)

Despite its amazing biodiversity, the Eastern Mediterranean remains a highly understudied region when compared withthe Western Mediterranean, restricting our understanding of diversity across the entire Mediterranean. Here we use a combination of molecular markers and presence/absence data from all species of the Eastern Mediterranean genus Ricotia collected across its full geographic range to determine historical, ecological, and evolutionary factors responsible for lineage-specific diversification in the Eastern Mediterranean. Network analysis based on molecular data revealed a high genetic structure within all lineages, and phylogenetic reconstructions based on the multispecies coalescent showed that within-lineage diversification corresponded to the onset of the Mediterranean climate. Reconstruction of ancestral histories indicates that the genus originated within Anatolia and spread across the Eastern Mediterranean and Levant using the Taurus mountains. Ecological niche models suggest that local populations did not go through any major distributional shifts and have persisted in present-day habitats since the Last Glacial Maximum. Furthermore, niche differentiation tests revealed significant differences between closely related species and showed the main variables predicting species limits to be different for each species. Our results give crucial information on the patterns and processes shaping diversity in the Eastern Mediterranean and show the main factors promoting diversification to be local environmental dynamics and ecological specialization and not large-scale latitudinal movements, as often reported for southern Europe. By determining local and regional patterns of diversification in an Eastern Mediterranean genus, we further our understanding of the major trends influencing plant diversity in the Mediterranean basin as a whole.     

Transformation of rapid cycling cabbage (Brassica oleracea var. capitata) with Agrobacterium rhizogenes

Summary Genetically transformed cabbage (Brassica oleracea var. capitata) roots were obtained after inoculation with two engineered Agrobacterium rhizogenes strains, each harbouring a plant selectable marker gene in their T-DNA. Axenic root clones resistant to kanamycin or hygromycin B were established, most of which did not exhibit the phenotypic characteristics of Ri-transformed roots. Shoot regeneration was induced from roots after treatment with 2,4-dichlorophenoxyacetic acid (2,4-D). The resulting plants exhibited various phenotypes: some looked normal, while others showed the transformed phenotype observed in other species. Direct evidence for genetic transformation was obtained by molecular hybridization. The trait was transmitted to the progeny. Transformed cabbage plants can be obtained within 6 months using this approach.     

A taxonomic revision of Crambe, sect. Leptocrambe (Brassicaceae)

As part of a revision of the genus Crambe based on the morphological study of herbaria and cultivated material, the systematics of sect. Leptocrombe DC. is presented here. Section Leptocrambe is considered to comprise five species: C. kilimandscharica O. E. Schulz, C. sinuatodentata Hochst. ex Petri, C. hispanica L., C. filiformis Jacq. and C. kralikii Coss. C. hispanica includes three subspecies, subsp. hispanica , subsp. glabrata (DC.) Cout. and subsp. abyssnica (Hochst. ex R. E. Fr.) stat. nov. which includes var. dyssinica and var. meyeri (O. E. Schulz) comb. nov. C. kralikii includes two subspecies, subsp. kralikii and subsp. garamas (Maire) Podlech.     

Reproductive ecology and genetic variability in natural populations of the wild potato,Solanum kurtzianum

The cultivated potato (Solanum tuberosum ssp. tuberosum) has more than 200 related wild species distributed along the Andes, adapted to a wide range of geographical and ecological areas. Since the last century, several collection expeditions were carried out to incorporate genetic variability into the potato germplasm around the world. However, little is known about the reproductive ecology and genetic population structure of natural potato population from field studies. The aim of this work is to study, in the field, the genetic variability and reproductive strategies of populations of one of the most widely distributed potato species in Argentina, Solanum kurtzianum, growing in Mendoza province. AFLP markers showed that the genetic variability is mainly present among plants within populations, indicating that in the sampled populations, sexual reproduction is more relevant than clonal multiplication (by tubers). Additional evidence was obtained evaluating the genetic diversity in populations with a distribution in patches, where several genotypes were always detected. From a field study performed in the Villavicencio Natural Reserve, we found that the average number of plump seeds per fruit was 94.3, identified and calculated the foraging distance of four insect pollinators, and demonstrated the seed dispersal by storm water channels. We argue that the breeding system, the two modes of reproduction and the ecological interaction described here may have a prominent role in determining the genetic structure of S. kurtzianum populations, and discuss the importance of field studies on population genetics, reproductive biology and ecology to design collections and conservation strategies.     

Response of Brassica oleracea to temporal variation in attack by two herbivores affects preference and performance of a third herbivore

1. Plants are frequently under attack by multiple insect herbivores, which may interact indirectly through herbivore‐induced changes in the plant's phenotype. The identity, order, and timing of herbivore arrivals may influence the outcome of interactions between two herbivores. How these aspects affect, in turn, subsequently arriving herbivores that feed on double herbivore‐induced plants has not been widely investigated. 2. This study tested whether the order and timing of arrival of two inducing herbivores from different feeding guilds affected the preference and performance of a subsequently arriving third herbivore, caterpillars of Mamestra brassicae L. (Lepidoptera: Noctuidae). Aphids [Brevicoryne brassicae L. (Hemiptera: Aphididae)] and caterpillars [Plutella xylostella L. (Lepidoptera: Yponomeutidae)] were introduced onto wild Brassica oleracea L. (Brassicaceae) plants in different sequences and with different arrival times. The effects of these plant treatments on M. brassicae caterpillars were assessed in pairwise preference tests and no‐choice performance tests. 3. The caterpillars of M. brassicae preferred to feed from undamaged plants rather than double herbivore‐induced plants. Compared with undamaged plants, they preferred plant material on which aphids had arrived first followed by caterpillars, whereas they avoided plant material with the reverse order of herbivore arrival. Performance of the caterpillars increased with increasing arrival time between herbivore infestations in double herbivore‐induced plants. Although M. brassicae grew faster on plants induced by aphids than on those induced by caterpillars alone, its performance was not affected by the order of previous herbivore arrival. 4. These results imply that the timing of colonisation by multiple herbivores determines the outcome of plant‐mediated herbivore–herbivore interactions.