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1.
A. J. Wright 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1973,43(2):79-82
Summary As a criterion for the selection from a population of individuals with a high potential as parents of synthetic varieties, the general varietal ability of an individual is defined as the mean expression of all possible synthetics of a given size(s) having this plant as a common parent. Using known expressions for the prediction of the performance of advanced generations of diploid synthetic varieties, general varietal ability is expressed in terms of the F
1 and I
1 progenies of the plants under test, and is found to be a simple function of the polycross (g.c.a.) and inbred progeny means, where the contribution of the inbred progeny varies according to n and s. The implications and use of such a progeny test in the breeding of out-pollinating crops is discussed. 相似文献
2.
Butrón A. Tarrio R. Revilla P. Malvar R.A. Ordás A. 《Molecular breeding : new strategies in plant improvement》2003,12(4):329-333
A generalized way to obtain a maize (Zea mays L.) synthetic variety is to randomly mate all possible crosses among inbred lines, but, when the number of lines is large, it would save time and effort to use other mating methods. This work is aimed to determine the utility of two alternative methods, assuming that an equal contribution of each inbred line to the synthetic is the goal (; 1993). Eight Reid inbred lines originated from the U.S. Corn Belt population Reid, and eight non-Reid unrelated inbreds were the base meterial for synthetic verieties EPS20 and EPS21, respectively . Each variety was built using both alternative methods: i) controlling the balanced contribution of each parental inbred (convergent cross method), and ii) randomly mating a seed mixture from the eight inbreds (random method). In the convergent cross method, single crosses between inbreds, and double crosses were performed in 1995, and 1996, respectively, as the first step to create EPS20c and EPS21c. Finally, in 1997, about 40 plants from each double-cross hybrid were mated only once (as male or female) in plant-to-plant crosses between double cross-hybrids, to generate about 20 ears that provided the base material for synthetics EPS20c and EPS21c. In the random method, a total of 304 seeds from the eight inbred lines, 38 seeds from each one, were bulked and sown in ten rows of 15 two-kernel hills per row in 1998 to form EPS20r and EPS21r. After thinning, 150 plants were left, and random plant-to plant crosses were made (where each plant was used only once as male or female), that resulted in 38 and 39 ears, respectively. The two crossing schemes were followed by two generations of recombination. A sample of 40 individuals from each synthetic variety was genotyped with 17 SSR (simple sequence repeat) markers loci. Primer sequences and chromosomal locations are available at the MaizeDB (www.agron.missouri.edu/ssr.html). Genetic drift due to the relatively small samples used to constitute balanced synthetic varieties, and/or natural selection could modify the original frequencies, but did not cause allele or heterozygosity losses. Therefore, the convergent cross method appeared to be appropriate for developing synthetic varieties either from related or non related inbreds. The random method should be used with caution, especially when inbred parents are genetically different, since relative adaptive advantages of some inbred lines could cause loss of genetic variability. 相似文献
3.
Golmirzaie A Ortiz R 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2002,104(1):161-164
A true potato seed (TPS) synthetic cultivar from open pollination may broaden the genetic base in potato. A synthetic cultivar
can also reduce the effect of inbreeding and maintain the productivity from generation to generation. Selected tetraploid
parental genotypes, based on combining-ability tests, were chosen for isolated polycrosses to obtain tetraploid offspring.
A series of experiments were undertaken to investigate the development of these TPS synthetic populations in two Peruvian
locations: San Ramon, a rainfed, humid, mid-altitude environment, and La Molina, an arid, coastal environment under irrigation.
Natural open-pollinated synthetics or control-mixture synthetics, involving two to six parents, had a similar tuber set but
plant survival and tuber weight were higher in control synthetics including two or six parents. The results suggest that two-parent
open-pollinated TPS synthetics may be a feasible option by selecting the right parents for the base population. A subsequent
experiment showed that four-parent control synthetics (i.e. double crosses) were the best for tuber weight and size, followed
by the two-parent control synthetics. Synthetic breeding populations could be shared with other breeders, who in cooperation
with their local farmers may select promising genotypes for further cultivar release.
Received: 15 December 2000 / Accepted: 4 April 2001 相似文献
4.
Melchinger AE Geiger HH Utz HF Schnell FW 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2003,106(2):332-340
Recombination of selected genotypes plays a key role in plant breeding for generating new base populations. We investigated the influence of recombination in two parent populations on the means and combining ability variances of their hybrid population by (1) quantitative genetic theory and (2) experiments with maize. The two parent populations were founded by four early flint and four early dent inbred lines, respectively. Each population was studied in three generations: Syn-0, the four inbred lines themselves; Syn*-1, the six intrapool single crosses (SC); and Syn*-2, the three intrapool double crosses (DC). Four interpool hybrid populations were created: (1) all 16 SC and (2) all 36 DC were produced from generations Syn-0 and Syn*-1, respectively, (3) 168 biparental progenies (BIP) of type flint x dent (female x male), and (4) 168 BIP of type dent x flint were produced according to NC-design I with randomly sampled plants of generation Syn*-2. The half-sib and full-sib families obtained in this manner were evaluated for grain yield, dry matter concentration and plant height. According to theoretical results, differences in the population means of these hybrid populations indicate the presence of various types of epistasis. Changes in combining ability variances from SC to DC reflect different levels of parental inbreeding (F = 1 vs F = 0), whereas changes from DC to BIP only reflect the effects of recombination and are attributable to covariances between additive and dominance effects caused by linkage disequilibrium in the Syn-0 generations. The experimental results showed a significant decline in yield from DC to BIP due to a loss of gene combinations with favourable epistatic effects. Estimates of sigma(2)(GCA) attributable to flint or dent lines decreased or remained unchanged from SC to DC, but generally increased in the BIP populations. The consequences of these trends for developing improved interpool hybrids are discussed. 相似文献
5.
S. I. Maletsky N. J. Weisman 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1978,52(1):21-28
Summary A population genetic model is proposed for the reproduction of self-incompatible inbred lines in which incompatibility is controlled by 1–4 loci. From theoretical considerations it was expected that: a) with the random matings of lines In, (obtained by self-pollination of n generations), some lines would be cross-incompatible (all the plants within these lines would be homozygous for S-genes) and the rest would be cross-compatible (retain heterozygosity for one or more S-genes); b) in the case of random matings of Unes InGm (obtained by self-pollination of n generations and by random pollination for m generations), some lines would be cross-incompatible (heterozygous for one S-gene) and the rest would be cross-compatible (retain heterozygosity for two or more S-genes); c) the relative proportion of sterile plants, obtained by random pollination of cross-compatible lines, would be related to the number of segregating S-loci and to the generation in which the lines are studied.Forty-four inbred lines of sugar beet derived from self-incompatible plants of a population were analysed. Comparisons of the observed values with the theoretically expected ones demonstrated that: a) of 18 In (I1-I4) lines, 6 were cross-incompatible (homozygous for S-genes) and 12 were cross-compatible having one S-locus segregating in 7 lines and two S-loci segregating in 5 lines; b) of 22 InG1 (I2G1 and I3G1) lines, one line was self-fertile, 7 lines were cross-incompatible (heterozygous for one S-loci) and 14 lines were cross-compatible (heterozygous for two S-loci).No line was found to have three or more segregating S-loci. The results of this population genetics analysis of self- and cross-incompatibility in sugar beet comply with diallel analysis data on sugar beet incompatibility and indicates that it is under the gametophytic control of two basic S-loci. 相似文献
6.
7.
Lidia Skuza Stanis?awa M. Rogalska Stanis?aw M. Dyba Jan Bocianowski 《Central European Journal of Biology》2013,8(1):38-47
Genetic diversity between synthetic cultivars (Syn5, Syn7), inbred lines (D3, D5, E1/2, G1/1, G1/2) and ecotypes (E16, E51, E182, E231) of lucerne (Medicago sativa L.) was studied using the RAPD-PCR method. The plants differed in the efficiency of seed set and in the yield of green mass. The ecotypes E182 and E231 and the synthetic population Syn5 showed the highest fertility. Additionally, Syn5 also showed the highest efficiency of seed set and the yield of green mass. Among the inbred lines, D3 was characterised by the highest yield of green mass and E1/2 by the highest fertility. An optimal combination of yield and biomass was observed for the synthetic population Syn5, obtained by crossing the lines D3, D5 and G1/1, as demonstrated using comparative analysis. A total of 338 polymorphic products were generated using 20 arbitrary primers. Cluster analysis using the Unweighted-Pair Group Method with Arithmetic Mean (UPGMA) in the Molecular image Gel Doc? XR (Bio-Rad) software based on the Dice’s coefficient of genetic similarity showed a division of the studied forms into two groups based on genetic similarity. The ecotype E16 formed one of the groups whereas all of the other ecotypes observed in this study clustered into the second group. A high level of polymorphism among the studied lucerne forms was detected indicating an interesting gene pool awaiting future exploration. Analysis of variance also supported a high diversity among the studied forms. This study provides insightful information into the heterosis effect of synthetic populations or hybrids of F1 lucerine by providing correlations between the genetic background of the inbred lines and their ability to produce a specific yield. 相似文献
8.
Pollinating insects are not only important in wild plant pollination, but also in the production of a large number of crops. Oilseed rape production is increasing globally due to demands for biofuels which may have impacts on pollinating insects which visit the crop and on the pollination services delivered to co-flowering wild plants. In this study, we tested (1) the degree of pollinator sharing between oilseed rape and native wild plants in field margins and hedgerows and (2) the effects of oilseed rape on the quality of pollination service delivered to these wild plants. We found large overlap between flower visitors of wild plants and oilseed rape, but the composition of species overlap differed with respect to each wild plant species. Nearly all individual visitors caught on both the crop and foraging on wild species carried crop pollen, but more than half the insects also carried pollen from wild plants. However, very little oilseed rape pollen was deposited on wild plant stigmas. This shows that (1) oilseed rape overlaps in pollinator niche with most co-flowering wild plants, and (2) crop pollen deposition on wild plant stigmas is low which may indicate that it is unlikely to cause reductions in seed set of wild plants, although this was not measured here. Furthermore, wild plants in field margins and hedgerows are important sources of alternative forage for pollinating insects even when a crop is mass flowering, and we suggest maintenance and augmentation of field margins and hedgerows to provide alternative forage for pollinator conservation to continue provision of pollination services to both crops and wild plants. 相似文献
9.
Phenotypic plasticity is an organism's ability to alter its development and life history in response to environmental conditions. In plants, biotic and abiotic factors drive the distribution of resources between growth and reproductive traits. One such biotic factor is pollination. Studies show that wind and insect pollination enhance oilseed rape (Brassica napus) yield. However, the impact of pollination on resource allocation towards growth and reproduction is less understood. We conducted a controlled experiment to assess the effect of pollination on growth and functional reproductive traits. We compared two simulated supplementary pollen deposition methods (representing wind and insect pollination) alongside a non-supplementary control. Pollinated plants allocated resources towards growth and reproduction similarly, irrespective of deposition method. Plants receiving no supplementary pollination produced fewer seeds, allocating resources to growth, more prolific and persistent flowering, and heavier seeds. Pollinated plants had a reduced flowering period and were shorter, indicating resources were allocated to seed production rather than growth or the production of additional flowers. This allocation of resources from growth and flowering metrics can increase yield directly through increased seed production and indirectly through shorter plants and a reduced flowering period with seeds that mature earlier (agronomically beneficial traits).Wind and insect pollination can enhance and stabilise oilseed rape yield under various environmental conditions by acting in complementary ways. Since pollination limits yield in oilseed rape, it must be considered an input that can be actively managed. Successful management of pollination services requires growers to detect pollination deficits. Inadequately pollinated oilseed rape plants exhibit apparent morphological changes (e.g. taller plants that flower for longer), acting as an early warning to growers. Equipping growers with this knowledge provides them with a means of detecting deficits and thus enables them to take positive action to restore pollination services by introducing honeybees or enhancing wild pollinators. 相似文献
10.
A. Gallais 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1990,79(3):417-421
Summary From the consideration of the expressions of the mean and of the variances amongk-parent synthetics, it is possible, in the absence of epistasis, to give an algebraic determination of the optimum number of parents to include in a synthetic. The knowledge of four components of variance of inbred populations is necessary. Such components can be replaced by four simple statistics for the plant breeder: variances of general and specific combining abilities, variance among S1 families from the parents, and covariance between S1 value and general combining ability (GCA). A numerical study shows that this optimum is rather broad for a number of parents greater than four. As expected, the optimum tends to be higher for greater inbreeding depression. With inbreeding depression greater than 0.30, the maximum gain, in comparison to the random mating population with realistic selection intensity, would be less than 5%. In such a situation it will be better to use as synthetic the population improved by recurrent selection. 相似文献
11.
The genetics of selfing with concurrent backcrossing in breeding hybrid sugar beet (Beta vulgaris altissima L.) 总被引:1,自引:0,他引:1
I. J. Mackay J. P. Gibson P. D. S. Caligari 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,98(6-7):1156-1162
Sugar beet hybrids are produced by crossing a cytoplasmic male-sterile (CMS) line with a pollinator. New CMS lines are produced
by crossing a fertile plant to an existing CMS line. The fertile plant is also selfed. In the following generation, one of
the selfed, fertile progeny is paired and isolated with one of the crossed, CMS progeny, to give a second generation of selfing
and crossing. Over a series of such crosses and selfs, a new fertile inbred line and its corresponding, near-isogenic CMS
partner are produced. Selection among lines takes place at one or more stages of the backcrossing programme. A method is presented
here for calculating the genetic variances and covariances within and between lines and generations based on a derivation
of additive genetic relationships modified from an approach widely employed in animal breeding. The genetic variances and
covariances are used to predict response to selection from varying strategies, from which optimum schemes can be determined.
Results suggest that selection should generally take place after three generations of backcrossing when the fertile plant
used to initiate the backcrossing process is not inbred, but can take place after generation two when the fertile plant is
inbred. Doubled haploid production is unlikely to provide an extra advantage that would be worthwhile in such a system. The
method developed here can be used to explore a wide range of more complex breeding systems.
Received: 27 July 1998 / Accepted: 19 October 1998 相似文献
12.
C. Scotti F. Pupilli S. Salvi S. Arcioni 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2000,101(1-2):120-125
The effect of selfing on vigour and heterozygosity was analysed in six independent families obtained by recurrent cycles of
self-fertilization and selection until the S3 generation. The heterozygosity level, estimated by means of 11 homologous probes, decreased from the S0 to S3 generations and was partially restored in S2×S2 polycrosses. The decreasing trend was influenced by the inbreeding level of the chosen mother plant in each self generation
to advance in subsequent selfing. Plant vigour estimated by Dry Matter Yield (DMY) decreased during inbreeding, and phenotypic
selection of S2 individuals seemed to prove effective as the differences in DMY between vigorous and weak plants were maintained in S2×S2 crosses. No correlation between plant vigour and heterozygosity was found between subgroups of vigorous and weak plants selected
within the same S2 family. Results are discussed with a view to selecting the best performing and least heterozygous plants during inbreeding
to isolate useful genes and linkats in superior partially inbred parental lines.
Received: 4 August 1999 / Accepted: 6 December 1999 相似文献
13.
The signal from organelle to nucleus, namely retrograde regulation of nuclear gene expression, was largely unknown. Due to the nuclear-cytoplasmic incompatibility in cytoplasmic male-sterile (CMS) plants, we employed CMS Brassica juncea to investigate the retrograde regulation of nuclear gene expression in this study. We studied how reduced BjRCE1 gene expression caused by the nuclear-cytoplasmic incompatibility altered the auxin response in CMS of B. juncea. We isolated the BjRCE1 gene that was located in the nucleus from B. juncea. Over-expression of BjRCE1 enhanced auxin response in transgenic Arabidopsis. The expression of BjRCE1 was significantly reduced in CMS compared with its maintainer fertile (MF) line of B. juncea. There were fewer lateral roots in CMS than MF under normal and treatment of indole-3-acetic acid (IAA) conditions. Expression patterns of several auxin-related genes together with their phenotypes indicated a reduced auxin response in CMS compared to MF. The phenotypes of auxin response and auxin-related gene expression pattern could be mimicked by inhibiting mitochondrial function in MF. Taken together, we proposed reduced expression of BjRCE1 gene modulated by nuclear-cytoplasmic incompatibility alters auxin response in CMS B. juncea. This may be an important mechanism of retrograde regulation of nuclear gene expression in plants. 相似文献
14.
Reduced expression of CTR1 gene modulated by mitochondria causes enhanced ethylene response in cytoplasmic male-sterile Brassica juncea 总被引:1,自引:0,他引:1
We studied how mitochondria affect ethylene response via modulation of CTR1 expression in cytoplasmic male-sterile (CMS) Brassica juncea. The expression of CTR1 gene was reduced in CMS compared with male-fertile (MF) lines. We observed that hypocotyl and root lengths were shorter than in the MF line during germination in the dark. An enhanced ethylene response was observed in CMS plants as shown by the CMS and maintainer line phenotypes treated with 1-aminocyclopropane-1-carboxylic acid. The phenotype in CMS plants could be recovered to the maintainer line when treated with Ag(+) . One ethylene response gene, plant defensin gene, was detected to be induced in CMS. The behavior of this phenotype could be mimicked by treating the maintainer line with antimycin A that disturbs mitochondrial function, which showed reduced length of hypocotyl and roots, and resulted in similar expression patterns of ethylene-related genes as in CMS. The reduced length of hypocotyl and roots could be recovered to the maintainer line by treatment with gibberellic acid (GA(3) ). In addition, the GA(3) content was reduced in CMS plants and in the MF line treated with antimycin A. Ethylene treatment markedly affects GA(3) content; however, GA(3) did not significantly affect ethylene-related gene expression in regards to regulation of hypocotyl and root length, which suggests that ethylene acts upstream via gibberellin to regulate hypocotyls and root development. Taken together, our results suggest a link between mitochondrial modulation of the ethylene and gibberellin pathway that regulates the development of hypocotyl and roots. 相似文献
15.
Increasing cultivation of oilseed rape may have consequences for pollinators and wild plant pollination. By providing pollinating insects with pollen and nectar, oilseed rape benefits short-tongued, generalist insect species. Long-tongued bumble bee species, specialized to other flower types, may instead be negatively affected by increased competition from the generalists (e.g. due to nectar-robbing of long-tubed flowers) after oilseed rape flowering has ceased. We expected that the increased abundance of short-tongued pollinators and reduced abundance of long-tongued bumble bees in landscapes with a high proportion of oilseed rape would impact the pollination of later flowering wild plant species. In addition, we expected contrasting effects on plants pollinated by short-tongued pollinators and those pollinated by long-tongued bumble bees. We predicted that semi-natural grasslands, which provide insects with alternative floral resources, would reduce both negative and positive effects on pollination by mitigating competition between pollinators.In 16 semi-natural grasslands, surrounded by agricultural landscapes, with a variation in both the proportion of oilseed rape and the proportion of semi-natural grassland within 1 km, we studied reproductive output in two species of potted plants with different pollination strategies: the woodland strawberry (Fragaria vesca) and red clover (Trifolium pratense). The first species is mainly pollinated by short-tongued pollinators, e.g. hoverflies and solitary bees, and the latter by long-tongued bumble bees. Both species flowered after oilseed rape.Strawberry weight was higher in landscapes with a high proportion of oilseed rape, but only in landscapes with a low proportion of semi-natural grassland. The proportion of developed achenes was also positively related to the proportion of oilseed rape, but only during the latest flowering period. In contrast, red clover seed set was unrelated to the proportion of oilseed rape. Whereas the discrepancy between the two strawberry measurements calls for further research, this study suggests that oilseed rape can affect later flowering plants and that the impact differs among species. 相似文献
16.
Pollinators are beneficial for many wild and crop plants. As a mass-flowering crop, oilseed rape has received much focus in terms of its pollination requirements but despite a threefold increase in area of cultivation of this crop in Ireland over the past 5 years, little is known about its pollination here. We surveyed the flower visiting insects found in commercial winter oilseed rape fields and evaluated the importance of different pollinator groups, investigated the contribution of insect pollination to oilseed rape seed production, and estimated the economic value of insect pollination to the crop at a national level. Our data showed that winter oilseed rape is visited by a wide variety of insect species, including the honeybee, bumblebees, solitary bees, and hoverflies. The honeybee, Eristalis hoverflies and bumblebees (especially Bombus sensu stricto and B. lapidarius) were the best pollinators of winter oilseed rape based on the number of pollen grains they carry, visitation rates per flower and their relative abundance per field. Exclusion of pollinators resulted in a 27 % decrease in the number of seeds produced, and a 30 % decrease in seed weight per pod in winter crops, with comparable values from a spring oilseed rape field also. The economic value of insect pollination to winter oilseed rape was estimated as €2.6 million per annum, while the contribution to spring oilseed rape was €1.3 million, resulting in an overall value of €3.9 million per annum. We can suggest the appropriate conservation and management of both honeybees and wild pollinators in agricultural areas to ensure continued provision of pollination services to oilseed rape, as a decrease in insect numbers has the potential to negatively influence crop yields. 相似文献
17.
18.
通过对若干个玉米杂交及其亲本自交授粉后1天、3天、7天、10天胚中ATP酶活性、RNA酶活性及蛋白质变化的比较来探讨杂种优势产生的生化机理。结果表明,30个组合的玉米授粉后一天,有90%组合杂交胚中ATP酶活性超过双亲或母本自交胚中ATP酶活性。授粉后3天杂交胚中ATP酶活性多数低于双亲自交胚中的ATP酶活性,看来这一表现与自交授粉后胚中合子细胞分裂较迟缓有关。以上四个时期授粉后,杂交胚中RNA酶活性介于双亲之间或低于双亲,这可能与杂交胚中核酸分解的速度较慢有关。杂交胚中蛋白质含量变化不同时期各组合间表现不同,杂交后胚胎发育初期胚中蛋白质的变化不一定是总的数量的增加,而是某些蛋白质或酶的变化。 相似文献
19.
Siberian dwarf pine, or Japanese stone pine, Pinus pumila (Pall.) Regel is widespread in eastern Siberia and the Russian Far East; the species is bird-dispersed and has a unique spreading or shrub living form. A mixed mating system (predominant outcrossing with self-pollination and matings of close relatives) leads to the formation of partly inbred progenies in P. pumila, as in the majority of other conifers. The question arises as to whether inbred individuals persist in the reproductive part of a population, which can have negative genetic consequences. The ADH, FDH, FEST, GDH, GOT, IDH, LAP, MNR, MDH, PEPCA, 6-PGD, PGI, PGM, SKDH, and SOD isozyme systems were analyzed to study the dynamics of heterozygosity in four P. pumila natural populations from the Pacific region, optimal for the species. Samples were collected in northern Koryakia, southern Kamchatka (two samples), and the Kunashir Island (Kurils). Wright's fixation index was used to estimate the level of inbreeding in embryos from dormant seeds resulting from free pollination and in maternal plants. A substantial level of inbreeding (F(IS) = 0.124-0.342) was observed in the embryo samples but not in three out of the four adult samples. The inbreeding level at the reproductive age was high only in the sample from Koryakia, which was explained by a relatively young age of plants in the population frequently affected by fires. A general increase in heterozygosity, characteristic of other conifers as well, was attributed to elimination of inbred progenies and by balancing selection for heterozygotes, which is a key factor maintaining allozyme polymorphism in populations. 相似文献
20.
John Cussans David Goulson Roy Sanderson Louis Goffe Ben Darvill Juliet L. Osborne 《PloS one》2010,5(7)