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PubMed2005

Variations of main quality components of tea genetic resources [Camellia sinensis (L.) O. Kuntze] preserved in the China National Germplasm Tea Repository.

The variations of the main quality components of tea, tea polyphenols, catechins, amino acids, caffeine, and water extract of 596 accessions Chinese tea genetic resources, preserved in the China National Germplasm Tea Repository (CNGTR), were analyzed. Tea polyphenols content on a dry weight basis varied from 13.6 to 47.8%, averaging 28.4%. The tea polyphenols content increases gradually from northern and eastern provinces to southern provinces, the highest is in Yunnan tea resources. The content of catechins ranged from 81.9 g/kg to 262.7 g/kg, averaging 144.6 g/kg. The genetic resources from Hunan province had the highest catechins content, inconsistent with the tea polyphenols, which were highest in Yunnan tea resources. The amino acids content ranged from 1.1 to 6.5%, with an average of 3.3%. It was much lower in the southern provinces compared with northern and eastern provinces. The average caffeine content was 4.2%, varying from 1.2 to 5.9%. Yunnan province has plentiful high caffeine genetic resources, next is Fujian province. Caffeine content of Chinese and Japanese tea genetic resources were very similar. The average of water extract content was 44.7%, varying from 24.4 to 57.0%. The variation pattern was similar to that of tea polyphenols. Tea genetic resources of transnormal components are valuable and they could be used directly or indirectly for commercial functional components extract, breeding, and production.

Amino Acids↗
PubMed2006

Asian prunus viruses: New related members of the family Flexiviridae in Prunus germplasm of Asian origin.

Serological reactivity to Plum pox virus (PPV) antisera has been described in several Prunus sources of Asian origin that are free of PPV infection. Using polyvalent or specific PCR assays, the presence of three closely related agents in two of these sources, Prunus mume cv. Bungo and P. persica cv. Ku Chu'a Hung, was demonstrated. Similarities in genome organization and sequence comparisons indicate that these agents should be regarded as members of the genus Foveavirus, their only singular trait being a very large (>800 nt) 3' non-coding region (NCR), as compared to the ca. 130-180 nt 3' NCR observed in other Foveaviruses. The three agents are very divergent from known Foveaviruses but are also significantly removed one from the others, with overall nucleotide sequence identity levels in the sequenced region of ca. 74-76% and of only 60.8-67.5% in their complete CP gene (61.9-71.3% amino acid sequence identity). Given the species discrimination criteria in the family Flexiviridae, these three agents should be regarded as three related yet distinct new viruses belonging to the Foveavirus genus, for which the names Asian prunus virus 1, 2 and 3 are proposed. Evidence is provided for the presence of variants of these new viruses in other Prunus germplasm of Asian origin.

Amino Acid Sequence↗
PubMed2003

Water status and thermal analysis of alginate beads used in cryopreservation of plant germplasm.

Encapsulation and dehydration techniques using alginate beads are used increasingly for the pre-treatment of various plant materials for cryopreservation to improve survival post-cryogenic storage. This study reports the effects of the water content of beads (formed with 3% (w/v) alginic acid in liquid S-RIB), polymerisation time (in 100 mM calcium chloride solution), osmotic dehydration (in 0.75 M sucrose solution), and evaporative air desiccation on the thermal properties of alginate beads used in cryopreservation protocols. Experimental beads were assayed using a differential scanning calorimeter (DSC) with a cooling programme to -150 degrees C, followed by re-warming. Resultant thermograms were evaluated with particular reference to the onset temperature and enthalpy of the melt endotherm from which the quantities of frozen and unfrozen water were calculated. Treatments were applied sequentially to samples of beads and their thermal features evaluated at each stage of the protocol. Using 'standard' beads (40-55 mg fresh weight), formed using plastic disposable pipettes, the degree of polymerisation (>10 min) proportionally reduced their dry weight and increased their water content. Thermal characteristics of the beads were unaffected by polymerisation times >10 min, but the maximum level (23%) of unfrozen (osmotically inactive) water was achieved after 15 min polymerisation. Osmotic dehydration using 0.75 M sucrose significantly lowered bead water content and mean dry weight approximately doubled with 20-24 h immersion time. Bead desiccation in still air reduced their water content by 83% of fresh weight, whilst dry weight remained constant. After 8 h desiccation in air between 27 and 37% of the water in the bead was osmotically inactive (unfrozen) in DSC scans. Desiccation >18 h reduced this fraction to zero. The melt onset temperature and the enthalpy of melting were directly related to bead water content. The unfrozen water fraction increased substantially with reduced water content of the beads (from 23 to 37% of total water content), concomitant with a reduction in the ratio of unfrozen to frozen water from 1:3 to 1:2. For successful vitrification and the production of a glass that did not destabilise on rewarming, a bead water content of ca. 26% of fresh weight (0.4 g waterg(-1) dry weight) was required, much of which was osmotically inactive water. These data are discussed in relation to optimal pre-treatments for alginate bead encapsulation techniques used in the cryopreservation of a range of plant germplasm. It is proposed that increased standardisation of alginate beads, in terms of volume, fresh weight, and water content, is required to reduce the variability in physical and thermal features, which in turn will improve survival of plant samples post-cryopreservation.

Alginates↗
PubMed2001

Comparison of oil and phytosterol levels in germplasm accessions of corn, teosinte, and Job's tears.

Seeds of 49 accessions of corn (Zea mays ssp. mays), 9 accessions of teosinte (Zea species that are thought to be ancestors and probable progenitors to corn), and 3 accessions of Job's tears (Coix lacryma), obtained from a germplasm repository, were ground and extracted with hexane. Whole kernel oil yields and levels of four phytonutrients (free phytosterols, fatty acyl phytosterol esters, ferulate phytosterol esters, and gamma-tocopherol) in the oils were measured. Among the seeds tested, oil yields ranged from 2.19 to 4.83 wt %, the levels of ferulate phytosterol esters in the oil ranged from 0.047 to 0.839 wt %, the levels of free phytosterols in the oil ranged from 0.54 to 1.28 wt %, the levels of phytosterol fatty acyl esters in the oil ranged from 0.76 to 3.09 wt %, the levels of total phytosterols in the oil ranged from 1.40 to 4.38 wt %, and the levels of gamma-tocopherol in the oil ranged from 0.023 to 0.127 wt %. In general, higher levels of all three phytosterol classes were observed in seed oils from accessions of Zea mays ssp. mays than in seed oils from accessions of the other taxonomic groups. The highest levels of gamma-tocopherol were observed in teosinte accessions.

Corn Oil↗
PubMed2006

Extractable amounts of trans-resveratrol in seed and berry skin in Vitis evaluated at the germplasm level.

Extractable amounts of resveratrol in berry skins and seeds were studied in 120 grape (Vitis) germplasm cultivars during two consecutive years to determine the distribution of resveratrol among the main grape genotypes. Interspecific rootstock cultivars had much higher extractable amounts of resveratrol in skin and seed than all other grape genotypes studied in both years. Extremely high extractable amounts of resveratrol in berry skins [>100 microg g(-1) of skin fresh weight (FW)] and seeds (>20 microg g(-1) of seed FW) were observed on two rootstock cultivars obtained from hybrids of V. monticula x V. riparia. Extractable amounts of resveratrol in berries of rootstock cultivars that are the descendants of V. riparia were also very high. The cultivated European type (V. vinifera) cultivars and their hybrids with V. labrusca had relatively low levels of extractable resveratrol in berry skin and seed, and the extractable amounts of resveratrol in berry skin and seeds were, with a few exceptions, <2 microg g(-1) of skin or seed FW. Extractable amounts of resveratrol in berry skin and seeds were closely related with fruit traits or purpose of uses and climate. Significantly higher extractable amounts of resveratrol in berry skin were found in seeded cultivars than in seedless ones, in both berry skin and seeds in winemaking grapes than in table grapes, and in red grapes than in green ones. Moreover, rainfall during fruit development resulted in higher extractable amounts of resveratrol in berry skin, whereas resveratrol synthesis and accumulation in grape seeds were not related to climate change.

Fruit↗
PubMed2003

Cacao domestication II: progenitor germplasm of the Trinitario cacao cultivar.

Cacao (Theobroma cacao L.) has been cultivated in Central America since pre-Columbian times. The type of cacao cultivated in this region was called Criollo; cacao populations from the Amazon basin were called Forastero. The type of Forastero most commonly cultivated until 1950 was named Amelonado. Historical data show Trinitario cacao to have originated in Trinidad, resulting from natural hybridisation between Criollo and Amelonado Forastero. Doubts persist on the source of the Amelonado Forastero involved in the origin of Trinitario; the Amelonado parent may have come from the Lower Amazon, the Orinoco or the Guyanas. Most of the cacao cultivated worldwide until 1950 consisted of Criollo, Trinitario and Amelonado. From the early 1950s, Forastero material collected in the Upper Amazon region during the 1930s and 1940s began to be employed in breeding programmes. To gain a better understanding of the origin and the genetic basis of the cacao cultivars exploited before the utilisation of germplasm collected in the Upper Amazon, a study was carried out using restriction fragment length polymorphism and microsatellite markers. Trinitario samples from 17 countries were analysed. With molecular markers, it was possible to clearly identify three main genotypes (represented by clones SP1, MAT1-6 and SIAL70) implicated in the origin of most Trinitario clones.

Cacao↗
PubMed1995

Determinants of the high-methionine trait in wild and exotic germplasm may have escaped selection during early cultivation of maize.

The 18 kDa high-methionine delta-class zein gene from maize has been cloned, and its regulation, structure, and map position studied. These studies have shown that (i) zein genes may also contain tryptophan and lysine codons, (ii) the 18 kDa and the related 10 kDa zein gene are coordinately regulated, but their products accumulate to different levels in a genotype-dependent manner, (iii) the duplication of delta-zein genes probably involved unequal crossing over, (iv) no copy correction in either direction has occurred from teosinte to modern corn, and (v) the duplication of of the 18 kDa zein gene probably occurred before the tetraploidization of a progenitor chromosome. The work shows that important nutritional quality determinants like the high-methionine seed proteins are abundant in several exotic and wild corn varieties and low in most of the inbreds screened. The lack of a selectable phenotype for such quality traits during initial domestication and breeding of corn would have eliminated cis and trans regulatory determinants from the germplasm used in modern corn breeding. Examples of the high-methionine delta-class zeins shown here may be generally applicable in explaining the low nutritional quality of most present-day corn grown.

Amino Acid Sequence↗
PubMed1997

Endosperm balance number manipulation for direct in vivo germplasm introgression to potato from a sexually isolated relative (Solanum commersonii Dun.).

Diploid (2n = 2x = 24) Solanum species with endosperm balance number (EBN) = 1 are sexually isolated from diploid 2EBN species and both tetraploid (2n = 4x = 48, 4EBN) and haploid (2n = 2x = 24, 2EBN) S. tuberosum Group Tuberosum. To sexually overcome these crossing barriers in the diploid species S. commersonii (1EBN), the manipulation of the EBN was accomplished by scaling up and down ploidy levels. Triploid F1 hybrids between an in vitro-doubled clone of S. commersonii (2n = 4x = 48, 2EBN) and diploid 2EBN clones were successfully used in 3x x 4x crosses with S. tuberosum Group Tuberosum, resulting in pentaploid/near pentaploid BC1 progenies. This provided evidence of 2n (3x) egg formation in the triploid female parents. Two selected BC1 pentaploid hybrids were successfully backcrossed both as male and as female parents with S. tuberosum Group Tuberosum. The somatic chromosome number varied greatly among the resulting BC2 progenies, which included hyperaneuploids, but also a number (4.8%) of 48-chromosome plants. The introgression of S. commersonii genomes was confirmed by the presence of S. commersonii-specific randomly amplified polymorphic DNA markers in the BC2 population analyzed. The results clearly demonstrate the feasibility of germplasm introgression from sexually isolated diploid 1EBN species into the 4x (4EBN) gene pool of the cultivated potato using sexual hybridization. Based on the amount and type of genetic variation generated, cumbersomeness, general applicability, costs, and other factors, it would be interesting to compare the approach reported here with other in vitro or in vivo, direct or indirect, approaches previously reported.

Journal Article↗
PubMed2005

Exploitation of wild Cicer reticulatum germplasm for resistance to Helicoverpa armigera.

In the absence of high levels of resistance to Helicoverpa armigera (Hübner) in the cultivated germplasm of chickpea, we evaluated accessions of Cicer spp. mostly Cicer reticulatum Ladzinsky, for resistance to this important pest. Under multichoice conditions in the field, 10 accessions showed lower leaf damage and lower numbers of eggs, larvae, or both of H. armigera. Of these, IG 69960, IG 72934, and IG 72936 showed significantly lower leaf feeding than the cultivated genotypes or other accessions at the vegetative and reproductive stages. Larval weight was lower or comparable with that on C. bijugum (IG 70019) and C. judaicum (IG 70032) in C. reticulatum accessions IG 72933, IG 72934, IG 72936, and IG 72953 at the seedling stage and on IG 69960 and IG 72934 at the flowering stage. The accessions showing resistance to H. armigera in the field and laboratory conditions were placed in different groups, indicating the presence of diversity in C. reticulatum accessions for resistance to this pest. Less than seven larvae survived on IG 70020, IG 72940, IG 72948, and IG 72949, and IG 72964 compared with 12 on ICC 506. Larval and total developmental periods were prolonged by 6-15 and 3-8 d, respectively, on C. reticultatum accessions compared with those on ICCC 37. Less than five larvae pupated on the C. reticulatum accessions (except IG 72958 and ICC 17163) compared with 11 in ICCC 37. Accessions showing lower leaf feeding and adverse effects on the survival and development can be used in increasing the levels and diversifying the basis of resistance to H. armigera in chickpea.

Animals↗
PubMed2006

Avian germplasm preservation: embryonic stem cells or primordial germ cells?

Presently, avian genetic resources are best maintained as living collections of birds. Unfortunately, these stocks have been under constant pressure to be destroyed because of the decline in the number of Poultry Science Departments and pressures to cut costs at land grant institutions. Cryopreservation of semen is often suggested as a means to bank avian germplasm. However, this is only applicable for single-gene traits and does not allow for full reconstitution of the genetics of the original line. Over the last 15 yr, advances in the manipulation of the early chick embryo, manipulation of primordial germ cells (PGC), and the culture of embryonic stem cells (ESC) suggests that cryopreservation of blastodermal cells, ESC, or PGC might offer a means to preserve the entire genome of highly selected, specialized stocks of poultry. Freezing each of these cell types is possible with varying degrees of efficiency. Similarly, the effectiveness of generating germ line chimeras using blastodermal cells, ESC, or PGC also varies greatly. Other factors that must be considered include the choice of the recipient lines to develop the germ line chimeras and the number of individuals needed to reconstitute the line. Finally, the low efficiency rate of reconstitution and the high cost associated with current technologies makes these approaches prohibitive. Significant challenges remain to be overcome before the entire genome of poultry stocks can be routinely cryoperserved and reconstituted.

Animals↗
PubMed2026

Large-Scale Genomic Analysis of Stripe Rust Resistance in Chinese Wheat Germplasm Using Multi-Environment Trial Data.

Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is a significant disease affecting global wheat crops and causing substantial economic losses. This study aimed to identify effective resistance genes by evaluating 120 common wheat accessions from diverse regions in China. These samples were tested with three Pst races at the seedling stage and with natural Pst inoculum at four field locations in three crop seasons. Genotypic data were collected through a Wheat55K iSelect single-nucleotide polymorphism array. The genome-wide association study identified 17 distinct loci linked to stripe rust response, accounting for 1.07 to 30.58% of the phenotypic variation across trials. These loci were distributed among three wheat genome groups: 2 in Group A, 10 in Group B, and 5 in Group D. Among these, eight loci overlapped with the reported stripe rust resistance genes or quantitative trait loci, while nine loci were novel and mainly distributed on chromosomes 2A, 6B, and 7D. This research enhances the understanding of genetic mechanisms underlying wheat stripe rust resistance and provides valuable germplasm resources for breeding new cultivars with enhanced disease resilience.

Puccinia striiformis f. sp. tritici↗
PubMed2005

Genetic diversity of loquat germplasm (Eriobotrya japonica (Thunb) Lindl) assessed by SSR markers.

Genetic relationships among 40 loquat (Eriobotrya japonica (Thunb) Lindl) accessions that originated from different countries and that are part of the germplasm collection of the Instituto Valenciano de Investigaciones Agrarias (IVIA) (Valencia, Spain) were evaluated using microsatellites. Thirty primer pairs flanking microsatellites previously identified in Malus x domestica (Borkh.) were assayed. Thirteen of them amplified polymorphic products and unambiguously distinguished 34 genotypes from the 40 accessions analyzed. Six accessions showing identical marker patterns were Spanish local varieties thought to have been derived from 'Algerie' by a mutational process very common in loquat species. A total of 39 alleles were detected in the population studied, with a mean value of 2.4 alleles per locus. The expected and observed heterozygosities were 0.46 and 51% on average, respectively, leading to a negative value of the Wright's fixation index (-0.20). The values of these parameters indicate a smaller degree of genetic diversity in the set of loquat accessions analyzed than in other members of the Rosaceae family. Unweighted pair-group method (UPGMA) cluster analysis, based on Nei's genetic distance, generally grouped genotypes according to their geographic origins and pedigrees. The high number of alleles and the high expected heterozygosity detected with SSR markers developed in Malus x domestica (Borkh.) make them a suitable tool for loquat cultivar identification, confirming microsatellite marker transportability among genera in the Rosaceae family.

Eriobotrya↗
PubMed2006

Evaluation of amplified fragment length polymorphism and simple sequence repeats for tomato germplasm fingerprinting: utility for grouping closely related traditional cultivars.

Cultivated tomato (Solanum lycopersicum L.) germplasm shows limited genetic variation. Many DNA marker systems have been used for genetic diversity studies in wild and cultivated tomatoes, but their usefulness for characterizing phenotypic differences among very closely related cultivars remains uncertain. We have used 19 selected simple sequence repeat (SSR) markers and 7 amplified fragment length polymorphism (AFLP) primer combinations to characterize 48 cultivars of tomato, mainly traditional cultivars from the south-east of Spain. The main types were Solanum lycopersicum L. 'Muchamiel', 'De la pera', and 'Moruno'. The robustness of the dendrograms and the discrimination power reached with each marker type were similar. Unique fingerprinting even of the most closely related tomato cultivars could be obtained using a combination of some SSR and AFLP markers. A better grouping of the 'Muchamiel' cultivars was observed with SSR markers, whereas the grouping of cultivars of 'De la pera' type was best achieved with AFLPs. However, both types of markers adequately grouped cultivars of the main types, confirming the utility of SSR and AFLP markers for the identification of traditional cultivars of tomato.

DNA Fingerprinting↗
PubMed2006

Genetic diversity of Crotalaria germplasm assessed through phylogenetic analysis of EST-SSR markers.

The genetic diversity of the genus Crotalaria is unknown even though many species in this genus are economically valuable. We report the first study in which polymorphic expressed sequence tag-simple sequence repeat (EST-SSR) markers derived from Medicago and soybean were used to assess the genetic diversity of the Crotalaria germplasm collection. This collection consisted of 26 accessions representing 4 morphologically characterized species. Phylogenetic analysis partitioned accessions into 4 main groups generally along species lines and revealed that 2 accessions were incorrectly identified as Crotalaria juncea and Crotalaria spectabilis instead of Crotalaria retusa. Morphological re-examination confirmed that these 2 accessions were misclassified during curation or conservation and were indeed C. retusa. Some amplicons from Crotalaria were sequenced and their sequences showed a high similarity (89% sequence identity) to Medicago truncatula from which the EST-SSR primers were designed; however, the SSRs were completely deleted in Crotalaria. Highly distinguishing markers or more sequences are required to further classify accessions within C. juncea.

Base Sequence↗
PubMed1992

Detection of polymorphic loci in Arachis germplasm using random amplified polymorphic DNAs.

The development of easily scoreable genetic markers in Arachis will facilitate the introgression of desirable traits from wild species into adapted germplasm. We have used random amplified polymorphic DNAs (RAPDs) to identify polymorphic molecular markers in a range of wild and cultivated Arachis species. From a total of sixty 10-mer oligonucleotide primers, 49 polymorphic loci were identified between cultivated A. hypogaea type (TMV-2) and a synthetic amphidiploid (B x C)2 created from a A. batizocoi and A. chacoense cross. The inheritance of polymorphic markers, both in the amphidiploid and in the F1 progeny in a TMV-2 x (B x C)2 cross, has also been demonstrated. The potential exploitation of RAPD markers in groundnut improvement programs is discussed.

Arachis↗
PubMed1994

The use of RAPD for identifying and classifying Musa germplasm.

Using the technique of random amplified polymorphic DNA (RAPD), we have identified 116 amplification products in Musa germplasm using nine primers. This has enabled us to identify RAPD markers that are specific to each of nine genotypes of Musa representing AA, AAA, AAB, ABB, and BB genomes. The pattern of variation observed following the application of multivariate analyses to the RAPDs banding data is very similar to the pattern of variation defined using morphological characters and used to assign Musa material into the different genome classes.

Base Sequence↗
PubMed1995

Analysis of genetic diversity in a sweetpotato (Ipomoea batatas) germplasm collection using DNA amplification fingerprinting.

A DNA amplification fingerprinting (DAF) approach was employed to develop individual-specific profiles and analyze genetic relationships among 73 plant introductions of sweetpotato (Ipomoea batatas (L.) Lam.) including unadapted lines from around the world and a few selected U.S.A. cultivars. Reliable and informative fingerprint profiles were obtained employing single octamer primers and Stoffel fragment Taq polymerase in the polymerase chain reaction, polyacrylamide-based vinyl polymer for electrophoresis, and silver staining to visualize the DNA. Using seven highly informative octamer primers, individual-specific DAF profiles were obtained for all accessions tested. The degree of polymorphism in the sweetpotato collection was very large, indicating a high level of genetic variability. Several accessions clustered together based on their geographic source. Most U.S.A. cultivars formed a separate cluster in the phenogram, while accessions from Papua New Guinea exhibited the highest genetic diversity. The wild species I. triloba and tetraploid I. batatas formed a group distinct from the cultivated sweetpotato. DAF appears to be useful in sweetpotato germplasm characterization and may be employed to identify duplicate accessions or for creation of core subsets. DAF data may also be useful for facilitating the selection of parents for a breeding program to ensure a broad genetic base.

Base Sequence↗