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1.
The present study was performed to investigate genetic diversity of Kenyan landraces of the white-flowered gourd (Lagenaria siceraria), which exhibits tremendous morphological variation. RAPD analyses were performed on 53 landraces of the cultivated species L. siceraria and 42 accessions of three wild species (40 L. sphaerica, 1 L. abyssinica, and 1 L. breviflora). A total of 432 polymorphic bands were detected using 54 primers. The four species were clearly differentiated from one another. Intra-specific variations were investigated with L. siceraria and its wild relative L. sphaerica. Landraces of the cultivated species collected from different ethnic communities or regions were differentiated. Morphological variations were not associated with RAPD variations. Bitter landraces collected in Maasai communities showed two specific RAPD bands. In the wild species, accessions collected from the eastern and western sides of the Great Rift Valley were genetically differentiated from each other. In both species, genetic and geographical distance matrices computed among all pairs of accessions were significantly correlated, implying that the observed geographical variation can be explained by the 'Isolation by distance model'. Progeny plants derived from a common mother in L. siceraria showed a low level of segregation in RAPD pattern, suggesting that collected landraces are cultivated, maintaining their inherent traits although they are monoecious and insect-pollinated, whereas the wild relative L. sphaerica showed a higher level of segregation. The morphological diversity observed among landraces of L. siceraria is the result of human selection and their genetic identities are maintained by inbreeding probably resulting from frequent self-pollination.  相似文献   

2.
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3.
To improve understanding of diversity of Lablab purpureus and establish relationships among 103 germplasm accessions collected from diverse geographic origins, amplified fragment length polymorphism markers were used. Four primer sets selected out of 16 produced 289 clear, repeatable polymorphisms. UPGMA analysis of similarity data clustered the accessions according to their subspecific taxonomic organization, i.e., subsp. purpureus and subsp. uncinatus, as well as to cultivated and wild forms. The well-represented landraces from Africa and Asia, belonging predominantly to subsp. purpureus, displayed moderate genetic diversity. Wild forms from Africa showed far greater levels of diversity that would justify taxonomic re-assessment of the wild subsp. uncinatus. The molecular analysis identified forms that were collected in the wild in India but were genetically placed intermediate between wild and cultivated forms. As these plant types did not exist among the African accessions, it is suggested that they might represent escapes from early attempts of domestication. These results support the suggested pathway of domestication and distribution of L. purpureus from Africa to Asia. Additional members to a previously published core collection of the species are proposed.  相似文献   

4.
Although originally domesticated in tropical America, the sweetpotato [Ipomoea batatas (L.) Lam.] has a long history of cultivation in the Pacific region. While the post-Columbus dispersal of sweetpotato to Asia and the Pacific is well documented, the hypothesis that there was a prehistoric transfer of sweetpotato by Peruvian or Polynesian voyagers from Peru to Oceania has long been a controversial issue. The objective of this study was to assess the genetic diversity and interrelationships of sweetpotato landraces from the Pacific region and Latin America, and test the hypothesis of human transfer of this crop to the Pacific Island in prehistoric times. Seventy-five sweetpotato landraces from Peru, Ecuador, Mexico, the Philippines, Papua New Guinea (PNG) and 5 Oceania countries were analyzed using amplified fragment length polymorphism (AFLP). Multidimensional scaling (MDS) and analysis of molecular variance (AMOVA) revealed a large genetic variation in the Oceania gene pool, far greater than that in Peru-Ecuador. The Mexican cultivars were grouped together with those of Oceania. In contrast, there is little association between the Peru-Ecuador germplasm and that of Oceania. These results suggest that Peru-Ecuador may not be the source of the Oceania sweetpotato germplasm. Natural dispersal from Mesoamerica is an alternative explanation, to the Kumara hypothesis, for the origin of the Oceania sweetpotato.  相似文献   

5.
Genetic diversity among some important Syrian wheat cultivars was estimated using Amplified Fragment Length Polymorphism (AFLP) markers. Five Triticum aestivum L. and 10 Triticum turgidum ssp. durum were analyzed with 11 EcoRI–MseI primer pair combinations. Of the approximately 525 detected AFLP markers, only 46.67% were polymorphic. Cluster analysis with the entire AFLP data divided all cultivars into two major groups reflecting their origins. The first one contained T. aestivum L. cultivars, and the T. turgidum ssp. durum cultivars and landraces were grouped in the second. Narrow genetic diversity among all cultivars was detected with an average genetic similarity of 0.884. The lowest similarity index (0.9) was found between Cham5 and Hamary (durum wheat), whereas this value was 0.93 between Salamony and Bouhouth 4 (T. aestivum L.). The narrow genetic diversity level indicates that these genotypes could be originated from the same source. AFLP analysis provides crucial information for studying genetic variation among wheat cultivars and provides important information for plant improvement.  相似文献   

6.
Cowpea is an important grain legume and hay crop of many tropical and subtropical regions, especially in the dry savanna region of West Africa. The cowpea gene pool may be narrow because of a genetic bottleneck during domestication. Genetic variation within specific breeding programs may be further restricted due to breeding methods, ‘founder effects’ and limited exchange of germplasm between breeding programs. Genetic relationships among 60 advanced breeding lines from six breeding programs in West Africa and USA, and 27 landrace accessions from Africa, Asia, and South America were examined using amplified fragment length polymorphism (AFLP) markers with six near infrared fluorescence labeled EcoRI + 3/1bases/MseI + 3/1bases primer sets. A total of 382 bands were scored among the accessions with 207 polymorphic bands (54.2%). Despite a diverse origin, the 87 cowpea accessions shared a minimum 86% genetic similarity. Principal coordinates analysis showed clustering of breeding lines by program origin, indicating lack of genetic diversity compared to potential diversity. Accessions from Asia and the Americas overlapped and were distinct from West African breeding lines, indicating that germplasm from Asia and the Americas have common origins outside West Africa. US and Asian breeding programs could increase genetic variability in their programs substantially by incorporating germplasm from West Africa, while national programs in West Africa should consider introgression of Asian germplasm and germplasm from other parts of Africa into their programs to ensure long-term gains from selection.  相似文献   

7.
Morphological data recorded from field trials using Citrullus lanatus germplasm collected in Namibia were used to analyse and compare the various morphotypes of this species. The experiment comprised wild types and local landraces as well as commercial cultivars. Cluster analysis supported the indigenous classification system used in Namibia, in which Citrullus types are distinguished based on gross morphology, ecology and usage and grouped into seed, cooking and fresh-eating (watermelon) types. Commercial watermelon cultivars formed a distinct cluster. Wide variation was found within the local types whereas the genetic basis of the commercial type appears to be narrow. The commercial cultivars were most closely related to local watermelon types and more distantly related to the wild types, whereas the cooking melons form an intermediate group.  相似文献   

8.
Morphological and physiological seed characteristics of the hyacinth bean (Lablab purpureus) were investigated in a set of 18 different germplasm accessions, from wild over semi-domesticated forms to landraces and current cultivars. The objective of this study was to improve the understanding of the domestication of this tropical legume crop. Wild accessions were easily distinguished by morphological characters, such as small, greyish-brown, mottled seeds. Cultivated or semi-domesticated forms showed a much wider variation in size, colour and shape. Seed mass of cultivated accessions reached up to almost 10 times that of wild accessions. Most wild accessions showed a greater spread of germination and larger proportions of hard seeds, up to about 70%, than most cultivated and so-called semi-domesticated accessions. Cluster analysis applied separately to morphological and germination data and a subsequent discriminant analysis did not help integrating the morphological variability observed. The presumed occurrence of semi-domesticated accessions within the germplasm tested as well as the crop's origin from Africa alone or both Africa and Asia are debated on the basis of seed germination and hard seed coat dormancy.  相似文献   

9.
The cultivated types of Brassica rapa L. em. Metzg. consist of morphologically distinct subspecies such as turnip, turnip rape, Chinese cabbage, pak choi and pot herb mustard which are classified as ssp. rapa, ssp. oleifera, ssp. pekinensis, ssp. chinensis and ssp. nipposinica (syn. ssp. japonica), respectively. We attempted to elucidate the phylogenetic relationships among the cultivated types of B. rapa. Thirty-two accessions from the Eurasian Continent were analyzed using AFLP markers with a cultivar of B. oleracea as an outgroup. In total, 455 bands were detected in the ingroup and 392 (86.6%) were polymorphic. The Neighbor-Joining tree based on the AFLP markers indicated that the accessions of B. rapa were congregated into two groups according to geographic origin. One group consisted of ssp. rapa and ssp. oleifera of Europe and Central Asia and the other included all the subspecies of East Asia. Our results suggest that cultivars from East Asia were probably derived from a primitive cultivated type, which originated in Europe or in Central Asia and migrated to East Asia. This primitive cultivated type was probably a common ancestor of ssp. rapa and ssp. oleifera. The Neighbor-Joining tree also shows that leafy vegetables in East Asia such as ssp. pekinensis, ssp. chinensis and ssp. nipposinica were differentiated several times from the distinct cultivars of ssp. oleifera in East Asia.  相似文献   

10.
Squash (Cucurbita spp.) is a common component in traditional cropping systems in Mexico, mainly in the agroecosystem known as the “milpa”, in which squash is cultivated in association with maize (Zea mays), the main crop. Using a questionnaire, 80 farmers were interviewed about crop production and selection practices in order to understand how these factors affect genetic diversity of local squash populations. We found that the most of the farmers who cultivate squash were elderly 59.8 ± 14.5 (mean ± SD; n = 78) years old. Squash varieties in the area were exclusively locally adapted landraces, and had not been replaced by modern squash cultivars. Two cultivated squash species, C. argyrosperma ssp. argyrosperma and C. moschata, had been grown intercropped with maize by 97.5% of the interviewed farmers, but only 50.0% were still producing squash at the time of the study. Farmers recognize typical characteristics of particular varieties within each of the local cultivated squash species, and selection is directed to maintain their identity. Nearly two thirds of the farmers (62.0%) had exchanged seeds of squash for planting, a practice that serves to increase genetic variability in the populations. All of the interviewed farmers were conscious of the possible hybridization between the wild gourd (C. argyrosperma ssp. sororia) and their cultivated squash. Despite various natural and human managed factors identified as contributing to enhancement of genetic diversity in these populations, results of the study show that genetic erosion of Cucurbita is likely in the region in the near future.  相似文献   

11.
Bottle gourd is an important crop in arid and semi-arid tropics where recurrent drought is the major constraint to crop production. Identification of drought-tolerant bottle gourd genotypes is fundamental to enhance productivity and for effective breeding and conservation. The objective of this study was to determine drought tolerance of a diverse set of bottle gourd landraces and to identify promising genotypes for direct production or breeding. A field study was conducted using a 12?×?2 factorial experiment involving 12 bottle gourd landraces under drought-stressed (DS) and non-stressed (NS) conditions. Significant differences were observed among bottle gourd landraces with respect to fruit yield under DS and NS conditions. The mean fruit yield under DS and NS conditions was 8.75 and 22.4?t?ha?1, respectively. Drought stress reduced fruit yield by 62%. Correlation and principal component analyses revealed the significance of yield-based indices of drought tolerance, such as tolerance index, geometric mean productivity, stress tolerance, mean productivity, yield index and harmonic mean, which allowed discrimination of drought-tolerant bottle gourd landraces. Such landraces as BG-79, BG-31, BG-67, BG-52, BG-78 and GC were identified useful for drought tolerance breeding or rootstock development programs.  相似文献   

12.
In order to shed light on the role of Iran in apple evolution and domestication, we chose to investigate the relationships of a collection of 159 accessions of wild and domesticated apples including Iranian indigenous apple cultivars and landraces, selected wild species, and old apple scion and rootstock cultivars from different parts of the world. The majority of the wild species belonged to M. sieversii, which is widely believed to be the main maternal wild ancestor of domestic apples, from Kazakhstan and M. orientalis, which is one of the probable minor ancestors of domestic apples, from Turkey and Russia located on the east and west of Iran, respectively. The accessions were assigned into six arbitrary populations for the purpose of generating information on genetic parameters. Nine simple sequence repeat (SSR) loci selected from previous studies in apple were screened over DNA extracted from all the accessions. Results showed that all SSR loci displayed a very high degree of polymorphism with 11–25 alleles per locus. In total, there were 153 alleles across all loci with an average of 17 alleles per locus. The SSR allelic data were then used for estimation of population genetic parameters, including genetic variation statistics, F-statistics, gene flow, genetic identity, genetic distance and then cluster analysis using POPGENE 1.32 software. The F-statistics and gene flow in particular, showed that there was more intra-population than between population variation. The genetic identity and genetic distance estimates, and the dendrogram generated from the un-weighted pair group arithmetic average (UPGMA) method of cluster analysis showed that the Iranian cultivars and landraces were more closely related to M. sieversii from Central Asia (east of Iran) and M. orientalis native to Turkey and Russia than to other accessions of Malus species. Also, the old apple cultivars from different parts of the world have a closer genetic relationship to M. sieversii, M. orientalis and the Iranian apples, than to other wild species. Based on these results, we suggest that the Iranian apples may occupy an intermediate position between the domesticated varieties and wild species. We propose that Iran could be one of the major players in apples’ domestication and transfer from Central Asia to the western countries.  相似文献   

13.
The Andaman and Nicobar (A&N) group of islands is immensely rich in plant biodiversity. Andaman’s native tribes are hunter-gatherers, sustaining on wild or marine food and practically do not have any cultivation. Diversity in cultivated crops is presently maintained in home gardens by settlers from the mainland and other adjoining countries. The National Bureau of Plant Genetic Resources (NBPGR) through explorations either alone or in association with CARI or with other ICAR institutes has collected 1234 accessions in 48 exploration and collection missions. Variability was collected in rice, cowpea, black gram, green gram, okra, Chinese spinach, ash gourd, taro, cucumber, pumpkin, bottle gourd, ridge gourd, bitter gourd, chilli, greater yam and coconut. Indigenous landraces are absent. The in situ conservation of the wild relatives of crops is well taken care of by a large number of protected forest reserves.  相似文献   

14.
Rice Diversity Collection,Conservation and Management in Northeastern India   总被引：3，自引：0，他引：3  
Rice is the principal crop of northeastern region of India, where a considerable range of diversity exists. The germplasm collection has also unfold the occurrence of large number of rice landraces in the region. Between 1985 and 2002, a total 2639 accessions of rice germplasms including their wild relatives have been collected. Most of these germplasm material have been conserved in the National Gene Bank, New Delhi following their necessary characterization and evaluation. With the establishment of the Regional Gene Bank Module with medium-term storage facilities (6–7°C with 40–45% relative humidity) at Barapani, Meghalaya, the rice germplasm conservation (ex situ) have been initiated in the region.  相似文献   

15.
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16.
The genetic diversity of high and low molecular weight glutenin subunits of 63 durum wheat landraces from different geographical regions in the Mediterranean Basin was studied using SDS-PAGE. Great variability in glutenin composition was found, with 42 high and low molecular weight glutenin haplotypes, 20 allele combinations at the HMW-GS loci, and 18 at the LMW-GS. All five possible LMW models were detected in all Mediterranean regions. Rare alleles were found at Glu-B1 locus in high frequencies and a priori related alleles to grain quality were also observed. Global genetic diversity index was relatively high (0.67); it ranged from 0.33 to 0.66. Cluster analysis on the frequency patterns of origins grouped genotypes following a geographical structure. Rogers’ distance coefficient on frequency pattern for each region of origin showed two germplasm pools with distinct quality profiles, where South West Asian landraces were very different from the landraces of other Mediterranean areas. The relationship between different regions of origin is discussed and two possible ways of introduction of wheat in the Iberian Peninsula (N Africa and SE Europe) are hypothesized. The use of Mediterranean durum wheat landraces as source of genetic variability for grain quality improvement is highly recommended.  相似文献   

17.
Lotus (Nelumbo nucifera Gaertn. ssp. nucifera), one of 12 aquatic species used as vegetable, has been cultivated for more than 2,000 years, and now has been widely cultivated in almost all provinces in China. The largest area under cultivation of lotus is located in the regions surrounding mid-down Yangtse River, including Hubei, Jiangsu, Zhejiang, Anhui, Jiangxi and Hunan provinces. According to different purposes or morphological differences, the Chinese lotus (N. nucifera ssp. nucifera) is usually classified into three types: rhizome lotus, seed lotus and flower lotus. Rhizome lotus is mainly cultivated in Hubei, Jiangsu, Anhui and Zhejiang provinces; Seed lotus in Jiangxi, Fujian and Hunan, and flower lotus in Wuhan, Hubei province, and Beijing. Up to the year 2002, a total of 572 lotus accessions (including landraces, cultivars and breeding lines) were conserved in National Garden of Aquatic Vegetable, Wuhan, Hubei province, including those collections from 153 counties in 18 provinces, and lines bred by breeders. Out of these accessions, 310 were rhizome lotus which contains 201 landraces and 109 breeding lines; 229 were flower lotus including 172 cultivars and 57 breeding lines; and the rest 33 were seed lotus with 18 cultivars.  相似文献   

18.
The Asian cultivated rice, Oryza sativa L. (spp. indica or japonica), is assumed to have originated from one or both of the two wild Asian species, O. rufipogon Griff. and O. nivara Sharma and Shastry. They occur throughout the monsoon Asia and west Oceania. Fragrance is the most important trait among the domesticated characters of basmati and jasmine rice of Asia. The gene for fragrance in a scented rice shows the presence of a mutated portion (i.e., an eight base pair deletion in exon 7) that result in its loss of fragrance. In the present study, 229 wild rice O. rufipogon accessions were genotyped for this locus using a PCR assay. The wild rice species contained the mutated allele of the fgr gene at a low frequencies of 0.23. The surveyed populations were in Hardy–Weinberg equilibrium. This observation supports the hypothesis that the allele for fragrance was already present in the wild rice, and that this trait appeared in scented rice cultivars because of selection by the farmers of genotypes possessing this character during the process of domestication.  相似文献   

19.
In order to evaluate and compare the germplasm resources of wheat in Tibet, we analyzed the genetic diversity of 136 Triticum aestivum ssp. tibetanum Shao and 119 Tibetan wheat landraces (Triticum aestivum L.) by using Intron-Splice Junction (ISJ) primers. The results showed that polymorphism of PCR products were obtained by 33 primer combinations, which accounted for 11% of the 300 primer combinations produced by 26 ISJ primers. A total of 333 stable bands can be amplified from the T. aestivum ssp. tibetanum Shao and 243 bands were polymorphic, which accounted for 72.9% of the total bands. Tibetan wheat Landraces produced 316 stable bands, of which 197 bands were polymorphic. The polymorphic bands accounted for 62.34% of the total bands produced from Tibetan wheat landraces. The genetic diversity of T. aestivum ssp. tibetanum Shao was higher than that of Tibetan wheat landraces in Tibet, suggesting that T. aestivum ssp. tibetanum Shao can be used as important genetic resource for the breeding and genetic improvement of wheat in Tibet. Matrix (1, 0) was generated according to the presence or absence of the bands produced from a particular wheat accession. Clustering and principle coordinates analysis showed that T. aestivum ssp. tibetanum Shao and Tibetan wheat landraces were divided into two groups. We conclude that high polymorphisms produced by ISJ primers can reflect the genetic diversity between T. aestivum ssp. tibetanum Shao and Tibetan wheat landraces.  相似文献   

20.
Two germplasm collections of Lablab purpureus L. Sweet totalling 249 accessions were grown in the field in Australia and Ethiopia and characterised using a common set of morphological and agronomic (M-A) attributes. Data from each site were analysed separately using multi-variate analysis and a classification constructed for each collection. There was considerable diversity within both collections, especially that maintained in Ethiopia. Time to flowering, seed weight, and plant height were the most important attributes in determining group allocation in both classifications. Both collections had a high proportion of L. purpureus subsp. purpureus, especially accessions similar to the Australian cultivars Highworth and Rongai. They also had good representation of the less common L. purpureus subsp. uncinatus Verdc. less common landraces and wild collections from either Africa or India. When combined, the two classifications provided an overview of diversity and highlighted the similarities and dissimilarities between the two collections. The vast range in plant types supported the view that lablab has the capacity to be a multi-purpose legume for both commercial and smallholder agriculture. Some important and less common germplasm identified were Ethiopian domesticated subsp. uncinatus, Ethiopian subsp. purpureus landraces collected from regional markets, semi-domesticated and wild accessions from southern Africa, and wild accessions from India. Using this overview, a core collection of germplasm was selected, which provides researchers with a sound basis for future plant breeding and agronomic studies with this important tropical legume.  相似文献   

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