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181.
David M. Cole Timothy L. White P. K. R. Nair 《Genetic Resources and Crop Evolution》2007,54(1):189-204
Knowledge of the effects of farmer practices on population genetic parameters of peach palm (Bactris gasipaes Kunth) is relevant to the improvement and conservation of the palm’s genetic resources. Microsatellite markers were used
to assess genetic diversity and population structure of peach palm in swidden-fallow agroforestry systems in northeastern
Peru. The study covered eight communities, comprising two study areas 160 km apart – one occupied by indigenous Amerindians
and the other by mixed race campesinos. Simultaneous analysis of an ex situ peach palm germplasm collection provided a means to compare population genetic parameters. Farmers who were surveyed on seed
selection practices for peach palm reported that an average of only four palms (4.3 for campesino and 1.5 for indigenous populations)
were used to provide seed for the establishment of the forest gardens sampled. As expected, inbreeding coefficients observed
within communities were relatively high (f = 0.105 − 0.210), however, observed heterozygosities within communities were also high (0.625–0.741). A metapopulation approach
was used to describe migration within and among regions, implying a hierarchical structure of gene flow which maintains relatively
high levels of genetic diversity. Seed migration was found to occur over longer distances (≤600 km) and at a higher frequency
(46% of palms sampled) in the indigenous study area, and a proportionally greater number of alleles was found (49 vs. 43 over
three loci) with twice as many private alleles occurring only in the indigenous populations. The farmers’ practice of preserving
remnant palms through successive swidden generations may have contributed to the maintenance of alleles by reducing the severity
of founder effects. Although the campesino study area exhibited a significant (20% of the variation; p < 0.01) isolation-by-distance relationship across 35 km distance, in general, both study populations had relatively limited
genetic structure (θ = 0.012–0.03), which is believed to have resulted from the exchange of seeds over long distances and
periods of time. 相似文献
182.
Vinod Kumar Yadav Sandeep Kumar Ravindra K. Panwar 《Genetic Resources and Crop Evolution》2007,54(6):1285-1289
The present investigation was carried out on fifteen germplasm lines of Pisum sativum L. were used for characterization using Randomly Amplified Polymorphic DNA (RAPD) markers. While 12 random primers were taken,
out of them 11 primers gave amplification. These primers gave a total of 133 bands out of which 106 were polymorphic. Genetic
similarities of the RAPD profiles were estimated by using Jaccard’s coefficient with NTSYSpc 2.0 software. The similarity
index values ranged from 0.263 to 0.793 indicating the presence of enormous genetic diversity at molecular level. A dendrogram
generated by cluster analysis divided fifteen fieldpea genotypes into two Groups A and B. Major Group A have five genotypes
and major Group B have nine genotypes. 相似文献
183.
Background, Aim and Scope The distribution of sediments in estuarine beaches is controlled by the interactions between sediment supply, hydrodynamic
processes and human intervention. The main purpose of this study is to characterize the sediments of Tagus estuarine beaches
in order to understand their origin and to contribute to a better knowledge of the Tagus estuary sediment budget.
Methods Surface sediment samples were collected across beach profiles and sand grain size analysis was performed by dry sieving. Grain
size statistics for the median (d50) and standard deviation (SDM) were obtained using the Moment method. This study was complemented by a qualitative evaluation
of the sediment composition. Cross-shore topographic surveys were conducted for selected sampling sites.
Results Tagus estuarine beach sediments are mainly composed of quartz sand particles which are fine-grained and well sorted near the
mouth of the estuary and medium to coarse-grained and moderately sorted in the inner domain. Compositional results show evidence
of active anthropogenic sediment sources, especially in the coarser fractions.
Discussion The analysis of the textural and compositional characteristics of beach sediments in the inner estuarine domain is compatible
with local sedimentary sources, while a marine signature is present at the mouth and inlet channel sediments. In the inner
domain, differences in the sedimentary processes are represented by the textural characteristics of the sediments, such as
the sorting degree and the gravel content. Sediment characteristics also reflect human intervention in the system, with the
introduction of anthropogenic and allochthonous particles and the mixture of sediments from different sources.
Conclusions The sediments of the inner Tagus estuarine beaches are derived from local Plio-Pleistocene outcrops while inlet and outer
estuary beaches reveal a dominant marine source. Beach textural variability observed in the inner domain is not related to
wave forcing gradients, but mainly to variations in the sedimentary processes along the estuarine margins and to human intervention.
Results show that the Tagus estuarine beaches depended, almost exclusively, on sediment input from local sources until the
last century. With increasing human occupation, sediment transfers became dominated by anthropogenically related activities
mainly connected with the occupation of estuarine margins and dredging.
Recommendations and Perspectives Further studies should extend the present level of knowledge in what concerns sand transport patterns through additional compositional
and geochemical analysis, and the development of new techniques in order to allow the quantitative evaluation of the impact
of human activities on the sediment budget. 相似文献
184.
Plants of white clover (Trifolium repens L.) cultivar Crau, a self-fertile Crau genotype, and nine generations of inbred progeny were raised in sand culture in a
glasshouse experiment. Digital images of the root systems were made and root morphological characteristics were determined
on all the plants. Root architectural parameters were measured on the Crau parent and the S1, S4, S6, and S9 inbred lines. The clover roots became shorter and thicker with inbreeding but the number of root tips per plant was unchanged.
Root architecture (branching pattern) was largely unaffected by inbreeding. It is concluded that inbreeding white clover will
lead to shorter, thicker roots, and reduced nutrient uptake efficiency compared with the parent clover. The degree to which
these deleterious traits are overcome during the development of F1 hybrids needs to be determined. 相似文献
185.
A major factor affecting spring canola (Brassica napus) production in Canada is killing frosts during seedling development in the spring and seed maturation in the fall. The objective
of this study was to explore the possibility of producing spring canola lines with mutations that have altered biochemical
pathways that increase cold tolerance. The approach was to generate UV point mutations in cultured microspores followed by
chemical in vitro selection of individual mutant microspores or embryos resulting in measurable alterations to various biochemical
pathways with elevated levels of key defense signaling molecules such as, salicylic acid (SA), p-Fluoro-d,l-Phenyl Alanine (FPA), and jasmonic acid (JA). In addition, since proline (Pro) is known to protect plant tissues in the cold-induced
osmotic stress pathway, mutants that overproduce Pro were selected in vitro by using three Pro analogues: hydroxyproline (HP),
azetidine-2-carboxylate (A2C); and, 3,4-dehydro-d,l-proline (DP). Of the 329 in vitro selected mutant embryos produced, 74 were identified with significant cold tolerance compared
to their donor parents through indoor freezer tests at −6°C, and 19 had better winter field survival than winter canola checks. All chemically selected mutant doubled haploids with increased
cold tolerance compared well with parent lines for all seed quality and agronomic parameters. Development of increased frost
tolerant cultivars should allow for spring canola to be produced in western Canada without compromising seed quality. 相似文献
186.
Mun Sup Yoon Jeongran Lee Chang Yung Kim Jung Hoon Kang Eun Gi Cho Hyung Jin Baek 《Euphytica》2009,165(1):69-77
Approximately 7,000 accessions of Korean soybean (Glycine max (L.) Merrill) landraces, largely composed of three collections, the Korea Atomic Energy Research Institute’s soybean (KAS),
the Korean Crop Experiment Station’s soybean (KLS) and the Korean Agricultural Development and Technology Center’s soybean
(KADTC) collections, have been conserved at the Rural Development Administration (RDA) genebank in Korea. The accessions within
collections were classified based on their traditional uses such as sauce soybean (SA), sprouted soybean (SP), soybean for
cooking with rice (SCR), and OTHERS. A total of 2,758 accessions of Korean soybean landraces were used to profile and to evaluate
genetic structure using six SSR loci. A total of 110 alleles were revealed by at the six SSR loci. The number of alleles per
SSR locus ranged from 9 to 39 in Satt187 and Satt_074, respectively. The number of alleles ranged from 87 in the KADTC collection
to 96 in the KLS collection, and from 63 in the SCR group to 95 in the SP group. Nei’s average genetic diversity ranged from
0.68 to 0.70 across three collections, and 0.64 to 0.69 across the usage groups. The average between-group differentiation
(G
st) was 0.9 among collections, and 4.1 among the usage groups. The similar average diversity among three collections implies
that the genetic background of the three collections was quite similar or that there were a large number of duplicate accessions
in three collections. The selection from the four groups classified based upon usage may be a useful way to select accessions
for developing a Korean soybean landrace core collection at the RDA genebank. DNA profile information of accessions will provide
indications of redundancies or omissions and aid in managing the soybean collection held at the RDA genebank. The information
on diversity analysis could help to enlarge the genetic diversity of materials in breeding programs and could be used to develop
a core collection. 相似文献
187.
The mechanism that controls the proportion of cannabichromene (CBC), a potential pharmaceutical, in the cannabinoid fraction
of Cannabis sativa L. is explored. As with tetrahydrocannabinol (THC) and cannabidiol (CBD), CBC is an enzymatic conversion product of the precursor
cannabigerol (CBG). CBC is reported to dominate the cannabinoid fraction of juveniles and to decline with maturation. This
ontogeny was confirmed in inbred lines with different mature chemotypes. A consistent CBC presence was found in early leaves
from a diverse clone collection, suggesting that CBC synthase is encoded by a fixed locus. Morphological variants possessing
a ‘prolonged juvenile chemotype’ (PJC), a substantial proportion of CBC persisting up to maturity, are presented. PJC is associated
with a reduced presence of floral bracts, bracteoles, and capitate-stalked trichomes. Genetic factors causing these features
were independent of the allelic chemotype locus B that was previously postulated and regulates THC and CBD synthesis and CBG accumulation. In contrast to previously described
Cannabis chemotypes, the cannabinoid composition of PJCs showed plasticity in that reduced light levels increased the CBC proportion.
The ability of PJC plants to enable the production of pharmaceutical raw material with high CBC purity is demonstrated. 相似文献
188.
189.
Pronob J. Paul Srinivasan Samineni Sobhan B. Sajja Abhishek Rathore Roma R. Das Sushil K. Chaturvedi G. R. Lavanya Rajeev K. Varshney Pooran M. Gaur 《Euphytica》2018,214(2):27
Chickpea is the most important pulse crop globally after dry beans. Climate change and increased cropping intensity are forcing chickpea cultivation to relatively higher temperature environments. To assess the genetic variability and identify heat responsive traits, a set of 296 F8–9 recombinant inbred lines (RILs) of the cross ICC 4567 (heat sensitive) × ICC 15614 (heat tolerant) was evaluated under field conditions at ICRISAT, Patancheru, India. The experiment was conducted in an alpha lattice design with three replications during the summer seasons of 2013 and 2014 (heat stress environments, average temperature 35 °C and above), and post-rainy season of 2013 (non-stress environment, max. temperature below 30 °C). A two-fold variation for number of filled pods (FPod), total number of seeds (TS), harvest index (HI), percent pod setting (%PodSet) and grain yield (GY) was observed in the RILs under stress environments compared to non-stress environment. A yield penalty ranging from 22.26% (summer 2013) to 33.30% (summer 2014) was recorded in stress environments. Seed mass measured as 100-seed weight (HSW) was the least affected (6 and 7% reduction) trait, while %PodSet was the most affected (45.86 and 44.31% reduction) trait by high temperatures. Mixed model analysis of variance revealed a high genotypic coefficient of variation (GCV) (23.29–30.22%), phenotypic coefficient of variation (PCV) (25.69–32.44%) along with high heritability (80.89–86.89%) for FPod, TS, %PodSet and GY across the heat stress environments. Correlation studies (r = 0.61–0.97) and principal component analysis (PCA) revealed a strong positive association among the traits GY, FPod, VS and %PodSet under stress environments. Path analysis results showed that TS was the major direct and FPod was the major indirect contributors to GY under heat stress environments. Therefore, the traits that are good indicators of high grain yield under heat stress can be used in indirect selection for developing heat tolerant chickpea cultivars. Moreover, the presence of large genetic variation for heat tolerance in the population may provide an opportunity to use the RILs in future-heat tolerance breeding programme in chickpea. 相似文献
190.
Soil enzymes are linked to microbial functions and nutrient cycling in forest ecosystems and are considered sensitive to soil
disturbances. We investigated the effects of severe soil compaction and whole-tree harvesting plus forest floor removal (referred
to as FFR below, compared with stem-only harvesting) on available N, microbial biomass C (MBC), microbial biomass N (MBN),
and microbial biomass P (MBP), and dehydrogenase, protease, and phosphatase activities in the forest floor and 0–10 cm mineral
soil in a boreal aspen (Populus tremuloides Michx.) forest soil near Dawson Creek, British Columbia, Canada. In the forest floor, no soil compaction effects were observed
for any of the soil microbial or enzyme activity parameters measured. In the mineral soil, compaction reduced available N,
MBP, and acid phosphatase by 53, 47, and 48%, respectively, when forest floor was intact, and protease and alkaline phosphatase
activities by 28 and 27%, respectively, regardless of FFR. Forest floor removal reduced available P, MBC, MBN, and protease
and alkaline phosphatase activities by 38, 46, 49, 25, and 45%, respectively, regardless of soil compaction, and available
N, MBP, and acid phosphatase activity by 52, 50, and 39%, respectively, in the noncompacted soil. Neither soil compaction
nor FFR affected dehydrogenase activities. Reductions in microbial biomass and protease and phosphatase activities after compaction
and FFR likely led to the reduced N and P availabilities in the soil. Our results indicate that microbial biomass and enzyme
activities were sensitive to soil compaction and FFR and that such disturbances had negative consequences for forest soil
N and P cycling and fertility. 相似文献