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621.
CARRIE S. THURBER MICHAEL REAGON BRIANA L. GROSS KENNETH M. OLSEN YULIN JIA ANA L. CAICEDO 《Molecular ecology》2010,19(16):3271-3284
Cultivated rice fields worldwide are plagued with weedy rice, a conspecific weed of cultivated rice (Oryza sativa L.). The persistence of weedy rice has been attributed, in part, to its ability to shatter (disperse) seed prior to crop harvesting. In the United States, separately evolved weedy rice groups have been shown to share genomic identity with exotic domesticated cultivars. Here, we investigate the shattering phenotype in a collection of U.S. weedy rice accessions, as well as wild and cultivated relatives. We find that all U.S. weedy rice groups shatter seeds easily, despite multiple origins, and in contrast to a decrease in shattering ability seen in cultivated groups. We assessed allelic identity and diversity at the major shattering locus, sh4, in weedy rice; we find that all cultivated and weedy rice, regardless of population, share similar haplotypes at sh4, and all contain a single derived mutation associated with decreased seed shattering. Our data constitute the strongest evidence to date of an evolution of weeds from domesticated backgrounds. The combination of a shared cultivar sh4 allele and a highly shattering phenotype, suggests that U.S. weedy rice have re‐acquired the shattering trait after divergence from their progenitors through alternative genetic mechanisms. 相似文献
622.
ANA M. IBARRA JESSICA L. PETERSEN THOMAS R. FAMULA BERNIE MAY 《Molecular ecology resources》2006,6(1):153-156
Four microsatellite‐enriched DNA libraries yielded 35 microsatellite loci from 100 primer pairs designed for Pacific lion‐paw scallop, Nodipecten subnodosus. The number of alleles ranged from four to 28. Three of the 35 loci were not in Hardy–Weinberg equilibrium and linkage disequilibrium was found for one pair of loci. These microsatellites will be used to analyse the population structure of the species in Mexico's Baja Peninsula to propose management strategies for scallop aquaculture development. Twenty‐six primer pairs cross‐amplified in Nodipecten nodosus, whereas none (Argopecten ventricosus) or few cross‐amplified in the Argopecten species. 相似文献
623.
ARGERICH COSME A; BRADFORD KENT J; TARQUIS ANA M. 《Journal of experimental botany》1989,40(5):593-598
The influence of seed priming and ageing treatments on viabilityand rate of germination of tomato (Lycopersicon esculentum Mill.)seeds was examined under both long-term and controlled-deteriorationstorage conditions. Seeds of a single lot of tomato were eitherprimed or aged to increase or decrease the rate of germination(Argerich and Bradford, 1989). They were then stored at 6% moisturecontent (dry weight basis) at either 4 ?C or 30 ?C for 1 year.Both viability and germination rate were unaffected by eitherstorage temperature in control seeds, or by 4 ?C storage inprimed or aged seeds. At 30 ?C, however, viability and germinationrate of primed and aged seeds was markedly reduced after 6 monthsof storage. The temperature dependence of the germination rateand the spread of germination times within the population wasalso adversely affected by high temperature storage, particularlyfor primed seeds. Under controlled deterioration conditions(13.5% moisture content and 50 ?C), the rate of loss of viabilitywas greater for primed seed than for control or aged seeds.The relationship between seed viability and the mean germinationrate, however, was not influenced by the seed treatments. Thesedata are analysed in relation to current models of seed deteriorationduring storage and seed repair during priming. The results indicatethat enhancement of seed germination rates by priming treatmentssimultaneously lowers the resistance of seeds to deterioration.Primed tomato seeds must, therefore, be considered to be vigorousseeds with a reduced storage life. Key words: Tomato, controlled deterioration, seed germination rate, seed viability 相似文献
624.
ROBIN ENGLER CHRISTOPHE F. RANDIN WILFRIED THUILLER STEFAN DULLINGER NIKLAUS E. ZIMMERMANN MIGUEL B. ARAÚJO PETER B. PEARMAN GWENAËLLE LE LAY CHRISTIAN PIEDALLU CÉCILE H. ALBERT PHILIPPE CHOLER GHEORGHE COLDEA XAVIER
De LAMO THOMAS DIRNBÖCK JEAN‐CLAUDE GÉGOUT DANIEL GÓMEZ‐GARCÍA JOHN‐ARVID GRYTNES EINAR HEEGAARD FRIDE HØISTAD DAVID NOGUÉS‐BRAVO SIGNE NORMAND MIHAI PUŞCAŞ MARIA‐TERESA SEBASTIÀ ANGELA STANISCI JEAN‐PAUL THEURILLAT MANDAR R. TRIVEDI PASCAL VITTOZ ANTOINE GUISAN 《Global Change Biology》2011,17(7):2330-2341
Continental‐scale assessments of 21st century global impacts of climate change on biodiversity have forecasted range contractions for many species. These coarse resolution studies are, however, of limited relevance for projecting risks to biodiversity in mountain systems, where pronounced microclimatic variation could allow species to persist locally, and are ill‐suited for assessment of species‐specific threat in particular regions. Here, we assess the impacts of climate change on 2632 plant species across all major European mountain ranges, using high‐resolution (ca. 100 m) species samples and data expressing four future climate scenarios. Projected habitat loss is greater for species distributed at higher elevations; depending on the climate scenario, we find 36–55% of alpine species, 31–51% of subalpine species and 19–46% of montane species lose more than 80% of their suitable habitat by 2070–2100. While our high‐resolution analyses consistently indicate marked levels of threat to cold‐adapted mountain florae across Europe, they also reveal unequal distribution of this threat across the various mountain ranges. Impacts on florae from regions projected to undergo increased warming accompanied by decreased precipitation, such as the Pyrenees and the Eastern Austrian Alps, will likely be greater than on florae in regions where the increase in temperature is less pronounced and rainfall increases concomitantly, such as in the Norwegian Scandes and the Scottish Highlands. This suggests that change in precipitation, not only warming, plays an important role in determining the potential impacts of climate change on vegetation. 相似文献
625.
A new Swartzia (Leguminosae: Papilionoideae: Swartzieae) species with trimorphic stamens from Amazonian Brazil 总被引:1,自引:0,他引:1
VIDAL DE FREITAS MANSANO ANA LUCIA DE SOUZA 《Botanical journal of the Linnean Society. Linnean Society of London》2005,147(2):235-238
A new species Swartzia trimorphica Mansano & A. L. Souza (Leguminosae, Papilionoideae, Swartzieae) from the Amazonian Brazil, is described and illustrated. The new species is notable and distinct from all the other species of Swartzia by its highly unusual trimorphic stamens, while the other species have either an isomorphic or a dimorphic androecium. The new species is included in the section and subsection Swartzia , ser. Orthostylae based on its bracteolate pedicels, the cauligerous inflorescences, lateral style and the relative size of the ovary compared to the style. The atypically small gynoecium in the material suggests the possibility that flowers may be functionally unisexual. Field observations and more collections are needed to resolve this question. © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 147 , 235–238. 相似文献
626.
JØRGEN A. MØLMANN DANIEL K.A. ASANTE JOHN B. JENSEN MARIA N. KRANE ARILD ERNSTSEN OLAVI JUNTTILA & JORUNN E. OLSEN 《Plant, cell & environment》2005,28(12):1579-1588
Juvenile trees of temperate and boreal regions cease growth and set buds in autumn in response to short day-lengths (SD) detected by phytochrome. Growth cessation and bud set are prerequisites for the development of winter dormancy and full cold hardiness. In this study we show that the SD-requirement for bud set and cold hardening can be overcome in hybrid aspen (Populus tremula L. × tremuloides Michx.) by low night temperature and inhibition of gibberellin (GA) biosynthesis. Bud set and increased cold hardiness were observed under normally non-inductive long day-length (LD) in wild-type plants, when exposed to low night temperature and paclobutrazol. In addition, the effect of PHYA overexpression could be overcome in transgenic plants, producing bud set and cold acclimation by treatment with: SD, low night temperature and paclobutrazol. After cold acclimation, the degree of bud dormancy was lower for wild-type plants prior treated with LD and transgenic plants (overexpressing PHYA), than SD-treated, wild-type plants. Thus, low night temperature in combination with reduced GA content induced bud set and promoted cold hardiness under normally non-inductive photoperiods in hybrid aspen, but was unable to affect development of dormancy. This might suggest separate signalling pathways from phytochrome regulating the induction of cold/cold hardiness and bud dormancy in hybrid aspen or alternatively, there might be one pathway that fails to complete its action in the transgenic and paclobutrazol treated plants. 相似文献
627.
The intergenic spacer of the ribosomal DNA is highly variable, but is location specific in the nucleolar organizer region
of the chromosomes. This study provides an event of high level of polymorphism / size variation and occurrence of 14 unique
phenotypes in 48 landraces of Portuguese bread wheat cultivars for IGS-amplified products obtained by PCR-RFLP technique performed
with TaqI. The attendant IGS polymorphism has been used to deduce affinities between landraces. Some of the high molecular weight
IGS allelic variants were also probed for their chromosomal localization by sequential silver nitrate staining and fluorescence
in situ hybridization. However, only the intergenic spacer allelic variant of 3.1 kb could be successfully hybridized, and was observed
to be physically located on the chromosome pair 1B in the NOR loci of the cultivar ‘Magueija’. 相似文献
628.
PATRIZIA TRIFILÒ FABIO RAIMONDO MARIA A. LO GULLO PIERA M. BARBERA SEBASTIANO SALLEO ANDREA NARDINI 《Plant, cell & environment》2014,37(11):2491-2499
Diurnal changes in percentage loss of hydraulic conductivity (PLC), with recorded values being higher at midday than on the following morning, have been interpreted as evidence for the occurrence of cycles of xylem conduits' embolism and repair. Recent reports have suggested that diurnal PLC changes might arise as a consequence of an experimental artefact, that is, air entry into xylem conduits upon cutting stems, even if under water, while under substantial tension generated by transpiration. Rehydration procedures prior to hydraulic measurements have been recommended to avoid this artefact. In the present study, we show that xylem rehydration prior to hydraulic measurements might favour xylem refilling and embolism repair, thus leading to PLC values erroneously lower than those actually experienced by transpiring plants. When xylem tension relaxation procedures were performed on stems where refilling mechanisms had been previously inhibited by mechanical (girdling) or chemical (orthovanadate) treatment, PLC values measured in stems cut under native tension were the same as those measured after sample rehydration/relaxation. Our data call for renewed attention to the procedures of sample collection in the field and transport to the laboratory, and suggest that girdling might be a recommendable treatment prior to sample collection for PLC measurements. 相似文献
629.
ANA PREVII CATHERINE WALTON† MLADEN KUINI PETAR T. MITRIKESKI MLADEN KEROVEC 《Molecular ecology》2009,18(4):634-647
The Balkan Peninsula is one of three major European refugial areas. It has high biodiversity and endemism, but data on the age and origin of its fauna, especially endemics, are limited. Mitochondrial sequence data (COI and 16S genes) were used to study the population structure and phylogeography of the caddisfly Drusus croaticus and the phylogeny and divergence of seven other Drusus species, mostly range-restricted endemics of the Dinaric region of the Balkan Peninsula. The divergence of D. croaticus populations in Croatia and allopatric Drusus species in Bosnia dated to the Pleistocene, showing the importance of this time period for the origin and diversification of Balkan endemic taxa. The divergence of more distantly related species dated to the Late Miocene/Early Pliocene. Population genetic and phylogeographic analysis of 115 individuals from 11 populations of D. croaticus revealed a high level of genetic differentiation and absence of gene flow between populations separated by more than 10 km. The existence of allopatrically fragmented lineages in D. croaticus and the endemic Bosnian species is most likely the result of long-term isolation in multiple microrefugia, probably due to the specific habitat requirements and life-history traits of Drusinae coupled with the topographic complexity and historical changes in geomorphology of the region. Overall, these findings shed light on the processes generating the high genetic complexity of this refugial region that parallels the 'refugia within refugia' pattern widely reported from the Iberian refugium. 相似文献
630.