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61.
The objective of this study was to identify molecular markers linked to fruit-related traits in the tomato subjected to high
temperatures. In total, 160 F2 plants derived from a cross between a heat-tolerant breeding line, CL5915-93D4-1-0-3 (Solanum esculentum), and a heat-sensitive wild accession, L4422 (S. pimpinellifolium), were grown in a greenhouse. Six traits including fruit number, fruit weight, brix, seed number, fruit setting, and flower
number were scored. The distributions of fruit number, fruit set, flower number, and seed number were skewed towards heat
susceptibility which is known to be characteristic of L4422. Polymorphic bands were generated by PCR-derived methods of RAPD,
ISSR and AFLP Polymorphism, the segregation ratio, and distribution over the genome of the above 3 markers were compared.
Ten linkage groups, ranging 20.6–151.6 cM in size, were constructed with 62 informative markers spanning a total of 776.3 cM.
Fruit-related quantitative trait loci (QTLs) were non-randomly distributed in the tomato genome. For the 6 traits investigated,
21 QTLs were dispersed on linkage groups 2–5. The genetic effects of the various QTLs were differently exhibited, in our study
we have respectively found from 10.5% to 30.2% of the variation explained by the QTL for flower number (FRN4) and brix (BX2).
Thirteen QTL-mapped markers were unique to 1 trait, and 4 markers were linked to more than 1 trait. Among them, QTLs linked
to the I868-470 marker had effects on fruit weight and brix, and a significant positive correlation between these 2 traits
was noted (r = 0.35, P < 0.05). Thus, the I868-470 marker may have the potential for simultaneous selection of high fruit weight and brix. These
markers also allowed us to align genome linkage maps across distantly related species and to reveal the co-localization between
these QTLs and major genes. 相似文献
62.
Bahiagrass (Paspalum notatum) is a warm-season grass used primarily in pastures and along highways and other low maintenance public areas in Florida.
It is also used in landscapes to some extent because of its drought tolerance. Bahiagrass can survive under a range of moisture
conditions from no irrigation to very wet conditions. Its well-watered consumptive use has not been reported previously. In
this study, bahiagrass crop coefficients (K
c) for an irrigated pasture were determined for July 2003 through December 2006 in central Florida. The eddy correlation method
was used to estimate crop evapotranspiration (ETc) rates. The standardized reference evapotranspiration (ETo) equation (ASCE-EWRI standardization of reference evapotranspiration task committee report, 2005) was applied to calculate
ETo values using on site weather data. Daily K
c values were estimated from the ratio of the measured ETc and the calculated ETo. The recommended K
c values for bahiagrass are 0.35 for January–February, 0.55 for March, 0.80 for April, 0.90 for May, 0.75 for June, 0.70 for
July–August, 0.75 for September, 0.70 for October, 0.60 for November, and 0.45 for December in central Florida. The highest
K
c value of 0.9 in May corresponded with maximum vapor pressure deficit conditions as well as cloud free conditions and the
highest incoming solar radiation as compared to the rest of the year. During the summer (June to August), frequent precipitation
events increased the cloud cover and reduced grass water use. The K
c annual trend was similar to estimated K
c values from another well-watered warm-season grass study in Florida. 相似文献
63.
Genetic variation of sweet potatoes (Ipomoea batatas L.) cultivated in Chile determined by RAPDs 总被引:1,自引:0,他引:1
Boris Sagredo Patricio Hinrichsen Horacio López Alberto Cubillos Carlos Muñoz 《Euphytica》1998,101(2):193-198
RAPD (randomly amplified polymorphic DNA) technology was applied to analyze the genetic variability of sweet potato germplasm
existing in Chile and elsewhere. Analysis of 28 cultivars from all over the world showed polymorphic bands with all 18 primers
tested. A total of 124 RAPD bands were scored with an average of 6.9 polymorphic bands per primer. These results confirm that
sweet potato exhibits high genetic variation. Two groups were distinguished: one containing Peruvian cultivars, and another
containing cultivars from the rest of the world. Analysis of 14 accessions from Central Chile and one from Northern Chile
showed polymorphic bands with 24 of 26 primers tested, but almost all of the 140 polymorphic bands merely showed the distinctness
of the Northern accession. The almost complete uniformity of the other 14 accessions shows that sweet potato germplasm collected
in Central Chile has very little genetic variability and may be derived from a single cultivar.
Based on these results and on historical records, some hypotheses are proposed to explain the origin of sweet potatoes cultivated
in Chile.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
64.
Isolated plant microspores, when stressed and cultured in vitro, can be diverted from their normal gametophytic pathway towards
sporophytic development, with the formation of haploid embryos and ultimately doubled-haploid plants. This process is called
androgenesis or microspore embryogenesis, and is widely used in plant breeding programmes to generate homozygous lines for
breeding purposes. Protocols for the induction of microspore embryogenesis and the subsequent regeneration of doubled haploid
(DH) plants have been successfully developed for more than 200 species. These practical advances stand in stark contrast to
our knowledge of the underlying molecular genetic mechanism controlling this process. The majority of information regarding
the genetic and molecular control of the developmental switch from gametophytic to sporophytic development has been garnered
from four intensely studied (crop) plants comprising two dicotyledonous species, rapeseed (Brassica napus) and tobacco (Nicotiana tabacum), and two monocotyledonous species, wheat (Triticum aestivum) and barley (Hordeum vulgare). In these species the efficiency of microspore embryogenesis is very high and reproducible, making them suitable models
for molecular studies. In the past, molecular studies on microspore embryogenesis have focussed mainly on the identification
of genes that are differentially expressed during this developmental transition and/or early in embryo development, and have
identified a number of genes whose expression marks or predicts the developmental fate of stressed microspores. More recently,
functional genomics approaches have been used to obtain a broad overview of the molecular processes that take place during
the establishment of microspore embryogenesis. In this review we summarise accumulated molecular data obtained in rapeseed,
tobacco, wheat and barley on embryogenic induction of microspores and define common aspects involved in the androgenic switch. 相似文献
65.
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
66.
Tartary buckwheat (Fagopyrum tataricum) is a highly nutritious crop that is widely grown in Asia, but the flour contains a large portion of the hull if it is ground
with industrial processing since the hull is very hard to remove as it adheres to the testa layer of the groat. Rice-Tartary,
a particular type of Tartary buckwheat, has seeds with a loose hull and the presence of splits on the sides of the seeds that
make dehulling easily. The present study reports on the first attempt of crop improvement in Tartary buckwheat breeding through
hybridization. Hybrids were obtained by hybridization of crosses between Tartary buckwheat and Rice-Tartary. Additional crosses
were made among selected progenies of these crosses. Based on progeny analysis of the F1, F2, and F3, the character of Rice-Tartary, as exhibited as the presence of splits on the sides of the seeds, is controlled by one gene
which is homozygous recessive. A Tartary buckwheat breeding program has been conducted for 6 years based on these crosses.
Advanced lines with easy dehull and yield potential are at the stage of ready for yield trials. Production of easy dehulling
Tartary buckwheat in the future could boost Canada’s domestic and international markets. 相似文献
67.
The height-reducing gene Rht8 was introduced into Italian wheats by breeder Nazareno Strampelli from the Japanese landrace Akakomugi, and has been widely
used in wheats adapted to southern and eastern European conditions. Following identification of a close linkage to Rht8, microsatellite marker Gwm261 has been used extensively to screen large numbers of diverse international germplasm. A 192bp allele at this locus has been
taken as “diagnostic” for Rht8 and used to infer the international distribution of Rht8. In this paper, we report several instances of cultivars and mapping populations that vary for the presence of the 192bp
allele at the Xgwm261 locus (Xgwm261
192
), but with no associated reduction in height, suggesting a lack of association with Rht8. For instance, in the population derived from a cross between Sunco (Rht-B1b, Xgwm261
165
) and Tasman (Rht-D1b, Xgwm261
192
), there were significant height differences associated with the segregation of Rht-B1b and Rht-D1b, but no height differences between Xgwm261 genotypes. Similar results were obtained in a population derived from the cross between Molineux (Rht-B1b, Xgwm261
192
) and Trident (Rht-D1b Xgwm261
208
). In contrast, the cross between Trident and Chuanmai 18 (Xgwm261
192
) gave significant height effects at both the Rht-D1 and Xgwm261 loci, with no epistatic interaction between loci. Chuanmai 18 is closely related to the Strampelli wheat Mara (ancestrally
derived from Akakomugi) and is therefore likely to carry Rht8. The old Japanese cultivar Norin 10, used by Norman Borlaug to introduce Rht-B1b and Rht-D1b into Mexican wheats, also has a 192bp allele at the Xgwm261 locus, and the sequence of the amplified product is identical to that of Akakomugi. We suggest that the widespread use of
Norin 10-derived germplasm during and after the Green Revolution introduced a second haplotype into international germplasm,
in which Xgwm261
192
has no association with Rht8. Therefore, the presence of Xgwm261
192
is only indicative of Rht8 in wheat cultivars that have inherited this allele from Akakomugi or a Strampelli wheat ancestor. 相似文献
68.
Lifang Liu Qianli Wang Longdi Cheng Jingfang Qian Jianyong Yu 《Fibers and Polymers》2011,12(1):95-103
Natural bamboo fibers have excellent properties suggesting that there is a good potential for them to be used in textiles;
however, they have not received the attention that they deserve owing to their coarse and stiff quality. Therefore, a chemical
method for extraction and modification of natural bamboo fibers for textile end uses were developed and optimized in this
paper. The quality of natural bamboo fibers were characterized by their chemical composition, linear density, and tenacity.
Experimental results show that the modified bamboo fibers are finer, with significant lower content of noncellulosic substances.
The processing parameters are optimized as: 20 g/l NaOH, 3 g/l Na5P3O10, 5 g/l Na2SO3, 3 g/l penetrating agent, with a fiber to liquid ratio of 1:10, at 100 °C for 2 h, and the bamboo fiber thus produced has cellulose
amount of 73.25 %, fineness of 3.26 tex, average length of 44.5 mm, breaking elongation of 2.8 % and tenacity of 2.41 cN/dtex.
The result of this study may offer a possibility of developing natural bamboo fibers into practical applications in textiles. 相似文献
69.
This study analyzes how the silhouette of virtual garments applied to virtual avatars is altered according to various virtual
fabric properties. This study measures the properties of real fabrics that include a charmeuse (#F1) and gabardine (#F2) using
the Fabric Analysis by Simple Testing system; in addition, the material properties of different real fabrics were applied
to that of the virtual fabric. It then evaluates the drape stiffness and silhouette of the virtual garments according to the
different fabrics. This study also compared the virtual garment silhouette of sample fabric #F1-S that changed only the stretch
property of the sample fabric #F1 with the virtual garment silhouette of sample fabric #F1. The results show that the fabric
properties including bend, thickness, weight, stretch, shear values affect the drape stiffness, silhouette, and fit of the
virtual garment simulated on virtual avatars and may be used for the realistic virtual garment technology. 相似文献
70.
This study developed a novel PHB-lignin-jute biodegradable composite with preferable mechanical properties and low water absorption.
The appearances of fracture surface of composites were analyzed by scanning electron microscope. The result suggested a Gaussian-like
distribution of the size particles supporting the presence of lignin with a radius smaller than 0.5 μm. According to X-ray
diffraction, the presence of lignin and jute fibers was decreased the crystallization of PHB. Moreover, the glass transition
temperature of PHB increased, and the endotherm during glass transition was decreased. The maximum tensile strength and modulus
of composites were obtained with 30 wt% jute fiber contents and 4 wt% lignin contents. The presence of jute fibers was largely
increased the water absorption of composites. However, the presence of lignin was effectively decreased the water absorption
of composites at saturation levels. 相似文献