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1.
Citrus indica and C. macroptera are the wild endangered species of Citrus occurring in northeastern India. Surveys were undertaken in this region for ascertaining distribution, studying variability and for collection of germplasm of these two species. C. indica, an endemic species of this region, was collected from the Citrus Gene Sanctuary located in buffer zone of Nokrek Biosphere Reserve in the Garo hills of Meghalaya. In addition, a putative natural hybrid of C. indica and C. limon was collected for the first time from the south Garo hills. C. macroptera had much wider distribution and was collected from Mizoram and Meghalaya states. In Jantia hills of Meghalaya, natural populations of this species are in a highly threatened state. The two species were unevenly distributed all over the explored territory. Morphological characterization of leaves, fruits and seeds indicated the presence of sizable variability within collected accessions of these two Citrus species. Indigenous technical knowledge gathered on the use and socio-economic importance indicated commercial potential for these two species in northeastern India. However, lack of cultivation of these species and clearing of forest cover at an alarming rate has led to an urgent need to adopt complementary conservation strategies to safeguard these species and to ensure their availability for future utilization. A major emphasis on developing methods for their propagation, multiplication and regeneration in in situ and ex situ conditions is required.  相似文献   

2.
Molecular differentiation in 24 accessions representing 19 taxa of Indian Citrus has been examined through sequence analysis of Internal Transcribed Spacer (ITS) region of nrDNA. Sequence length in the 24 accessions of Citrus taxa ranged from 512 to 665 bp (ITS1 & ITS2 partial and 5.8S complete sequence). The ITS sequences were very rich in G+C content ranging from 61.40 to 66.60% with an average of 64.2%. Genetic distance within Citrus group ranged from 0 to 13.4% with an average of 4.6%, showing moderate rate of nucleotide divergence. The phylogeny was inferred using the Maximum parsimony (MP) and Neighbor-Joining (NJ) methods. Both MP and NJ trees separated all the 24 accessions of Citrus into six distinct clusters. The disposition of all the accessions of Citrus in separate clusters in ITS-derived dendrograms was partly in accordance with the morpho-taxonomic affinities of the target taxa. This study supports the concept of Citrus medica (citron), C. reticulata (mandarin), and C. maxima (pummelo) as the basic species of the genus. However, ITS marker could not find any clear cut differentiation between subgenera Citrus and Papeda as proposed in Swingle’s Citrus classification system. The present study also supports the distinctiveness of C. indica (Indian wild orange), C. latipes (Khasi papeda) and C. hystrix (Melanesian papeda) as true species, besides elucidating the probable hybrid origin and relationships among the cultivated species/biotypes, such as Citrus ×aurantiifolia (sour lime) C. ×limon (lemon), C. ×taitensis (Indian rough lemon), C. limettioides (sweet lime), C. ×aurantium (including sour and sweet oranges and grapefruit), and other indigenous varieties of Indian origin: C. megaloxycarpa (sour pummelo), C. karna (karna orange), C. pseudolimon (Hill lemon), ‘Memang athur’, ‘Pummelo-lemon’ and ‘Kathairi nimbu’.  相似文献   

3.
The North-eastern region of India is rich treasure of various Citrus species. A vast reservoir of Citrus diversity exists in wild, semi wild form and is found scattered here and there without commercial cultivation and much care. The edaphic and climatic set up as well as the physiographic condition of the region makes it possible to grow a number of species, landraces and probable hybrids of Citrus without any care. But of now with the population increase, changing attitude of the farmers towards some newly introduced cash crops there is genetic erosion of the valuable resources and most of them are in verge of extinction. So, it is the high time for the scientific community to exploit all the rare and endangered resources of Citrus of north eastern region and for their conservation. In addition molecular and morphological characterization of the reported germplasm, evaluation and screening against biotic and abiotic stresses should also be needed to safeguard the existing population of Citrus and for future Citrus improvement programme.  相似文献   

4.
The Glycine subgenus Soja includes two species, cultivated soybean [(Glycine max (L.) Merr.)] and the progenitor wild soybean (G. soja). However, a morphologically intermediate form, the semi-wild soybean (G. gracilis), exists between the two species, and its taxonomic position is under debate. In this study, we evaluated phylogenetic relationships and occurrence events within the subgenus Soja based on genetic variation of SSR loci using a set of accessions comprising wild soybeans (≤3.0?g 100-seed weight), semi-wild soybeans (>3.0?g) and soybean landraces (≥4.0?g). The results showed that semi-wild soybean accessions collected in natural fields should be treated as a variant of G. soja and not of G. max, and were genetically differentiated from the soybean landraces, even large-seeded semi-wild soybean accessions (6.01–9.0?g) with seed weights overlapping with or exceeding those of soybean landraces. Evolutionary bottleneck analysis indicated that semi-wild soybean is not a transitional form in the domestication of cultivated soybeans from wild soybean. G. soja contained two genetically differentiated forms, small-seeded type (typical, plus 2.01–2.50?g) and a large-seeded type (2.51–3.0?g). Genetically, the large-seeded wild soybean was closer to the semi-wild soybean, although in morphology it resembled the typical wild soybean. Ancestry analysis confirmed that cultivated soybean genes have introgressed into modern wild soybean populations. The green cotyledon character and other rare characters such as white flower, grey pubescence, no-seed bloom, and coloured seed-coats (brown, green, and yellow) in wild soybean were shown to be involved in introgression from cultivated soybeans.  相似文献   

5.
Domestication is an evolutionary process that modifies morphological, physiological, chemical and genetic features of wild plants, and is a product of artificial selection. A gradient of domestication can be appreciated in species of the Opuntia genus. There are wild species like O. streptacantha, others semi-domesticated like O. hyptiacantha O. megacantha and O. albicarpa, or other like O. ficus-indica with the highest degree of domestication. At the same time, some structural polysaccharides have been associated with plant drought and freeze resistance. This study aimed at quantify five groups of structural polysaccharides in 14 variants of nopalitos (edible young cladodes of flat-stemmed spiny cacti consumed as vegetables) of Opuntia spp. in a domestication gradient. Given that extreme environment is less frequent under cultivation than in the wild, we hypothesized that structural polysaccharides in nopalitos are reduced throughout the domestication process. The experiment was conducted as a completely randomized design with a 5?×?14 two-factor factorial treatment structure, with four replications. Mucilages, pectins, hemicelluloses and cellulose were extracted and dietary fiber content was calculated. ANOVA of data was performed, pair wise comparisons of species and variants were conducted by Tukey test and principal components analysis was carried out. Mucilages were higher in O. ficus-indica (12% of total dry mass) and pectins, loosely and tightly bound hemicelluloses in O. streptacantha (2.5, 9 and 3%, respectively). All five species had similar content of cellulose (5.1% dry mass); but, O. streptacantha presented more dietary fiber. Higher pectins and both loosely and tightly bound hemicelluloses content in wild species can be related to genotype and the persistence of reaction to a wild environment. Mucilages which are one of the main characteristics of consumer preference and loosely bound hemicelluloses could have impact for selection during Opuntia domestication.  相似文献   

6.
Cucumis setosus Cogn. is a rare, endemic, wild gathered or semi-domesticated vegetable restricted to Maharashtra state and border districts of adjoining states in India. Herbarium and literature survey shows that it is poorly collected and inadequately studied. Morphological characters, basic chromosome number and crossability barriers indicate that Cucumis setosus is a valid species, distinct from C. sativus and endemic to western India. Its morphology, basic cytology, crossability relationship with other Cucumis species, taxonomy, distribution, ecology, conservation, economic importance and viability under cultivation are discussed. Besides, a key to distinguish it from C. sativus var. hardwickii (wild and feral form of C. sativus) and other species having sympatric distribution in the area is also presented. Absence of bitter principle in the fruits makes it a potential germplasm for melon and cucumber improvement as well as direct domestication as a future crop.  相似文献   

7.
Indica–japonica variation represents the most significant genetic differentiation in Asian cultivated rice (Oryza sativa L. subsp. indica Kato or subsp. japonica Kato). Understanding the differentiation and distribution patterns of cultivated rice along altitude gradients will facilitate strategic utilization and conservation of rice germplasm from mountainous regions. In this study, we analyzed 203 varieties and 14 wild accessions of rice collected from localities across an altitude gradient between 450 and 2,350 m above sea level in Yunnan, China, applying the “InDel molecular index” developed recently. Results from PCA of the InDel data demonstrated significant genetic differentiation of rice varieties from Yunnan into indica and japonica types. A few cultivars and nearly all wild rice accessions showed only moderate or no differentiation. Further analyses demonstrated a clear distribution pattern of the rice varieties in the mountainous region: indica varieties were grown across the entire altitude gradient in the sampling areas, but most japonica varieties were found above 1,400 m. These results clearly indicated that indica rice could be cultivated in areas at much higher altitudes than those categorized by the traditional methods. The knowledge opens a new dimension for introducing indica rice varieties to mountainous regions at higher altitudes and for selecting rice germplasm in these regions. In addition, the pattern of significant indica–japonica differentiation in rice varieties from Yunnan suggested the exotic origin of cultivated rice, which did not support the hypothesis that Yunnan is a part of the center of origin of rice, although it is certainly one of the centers of genetic diversity for rice.  相似文献   

8.
In order to formulate appropriate strategies for the conservation and utilization of the wild mulberry genetic resources available in India, a study was undertaken with 20 mulberry genotypes from the four different species. Seventeen intersimple sequence repeat primers were used to generate a total of 114 markers, of which 98 (85.96%) were polymorphic. Seven unique bands for Morus serrata Roxb. and one for both M. serrata Roxb. and Morus macroura Miq. were identified, of which one fragment has been sequenced and deposited in the EMBL-GeneBank (AJ-585512). The genetic dissimilarity coefficients varied from 0.078 to 0.530 among these genotypes and from 0.168 to 0.465 among the species. The dendrograms realized from these markers clustered the genotypes into three groups. The outermost group was M. serrata Roxb., which was followed by the group of M. macroura Miq. and the innermost group contained genotypes of Morus indica L. and Morus alba L. This intermixing of genotypes of M. indica and M. alba supports the view that M. indica is merely a synonym of M. alba. Distribution of the genotypes on a two-dimensional figure upon multidimensional scaling with ALSCAL program, further, confirmed the genetic divergence between the cultivated and wild mulberry groups. On the basis of the results a few potential wild mulberry genotypes were identified for its conservation and utilization in breeding programs to confer the stress tolerance to the cultivated varieties of mulberry.  相似文献   

9.
Thus far, there is little knowledge of the genetic diversity, structure and gene flow dynamics in rare wild and semi-wild soybean mixed populations, and such information is vital for understanding of the origin of semi-wild soybean (Glycine gracilis) and the biosafety protection of wild soybean from transgenic soybeans. Population eco-genetic data are necessary to provide a more coherent and comprehensive understanding of the genetic events that occurred in the natural habitats of wild soybean (Glycine soja). We tested genetic diversity and structure of 11 wild mixed populations of wild soybean (Glycine soja) and semi-wild soybean (G. gracilis), 1 wild soybean population, and 1 cultivated soybean variety population were studied using 20 nuclear microsatellite markers (SSRs). We found based on microsatellite polymorphisms that the mixed populations were characterized by higher mean heterozygosity (H o = 0.029) and outcrossing rate (t m = 6.35 %), and lower fixation index (F is = 0.891), and the semi-wild plants had distinctly higher heterozygosity (H o = 0.081) than that of the wild plants (H o = 0.007). The occurrence of semi-wild plants influenced population genetic structure but not geographical population differentiation. These mixed populations exhibited strong ecogeographical differentiation, which suggests that their original populations were colonized over a long phytogeographical history. The introgression occurred through pollen gene flow from the soybean fields into wild populations and created the semi-wild plants, with significant genetic differentiation from the typical wild ones. Introgressive genes could become established by two possible modes in wild soybean populations by both self-segregation and/or intrapopulation secondary hybridization. The latter deserves attention because of the possibility of rapid transgene escape.  相似文献   

10.
A number of genes that contribute to the domestication traits of cultivated rice have been identified. These include Sh4, Rc, PROG1 and LABA1, which are associated with non-shattering rachis, white pericarp, erect growth and barbless awns, respectively. The mutations giving rise to the “domestication alleles” of these genes are either invariable in cultivated rice, or have variability that is strictly associated with the phenotypic trait. This observation forms the basis to those current rice domestication models that envisage a single origin for the domesticated phenotype. Such models assume that the domestication alleles are absent or rare in wild rice, emerged under cultivation and spread across all rice groups by introgressive hybridization. We examined whole-genome sequencing datasets for wild and cultivated rice to test the former two assumptions. We found that the rc and laba1 alleles occur in wild rice with broad geographical distribution, and reach frequencies as high as 13 and 15%, respectively. These results are in agreement with previous observations of the prog1 and sh4 domestication alleles in wild populations. We also show that the diversity of the genomic regions surrounding the rc, laba1, prog1 and sh4 alleles in wild accessions is greater than that in cultivated rice, suggesting that these alleles emerged prior to domestication. Our findings indicate that the possibility that independent rice groups obtained identical domestication alleles directly from the wild population needs to be considered.  相似文献   

11.
The north-eastern India is highly diverse in Citrus germplasm (23 taxa including their 68 varieties). The climate and soil factors are highly favourable for plant growth and fruit quality. Inspite of the high potentialities, the Citrus had remained more or less a family need based cultivated plant. The large variation in traditional agro-ecosystems of the region has evolved and preserved highly valuable genetic resources under different species. The value of certain taxa as rootstocks has been outlined. The conservation of germplasm and research gaps has been emphasised.  相似文献   

12.
The genus Glycine subgenus Soja includes two species, the important crop, soybean (G. max), and its wild progenitor (G. soja), and an intermediate semi-wild type (G. gracilis). However, the origin of the semi-wild type is in dispute, from independent evolutionary processes or from sympatric hybridization, although many studies support the hypothesis of a hybridization origin. Here, we reveal conclusive evidence for the natural occurrence of sympatric hybridization between wild and cultivated soybeans leading to G. gracilis by capturing natural F1 seeds based on phenotypic and molecular signatures. The F1 hybrids occurred through pollen flow between wild and cultivated soybeans, with many heterozygous loci and similar genetic parameters compared to the maternal wild populations; while paternal soybeans showed the lowest genetic diversity. The F-statistics showed genetic differentiation of the hybrids from the paternal soybeans and maternal wild populations; the differentiation of hybrids from wild soybeans was less than that of hybrids from cultivated soybeans. Natural F1 hybrids generated various seed sizes in the offspring, suggesting that cultivar-genes introgressed into wild soybeans, and the degree of outcrossing in wild soybeans seems to be very important for gene spread, exchange and recombination in the evolution of populations.  相似文献   

13.
Crop domestication has lead to the selection of a wide range of traits that distinguish domesticated crops from their wild ancestors. Over the past four decades, concerted efforts by archaeologists and geneticists have provided novel insights into the domestication of crops. However, minor crops are rarely a subject for intensive domestication studies and very less is known on the domestication of guar [Cyamopsis tetragonoloba (L.) Taub.] except the trans-domestication hypothesis. The hypothesis proposes that the domestication of guar took place in recent times in the dry areas of the northwestern region of Indo-Pakistan subcontinent and the African wild species, C. senegalensis Guill. et Perr., as its ancestor. However, the process by which the wild species was domesticated is not fully understood. The present paper describes the exploration, collection and in situ characterization of the primitive weedy forms of guar that could be the missing link between the wild and cultivated species. Adak guar is found to grow along with cultivated guar as a weed and is characterized by several primitive characters, prominent among which are spreading habit, small inedible pods which shatter at maturity, hard seed coat and seed dormancy. A total of 66 germplasm collections of these primitive weedy forms of guar have been made from naturally occurring populations in the arid regions of northwestern India. Systematic studies involving these primitive weedy forms can help in understanding the domestication bottlenecks and in utilizing the genetic variation lost during the process of domestication for the improvement of cultivated guar.  相似文献   

14.
This study focused on clarifying phylogenetic relationships among Citrus accessions from Vietnam. Our phylogenetic analysis based on nucleotide sequences from the ITS of the ribosomal DNA included 69 accessions belonging to Citrus and related (sub)genera. Maximum parsimony and Bayesian analysis confirmed a clear separation of the three ‘true’ Citrus species (C. medica, C. maxima and C. reticulata). Confirming recent taxonomic revisions, Fortunella, Poncirus trifoliata and Citrus hystrix are clustered among the accessions of subgenus Citrus. C. × sinensis accessions revealed a close evolutionary relationship to either C. maxima or C. reticulata, thereby confirming their involvement in its hybrid origin. Also, some other hybrid taxa and their proposed parental species were investigated and their origin could in some cases be confirmed using the ITS sequence data.  相似文献   

15.
Genetic variation and phylogenetic relationships among 50 wild and cultivated accessions of 19 Indian Citrus genotypes were examined through comparison of Directed Amplification of Minisatellite DNA (DAMD) markers and morphological characters. DAMD-PCR analysis with four primers resulted in amplification of a total of 45 bands, of which 35 (78 %) were polymorphic. Morphometric evaluation using 76 morphological characters showed high level of variability ranging from 0.18 to 1.00 (avg 0.39), whereas the Jaccard’s coefficient values of genetic similarity calculated from DAMD data ranged from 0.41 to 1.00 (avg 0.68), indicating moderate genetic divergence among the accessions studied. UPGMA dendrograms generated separately from morphometric and DAMD data segregated all the accessions of Citrus into four main clusters, each containing a true basic species and their probable hybrids. The grouping of individual accessions/genotypes under respective species or cultivars in DAMD dendrogram was based purely on their genetic relationships rather than geographical origin. There was no absolute congruence between the data and dendrograms generated from morphometric and DAMD analyses. The study demonstrates the resolving power of DAMD markers for discrimination of individual genotypes of Citrus under its respective species, hybrid or cultivar groups and inferring their genetic and phylogenetic relationships as well. This is the first report on application of DAMD markers in Citrus.  相似文献   

16.
Immature fruits of cultivated species of Luffa are commonly used as summer vegetable in India. Rich morphological variability occurs in cultivated species of Luffa in different growing regions of the country. To study morphological variability in cultivated and wild Luffa from different agro-ecological regions of India, a total of seventy accessions were assembled. Morphological variations in leaf, fruit and seed characters were found to delimit cultivated and wild Luffa species. Cluster analysis revealed two major clusters, one comprising of 36 accessions of Luffa acutangula and the other of 30 accessions belonging to L. aegyptiaca. A local cultivar “Satputia” (L. hermaphrodita) was classified along with cultivated L. acutangula and wild L. acutangula var. amara. Wild species namely L. graveolens and L. echinata were clustered closer to the L. acutangula.  相似文献   

17.
Among the 52 species reported in Cucumis, cucumber and muskmelon are the most important species, extensively cultivated by the human for consumption. Diversity has been reported in the wild species of Cucumis from India. Considering the status of genetic erosion of the variability in the various species of Cucumis, a total of 121 germplasm accessions of five different Cucumis species were collected through three explorations in the parts of Aravalli ranges of northwestern India. The paper presents the distribution, collection, extent of variability, associated indigenous traditional knowledge, conservation status of these Cucumis species and prospects of their utilization in crop improvement.  相似文献   

18.
The intense exploitation of turtles in Asian markets has contributed to declines in turtle populations across the continent. Three-quarters of Asia’s turtles are threatened and half are endangered. A recent workshop on the Asian turtle crisis identified taxonomic studies of widespread species as a priority for research because these low risk species may include unrecognized, narrowly distributed taxa of much higher concern. Chitra indica is a widely exploited softshell turtle (family Trionychidae) found across southern Asia. Individuals from Thailand have been described as a separate species, Chitra chitra, but this has not been universally accepted, and many sources consider Chitra monotypic. Phylogenetic analysis of sequence data from the mitochondrial ND4 gene revealed three deeply divergent, monophyletic lineages within Chitra: C. indica, C. chitra, and a third unnamed form from Myanmar. This new form is probably Critically Endangered, which highlights the importance of systematic studies in determining conservation priorities.  相似文献   

19.
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   

20.
The genetic diversity in genus Prunus is mainly confined to temperate regions of Himalaya and to a lesser extent in the sub-montane and hilly regions of peninsular India. The cultivated and wild species of Prunus have tremendous potential for improvement and utilization. This paper includes the genetic resources of cultivated and wild useful species of Prunus in India with emphasis on their distribution, potential traits/ useful characteristics and utilization. The information on potential genetic resources of Prunus would be helpful in collection, evaluation, conservation and utilization of species.  相似文献   

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