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1.
Sequence diversity in the two barley (Hordeum vulgare L.) genes encoding sucrose synthase I (SSI) and sucrose phosphate synthase II (SPSII), both of which are involved in sucrose accumulation and grain filling, was studied by partial resequencing of eight reference genotypes and SNP analysis by pyrosequencing in a panel of 94 spring and 96 winter European barley varieties. The resequencing was based on two adjacent SSI fragments of size 880 and 820 bp, and a 2,322 bp SPSII fragment. In the SSI gene, 26 SNPs were present in the larger fragment, and 25 in the smaller one, and 11 of these were exploited to develop high-throughput SNP assays used for haplotype analysis. An association analysis based on either a general or a mixed linear model suggested that the predominant three haplotypes influenced certain components of both kernel and malting quality. However, the level of phenotype/haplotype association shown with the SPSII gene was rather low. SNP variation of SSI was used to map the locus to chromosome 7H.  相似文献   

2.
Barley yellow mosaic virus disease caused by different strains of BaYMV and BaMMV is a major threat to winter barley cultivation in Europe. Different resistance genes against these viruses have been mapped and suitable PCR-based markers have been developed. In this respect doubled haploid (DH) populations proved to be advantageous as they facilitate a repeated test for resistance against all agents of the barley yellow mosaic virus complex and besides this, dominant marker systems are as informative as co-dominant ones in DHs due to the lack of heterozygous genotypes. Using DH populations resistance genes rym4, rym5, rym11, rym13, rym15 and the BaYMV/BaYMV-2 resistance of the barley cultivar ‘Chikurin Ibaraki 1’ have been mapped. DHs are also well suited to pyramiding resistance genes against BaMMV and BaYMV. Since homozygous recessive genotypes are more frequent in DHs than in segregating F2 populations, DHs can be efficiently used to create broad-spectrum resistance and to extend the usability of partly overcome resistance genes. Results from employing two different strategies for pyramiding, based on one and two DH-steps, respectively, combining three recessive resistance genes, i.e. rym4/rym5, rym9 and rym11, are presented. The faster strategy based on one haploidy step resulted in the identification of all three and two-way combinations of the respective resistance genes.  相似文献   

3.
Rice is highly susceptible to drought and cold. The goal of this study was to identify the QTLs affecting the rice heading date (HD), leaf area (LA) and chlorophyll content (CC) under cold and drought stress. A total of twenty‐nine and thirty‐eight additive QTLs were detected from two crosses of ‘Dongnong422’/‘Kongyu131’ and ‘Xiaobaijingzi’/‘Kongyu131’, respectively. qHD1‐7‐1, qHD1‐7‐2, qHD1‐2‐1, qLA1‐7‐1, qLA1‐6‐3 and qCC1‐7‐1 show adaptive effects under cold treatment, while qHD2‐2‐3, qHD2‐2‐2, qLA2‐7‐3 and qCC2‐5‐1 were important for explaining the genetic mechanism during drought tolerance. Additionally, nine and five additive × environment interaction QTLs were detected for two RILs, respectively. RIL26 and RIL73 were two lines that are associated with cold and drought for HD. 339 QTLs related to HD, CC and LA of rice from database and our research were projected onto the genetic map. Nine cloned genes and nineteen homologous candidate genes related to HD, CC, cold tolerance and drought tolerance were mapped by meta‐analysis. These results lay the foundation for the fine mapping of QTLs related to HD, LA and CC for marker‐assisted selection.  相似文献   

4.
Five candidate genes LpIAA1, LpRUB1, LpBRI1, LpSHOOT1 and LpTB1 with putative function in plant architecture were allele sequenced in a panel of 96 diploid perennial ryegrass genotypes of diverse origin. The total length of the non‐redundant genomic DNA alignment was 5425 bp and revealed 270 polymorphic sites in total. A negative significant Tajima's D value was detected in LpTB1 gene, suggesting selection pressure for low‐frequency alleles in this gene. All 96 genotypes were evaluated for plant height and dry matter yield over two years. Marker–trait associations were calculated between polymorphic sites and both phenotypic traits. Three indels and three single nucleotide substitutions in LpTB1 gene were significantly (P < 0.05, q < 0.05) associated with plant height, while one indel was associated with dry matter yield. The results suggest putative role of LpTB1 gene in plant height determination in perennial ryegrass and provide means for target allele selection.  相似文献   

5.
The wheat (Triticum aestivum L.) gene Lr34/Yr18 conditions resistance to leaf rust, stripe rust, and stem rust, along with other diseases such as powdery mildew. This makes it one of the most important genes in wheat. In Canada, Lr34 has provided effective leaf rust resistance since it was first incorporated into the cultivar Glenlea, registered in 1972. Recently, molecular markers were discovered that are either closely linked to this locus, or contained within the gene. Canadian wheat cultivars released from 1900 to 2007, breeding lines and related parental lines, were tested for sequence based markers caSNP12, caIND11, caIND10, caSNP4, microsatellite markers wms1220, cam11, csLVMS1, swm10, csLV34, and insertion site based polymorphism marker caISBP1. Thirty different molecular marker haplotypes were found among the 375 lines tested; 5 haplotypes had the resistance allele for Lr34, and 25 haplotypes had a susceptibility allele at this locus. The numbers of lines in each haplotype group varied from 1 to 140. The largest group was represented by the leaf rust susceptible cultivar “Thatcher” and many lines derived from “Thatcher”. The 5 haplotypes that had the resistance allele for Lr34 were identical for the markers tested within the coding region of the gene but differed in the linked markers wms1220, caISBP1, cam11, and csLV34. The presence of the resistance or susceptibility allele at the Lr34 locus was tracked through the ancestries of the Canadian wheat classes, revealing that the resistance allele was present in many cultivars released since the 1970s, but not generally in the older cultivars.  相似文献   

6.
Drought stress is a major limiting factor for crop production in the arid and semi‐arid regions. Here, we screened eighty barley (Hordeum vulgare L.) genotypes collected from different geographical locations contrasting in drought stress tolerance and quantified a range of physiological and agronomical indices in glasshouse trails. The experiment was conducted in large soil tanks subjected to drought treatment of eighty barley genotypes at three‐leaf stage and gradually brought to severe drought by withholding irrigation for 30 days under glasshouse conditions. Also, root length of the same genotypes was measured from stress‐affected plants growing hydroponically. Drought tolerance was scored 30 days after the drought stress commenced based on the degree of the leaf wilting, fresh and dry biomass and relative water content. These characteristics were related to stomatal conductance, stomatal density, residual transpiration and leaf sap Na, K, Cl contents measured in control (irrigated) plants. Responses to drought stress differed significantly among the genotypes. The overall drought tolerance was significantly correlated with relative water content, stomatal conductance and leaf Na+ and K+ contents. No significant correlations between drought tolerance and root length of 6‐day‐old seedling, stomatal density, residual transpiration and leaf sap Cl? content were found. Taking together, these results suggest that drought‐tolerant genotypes have lower stomatal conductance, and lower water content, Na+, K+ and Cl? contents in their tissue under control conditions than the drought‐sensitive ones. These traits make them more resilient to the forthcoming drought stress.  相似文献   

7.
Drought stress is one of the most important environmental factors that limit plant growth and development, thus reducing yield. The objective of the present research was to correlate the genetic structure of different Fragaria genotypes, as assessed by Expressed Sequence Tag (EST) and Amplified Fragment Length Polymorphism (AFLP) markers, and plant responses to drought stress. Firstly, physiological parameters related to the plant response to drought stress such as leaf relative water content (RWC) and water losing rate (WLR) were measured. WLR and RWC were compared for 20 cultivars of the octaploid Fragaria × ananassa, two ecotypes of the diploid species F. vesca and one octaploid species F. chiloensis. These parameters could discriminate genotypes showing a contrasting response to water stress. Secondly, AFLP and ESTs were compared in terms of their information content and efficiency in the study of genetic diversity and relationships among these 23 Fragaria genotypes. To evaluate the genetic basis for the observed variation in the measured physiological parameter, the effect of specific AFLP/EST loci on WLR and RWC for the different Fragaria genotypes was quantified by Kruskal–Wallis analysis. By Mantel testing, the hierarchical clustering of the Fragaria genotypes based on associated EST or AFLP markers was compared to the observed eco-physiological relevant grouping. A better discriminating capacity for associated markers was noted, enabling a functional marker selection approach to screen the strawberry gene pool for drought tolerance. Correlation of EST markers to leaf RWC and WLR enforces them as potential candidate genes in control of plant responses to drought stress in Fragaria sp.  相似文献   

8.
以39份抗旱性不同的普通小麦、5份A基因组材料、4份拟斯卑尔脱山羊草（Aegilops speltoides）、6份粗山羊草（Aegilops tauschii）和2份四倍体小麦,分析TaMyb2基因的核苷酸序列长度多态性和单核苷酸多态性,及其与抗旱性的关系。结果发现,TaMyb2在A基因组材料中无目标片段扩增,在其他材料中检测到Ⅰ、Ⅱ、Ⅲ 3种类型序列。经详细分析,TaMyb2-Ⅱ序列长1 606 bp,在供试材料77 088 bp的核苷酸序列中包括34个单核苷酸变异,其中26个SNP,8个InDel,二者出现的频率分别为1/2 965 bp和1/9 636 bp,编码区π值（0.00055）小于非编码区的π值（0.00185）, 说明编码区的遗传变异小于非编码区的遗传变异。从SNP水平上分析,发现普通小麦与其D基因组供体种粗山羊草及四倍体小麦的亲缘关系较近,与B基因组供体种拟斯卑尔脱山羊草的亲缘关系较远。48份材料的TaMyb2-Ⅱ序列共分为18个单倍型（haplotype）,其中haplotype 2、3、5、6、8、9均为旱地栽培的普通小麦品种,说明普通小麦TaMyb2-Ⅱ的这几个haplotype结构可能与抗旱性有关。  相似文献   

9.
Tomato mosaic virus (ToMV) is an important Tobamovirus that causes significant crop losses. Resistance to the ToMV is conferred by the genes Tm1, Tm2 and Tm2a. Among these three genes, Tm2a confers resistance to most strains of the ToMV. Screening of genetic lines under field conditions based on phenotype is time‐consuming and challenging due to concerns associated with stability of the virus and its potential transmission to other plants. Tightly linked molecular markers associated with resistance genes can improve selection efficiency and avoid these problems. This study developed a PCR‐based marker based on restriction site differences from Tm2a locus‐specific sequences, which was found to be useful in identifying the resistant and susceptible genotypes and was consistent with phenotypic data. The marker is a codominant cleaved amplified polymorphic sequence (CAPS) marker producing 270‐ and 600‐bp DNA fragments from resistant genotypes and an 870‐bp fragment from susceptible genotypes when digested with HaeIII restriction enzyme. This novel marker can be useful for tomato breeders to screen progeny from segregating populations for ToMV resistance.  相似文献   

10.
To identify scorable marker traits that can be used in cereal breeding programs for selecting drought tolerant individuals, we investigated the correlation among the drought-associated traits in two F2 populations derived from the crosses made between drought tolerant and sensitive barley and wheat parental genotypes. The parental genotypes of these crosses also differed by at least three other traits – paraquat tolerance, leaf size, and the relative water content. These three traits were scored in two F2populations of 80 individuals for each barley and wheat cross. Analysis of results indicated that the enhanced tolerance to paraquat was correlated with reduced leaf size and increased relative water content, two traits associated with water stress phenotypes of the drought tolerant barley and wheat parents. Our results suggested that the selection based on paraquat tolerance istechnically less demanding and thus useful for rapid screening of individuals for enhanced drought tolerance in segregating populations. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

11.
PI284752, an accession of wild barley (Hordeum vulgare ssp. spontaneum) resistant to powdery mildew caused by Blumeria graminis f.sp. hordei, was studied with the aim of identifying genes involved in powdery mildew resistance. An F2 population (456 plants) was established from a cross between the winter barley variety ‘Tiffany’ and PI284752. This cross demonstrated a two-locus model of resistance. Linkage analysis using polymorphic DNA markers was carried out on 180 plants. The RGH1a gene sequence from the Mla locus was used as a source for developing the RGH1aE2I2 marker. By interval mapping on chromosome 1HS, one resistance gene was found to be tightly linked with RGH1aE2I2 and it was found to be located 2 cM from GBMS062. In F2 plants exhibiting resistance reaction type (RT) 0, specific DNA fragments for the RGH1aE2I2 marker were amplified. In plants with RT1 to RT2-3, the resistance was conferred exclusively by the second R gene that we identified, which is linked with Bmac0134 and GBMS247 on chromosome 2HS. The aforementioned markers may be valuable candidates for marker-assisted selection of resistant genotypes conferred by one or both genes.  相似文献   

12.
A novel and stable cytoplasmic male sterility CMS line of tuber mustard has been bred by subsequent backcrosses for 10 years. Two specific markers atpA and orf220 were cloned and partially characterized in our previous study (Zhang et al. 2003). In this study, two new molecular markers, orf256 and orf305/orf324, have been isolated and identified. The orf256 gene size was found to be 825 bp in CMS line and a 1,357 bp in its maintainer line. Sequence analysis indicated that the orf256 gene was an entire coding sequence and downstream of the cox1 gene. Interestingly, the 906 bp fragment, which contains part of the sequence of orf222, nad5 and orf139 genes, was found to be inserted from the 451st bp of 5′-flank of the 1,357 bp fragment. In the same way, the orf324 gene was isolated from CMS line and orf305 gene from its maintainer line. Both of them are entire coding sequences, upstream from nad3 and rps12 gene, and co-transcribed with the nad3 and rps12 genes. In addition, two molecular markers, orf256 and orf324/orf305, have been successfully converted into the SCAR markers. Subsequently, ORF256, ORF324, ORF305 protein and ORF256-M-431 fragment are predicated to contain signal peptide sequences, and ORF220 was predicated to contain signal anchor sequence. RFLP analysis results revealed that all of the molecular markers exhibited polymorphisms. Northern blot analysis indicated that the expression level of these genes in CMS line is higher than that of the maintainer line. In the mass, all of these genes are expressed lower in the leaf than that of floral organs between the CMS line and its maintainer line. The difference in expression pattern of different mitochondrial specific marker genes suggests that the abundance of mitochondrial proteins is differentially regulated in the organ/tissue development in tuber mustard. Results of this study also provide some novel and useful clues to explore the biological function of these specific marker genes in the tuber mustard.  相似文献   

13.
Pre-harvest sprouting (PHS) greatly reduces the quality and economic value of wheat grain. In this study, a total of 168 International Maize and Wheat Improvement Center (CIMMYT) wheat germplasm lines were examined to characterize the haplotypes of Vp-1A, Vp-1B and Vp-1D, which are located on the long arms of chromosomes 3A, 3B and 3D, respectively. Among them, five new alleles of Vp-1Aa (the wild allele) were identified on chromosome 3A, and designated as Vp-1Ab, Vp-1Ac, Vp-1Ad, Vp-1Ae and Vp-1Af, respectively. The main difference between Vp-1Aa and the newly identified alleles was in the numbers of CTT repeats located in the third intron, but Vp-1Af also had 6 and 2 bp deletions at positions 2860–2865 bp and 2880–2881 bp, and possessed five SNPs within the same intron region. In the Vp-1B locus, several alleles (Vp-1Ba, Vp-1Bb, Vp-1Bc, Vp-1Bd, Vp-1Be and Vp-1Bf) have already been identified. In the present material only two, the already known allele Vp-1Bc, and a new one, designated as Vp-1Bg, were detected. Compared with Vp-Ba, Vp-1Bg had additional insertion of TCC at position 2372 bp and a 9 bp change from CTGCATC AC to GCATCAGTG at 2417–2425 bp. However, no polymorphism was detected in Vp-1D. The frequencies of Vp-1Aa Vp-1Ab, Vp-1Ac, Vp-1Ad, Vp-1Ae, and Vp-1Af were 65, 10, 11, 4, 5 and 5%, respectively. For Vp-1B, 155 out of the 168 lines were Vp-1Bc; the remaining 13 were Vp-1Bg. Analyses of the germination index (GI) and abscisic acid (ABA) sensitivity showed that genotypes with Vp-1Ab or Vp-1Af showed higher PHS resistance than the ones with other alleles, suggesting that they might be valuable for CIMMYT breeding program or germplasm introduction. The results presented here will underpin the introduction of germplasm from CIMMYT and the improvement of PHS resistance, both in CIMMYT and elsewhere.  相似文献   

14.
Fusarium head blight (FHB) is a highly destructive disease of wheat and other cereals which causes serious mycotoxin contaminations of grain. A number of molecular mapping studies led to the detection of QTL with small to moderate effects on FHB resistance in European winter wheat. Genes involved in the defence reaction of these genotypes remain largely unknown. WIR1 (wheat induced resistance 1) genes have been shown to be upregulated in cereals during attack of various fungal pathogens; however, their role in resistance is ambiguous. In this study, the expression of three WIR1 genes and a gene with high sequence similarity to WIR1 was investigated in European winter wheat genotypes after inoculation with Giberella zeae. Floret tissues of four winter wheat genotypes (Dream, Lynx, G16-92, Hussar) were challenged with G. zeae conidia or water (control) and sampled six times during 0–96 h after inoculation. Quantitative real-time PCR showed that all four genes were highly upregulated in the resistant genotypes compared to the susceptible ones. WIR1b and a gene with sequence similarity to WIR1 genes mapped to chromosome 5DS in the G16-92/Hussar mapping population. Two genes annotated as WIR1a mapped in the interval of a FHB resistance QTL on chromosome 7BS in the Dream/Lynx mapping population. These could be considered possible candidate genes for quantitative FHB resistance.  相似文献   

15.
Leaf rust of barley, caused by Puccinia hordei, occurs in all barley‐growing regions of Australia causing significant yield losses under epidemic conditions. The development and use of resistant cultivars are the most economical and environmentally sustainable method to control leaf rust which in turn relies on ongoing efforts to identify and characterize new sources of resistance. The aim of this study was to postulate known genes and/or identify new sources of resistance to P. hordei. Fifty‐two genotypes were assessed at the seedling and adult plant growth stages. On the basis of multipathotype tests, 39 genotypes lacked detectable seedling resistance, and nine were postulated to carry the genes Rph2, Rph4, Rph12 and Rph19 singly. Four genotypes carried uncharacterized seedling resistance; however, the gene(s) present in each were ineffective to at least one of the pathotypes used. Field tests at the adult plant growth stage revealed the presence of adult plant resistance (APR) in 12 genotypes. Tests of allelism and marker analysis indicated that resistance genes present in these genotypes were independent of the APR gene Rph20.  相似文献   

16.
Brian J. Steffenson 《Euphytica》1992,63(1-2):153-167
Summary Since the mid-1940's, barley cultivars grown in the northern Great Plains of the USA and Canada have been resistant to stem rust caused byPuccinia graminis f. sp.tritici. This durable resistance is largely conferred by a single gene,Rpg1, derived from a single plant selection of the cultivar Wisconsin 37 and an unimproved Swiss cultivar. At the seedling stage, barley genotypes withRpg1 generally exhibit low mesothetic reactions at 16–20° C and slightly higher mesothetic reactions at 24–28° C to many stem rust pathotypes. This resistance is manifested by a low level of rust infection and mostly incompatible type uredia on adult plants.Rpg1 reacts in a pathotype-specific manner since some genotypes ofP. g. f. sp.tritici are virulent on cultivars carrying this gene in the field. Several factors may have contributed to the longevity of stem rust resistance in barley, a) since barley is planted early and matures early, it can sometimes escape damage from stem rust inoculum carried from the south; b) one or more minor genes may augment the level of resistance already provided byRpg1; c) the cultivation of resistant wheat cultivars and eradication of barberry have reduced the effective population size and number of potential new pathotypes ofP. g. f. sp.tritici, respectively; and d) virulent pathotypes ofP. g. f. sp.tritici andP. g. f. sp.secalis have not become established. This situation changed in 1989 when a virulent pathotype (Pgt-QCC) ofP. g. f. sp.tritici became widely distributed over the Great Plains. However,Rpg1 may still confer some degree of resistance to pathotype QCC because stem rust severities have been low to moderate and yield losses light on barley cultivars carrying the gene during the last four seasons (1989–1992). Several sources of incomplete resistance to pathotype QCC have been identified in barley. To facilitate the transfer of resistance genes from these sources into advanced breeding lines, molecular marker assisted selection is being employed.  相似文献   

17.
Comparative osmotic adjustments in barley and tetraploid wheats   总被引：3，自引：0，他引：3  
B. Teulat    D. Rekika    m. m.  nachit p.  monneveux 《Plant Breeding》1997,116(6):519-523
Five barley (Hordeum rulgare L.), five durum wheat (Triticum turgidum concar. durum L.) and one wild emmer wheat (Triticum turgidum conrar dicoccoides) genotypes from different origins and differing for drought tolerance and potential yield, were studied for their osmotic adjustment capacity at the same stage and under similar water stress conditions. Differences for water status parameters between barley and tetraploid wheat genotypes were noted and discussed. The lowest osmotic adjustment capacities were noted in drought susceptible varieties, while a high capacity was found in genotypes exhibiting a high yield stability across contrasting environments. Relative water content, leaf osmotic potential and accumulation of soluble sugars were found to be highly related with osmotic adjustment: they could be used as criteria for a rapid evaluation of osmotic adjustment in segregating populations.  相似文献   

18.
Drought is one of the major factors limiting barley yields in many developing countries worldwide. The identification of molecular markers linked to genes controlling drought tolerance in barley is one way to improve breeding efficiency. In this study, we analyzed the quantitative trait loci (QTL) controlling chlorophyll content and chlorophyll fluorescence in 194 recombinant inbred lines (RILs) developed from the cross between the cultivar ‘Arta’ and Hordeum spontaneum 41-1. Five traits, chlorophyll content, and four chlorophyll fluorescence parameters, namely initial fluorescence (Fo), maximum fluorescence (Fm), variable fluorescence (Fv), and maximum quantum efficiency of PSII (Fv/Fm) which are related to the activity of the photosynthetic apparatus, were measured under well-watered and drought stress conditions at post-flowering stage. QTL analysis identified a total of nine and five genomic regions, under well-watered and drought stress conditions, respectively, that were significantly associated with the expression of the five target traits at post-flowering stage. No common QTL was detected except one for chlorophyll content, which was identified in both growth conditions, demonstrating that the genetic control of the expression of the traits related to photosynthesis differed under different water conditions. A QTL for Fv/Fm, which is related to the drought tolerance of photosynthesis was identified on chromosome 2H at 116 cM in the linkage map under drought stress. This QTL alone explained more than 15% of phenotypic variance of maximum quantum yield of PSII, and was also associated with the expression of four other traits. In addition, another QTL for Fv/Fm was also located on the same chromosome (2H) but at 135.7 cM explaining around 9% of the phenotypic variance under drought conditions. The result presented here suggest that two major loci, located on chromosome 2H, are involved in the development of functional chloroplast at post-flowering stage for drought tolerance of photosynthesis in barley under drought stress. If validated in other populations, chlorophyll fluorescence parameters could be used as selection criteria for drought tolerance.  相似文献   

19.
The greenbug [Schizaphis graminum (Rondani)] is an extremely damaging pest of barley (Hordeum vulgare L), particularly in the southern Great Plains of the USA. Two greenbug resistance genes, Rsg1a (in ‘Post 90’) and Rsg2b (in PI 426756), available for developing resistant barley cultivars, have similar phenotypes when challenged by various greenbug biotypes. This study was conducted to separate these two resistance genes via differential plant reactions to a recently collected field isolate of greenbug. Four barley entries and one wheat germplasm were challenged with two greenbug isolates and damage ratings were recorded for each combination. One greenbug isolate used in this study (TX1) was able to differentiate Rsg1a from Rsg2b through dramatically different plant responses (Rsg2b conferred resistance, Rsg1a did not). The results indicate the potential vulnerability of greenbug resistance genes in barley. Based on these and other reported results, we propose that gene symbol designations for greenbug resistance in barley be changed from Rsg1a to Rsg1 and Rsg2b to Rsg2.  相似文献   

20.
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