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1.
Wild relatives of the cultivated tomato (Solanum lycopersicum L.) are major sources of new genetic diversity for tomato improvement. Introgression lines (IL) are near-isogenic lines homozygous for one or several mapped wild DNA fragments in a common recurrent parent. A set of ILs developed by Cornell University from Solanum habrochaites accession LA1777 and recurrent parent E6203 has been made publicly available through the Tomato Genetics Resource Center of the University of California-Davis. Our objective was to identify LA1777 introgressions with potential to increase the marketable fruit yield of tomato grown in the tropics. A subset of ILs were each crossed to CLN2498E (resistant to bacterial wilt and some begomoviruses) to create IL hybrids (ILH). ILH, IL recurrent parent E6203, CLN2498E, and CLN2498E × E6203 (Hchk) were evaluated in replicated trials in Thailand, India, and Taiwan during two dry seasons. Highly significant effects for marketable fruit yield were detected in Thailand and Taiwan. ILH heterozygous for S. habrochaites segments at the bottom of chromosome 1 yielded about 20% than the Hchk at Thailand and Taiwan. Our results agree with previous results from Cornell University researchers who found a segment of S. habrochaites DNA located between TG158 and TG27 associated with increased total fruit yield in previous trials conducted in upper state New York. Yield improvement due to this S. habrochaites introgression can occur over a wide range of environments.  相似文献   

2.
Introgression libraries can be used to localize genomic regions carrying quantitative trait loci (QTL). We used this approach to detect QTL regions affecting the per se performance of agronomic and quality traits with two rye (Secale cereale L.) introgression libraries. Our objectives were to detect candidate introgression lines (pre‐ILs) that have a different per se performance than the recurrent parent and to identify the underlying QTL regions. The introgression libraries containing 40 BC2S3 lines each were established with marker‐assisted backcrossing from crosses of the heterozygous Iranian primitive rye accession Altevogt 14160 and the elite inbred line L2053‐N. To assess the phenotypic effect of the donor chromosome segments (DCS) the pre‐ILs were evaluated for grain yield, plant height, thousand‐kernel weight, test weight, falling number and protein content in replicated field trials at five locations in Germany over 2 years. In total, 58 significant (P < 0.05) differences between pre‐ILs and L2053‐N were observed in each introgression library. The DCS in pre‐ILs differing from the recurrent parent possess most likely the responsible QTL. Genomic regions carrying favourable QTL alleles were detected for test weight, thousand‐kernel weight and protein content. We conclude that Altevogt 14160 can not only be used to enrich the genetic variation of the restricted hybrid rye gene pools but will also allow the breeder to efficiently detect favourable QTL for marker‐assisted selection.  相似文献   

3.
Introgression populations are developed to make genetic resources for breeding purposes available. In the case that the number of donor segments exceeds the number of lines, genome‐wide prediction (GWP) methods are suggested as promising for the analysis of such populations. Our objectives were to characterize a rye introgression population with the Rye5K SNP assay and to apply a GWP model with a modification of the restricted maximum likelihood procedure that yields heteroscedastic variances to detect significant donor effects. The introgression lines (ILs) carried on average 4.6 donor segments with a mean length of 27 cM and represented 94% of the donor genome. Two donor effects were detected that significantly increased thousand‐kernel weight. We found four donor effects for protein, total pentosan and starch content that can improve baking quality. Three donor effects for protein content were observed for improving feeding purposes and one donor effect for starch content to improve ethanol production. The effects were localized to small genomic regions. Consequently, these ILs can improve rye breeding by directly employing them in breeding programmes for variety development.  相似文献   

4.
The nearly isogenic nature of the introgression lines (ILs) provides a relative advantage over other segregating populations in the rapid implementation of pyramiding approach through crosses and marker analysis. A set of 126 ILs carrying various introgressed segments from a presumed wild progenitor, Oryza rufipogon Griff. Acc. W1944 in the background of an elite Korea japonica cultivar (O. sativa L.), Hwayeongbyeo, was constructed using the marker assisted selection (MAS) technique combined with repeated backcrosses. The 126 ILs have different W1944 segments on each chromosome, with 100% coverage of wild segments on chromosome 1, while for chromosome 10, the coverage was only 33.3%. The mean number of homozygous and heterozygous donor segments were 3 (ranging from 0 to 7) and 4.7 (ranging from 1 to 14.5), respectively, and 31.6% of introgressed segments had sizes of less than 10.5 cM. A total of 41 quantitative trait loci (QTLs) and two loci associated with pericarp coloration were identified. The number of QTLs per trait ranged from 2 to 6. Phenotypic variance associated with each QTL varied from 9.1 to 52.2%, with an average of 17.1%. For 11 (26.8%) of the QTLs detected in this study, the O. rufipogon-derived alleles contributed the desired agronomic effect despite the overall inferior characteristics of the wild phenotype. Favorable alleles from the O. rufipogon accession were identified for panicle number, panicle length, days to heading, secondary branches, spikelets per panicle, and 1,000-grain weight.  相似文献   

5.
Zea mays ssp. mexicana, an annual wild relative of maize, has many desirable characteristics for maize improvement. To transfer alien genetic germplasm into maize background, F1 hybrids were generated by using Z. mays ssp. mexicana as the female parent and cultivated maize inbred line Ye515 as the male parent. Alien introgression lines, with a large range of genetic diversity, were produced by backcross and successive self-pollinations. A number of alien introgression lines with the predominant traits of cultivated maize were selected. Genomic in situ hybridization (GISH) proved that small chromosome segments of Z. mays ssp. mexicana had been integrated into the maize genome. Some outstanding alien introgression lines were evaluated in performance trials which showed 54.6% hybrids had grain yield greater than that of hybrid check Yedan12 which possessed 50% Ye515 parentage, and 17.1, 9.9% hybrids had grain yield competitive or greater than those of Nongda108 and Zheng958, which were elite commercial hybrids in China, respectively. The results indicated that some of the introgression lines had excellent agronomic traits and combining ability for maize cultivar, and demonstrated that Z. mays ssp. mexicana was a valuable source for maize breeding, and could be used to broaden and enrich the maize germplasm.  相似文献   

6.
Vivek Maize Hybrid 9‐ a popular single‐cross hybrid developed by crossing CM 212 and CM 145 was released for commercial cultivation in India. The parental lines, being deficient in lysine and tryptophan, were selected for introgression of opaque‐2 allele using CML 180 and CML 170 as donor lines through marker‐assisted backcross breeding. The opaque‐2 homozygous recessive genotypes with >90% recovery of the recurrent parent genome were selected in BC2F2, and the seeds with <25% opaqueness in BC2F3 were forwarded for seed multiplication. Vivek Quality Protein Maize (QPM) 9, the improved QPM hybrid, showed 41% increase in tryptophan and 30% increase in lysine over the original hybrid. The grain yield of the improved hybrid was on par with the original hybrid. The newly improved QPM maize hybrid released in 2008 will help in reducing the protein malnutrition because its biological value is superior over the normal maize hybrids. This short duration QPM maize hybrid has been adopted in several hill states of North Western and North Eastern Himalayan regions.  相似文献   

7.
以96对SSR引物对BC3F2群体进行辅助筛选,构建了一组基本覆盖野生大麦ISR42-8染色体,并导入轮回亲本Scarlett的1H~7H全基因组的外源基因渗入系,为大麦QTL精细定位提供了良好的作图群体。这组渗入系一共66个,目标片段平均长度为27.6 cM,最长的系IL-52片段长度为100.5 cM,最短的系IL-50片段长度为1.5 cM。含单个渗入片段的有33个系。聚类分析结果表明,66个渗入系的遗传背景高度相似,遗传相似系数变幅为0.708~1.000,平均值为0.917。检测到一个位于4H染色体87.5 cM到110.0 cM区间的分蘖相关QTL,长度为22.5 cM,其中包含多态标记MGB396。  相似文献   

8.
A previously constructed introgression lines (ILs) population including 239 lines was used to evaluate the cold-tolerant ability. The ILs with strong cold tolerance which were identified in the present study were used for further cytological and microsatellite (SSR) marker analyses. The results showed that the IL5243 and IL5335 had strong cold-tolerant ability. Cytological analysis showed that the rate of pollen mother cells (PMCs) with normal meiotic behavior in the IL5243 and IL5335 was to 89.93 and 90.22 %, respectively, and finally formed normal mature pollen. And meanwhile, the low frequency of abnormal chromosome behavior was observed in the IL5243 and IL5335, such as univalent, 8-shape bivalent, multivalent at diakinesis. At anaphase I, one or two lagging chromosomes were observed in some PMCs (3.95–5.15 %). The results of SSR marker analysis further confirmed that partial alien DNA of common wild rice has been transferred into the IL5243 and IL5335. These results implied that the IL5243 and IL5335 might be excellent bridging germplasm for exploring and utilizing the cold-tolerant gene of common wild rice. In addition, IL5243 and IL5335 would provide a better experimental system for understanding some epigenetic phenomenon induced by alien gene introgression.  相似文献   

9.
构建水稻优良恢复系背景的重叠片段代换系及其效应分析   总被引：7，自引：2，他引：5  
通过回交程序结合分子标记辅助选择构建了一套以优良籼稻恢复系9311为背景、导入片段来源于粳稻日本晴的代换系群体。该套群体由125个代换系组成,每系含有单一或少量导入染色体片段,导入片段间相互重叠或衔接能覆盖粳稻全基因组。代换系的平均背景回复率为98.4%,导入片段平均长度为20.9 cM,纯合和杂合导入片段分别占水稻基因组的1.4%和0.2%。利用该群体,两年共检测到31个QTL影响水稻穗重、穗长、结实率和秃顶等性状;导入片段QTL对穗重和结实率均起减效作用。该套重叠片段代换系将为重要性状的基因定位、功能鉴定以及籼粳杂交育种研究提供极有价值的遗传材料。  相似文献   

10.
以珍汕97B和9311为背景的导入系构建及其筛选鉴定   总被引：9，自引：0，他引：9  
以我国主要推广的优良杂交稻亲本（珍汕97B和9311）为受体亲本,以从国际合作网络所征集的品种资源150多份为供体材料,进行了大规模杂交、3-4次回交,1～2次自交,培育珍汕97B和9311为背景的近等基因导入系近5000多份。通过对导入系材料进行品质、耐盐、耐旱、磷高效、氮高效利用等性状的筛选鉴定,获得了大量目标性状的导入系。通过对品质性状导入系的基因型分析,定位了影响粒型的15个染色体区段（或基因）。同时,构建了一套来源于粳稻日本晴的单片段导入系群体。创建的近等基因导入系（群体）为目标基因的发掘、新品种的培育提供重要的材料基础。  相似文献   

11.
The wheat progenitors and other wild relatives continue to be important sources of genes for agronomically desirable traits, which can be transferred into durum wheat (Triticum turgidum; 2n = 4x = 28; AABB genomes) cultivars via hybridization. Chromosome pairing in durum × alien species hybrids provides an understanding of genomic relationships, which is useful in planning alien gene introgression strategies. Two durum cultivars, ‘Lloyd’ and ‘Langdon’, were crossed with diploid wheatgrass, Thinopyrum bessarabicum (2n = 2x = 14; JJ), to synthesize F1 hybrids (2n = 3x = 21; ABJ) with Ph1. ‘Langdon’ disomic substitution 5D(5B) was used as a female parent to produce F1 hybrids without Ph1, which resulted in elevation of pairing between durum and grass chromosomes – an important feature from the breeding standpoint. The F1 hybrids were backcrossed to respective parental cultivars and BC1 progenies were raised. ‘Langdon’ 5D(5B) substitution × Th. bessarabicum F1 hybrids were crossed with normal ‘Langdon’ to obtain BC1 progeny. Chromosome pairing relationships were studied in F1 hybrids and BC1 progenies using both conventional staining and fluorescent genomic in situ hybridization (fl‐GISH) techniques. Multicolour fl‐GISH was standardized for characterizing the nature and specificity of chromosome pairing: A–B, A–J and B–J pairing. The A–J and B–J pairing will facilitate gene introgression in durum wheat. Multicolour fl‐GISH will help in characterizing alien chromosome segments captured in the durum complement and in their location in the A and/or B genome, thereby accelerating chromosome engineering research.  相似文献   

12.
Trifolium occidentale is a diploid wild relative with the potential to improve the drought and salt tolerances of white clover (Trifolium repens). Previous work has shown that it is possible to efficiently produce large T. repens × T. occidentale breeding populations using colchicine‐doubled (4×) T. occidentale. For effective introgression (backcross) breeding, it is also essential that interspecific chromosome pairing and recombination occur. In this study, it was apparent that chromosome pairing was occurring not only between T. occidentale and T. repens subgenomes, but also between the ancestral subgenomes of T. repens. Thus, interspecific hybridization has the potential for major genome recombination and opens the way for introgression of traits from T. occidentale into white clover.  相似文献   

13.
The introgression lines (ILs) of the wild tomato species Solanum pennellii have been widely used to identify genes related to yield, texture, disease resistance and stress tolerance. In addition to flavour, fruit firmness is an important evaluation index and essential trait indicating tomato fruit quality. Quantitative trait loci (QTL) for fruit firmness have been identified through hand squeezing and pericarp puncturing. However, these techniques hardly reveal the force value of the whole fruit suffering from rupture or deformation. In this study, S. pennellii ILs were used to identify QTLs related to fruit firmness through flat‐plate compression. Nine QTLs for enhancing and sixteen QTLs for decreasing fruit firmness were successfully identified. Compared with that of ‘M82’, the amount of QTLs that enhance fruit firmness increased by 8.76% to 21.00%, and the amount of QTLs that reduce fruit firmness decreased by ?8.27% to ?30.80%. The QTL Crf12a and Crf‐R‐7b is the strongest and weakest QTL, respectively, while they are very stable in all independent biological trials. Six QTLs should be further confirmed through open‐field trials.  相似文献   

14.
Drought stress is severely damaging during seedling stage of rice (Oryza sativa L.), which can lead to significant yield reductions. Dongxiang common wild rice (Oryza rufipogon Griff., hereafter referred to as DXWR), with strong drought resistance, could be a favorable genetic resource to improve the drought resistance of cultivated rice. Xieqingzao B (O. sativa L. ssp. indica, hereafter referred to as XB) is a representative maintainer line in hybrid rice breeding system in China. By using DXWR as donor parent, XB as recurrent parent, through continuous selfing, backcrossing and strict drought-resistant screening, we developed a strong and stable drought-resistant introgression line IL395 (BC5F10), whose ability of drought resistance was significantly increased than that of the recurrent parent XB at the seedling stage. Meanwhile, no significant differences existed among other major agronomic traits under normal condition, except for plant height. Physiological assessment revealed that IL395 exhibited a significant increase in levels of free proline and soluble sugars, which was associated with drought resistance. Whole genome marker analyses identified genomic segments of DXWR linking with RM171 and RM590 (chr. 10) and RM235 (chr. 12) that require further analysis as possible sources of drought resistance trait. These results suggest that DXWR could be a favorable genetic resource to improve the drought resistance of cultivated rice, and the IL395 might be a useful resource for excavating the drought-resistant genes from DXWR.  相似文献   

15.
Rice blast, caused by fungus Magnaporthe grisea, is a serious disease causing considerable economic damage worldwide. Best way to overcome disease is to breed for disease‐resistant cultivars/parental lines of hybrids. Pusa RH10, first aromatic, fine‐grain rice hybrid released and cultivated extensively in India. Hybrid and its parental lines, Pusa 6A and PRR78, are highly susceptible to blast. CO39 pyramid carrying two dominant, broad‐spectrum blast‐resistance genes, viz. Pi‐1 and Piz‐5, used as a donor parent to introgress these genes into PRR78 using marker‐assisted backcrossing (MABC). Microsatellite markers RM5926 and AP5659‐5 tightly linked to Pi‐1 and Piz‐5 genes, respectively, were used for foreground selection to derive introgression lines. Further, these lines were evaluated for agronomic performance, disease reaction and cooking quality traits along with PRR78. Most of the improved lines were on par with PRR78 for all traits evaluated except gelatinization temperature. Recurrent parent genome percentage (RPG) study also revealed similarity of these lines with PRR78. Hybrids derived using improved PRR78 lines were superior over Pusa RH10 in terms of yield.  相似文献   

16.
Summary Experiments were carried out for adding the chromosome carrying resistance to beet root nematode (Heterodera schachtii) from the wild Beta species of the section Patellares (B. procumbens, B. webbiana and B. patellaris) to the genome of B. vulgaris. Preliminary experiments indicated that crosses between the wild species and B. vulgaris cultivars of the mangold type yielded on average more viable F1 hybrids than crosses with sugar and fodderbeet. However, crossability varied strongly between individual parental combinations. It was concluded that most types of B. vulgaris can be hybridized with the wild species of the section Patellares if a sufficient number of pair-crosses is made. Crosses between diploid cultivars or species of the section Vulgares and diploid wild species of the section Patellares yielded many hybrids which, however, were highly sterile. From crosses between tetraploid B. vulgaris and the wild species a great number of viable allotriploid and allotetraploid hybrids was obtained. In the backcross progenies of allotriploid hybrids 26% alien monosomic additions occurred, of which 4.1% carried the resistance bearing chromosome of B. procumbens or B. patellaris. The programme will be continued by sereening progenies of the resistant monosomic addition plants for the occurrence of resistant disomic introgression products.  相似文献   

17.
Modern rice varieties that ushered in the green revolution brought about dramatic increase in rice production worldwide but at the cost of genetic diversity at the farmers’ fields. The wild species germplasm can be used for broadening the genetic base and improving productivity. Mining of alleles at productivity QTL from related wild species under simultaneous backcrossing and evaluation, accompanied by molecular marker analysis has emerged as an effective plant breeding strategy for utilization of wild species germplasm. In the present study, a limited backcross strategy was used to introgress QTL associated with yield and yield components from Oryza rufipogon (acc. IRGC 105491) to cultivated rice, O. sativa cv IR64. A set of 12 BC2F6 progenies, selected from among more than 100 BC2F5 progenies were evaluated for yield and yield components. For plant height, days to 50% flowering and tillers/plant, the introgression lines did not show any significant change compared to the recurrent parent IR64. For yield, 9 of the 12 introgression lines showed significantly higher yield (19–38%) than the recurrent parent IR64. Four of these lines originating from a common lineage showed higher yield due to increase in grain weight and another three also from a common lineage showed yield increase due to increase in grain number per panicle. For analyzing the introgression at molecular level all the 12 lines were analyzed for 259 polymorphic SSR markers. Of the total 259 SSR markers analyzed, only 18 (7.0%) showed introgression from O. rufipogon for chromosomes 1, 2, 3, 5, 6 and 11. Graphical genotypes have been prepared for each line and association between the introgression regions and the traits that increased yield is reported. Based on marker trait association it appears that some of the QTL are stable across the environments and genetic backgrounds and can be exploited universally.  相似文献   

18.
Yuval Eshed  Dani Zamir 《Euphytica》1994,79(3):175-179
The cultivated tomato contains only a small fraction of the genetic variation present in its wild relatives. In order to use the wild germplasm in tomato breeding and genetic studies we developed a new kind of genetic resource which is composed of 50 L. esculentum lines each containing a single introgression from the green fruited species L. pennellii (LA 716). Each of the introgression lines is nearly isogenic to the cultivated tomato; these lines provide complete coverage of the wild species genome. The lines contain on the average an introgression of 33 cM from a total genome size of 1200 cM. The size and identity of the introgressed segments was determined based on RFLP analysis of 350 markers. This resource can be viewed as a genomic library of the wild species in the cultivated background. It covers the entire genome with single independent inserts per line and therefore every phenotypic difference between the introgression lines can be associated with the unique introgressed segment. The development and potential application of this resource are discussed.  相似文献   

19.
Z. Hao  X. Liu  X. Li    C. Xie    M. Li    D. Zhang    S. Zhang    Y. Xu 《Plant Breeding》2009,128(4):337-341
The maize genome hosts tremendous phenotypic and molecular diversity. Introgression lines (ILs), developed by continuous backcrossing to recurrent parents, could provide a unique genetic stock for quantitative trait locus (QTL) mapping. Using maize lines from six heterotic groups of different ecological zones, we developed >500 BC2F2 IL sets by crossing 11 inbred lines (as recurrent parents) with >200 local maize inbred lines (as donor parents). Of them, 34 IL sets were selected as a subset for drought tolerance screening and a total of 417 ILs survived under severe water stress at seedling stage. One set of 32 surviving ILs, derived from Chang7-2/DHuang212, was used for QTL mapping with simple sequence repeat markers covering the whole genome, with seven QTL detected. Furthermore, investigating all surviving ILs, we identified two common regions in bin 3.04, corresponding to marker intervals bnlg1904–umc1772 and umc1223–bnlg1957, respectively, which shared high genetic variation in three IL sets. Our results indicated that selective genotyping can be used to identify genetic loci for complex traits. The ILs, highly selected for drought tolerance in this study, provide a unique set of materials for both genomic studies and development of enhanced germplasm resources.  相似文献   

20.
To integrate the gene pool of a wild species (primarily diploid) into a cultivated pool (primarily tetraploid), a crossing between a dihaploid cultivated rose and a hybrid of Rosa wichurana allowed to obtain interspecific diploid hybrids that produced 2n pollen grains. A return to a tetraploid level sought by breeders can then be considered using sexual polyploidization, obtained by crossing a tetraploid cultivated rose with these hybrids. Application of a high‐temperature regime led to a small but significant increase in the percentage of 2n pollen grains in these hybrids of up to 4.6%. This result was obtained by applying high temperatures close to 32°C during the day to plants cultivated in a glasshouse during recurrent cycles of bloom. Crosses were made between an unreleased tetraploid hybrid tea rose, as a female, and the diploid hybrid that produces the most 2n pollen grains. Tetraploid (42.1%) and triploid (57.9%) offspring were obtained. The use of these 2n pollen grains of the first division restitution type should facilitate the introgression of complex traits of interest.  相似文献   

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