Morphological variation of henequen (Agave fourcroydes, Agavaceae) germplasm and its wild ancestor (A. angustifolia) under uniform growth conditions: diversity and domestication

Extant variants of henequen (Agave fourcroydes Lem.) and wild populations of its putative ancestor A. angustifolia Haw. were grown in the Mexican state of Yucatan for 10 yr under homogeneous conditions. A statistical and numerical analysis of their patterns of morphological variation was performed as part of broader research to provide evidence of its genetic diversity, evolutionary relationships and changes under human selection. A comparison with results of a similar analysis under natural growing conditions was also made. The study indicated the following. (1) Under natural growth conditions, the three putative wild ecotypes are morphologically distinct, but under uniform conditions only populations growing in Tropical subdeciduous forest may be distinguished from the other two, thus indicating the probable existence of only two ecotypes: one growing in Coastal dunes and Tropical subdeciduous forest, and the other growing in Tropical deciduous forest. (2) This last ecotype is the most similar to cultivated variants. Within its populations, the most similar to the cultivated is that known as Chelem White, gathered by artisans for its textile use. (3) The cordage-cultivated Sac Ki and Yaax Ki differ from wild populations in four syndromes of domestication: gigantism, greater fibrosity, less thorniness, and less reproductive capacity. The lower cv of their characteristics compared with those of wild populations suggest less genetic diversity. (4) Kitam Ki is probably a textile-cultivated variant of recent introduction and/or a variant in which the artificial selection process has had different direction and intensity. (5) Improved growth conditions in the botanic garden resulted in a decreased cv, an increase in size and fiber content, and a reduction of thorniness for both wild and cultivated variants. Given that wild populations with desirable characteristics exist and that these characteristics are highly plastic and respond positively to cultivation, then selection and cultivation of populations such as those from Tropical deciduous forest may well have been the path taken by the ancient Maya during henequen domestication.     

Patterns of morphological variation,diversity, and domestication of wild and cultivated populations of agave in Yucatan,Mexico

This work presents a statistical and numerical analysis of the patterns of morphological variation of the cultivated variants of henequén (Agave fourcroydes Lem.) presently found in the Mexican state of Yucatan and of the wild populations of A. angustifolia Haw., its putative progenitor. This is the first step in the study of the intrageneric genetic diversity and evolutionary relationships. The study indicated that: (1) There exists a significant discontinuation in morphological variation corresponding to the cultivated variants of traditionally recognized henequén: Sac Ki, Yaax Ki, and Kitam Ki, and to three possible ecotypes of A. angustifolia Haw.: Coastal Dunes, Tropical Deciduous Forest, and Tropical Subdeciduous Forest. (2) Sac Ki and Yaax Ki differ from wild populations in four syndromes of domestication: gigantism, greater fibrosity, less thorniness, and less reproductive capacity. The lower coefficient of variation of their characteristics compared with the wild populations suggests less genetic diversity. This fact, and the disappearance of four out of the seven variants existing early in this century, indicate a dramatic genetic erosion of this crop. (3) Kitam Ki is the cultivated variant more similar to wild ones. Differences with them suggest recent introduction and an artificial selection process with different direction and intensity than the other cultivated variants. (4) A tendency from more to less is observed for characteristics indicating degree of domestication: Sac Ki, Yaax Ki, and Kitam Ki. (5) The differences among the possible wild ecotypes may be associated with the soil conditions and precipitation.     

Reproductive biology of henequen (Agave fourcroydes) and its wild ancestor Agave Angustifolia (Agavaceae). i. Gametophyte development

The pathways of micro- and megagametophyte development in Agave fourcroydes (henequén) and A. angustifolia were studied. We used histology and light microscopy to observe anther ontogeny and ovary differentiation in relation to flower bud size. Both species have the same sexual reproductive strategies and gametophyte development that may be divided into three phases: (1) premeiotic, which includes the establishment of the megaspore mother cell and the pollen mother cell; (2) meiotic, the formation of mature microspores and functional megaspores; (3) postmeiotic, which encompasses the development of mature pollen grains and the formation of the embryo sac. A successive type microsporogenesis was found in both species with formation of T-shaped tetrads and binuclear pollen grains. In vitro germination tests revealed very low pollen fertility. The female gametophyte is formed from two micropylar megaspore cells after the first meiotic division (bisporic type). Male and female gametogenesis occur asynchronously with microsporogenesis finishing before macrosporogenesis. The results so far show that the formation of male and female gametophytes in henequén is affected at different stages and that these alterations might be responsible for the low fertility shown by this species.     

Genetic diversity in two populations of the snail Strombus gigas (Gastropoda: Strombidae) from Yucatan, Mexico, using microsatellite

The pink conch Strombus gigas is an important fisheries resource in the Caribbean region, including the Yucatán Peninsula. We analyzed the genetic diversity and genetic structure of two populations (Alacranes Reef and Chinchorro Bank) with the use of five microsatellite molecular markers. The results indicate that the two populations are in the same rank of genetic diversity (He), from 0.613 to 0.692. Significant deviation from H-WE was observed in the both populations due to deficit to heterozygotes, this was attributed to inbreeding as a consequence of over-fishing; nevertheless, other possible causes considered are mixing of individuals from two or more populations, and the existence of null alleles. Levels of genetic differentiation indicated the existence of a single homogenous population in the Yucatan Peninsula (F(ST) de 0.003, p = 0.49), which fits with highest levels of gene flow is significant (2.3 individuals) between both populations. Results from this study support the hypothesis that S. gigas is part of a single panmictic population in the Yucatan Peninsula; therefore, this fishery resource should be regulated the same way for both areas.     

Genetic Structure of Remnant Populations and Cultivars of Switchgrass (Panicum virgatum) in the Context of Prairie Conservation and Restoration

Switchgrass (Panicum virgatum L.) is a dominant, perennial C₄ grass of North American tallgrass prairies with cultivars that are widely used in grassland restoration, pastures, and landscaping. However, these cultivars may be genetically dissimilar to small, remnant populations, raising concerns about altered genetic composition of native populations through gene flow. To address this issue on a local scale in Ohio and Illinois, we used microsatellite markers to characterize genetic diversity and differentiation of 10 remnant prairie populations (5 in each state) and 8 common cultivars. The bulk of genetic variation was found to reside within rather than among wild populations, consistent with the outcrossing breeding system of switchgrass. Genetic diversity was similar among the remnant populations despite large differences in area (approximately 2–2,590 ha), highlighting the importance of small native populations as reservoirs of variation and potential seed sources for prairie restoration. Cultivars generally had similar levels of variation to the wild populations, but we found clear genetic dissimilarity between wild and cultivated gene pools (especially for Kanlow, but also Trailblazer, Blackwell, Dacotah, Summer, and Sunburst cultivars). This suggests that using cultivars in local prairie restoration efforts may alter the genetic composition of wild populations. Whether such changes are deemed as negative depends on the cultivar under consideration and specific conservation goals for preserving native switchgrass populations. Patterns of genetic variation in remnant prairie populations and potential cultivar sources can be used to develop guidelines for restoration as well as future planting of cultivars for biofuels.     

Life‐history traits and geographical divergence in wild rice (Oryza rufipogon) gene pool in Indochina Peninsula region

Indochina Peninsula is the primary centre of diversity of rice and lies partly in the centre of origin of cultivated rice (Oryza sativa) where the wild ancestor (Oryza rufipogon) is still abundant. The wild gene pool is potentially endangered by urbanisation and the expansion of agriculture, and by introgression hybridisation with locally cultivated rice varieties. To determine genetic diversity and structure of the wild rice of the region we genotyped nearly 1000 individuals using 20 microsatellite loci. We found ecological differentiation in 48 populations, distinguishable by their life‐history traits and the country of origin. Geographical divergence was suggested by isolation of the perennial Myanmar populations from those of Cambodia, Laos and Thailand. The annual types would be most likely to have lost genetic variation because of genetic drift and inbreeding. The growing of cultivated and wild rice together, however, gives ample opportunities for hybridisation, which already shows signs of genetic mixing, and will ultimately lead to replacement of the original wild rice gene pool. For conservation we suggest that wild rice should be conserved ex situ in order to prevent introgression from cultivated rice, along with in situ conservation in individual countries for the recurrent evolutionary process through local adaptation, but with sufficient isolation from cultivated rice fields to preserve genetic integrity of the wild populations.     

Population variation of leaflet sleep movements in Oxalis grandis (Oxalidaceae)

To identify intraspecific variation in the expression of circadian leaflet movements, we observed changes in leaflet elevation angle in a controlled environment and in the field. Two morphologically and ecologically distinct populations of Oxalis grandis were compared: a typical mesic forest ecotype and an atypical, densely hirsute ecotype found on partially exposed shale outcroppings. Significant genotypic variation was detected within both populations. The controlled environment experiment revealed significant differences in the intrinsic rhythm between the two populations, primarily at the beginning and end of the photophase. We observed leaflet ascent and descent prior to lights-on and lights-off, respectively, processes we define as anticipatory. Hirsute ecotype plants showed a greater anticipation of lights-on, whereas the mesic ecotype plants showed a greater anticipation of lights-off. In the field, significant differences in leaflet elevation between the populations occurred in early morning and late afternoon, but not immediately preceding dusk. Contrary to the controlled environment experiment, mesic ecotype plants showed greater anticipation of dawn; plants from both populations showed similar anticipation of dusk. Plants of the hirsute ecotype exhibited higher sensitivity to sudden fluctuations in light level. We hypothesize that differences in light sensitivity partially explain the differences in the leaflet angle patterns between the field and controlled environments.     

Effects of domestication on genetic diversity in Chimonanthus praecox: Evidence from chloroplast DNA and amplified fragment length polymorphism data

Chimonanthus praecox (L.) Link is a widely cultivated endemic winter-flowering plant in China that has a long cultivation history. Genetic diversity and genetic structure were compared between wild and cultivated groups to reveal the geographic origin of the cultivated genotypes using chloroplast DNA (cpDNA) sequences and amplified fragment length polymorphism (AFLP) markers. Nine haplotypes were identified using three combined chloroplast fragments. Based on chloroplast data, the wild group showed greater genetic variation and genetic differentiation and a lower measure of gene flow compared to the cultivated group. The AFLP markers also supported this trend. More than 40% of the cpDNA haplotypes were shared between wild and cultivated groups, with shared haplotypes originating from multiple wild populations, suggesting multiple origins of cultivated plants. Moreover, principal coordinate analysis, UPGMA, and structure analysis of AFLP markers revealed that two wild populations clustered with most of the cultivated populations of Ch. praecox, suggesting that most of the cultivated populations mainly originated from these two populations. The combined cpDNA and AFLP results indicated that modern cultivated Ch. praecox experienced multiple events of origin involving two geographic origins, eastern China (Tianmu Mountain) and southwestern China (the border of Hunan–Guangxi–Sichuan–Guizhou).     

Genetic variation in the endangered wild apple (Malus sylvestris (L.) Mill.) in Belgium as revealed by amplified fragment length polymorphism and microsatellite markers

The genetic variation within and between wild apple samples (Malus sylvestris) and cultivated apple trees was investigated with amplified fragment length polymorphisms (AFLP) and microsatellite markers to develop a conservation genetics programme for the endangered wild apple in Belgium. In total, 76 putative wild apples (originating from Belgium and Germany), six presumed hybrids and 39 cultivars were typed at 12 simple sequence repeats (SSR) and 139 amplified fragment length polymorphism (AFLP) loci. Principal co-ordinate analysis and a model-based clustering method classified the apples into three major gene pools: wild Malus sylvestris genotypes, edible cultivars and ornamental cultivars. All presumed hybrids and two individuals (one Belgian, one German) sampled as M. sylvestris were assigned completely to the edible cultivar gene pool, revealing that cultivated genotypes are present in the wild. However, gene flow between wild and cultivated gene pools is shown to be almost absent, with only three genotypes that showed evidence of admixture between the wild and edible cultivar gene pools. Wild apples sampled in Belgium and Germany constitute gene pools that are clearly differentiated from cultivars and although some geographical pattern of genetic differentiation among wild apple populations exists, most variation is concentrated within samples. Concordant conclusions were obtained from AFLP and SSR markers, which showed highly significant correlations in both among-genotypes and among-samples genetic distances.     

Chloroplast DNA phylogeography of European ashes, Fraxinus sp. (Oleaceae): roles of hybridization and life history traits

We investigated range-wide phylogeographic variation in three European ash species (Fraxinus sp., Oleaceae). Chloroplast DNA (cpDNA) microsatellites were typed in the thermophilous Fraxinus angustifolia and Fraxinus ornus and the observed haplotypes and the geographic distribution of diversity were compared to cpDNA data previously obtained in the more cold-tolerant Fraxinus excelsior. We found wide-ranging haplotype sharing between the phylogenetically close F. angustifolia and F. excelsior, suggesting hybridization (i) in common glacial refuges in the Iberian Peninsula, northern Italy, the eastern and/or Dinaric Alps and the Balkan Peninsula, and/or (ii) during postglacial recolonization. The data allowed us to propose additional glacial refuges for F. angustifolia in southern Italy and in Turkey, and populations from the latter region were particularly polymorphic. There was evidence for refuge areas in Italy, the Balkan Peninsula and Turkey for F. ornus, which did not share any single chloroplast haplotype with the other species. In both F. angustifolia and F. ornus, cpDNA diversity (h(S) = 0.027 and h(S) = 0.009, respectively) was lower and fixation levels (G(ST) = 0.964 and G(ST) = 0.983, respectively) higher than in sympatric F. excelsior (h(S) = 0.096, G(ST) = 0.870). These diversity patterns could be due to temperature tolerance or the demographic history.     

Genetic variation among wild and cultivated populations of the Chinese medicinal plant Coptis chinensis (Ranunculaceae)

To examine if the cultivation process has reduced the genetic variation of modern cultivars of the traditional Chinese medicinal plant, Coptis chinensis, the levels and distribution of genetic variation was investigated using ISSR markers. A total of 214 C. chinensis individuals from seven wild and three cultivated populations were included in the study. Seven ISSR primers were used and a total of 91 DNA fragments were scored. The levels of genetic diversity in cultivated populations were similar as those in wild populations (mean PPL = 65.2% versus PPL = 52.4%, mean H = 0.159 versus H = 0.153 and mean I = 0.255 versus I = 0.237), suggesting that cultivation did not seriously influence genetic variation of present-day cultivated populations. Neighbour-joining cluster analysis showed that wild populations and cultivated populations were not separated into two groups. The coefficient of genetic differentiation between a cultivar and its wild progenitor was 0.066 (G(st)), which was in good accordance with the result by amova analysis (10.9% of total genetic variation resided on the two groups), indicating that cultivated populations were not genetically differentiated from wild progenitors. For the seven wild populations, a significant genetic differentiation among populations was found using amova analysis (45.9% of total genetic variation resided among populations). A number of causes, including genetic drift and inbreeding in the small and isolated wild populations, the relative limited gene flow between wild populations (N(m) = 0.590), and high gene flow between cultivars and their wild progenitors (N(m) = 7.116), might have led to the observed genetic profiles of C. chinensis.     

Riparian populations of minnesota reed canarygrass (Phalaris arundinacea) are most likely native,based on SNPs (DArTseqLD)

The native vs. exotic status of reed canarygrass (RCG), a major invasive species of Minnesota wetlands, is unknown. The aim of this study was to investigate this native vs. exotic status to enhance its management. Genetic comparison of wild RCG populations from six Minnesota and six Czech Republic rivers was performed. A total of 2521 polymorphic SNP markers (single nucleotide polymorphisms) were used to evaluate 478 RCG samples across all collections. In the PCoA, all (n = 256) tested extant wild, riparian RCG genotypes from six Minnesota Rivers and six Czech Republic Rivers were genetically distinct, although some SNPs were common in both populations since they are the same species. DAPC analysis also resulted in the formation of two primary clusters separating the Minnesota Rivers and Czech Republic Rivers riparian samples, with little overlap; STRUCTURE analysis also supported this clustering with k = 4 groups as it separated the Czech Republic Rivers populations into three groups, along with Minnesota Rivers. The uniformity of PCoA, DAPC, STRUCTURE, and Evanno results indicates the distinct separation of Minnesota Rivers and Czech Republic Rivers populations. Portions of the genome (specific SNPs) are preserved or in common across continents, as indicated by STRUCTURE similarities. Nonetheless, overall significant SNP differences between the continents indicate that the Minnesota riparian populations are distinct enough from the European (Czech) collections to be delineated as native N. American RCG. PCoA of all the Minnesota RCG collections clustered Minnesota Rivers, Herbarium, Extant Herbarium, Research Field and Native Field collections together. STRUCTURE analysis (k = 2; Evanno) divided these Minnesota collections from the Commercial Field and Cultivars collections. There are two genetically distinct groups of RCG in Minnesota and since the Minnesota Rivers, the Research Field, the Native Field and pre-1930 herbaria collections clustered together, they are most likely native N. American types. Analysis of molecular variance (AMOVA) indicated that the genetic variation was more significant within, rather than among, the RCG populations. Native, historic herbaria types cluster together with all wild RCG river populations in Minnesota, all of which were distinct from those in Central Europe, suggesting native RCG type persistence in N. America. Also, cultivated forage types of RCG are distinct from wild RCG Minnesota river populations. The SNP genetic data shows that riparian Minnesota RCG populations are native. These data will facilitate future management strategies to control RCG as a native, but invasive, species.

     

Agave studies in Yucatan,Mexico. I. Past and present germplasm diversity and uses

Henequén (Agave fourcroydes) is believed to have been domesticated by the Maya fromAgave angustifolia and has been of great economical and cultural relevance in the Mexican State of Yucatan since pre-Hispanic times. Although at the beginning of this century, the recorded diversity included eight cultivated variants, our ethnobotanical exploration reveals only three, one of them in very small populations. Three wild variants with different fiber quality and possibly three ecotypes were found in our study. The documented use of agaves in the Peninsula of Yucatan is as a source of fiber. However, ethnobotanical exploration revealed that wild and cultivated variants have over 40 traditional uses. Medicinal use is the most diverse, followed by its use in construction, as utensils, and for textiles. The most frequent uses are as fiber, fuel, construction material, and medicine. One of the most interesting uses of these species is as food; this may have been important in the domestication of the plant.     

Population structure of the wild soybean (Glycine soja) in China: implications from microsatellite analyses

Background and Aims Wild soybean (Glycine soja), a native species of East Asia, is the closest wild relative of the cultivated soybean (G. max) and supplies valuable genetic resources for cultivar breeding. Analyses of the genetic variation and population structure of wild soybean are fundamental for effective conservation studies and utilization of this valuable genetic resource. Methods In this study, 40 wild soybean populations from China were genotyped with 20 microsatellites to investigate the natural population structure and genetic diversity. These results were integrated with previous microsatellite analyses for 231 representative individuals from East Asia to investigate the genetic relationships of wild soybeans from China. Key Results Analysis of molecular variance (AMOVA) revealed that 43·92 % of the molecular variance occurred within populations, although relatively low genetic diversity was detected for natural wild soybean populations. Most of the populations exhibited significant effects of a genetic bottleneck. Principal co-ordinate analysis, construction of a Neighbor-Joining tree and Bayesian clustering indicated two main genotypic clusters of wild soybean from China. The wild soybean populations, which are distributed in north-east and south China, separated by the Huang-Huai Valley, displayed similar genotypes, whereas those populations from the Huang-Huai Valley were different. Conclusions The previously unknown population structure of the natural populations of wild soybean distributed throughout China was determined. Two evolutionarily significant units were defined and further analysed by combining genetic diversity and structure analyses from Chinese populations with representative samples from Eastern Asia. The study suggests that during the glacial period there may have been an expansion route between south-east and north-east China, via the temperate forests in the East China Sea Land Bridge, which resulted in similar genotypes of wild soybean populations from these regions. Genetic diversity and bottleneck analysis supports that both extensive collection of germplasm resources and habitat management strategies should be undertaken for effective conservation studies of these important wild soybean resources.     

Testing the cultivar vigor hypothesis: comparisons of the competitive ability of wild and cultivated populations of Pascopyrum smithii along a restoration chronosequence

Restoration practitioners often rely on seeds of widely available cultivars representing native species but nonlocal germplasm. Cultivation improves the supply of plant materials and minimizes revegetation costs, but can also favor agronomic traits, and resulting vigor may affect the competitive ability and long‐term persistence of cultivated genotypes at restoration sites. We compared cultivated, restored, and wild populations of Pascopyrum smithii (western wheatgrass) in a greenhouse study to test the extent to which cultivars outcompete local plants in biomass production, and to determine if morphological differences (including height and number of leaves) among cultivated and wild populations persist at restoration sites over time. We found evidence of vigor and greater competitive ability of cultivars in seed mass, growth rate, plant height, and biomass and this advantage occurred when plants were grown alone or in competition with other seed sources. Cultivar vigor persisted at restoration sites over 30 years, but restored populations more closely resembled wild, local populations when cultivars were planted in closer proximity to nearby undisturbed sites. This study supports the cultivar vigor hypothesis and provides evidence for the long‐term persistence of cultivated traits in the environment.     

Hybridization between Crocodylus acutus and Crocodylus moreletii in the Yucatan Peninsula: II. Evidence from microsatellites

Detecting and quantifying hybridization between endangered or threatened taxa can provide valuable information with regards to conservation and management strategies. Hybridization between members of the genus Crocodylus has been known to occur in captivity and in some wild populations. We tested for hybridization among wild populations of American crocodile (C. acutus) and Morelet's crocodile (C. moreletii) in the Yucatan Peninsula by comparing Bayesian assignment tests, based on microsatellite data, to mitochondrial and morphological assignments. Skin clips from 83 individuals were taken for genetic identification, and a total of 32 individuals (38.6%) exhibited some evidence of hybridization by combined morphological, mitochondrial and microsatellite analyses. The majority of hybrids were classified as F(2) hybrids and backcrosses to C. moreletii. Most of the introgression occurs in two national biosphere reserves located on the northern and eastern coasts of the Yucatan Peninsula. Preliminary tests did not find a significant decrease in hybridity across three life stages, thus far indicating a low level of selection against hybrids. Model-based analyses on multilocus genotypes of pure individuals returned little geographic partitioning in both C. acutus and C. moreletii.     

Wild pearl millet population (Pennisetum glaucum,Poaceae) integrity in agricultural Sahelian areas. An example from Keita (Niger)

Morphometric and isozymic analyses of adjacent cultivated and spontaneous populations of pearl millet in Niger revealed in the field a unique continuous distribution of phenotypes ranging from the most cultivated one to a typical cultivated × wild hybrid. The natural population was subdivided into a major wild group and a hybrid wild × cultivated group. Cultivated millet displayed an equilibrium state between recombined domesticated and wild genes. The natural population, in spite of a high rate of immigration by pollen from cultivated plants, retained its structure by apparently reproducing itself exclusively from the major wild group.     

低温条件下中国野生拟南芥种群中CBF3与ROS浓度的相关性

活性氧(ROS)是植物光合作用和呼吸作用的副产物, 环境胁迫可加速植物体内ROS的产生, 造成植物细胞膜的过氧化, 同时给光反应中心II带来光伤害。RFOs是植物体内的1类寡聚糖家族, 其对环境胁迫的响应很可能与清除过剩的ROS相关。前期的研究显示, 由于中国长江流域野生拟南芥(Arabidopsis thaliana)种群中CBF3基因的变异, 种群的冰冻耐受性和体内RFOs含量的积累普遍低于Col生态型。研究表明, 长江流域种群中ROS代谢通路在低温处理后的表达与Col生态型相比发生了明显的分化, 并且植物体内ROS的浓度增高; 而将Col生态型中能正常响应环境冷信号的CBF3基因转入长江流域种群后, 转基因植株的冰冻耐受性得到显著提高, 体内RFOs积累亦增加, 而ROS浓度显著降低。这些结果说明, 低温条件下CBF3很可能通过直接调控植物体内RFOs的生物积累来参与调控下游过剩ROS的清除过程。中国长江流域野生拟南芥种群低温条件下体内ROS浓度的升高, 很可能是由于种群中CBF3基因发生了自然变异从而丧失了冷响应能力造成的。     

Agave studies in Yucatan,Mexico. II. Nutritional value of the inflorescence peduncle and incipient domestication

Recent ethnobotanical exploration of henequen (Agave fourcroydes) in the Peninsula of Yucatan, Mexico, finds that inflorescence peduncles are used as emergency food and in the preparation of a fermented drink. Bromatological analysis and determination of total carbohydrates were made for the two length classes (ca. 3.30 m and ca. 0.60 m) which are consumed. The analysis of both the cultivated plant and its putative wild ancestor (Agave angustifolia) suggests that utilization of the inflorescence peduncles as food may have been involved in the initial stages of the history of its evolution under artificial selection, because the wild and the cultivated plants have similar palatability. The subsequent agricultural prevalence of annual crop species in the region was possibly responsible for the abandonment of henequen in the local diet. No significant differences are observed between the bromatological and total carbohydrate values of domesticated and wild plants. The preference for small inflorescence peduncles as a vegetable is a consequence of its significantly minor content of raw fiber and its larger content of total carbohydrates. As a fermented drink, longer peduncles are preferred because they provide more substrate material and because fiber can be eliminated by filtering. This agricultural byproduct, almost totally wasted, has potential value as a source of carbohydrates and raw fiber.     

Population structure and genetic diversity distribution in wild and cultivated populations of the traditional Chinese medicinal plant Magnolia officinalis subsp. biloba (Magnoliaceae)

Magnolia officinalis subsp. biloba, a traditional Chinese medicinal plant, experienced severe declines in the number of populations and the number of individuals in the late 20th century due to the widespread harvest of the subspecies. A large-scale cultivation program was initiated and cultivated populations rapidly recovered the loss in individual plant numbers, but wild populations remained small as a consequence of cutting. In this study, the levels of genetic variation and genetic structure of seven wild populations and five domestic populations of M. officinalis subsp. biloba were estimated employing an AFLP methodology. The plant exhibited a relatively high level of intra-population genetic diversity (h = 0.208 and H _j = 0.268). The cultivated populations maintained approximately 95% of the variation exhibited in wild populations, indicating a slight genetic bottleneck in the cultivated populations. The analysis of genetic differentiation revealed that most of the AFLP diversity resided within populations both for the wild group (78.22%) and the cultivated group (85.92%). Genetic differentiation among populations in the wild group was significant (F _ST = 0.1092, P < 0.005), suggesting wild population level genetic structure. Principal coordinates analysis (PCO) did not discern among wild and cultivated populations, indicating that alleles from the wild population were maintained in the cultivated gene pool. Results from the present study provide important baseline data for effectively conserving the genetic resources of this medicinal subspecies.