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1.
A. Mejía-Jiménez C. Muñoz H. J. Jacobsen W. M. Roca S. P. Singh 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1994,88(3-4):324-331
Cultivated common bean (Phaseolus vulgaris L.) and tepary bean (Phaseolus acutifolius A. Gray) genotypes possessing desirable agronomic traits were hybridized. The F1 hybrids were backcrossed twice with the common bean (i.e., recurrent backcrossing). Also, alternate backcrosses with common and tepary beans (i.e., congruity backcrossing) were carried out. Embryo culture was necessary for all initial interspecific crosses, and its requirement was proportionally lower when the common bean was used as the recurrent parent and as the last parent of congruity backcrosses. Modification of the embryo culture technique was necessary to produce congruity hybrids. Effects of both tepary and common bean genotypes on the success rate of hybridization were observed. Tepary accession G 40001 and common bean cultivar ICA Pijao facilitated interspecies hybridization. Growth of hybrid embryos before rescue, recovery of mature hybrid plants, and the vigor and fertility of F1 hybrids all increased with increased recurrent and congruity backcrosses and intermatings between male-sterile F1 and selected fertile F2 plants of the third and fifth congruity backcrosses. Introgression of tepary genes was verified by means of seed protein electrophoretic analysis and morphological markers. The results suggest that congruity backcrossing can help to gradually reduce or overcome P. vulgaris x P. acutifolius hybridization barriers such as genotype incompatibility, early embryo abortion, hybrid sterility, and lower frequencies of hybridization. 相似文献
2.
Yanhao Xu Xiao-Qi Zhang Stefan Harasymow Sharon Westcott Wenying Zhang Chengdao Li 《Molecular breeding : new strategies in plant improvement》2018,38(5):63
Molecular marker-assisted backcrossing (MABC) is widely recommended for transferring favorable alleles from a donor to an elite variety. The question remains whether MABC is an effective approach to developing a competitive commercial variety. Here, we illustrate the transfer of a thermostable β-amylase allele Sd3 from wild barley into a commercial barley variety Gairdner. The elite lines were chosen for the Regional Crop Variety Test that followed a standard conventional breeding process. The results demonstrated that the Sd3 allele not only increased enzyme thermostability but dramatically enhanced diastatic power, an important malting quality trait. The BC1F1 individuals had a fundamental impact on the comprehensive agronomic and quality traits of the final progenies, demonstrating the importance of screening at the early stage of backcrossing in MABC. There was sufficient genetic variation in the BC3F3 families to select other malting quality and agronomic traits. Ten individual breeding lines with improved β-amylase thermostability also had improved yields and grain plumpness. Three elite lines with improved malting quality and agronomic traits were selected to provide a parental line to incorporate the wild barley allele for breeding a commercial variety. A new strategy should be considered that uses marker-assisted selection and backcrossing to transfer a favorable allele from a wild parent. 相似文献
3.
Summary An attempt was made to transfer the T-DNA of Agrobacterium tumefaciens, previously introduced into plant cells, via protoplast fusion from one species into another. For the experiments two cell lines were used: firstly, a Nicotiana paniculata cell line transformed with the Agrobacterium strain B6S3. This cell line exhibits both hormone independent growth and synthesis of octopine as a result of the incorporated T-DNA from Agrobacterium. These two markers are dominant. The second cell line was the nitrate reductase deficient cnx-68 cell line of N. tabacum which contains an intracellular calcium oxalate druse. These two markers are recessive. Isolated protoplasts of the donor cell line N. paniculata B6S3 were mitotically inactivated by X rays and fused with protoplasts of the cell line cnx-68. Asymmetric somatic hybrids were selected on hormone free agar medium supplemented with 50 mM KClO3. This compound is toxic for cells possessing nitrate reductase activity. From about 1.1×107 cultivated protoplasts 18 cell lines survived the selection treatment. Of these seven exhibited the two dominant and the two recessive markers, whereas the others showed either only one or none of the recessive or only one of the dominant markers. In dot-blot experiments using species specific DNA clones of the donor and the recipient plant species it was confirmed that besides the T-DNA other nuclear genomic DNA of the donor species had also been transferred in various amounts. The possible consequences of these results for plant breeding programmes are discussed. 相似文献
4.
Qiu YC Zhou RH Kong XY Zhang SS Jia JZ 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2005,111(8):1524-1531
A powdery mildew resistance gene from Triticum urartu Tum. accession UR206 was successfully transferred into hexaploid wheat (Triticum aestivum L.) through crossing and backcrossing. The F1 plants, which had 28 chromosomes and an average of 5.32 bivalents and 17.36 univalents in meiotic pollen mother cells (PMC),
were obtained through embryos rescued owing to shriveling of endosperm in hybrid seed of cross Chinese Spring (CS) × UR206.
Hybrid seeds were produced through backcrossing F1 with common wheat parents. The derivative lines had normal chromosome numbers and powdery mildew resistance similar to the
donor UR206, indicating that the powdery mildew resistance gene originating from T. urartu accession UR206 was successfully transferred and expressed in a hexaploid wheat background. Genetic analysis indicated that
a single dominant gene controlled the powdery mildew resistance at the seedling stage. To map and tag the powdery mildew resistance
gene, 143 F2 individuals derived from a cross UR206 × UR203 were used to construct a linkage map. The resistant gene was mapped on the
chromosome 7AL based on the mapped microsatellite makers. The map spanned 52.1 cM and the order of these microsatellite loci
agreed well with the established microsatellite map of chromosome arm 7AL. The resistance gene was flanked by the microsatellite
loci Xwmc273 and Xpsp3003, with the genetic distances of 2.2 cM and 3.8 cM, respectively. On the basis of the origin and chromosomal location of the
gene, it was temporarily designated PmU. 相似文献
5.
Novy RG Gillen AM Whitworth JL 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2007,114(7):1161-1172
Potato virus Y (PVY) and potato leafroll virus (PLRV) are two of the most important viral pathogens of potato. Infection of
potato by these viruses results in losses of yield and quality in commercial production and in the rejection of seed in certification
programs. Host plant resistance to these two viruses was identified in the backcross progeny of a Solanum etuberosum Lindl. somatic hybrid. Multiple years of field evaluations with high-virus inoculum and aphid populations have shown the
PVY and PLRV resistances of S. etuberosum to be stably expressed in two generations of progeny. However, while PLRV resistance was transmitted and expressed in the
third generation of backcrossing to cultivated potato (Solanum tuberosum L. subsp. tuberosum), PVY resistance was lost. PLRV resistance appears to be monogenic based on the inheritance of resistance in a BC3 population. Data from a previous evaluation of the BC2 progeny used in this study provides evidence that PLRV resistance was partly conferred by reduced PLRV accumulation in foliage.
The field and grafting data presented in this study suggests that resistance to the systemic spread of PLRV from infected
foliage to tubers also contributes to the observed resistance from S. etuberosum. The PLRV resistance contributed by S. etuberosum is stably transmitted and expressed through sexual generations and therefore would be useful to potato breeders for the development
of PLRV resistant potato cultivars. 相似文献
6.
为阐明黄土丘陵区氮磷添加对草地群落优势种养分利用特征的影响,探究群落结构和物种多样性的变化机制,选取5个典型优势种,即白羊草(Bothriochloa ischaemum)、长芒草(Stipa bungeana)、达乌里胡枝子(Lespedeza davurica)、铁杆蒿(Artemisia sacrorum)和猪毛蒿(Artemisia scoparia)为研究对象,采用裂区试验设计,以氮添加为主区处理, 包括:0(N0)、25(N25)、50(N50) 和100(N100) kg N hm-2 a-1;以磷添加为副区处理,包括:0(P0),20(P20),40(P40) 和80(P80) kg P2O5 hm-2 a-1,测定了各物种叶片氮磷比、氮磷重吸收效率、氮磷利用效率和相对生物量等参数。5种植物的氮和磷重吸收效率正相关,对氮磷添加量的响应具有耦合性。不同氮磷添加处理下,达乌里胡枝子叶片氮磷比最高,而氮磷重吸收效率最低;白羊草和长芒草的氮磷利用效率和重吸收效率高于其他物种。单施磷或N25与磷配施下,各物种相对生物量与氮磷比和磷利用效率呈正相关关系,与氮利用效率和氮磷重吸收效率呈负相关关系。单施氮、N50和N100与磷配施下,各物种相对生物量与氮磷利用效率和重吸收效率呈正相关,与氮磷比呈负相关。不施肥处理下,白羊草和长芒草相对生物量最高,低氮高磷下达乌里胡枝子相对生物量最高,高氮高磷下铁杆蒿和猪毛蒿相对生物量最高。不同优势种对氮磷添加的响应不同,生理生态过程各异,决定了其在群落中的优势度,这是氮磷添加后草地群落结构和物种多样性发生变化的关键机制。 相似文献
7.
S. Ayadi C. Karmous Z. Chamekh Z. Hammami M. Baraket S. Esposito S. Rezgui Y. Trifa 《The Annals of applied biology》2016,168(2):264-273
Durum wheat is an important staple food crop in Tunisia and other Mediterranean countries and is grown in various climatic conditions. Production and yield are however severely limited not only by drought events but also by reduced levels of nitrogen fertilisation. A study was carried out at two locations in the sub‐humid area of Tunisia: Mateur in 2009–10 and 2010–11 and Beja in 2011–12 and 2012–13 under rainfed conditions. Four durum wheat genotypes (landraces: Bidi, Azizi; improved: Om Rabia, Khiar) were evaluated for nitrogen agronomic efficiency and related agronomic traits under various nitrogen rates: 0, 50, 100, 150, 200 and 250 kg N ha?1, with three replications. There was a significant interaction effect (P ≤ 0.001) environments × genotypes × N treatments for grain yield (GY), biomass yield (BY), harvest index (HI), partial factor productivity of applied nitrogen (PFPN) and nitrogen agronomic use efficiencies (NAE). GY was the most affected trait by nitrogen applied showing an increase of 94% under high N treatment (250 kg N ha?1) compared to control plots without N treatments. A significant linear regression exists between GY (0 N) and GY for the different N rates (r = 0.70; P < 0.001). This effect was more pronounced for improved genotypes than landraces for all parameters excepting BY and NAEBY. BY showed +11% increase in landraces than improved genotypes. PFPN showed an average decrease of 65% under high‐N fertilisation with 10% prevalence for improved genotypes. Landraces tend to promote vegetative growth while grain filling efficiency was higher for improved genotypes. 相似文献
8.
Elkonin LA 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2005,111(7):1377-1384
Occurrence of genetic instability and formation of stable mutations are basic genetic processes. This study demonstrates that
nuclear background may influence the formation of stable dominant nuclear gene of male sterility (MS) on the basis of unstable
mutation, which was induced in tissue culture of the sorghum haploid (cv. Milo-145). The mutants with complete or partial
MS segregated in variable ratios in the progenies of diploid regenerants were obtained from different experiments on cultivation
of haploid tissues. In the Milo-145 genetic background the mutation demonstrated somatic instability and was gradually eliminated
by self-pollination of partially sterile plants. Hybridization of the MS-plants with the sorghum line SK-723, a fertility-restorer
of the cytoplasmic MS A1 (milo) type, maintained the induced mutation. By repeated backcrossing of MS-plants with SK-723, the male-sterile versions of this
line (SK-723- Ms
tc
) have been created. In BC-generations, fertile, partially and completely sterile plants were observed. The MS-plants from
BC-generations are proposed to contain a dominant gene Ms
tc
while fertile plants were ms
tc
/ ms
tc
homozygotes. Crossing the original MS-plants with SK-723 was a key factor in stabilization of the Ms
tc
gene. Dominant expression of the Ms
tc
was observed in male-sterile versions of other sorghum lines created by backcrossing to SK-723- Ms
tc
. The lines fertility-restorers for this mutation have been revealed. In the crosses of restored F1 hybrids with emasculated plants of the non-restoring line, the Ms
tc
has been transferred through the pollen and manifested in the F1 generation. The possibility of the Ms
tc
originating as a result of interaction of an unstable allele of the Milo-145 with the SK-723 genome is discussed. 相似文献
9.
Archna Suman A. K. Shrivastava Asha Gaur Pushpa Singh J. Singh R. L. Yadav 《Plant Growth Regulation》2008,54(1):1-11
The nitrogen fixing bacterial endophytes Gluconacetobacter diazotrophicus and Herbaspirillum spp. have been proposed to benefit sugarcane (Saccaharum spp. hybrids) growth. Variable populations of these endophytes exist depending upon ontogenic and climatic variations as
well. This study investigates the effect of variable chemical nitrogen application in soil on the population of endophytic
diazotrophs, acetylene reduction ability of excised roots, plant N-nutrient use efficiency and probable interactions among
different parameters in eight commercial sugarcane varieties of subtropical India. Recovery efficiency (RE), agronomic efficiency
(AE), partial factor productivity (PFP) and physiologic efficiency (PE) indicators were used for accounting N-nutrient use
efficiency. The population of G. diazotrophicus was more at N75 compared to N0 and N150, whereas Herbaspirillum population increased from N0 to N150. ARA was positively correlated with Gluconacetobacter population in rhizosphere and root, whereas it had poor correlation with Herbaspirillum population. Positive correlation of RE and AE with ARA of roots, Gluconacetobacter and Herbaspirillum populations in roots and stems indicate their positive contribution in total nitrogen uptake by the plant per kg of N applied.
Average PFP was 808.9 at N75 compared to 408.7 at N150 indicating that N was utilized efficiently at low N input status in sugarcane. Strong positive correlations of AE75 (agronomic efficiency from 75 kg N ha−1 to 150 kg N ha−1) with N-uptake (r
2 = 0.615), cane yield (r
2 = 0.758) and PFP (r
2 = 0.758) and other parameters compared to AE (agronomic efficiency from 0 kg N ha−1 to 75 kg N ha−1 or 150 kg N ha−1) correlations with N-uptake (r
2 = 0.111), cane yield (r
2 = 0.368) and PFP (r
2 = 0.190) indicated that the AE of sugarcane was strongly directed towards producing more cane yield per unit of N fertilizer
once the sugarcane plant has established using initial dose of nitrogen and thus AE75 seems to be a more appropriate indicator for accounting N-nutrient use efficiency in sugarcane. 相似文献
10.
P. L. J. Metz E. Jacobsen J. P. Nap A. Pereira W. J. Stiekema 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,95(3):442-450
There is strong evidence indicating that gene flow from transgenic B. napus into weedy wild relatives is inevitable following commercial release. Research should now focus on the transmission, stability,
and impact of transgene expression after the initial hybridization event. The present study investigated the transfer of a
phosphinothricin-tolerance transgene by inter-specific hybridization between B. rapa and two transgenic B. napus lines. The expression of the transgene was monitored in the F1 hybrids and in subsequent backcross generations. The transgene was transmitted relatively easily into the F1 hybrids and retained activity. Large differences in the transmission frequency of the transgene were noted between offspring
of the two transgenic lines during backcrossing. The most plausible explanation of these results is that the line showing
least transmission during backcrossing contains a transgene integrated into a C-genome chromosome. Approximately 10% of offspring
retained the tolerant trait in the BC3 and BC4 generations. The implications of these findings for the stable introgression of transgenes carried on one of the chromosomes
of the C-genome from B. napus and into B. rapa are briefly discussed.
Received: 5 November 1996 / Accepted: 21 February 1997 相似文献
11.
W. Welsh W. Bushuk W. Roca S. P. Singh 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1995,91(1):169-177
The value of intra- and interracial populations in common bean (Phaseolus vulgaris L.) needs to be determined in order to create useful genetic variation for maximizing gains from selection, broadening the genetic base of commercial cultivars, and making efficient use of available resources. Five large-seeded parents of race Nueva Granada (N), two small-seeded race Mesoamerica (M), and one medium-seeded race Durango (D) were hybridized to produce one intraracial (N x N) and three interracial (two N x M and one N x D) populations. Seventy-nine F2-derived F6 lines randomly taken from each population along with their parents were evaluated for agronomic traits and markers at Palmira and Popayán, Colombia, in 1990 and 1991. Variation for agronomic traits and for morphological, protein, and isozyme markers was larger in interracial populations than in the intraracial population. Mean seed yield of all lines as well as yield of the highest yielding line from two interracial populations were significantly higher than that of the intraracial population. The highest ( 0.80±0.15) heritability was recorded for 100-seed weight. Values for seed yield varied from 0.19±0.17 to 0.50±0.16. Gains from selection (at 20% selection pressure) for seed yield ranged from 3.9% to 11.4%. Seed yield was positively associated with biomass yield, pods/m2, and days to maturity, but harvest index showed negative correlations with these traits and a positive value with 100-seed weight. Polymorphism was recorded for phaseolin, lectins, protein Group-1 and protein Group-2 fractions, and six isozyme loci. Lines with indeterminate growth habit had significantly (P < 0.01) higher seed yield than lines with determinate growth habit in a Redkloud x MAM 4 population. Also, 23 other associations of markers with agronomic traits other than seed yield were recorded. Of these associations, lines with T phaseolin, the Diap1
2 allele, and lilac flower color tended to possess greater seed weight. 相似文献
12.
Green manure technology: Potential,usage, and limitations. A case study for lowland rice 总被引:1,自引:0,他引:1
The growing concern about the sustainability of tropical agricultural systems stands in striking contrast to a world-wide decline in the use of soil-improving legumes. It is timely to assess the future role that soil-improving legumes may play in agricultural systems. This paper reviews recent progress, potential, and limitations of green manure technology, using lowland rice cropping systems as the example.Only a few legume species are currently used as green manures in lowland rice. Sesbania cannabina is the most widely used pre-rice green manure for rice in the humid tropics of Africa and Asia. Astragalus sinicus is the prototype post-rice green manure species for the cool tropics. Stem-nodulating S. rostrata has been most prominent in recent research. Many green manure legumes show a high N accumulation (80–100 kg N ha-1 in 45–60 days of growth) of which the major portion (about 80%) is derived from biological N2 fixation. The average amounts of N accumulated by green manures can entirely substitute for mineral fertilizer N at current average application rates. With similar N use efficiencies, green manure N is less prone to loss mechanisms than mineral N fertilizers and may therefore contribute to long-term residual effects on soil productivity.Despite a high N2-fixing potential and positive effects on soil physical and chemical parameters, the use of green manure legumes for lowland rice production has declined dramatically world-wide over the last 30 years. Land scarcity due to increasing demographic pressure and a relatively low price of urea N are probably the main determining factors for the long-term reduction in pre-rice green manure use. Post-rice green manures were largely substituted for by high-yielding early-maturing grain legumes. Unreliability of green manure performance, non-availability of seeds, and labor intensive operations are the major agronomic constraints. The recognition and extrapolation of niches where green manures have a comparative advantage may improve an often unfavorable economic comparison of green manure with cash crop or fertilizer N. Socio-economic factors like the cost of land, labor, and mineral N fertilizer are seen to determine the cost-effectiveness and thereby farmers' adoption of sustainable pre-rice green manure technology. Hydrology and soil texture determine the agronomic competitiveness of a green manure with N fertilizers and with alternative cash crops. In general, the niches for pre-rice green manure are characterized by a relatively short time span available for green manure growth and a soil moisture regime that is unfavorable for cash crops (flood-prone rainfed lowlands with coarse-textured soils).Given the numerous agronomic and socio-economic constraints, green manure use is not seen to become a relevant feature of favourable rice-growing environments in the foreseeable future. However, in environments where soil properties and hydrology are marginal for food crop production, but which farmers may be compelled to cultivate in order to meet their subsistence food requirements, green manures may have a realistic and applicable potential. 相似文献
13.
In crop plants the shift from being annuals to perennials may allow future agricultural systems requiring less energy inputs.
The practicability of this was tested for Solanum melongena. Leaf protoplasts of S. melongena (2n = 2x = 24) and one of the related arborescent species Solanum marginatum (2n = 2x = 24) were electrofused and fertile somatic hybrids with arborescent habit regenerated. The magnetic cell sorter (MACS) technique
was used for the selection of heterokaryons. The hybrid nature of 18 regenerated plants was assessed on the banding patterns
generated by inter-simple sequence repeat PCR. When taken to maturity in the greenhouse, hybrids grew more vigorously compared
to the parental species. Their morphological traits were intermediate between those of S. melongena and S. marginatum. Hybrids flowered and produced an average of 85% stainable viable pollen and fertile fruits. The somatic hybrids were maintained
in the greenhouse for more than 3 years and continued to produce flowers developing into two types of fruits with plentiful
seeds. Fruits were either striated green containing non-germinable seeds or yellow with fully germinable seeds. Their S1 progenies showed common features with S0 hybrids, including fertility and arborescent habit. Cytologically, somatic hybrids exhibited the expected chromosome number
of 2n = 4x = 48, while chromosome pairing during microsporogenesis was associated with a low frequency of intergenomic pairing. It is
concluded that an arborescent perennial species has been obtained by somatic hybridization. The usefulness of this species
per se or in eggplant breeding will depend not only on the transmission of the arborescent habit to cultivated eggplant varieties,
but also on the variability that should be created from backcrossing the S. melongena + S. marginatum hybrids to S. melongena. 相似文献
14.
Summary Carbon dioxide concentrations were elevated in three estuarine communities for an entire growing season. Open top chambers were used to raise CO2 concentrations ca. 336 ppm above ambient in monospecific communities of Scirpus olneyi (C3) and Spartina patens (C4), and a mixed community of S. olneyi, S. patens and Distichlis spicata (C4). Nitrogen and carbon concentration (% wt) of aboveground tissue was followed throughout growth and senescence. Green shoot %N was reduced and %C was unchanged under elevated CO2 in S. olneyi. This resulted in a 20%–40% increase in tissue C/N ratio. There was no effect of CO2 on either C4 species. Maximum aboveground N (g/m2) was unchanged in S. olneyi, indicating that increased productivity under elevated CO2 was dependent on reallocation of stored N. There was no change in the N recovery efficiency of S. olneyi in pure stand and a decrease in the mixed community. Litter C/N ratio was not affected by elevated CO2 suggesting that decomposition and N mineralization rates will also remain unchanged. Continued growth responses to elevated CO2 could, however, be limited by the ability of S. olneyi to increase the total aboveground N pool. 相似文献
15.
J. Adam Langley Thomas J. Mozdzer Katherine A. Shepard Shannon B. Hagerty J. Patrick Megonigal 《Global Change Biology》2013,19(5):1495-1503
Elevated CO2 and nitrogen (N) addition directly affect plant productivity and the mechanisms that allow tidal marshes to maintain a constant elevation relative to sea level, but it remains unknown how these global change drivers modify marsh plant response to sea level rise. Here we manipulated factorial combinations of CO2 concentration (two levels), N availability (two levels) and relative sea level (six levels) using in situ mesocosms containing a tidal marsh community composed of a sedge, Schoenoplectus americanus, and a grass, Spartina patens. Our objective is to determine, if elevated CO2 and N alter the growth and persistence of these plants in coastal ecosystems facing rising sea levels. After two growing seasons, we found that N addition enhanced plant growth particularly at sea levels where plants were most stressed by flooding (114% stimulation in the + 10 cm treatment), and N effects were generally larger in combination with elevated CO2 (288% stimulation). N fertilization shifted the optimal productivity of S. patens to a higher sea level, but did not confer S. patens an enhanced ability to tolerate sea level rise. S. americanus responded strongly to N only in the higher sea level treatments that excluded S. patens. Interestingly, addition of N, which has been suggested to accelerate marsh loss, may afford some marsh plants, such as the widespread sedge, S. americanus, the enhanced ability to tolerate inundation. However, if chronic N pollution reduces the availability of propagules of S. americanus or other flood‐tolerant species on the landscape scale, this shift in species dominance could render tidal marshes more susceptible to marsh collapse. 相似文献
16.
Offspring from natural hybrids between octoploid Fragaria chiloensis (2n = 56) and diploid F. vesca (2n = 14) backcrossed under natural conditions to F. chiloensis were studied. The natural F1 hybrids themselves were of three kinds: (1) The expected pentaploids which resulted from the union of normally reduced gametes of diploid F. vesca and octoploid F. chiloensis; (2) A hexaploid F1 hybrid which resulted from the union of an unreduced gamete from diploid F. vesca with a normally reduced gamete from octoploid F. chiloensis; and (3) A 9-ploid F1 hybrid which probably arose from the union of an unreduced gamete of the octoploid F. chiloensis with a normally reduced gamete of diploid F. vesca. The progenies that resulted from the natural backcrossing of each of the three sorts of F1 hybrids to F. chiloensis were as follows: The pentaploid F1 hybrids (2n = 35) yielded mostly 9-ploid offspring from unreduced 5X gametes; a relatively high percentage of 14-ploid plants arising from doubled-unreduced 10 X gametes and a few 2N = ±46 aneuploids from reduced gametes. The hexaploid F1 hybrid (2n = 42) on backcrossing yielded over 50% 10-ploid offspring with the rest 2n = ±50 aneuploids from reduced gametes. The 9-ploid F1 hybrid (2n = 63) on backcrossing yielded mostly aneuploids normally distributed about a modal 2n = 59 chromosome class resulting from a 31 chromosome gamete, with a few 2n = 56 and 2n = 63 euploids. The 9-ploids may facilitate diploid Å octoploid introgression. Screening of the open-pollinated offspring from F. chiloensis revealed almost 2% 12-ploid (2n = 84) offspring from the union of the reduced and unreduced F. chiloensis gametes. The probable genomic constitution of the observed novel ploidy levels and those that theoretically may be generated from the known hybrids are presented. The origin of the existing polyploids from diploids through simple unreduction is postulated. 相似文献
17.
Observations were made over a period of one year on the performance of multi stage stabilization ponds treating domestic waste waters. The unit is composed of Primary anaerobic (P1) and two consecutive Secondary (P2) and Tertiary (P3) facultative ponds. The overall reduction in BOD, bacteria, PO4, SO4, NH3N, Cl− and total solids were 89.4, 99.8, 76.2, 47.7, 79.7, 18.6 and 74.0 percent, respectively. Elimination of H2S was 84.8% in the final effluents. Chlorella vulgaris was found to be the dominant alga followed by Euglena, Ankistrodesmus, Phacus and Synedra as subdominant forms. 9 species of protozoa have been recorded in the first pond and their number declined in the successive ponds. 相似文献
18.
More intense, more frequent, and longer heat-waves are expected in the future due to global warming, which could have dramatic ecological impacts. Increasing nitrogen (N) availability and its dynamics will likely impact plant responses to heat stress and carbon (C) sequestration in terrestrial ecosystems. This field study examined the effects of N availability on plant response to heat-stress (HS) treatment in naturally-occurring vegetation. HS (5 d at ambient or 40.5 ℃) and N treatments (±N) were applied to 16 1 m2 plots in restored prairie vegetation dominated by Andropogon gerardii (warm-season C4 grass) and Solidago canadensis (warm-season C3 forb). Before, during, and after HS, air, canopy, and soil temperature were monitored; net CO2 assimilation (Pn), quantum yield of photosystem Ⅱ (φPsⅡ), stomatal conductance (gs), and leaf water potential (Ψw) of the dominant species and soil respiration (Rsolf) of each plot were measured daily during HS. One week after HS, plots were harvested, and C% and N% were determined for rhizosphere and bulk soil, and above-ground tissue (green/senescent leaf, stem, and flower). Photosynthetic N-use efficiency (PNUE) and N resorption rate (NRR) were calculated. HS decreased Pn, gs, Ψw, and PNUE for both species, and N treatment generally increased these variables (±HS), but often slowed their poat-HS recovery. Aboveground biomass tended to decrease with HS in both species (and for green leaf mass in S. canadensis), but decrease with N for ,4. gerardii and increase with N for S. canadensis. For A. gerardii, HS tended to decrease N% in green tissues with N, whereas in S. canadensis, HS increased N% in green leaves.Added N decreased NRR for A. gerardii and HS increased NRR for S. canadensis. These results suggest that heat waves,though transient, could have significant effects on plants, communities, and ecosystem N cycling, and N can influence the effect of heat waves. 相似文献
19.
Lupins, canola, ryegrass and wheat fertilized with Na2
35SO4 and either 15NH4Cl or K15NO3(N:S=10:1), were grown in the field in unconfined microplots, and the sources of N and S (fertilizer, soil, atmosphere, seed)
in plant tops during crop development were estimated. Modelled estimates of the proportion of lupin N derived from the atmosphere,
which were obtained independently of reference plants, were used to calculate the proportion of lupin N derived from the soil.
Total uptake of N and S and uptake of labelled N and S increased during crop development. Total uptake of S by canola was
higher than lupins, but labelled S uptake by lupins exceeded uptake by canola. The form of N applied had no effect on uptake
of labelled and unlabelled forms of N or S. Ratios of labelled to unlabelled S and ratios of labelled to unlabelled N derived
from soil sources decreased during growth, and were less for S than for N for each crop at each sampling time. Although ratios
of labelled to unlabelled soil-derived N were similar between crops at 155, 176 and 190 days after sowing, ratios of labelled
to unlabelled S for lupins were higher than for the reference crops and declined during this period. The ratios of labelled
to unlabelled S in lupins and the reference plants therefore bore no relationship either to ratios of labelled to unlabelled
soil-derived N in the plants, or to total S uptake by the plants. Therefore the hypothesis that equal ratios of labelled N
to unlabelled soil-derived N in legumes (Rleg) and reference plants (Rref) would be indicated by equal ratios of labelled to unlabelled S was not supported by the data. The results therefore show
that the accuracy of reference plant-derived values of Rleg cannot be evaluated by labelling with 35S. 相似文献
20.
Improvement of transgenic alfalfa by backcrossing 总被引:1,自引:0,他引:1
M. C. Micallef S. Austin E. T. Bingham 《In vitro cellular & developmental biology. Plant》1995,31(4):187-192
Summary Two regenerative alfalfa genotypes were transformed withAgrobacterium tumefaciens with binary vectors containing the coding sequences for ?-glucuronidase (GUS) and npt II (kanamycin resistance). The regenerative
genotypes and their transgenic populations were agronomically inferior, and one was a somaclonal variant for flower color.
GUS was used as a dominant genetic marker in a model system for studying backcrossing to improve transgenic alfalfa. Agronomic
yield deficiencies and somaclonal changes were corrected by one to three backcrosses to cultivar genotypes, depending on the
vigor of the original transformant. Three backcrosses were considered optimal because progeny contain 94% cultivar germplasm
and could be used as parents of a new cultivar. Use of different cultivar genotypes each generation of backcrossing minimized
inbreeding and maximized the heterotic potential of backcross derivatives. The improvement of transgenic alfalfa by backcrossing
using a dominant marker required only as much time as the original transformation experiment. 相似文献