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1.
Hybrid rice technology offers a great promise to produce 15% to 20% more yield than pure line varieties. The success of hybrid rice hinges on developing superior parental lines. To improve the blast resistance of hybrid rice parental line RP5933-1-19-2R, crosses were made with donors of two major blast resistance genes namely, Pi54 (Tetep) and Pi9 (IR71033–121-15) and the resulting F1s were confirmed for their hybridity by using Pi54MAS and NMSMPi9-1 genic markers. The confirmed F1s were intercrossed to obtain ICF1s and selected positive plants by markers were backcrossed to the recurrent parent, as well as selfed for advancing further to BC1F3 and ICF4 generations. The segregating plants were phenotyped for blast resistance at Uniform Blast Nursery. The identified complete restorers namely, RP 6619-1, RP 6616-26, RP 6619-3 and RP 6619-11 with Pi9 and Pi54 genes would serve as donors for broad spectrum blast resistance. This could ultimately lead to the development of new rice hybrids with improved resistance to blast disease, which is crucial for sustainable rice production and food security.  相似文献   

2.
An F8 recombinant inbred population was constructed using a commercial indica rice variety Zhong 156 as the female parent and a semidwarf indica variety Gumei 2 with durable resistance to rice blast as the male parent. Zhong 156 is resistant to the fungus race ZC15 at the seedling stage but susceptible to the same race at the flowering stage. Gumei 2 is resistant to ZC15 at both stages. The blast resistance of 148 recombinant inbred lines was evaluated using the blast race ZC15. Genetic analysis indicated that the resistance to leaf blast was controlled by three genes and the presence of resistant alleles at any loci would result in resistance. One of the three genes did not have effects at the flowering stage. Two genes, tentatively assigned as Pi24(t) and Pi25(t), were mapped onto chromosome 12 and 6,respectively, based on RGA (resistance gene analog), RFLP and RAPD markers. Pi24(t) conferred resistance to leaf blast only, and its resistance allele was from Zhong 156. Pi25(t) conferred resistance to both leaf and neck blast, and its resistance allele was from Gumei 2. In a natural infection test in a blast hot-spot, Pi25(t) exhibited high resistance to neck blast, while Pi24(t) showed little effect. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

3.
The rice cultivar ‘Chumroo’ is commonly cultivated in the mid- and high-altitude areas of Bhutan. This cultivar has shown durable blast resistance in that area, without evidence of breakdown, for over 20 years. Chumroo was inoculated with 22 blast isolates selected from the race differential standard set of Japan. The cultivar showed resistance to all the isolates. To identify the resistance gene(s), Chumroo was crossed with a susceptible rice cultivar, Koshihikari. The F1 plants of the cross showed resistance. Segregation analyses of 300 F3 family lines fitted the segregation ratio of 1:2:1 and indicated that a single dominant gene controls the resistance to a blast isolate Ao 92-06-2 (race 337.1). The Chumroo resistance locus (termed Pi46(t)) was mapped between two SSR markers, RM6748 and RM5473, on the terminal region of the long arm of chromosome 4, using linkage analysis with SSR markers. The nearest marker, RM5473, was linked to the putative resistance locus at a map distance of 3.2 cM. At the chromosomal region, no true resistance genes were identified, whereas two field resistance genes were present. Therefore, we designated Pi46(t) as a novel blast resistance locus.  相似文献   

4.
IR 58025A is a very popular wild‐abortive cytoplasmic male sterile (WA‐CMS) line of rice and is extensively used for hybrid rice breeding. However, IR 58025A and many hybrids derived from it possess mild aroma (undesirable in some parts of India) and are highly susceptible to bacterial blight (BB) and blast diseases. To improve IR 58025A for BB and blast resistance, we have introgressed a major dominant gene conferring resistance against BB (i.e. Xa21) and blast (i.e. Pi54) into IR 58025B, the maintainer line of IR 58025A. An introgression line of Samba Mahsuri (i.e. SM2154) possessing Xa21 and Pi54 genes in homozygous condition and fine‐grain type was used as donor parent, and backcross breeding strategy was adopted for targeted introgression of the resistance genes. PCR‐based molecular markers tightly linked to Xa21 and Pi54 were used for selection of BB‐ and blast‐resistant lines, while closely linked markers were used for identification of backcross‐derived plants devoid of Rf4 and aroma. At BC2F5, four backcross‐derived lines possessing resistance against BB and blast, devoid of aroma, high yield, short plant stature, long‐slender grain type and with recurrent parent genome recovery ranging from 88.8% to 98.6% were selected and advanced for further evaluation. The improved versions of IR 58025B, viz. SB54‐11‐143‐9‐44‐5, SB54‐11‐143‐9‐44‐98, SB54‐11‐143‐9‐44‐111 and SB54‐11‐143‐9‐44‐171, behaved as perfect maintainers when test‐crossed with WA‐CMS lines. Agronomically superior lines of improved IR 58025B are being converted to CMS line through backcrossing for developing high‐yielding and biotic stress‐resistant rice hybrids.  相似文献   

5.
Rice blast, caused by the fungus Magnaporthe oryzae, is the most devastating fungal disease of rice. Mowanggu, a local japonica cultivar in Yunnan Province, China, confers broad-spectrum resistance to this pathogen. To identify the resistance gene(s) in Mowanggu, we obtained an F2 population and 280 F8 recombinant inbred lines (RILs) from a cross between Mowanggu and CO39, a highly susceptible indica cultivar. A linkage map with 145 simple sequence repeat (SSR) and single feature polymorphism markers over 12 chromosomes was constructed using the 280 RILs. The resistance evaluation of the F2 and F8 populations in both the growth chamber and in a natural rice blast nursery showed that a single dominant gene controls blast resistance in Mowanggu. Moreover, nine quantitative trait loci, which were responsible for different partial resistance components, were mapped on chromosomes 2, 3, 6, 8, 9, and 12, making contributions to the phenotypic variation ranging from 3.03 to 6.18 %. The dominant resistance gene, designated Pi49, was mapped on chromosome 11 with genetic distance of 1.01 and 1.89 cM from SSR markers K10 and K134, respectively. The physical distance between K10 and K134 is about 181 kb in the Nipponbare genome. The Pi49 gene accounted for the major phenotypic variation of disease severity in the growth chamber (where plants were inoculated with single blast isolates) and also accounted for most of the phenotypic variance of disease severity, lesion number, diseased leaf area, and lesion size in the blast nursery. Our study not only identified tightly linked markers for introgression of Pi49 into elite rice cultivars via marker-aided selection but also provides a starting point for map-based cloning of the new resistance gene.  相似文献   

6.
We investigated the mode of inheritance and map location of field resistance to rice blast in the elite rice strain Chubu 111, and yield under severe blast conditions. Chubu 111 carries the complete resistance gene Pii, although field testing showed this strain to be susceptible to infection. The level of field resistance of Chubu 111 was so high that chemicals used to control blast were not required, even in an epiphytotic area. Genetic analysis of field resistance to blast in 149 F3 lines derived from a cross between Chubu 111 and the susceptible cultivar ‘Mineasahi’ suggested that field resistance is controlled by a dominant gene, designated Pi39(t), that cosegregates with the single sequence repeat marker loci RM3843 and RM5473 on chromosome 4. Comparative studies of polymorphism at RM3843 among Chubu 111 and six cultivars or lines in its pedigree suggested that the donor of the resistance gene was the Chinese cultivar ‘Haonaihuan’. Marker‐assisted selection of Pi39(t) should be useful in rice‐breeding programmes for field resistance to blast.  相似文献   

7.
In Triticum durum Defs., gynogenesis was investigated on six genotypes, Cocorit, Isly, Jori, Oued Zénati, Sarif, issued from Morocco,and Cham1 from Syria. The experiments described here were made during two seasons (spring and summer) in which batches of 1,036 and 3,750 unpollinated ovaries were used. A 4 °C pretreatment was applied, during 7, 11 or 15 days and the A (modified Jähne's et al.,1991) and B (modifed San N?um's, 1976) induction media were compared. The spikes were harvested when microspores were at bi- or trinucleate stage. After the 4 °C cold pretreatment, they were sterilized, and the excised ovaries underwent the following phases and sequence of successive media. The A or B ‘induction’ media, induced cell divisions in the female gametophytes, and after 4 to 9 weeks in dark conditions, the swelling ovaries burst. The growing calluses were excised and transferred to 16 h. light onto a differentiation medium (dif); there generated shoots were then placed on a development (dev), followed by a rooting medium (r). The comparison of the two experiments showed that summer was the best season, for in vitro unpollinated ovary culture; this period corresponds to a growth of mother-plants during spring, while those developing in winter gave rise to lower scores. In Experiment 1 the best level of regenerated plants per 100 ovaries were obtained for Isly with 14.3% and for Oued Zénati with 10.1%. In Experiment 2, the best values were those of Isly with 21.8%, after a 7 day cold pretreatment and use of induction medium B, and of Cocorit with 18.1%. Jori, exhibited good results, in three define situations, with 17.1%, 16%, and 9.3%.Only Cham1 and Sarif showed very low scores or no plants. Jori remaining aside, for each genotype, the best values rose up from a specific treatment combination, as a very strong interaction was expressed between genotype, induction medium and cold pretreatment duration. After this ‘first phase’ of regeneration by ovary culture 150 haploid plants were obtained. When combining these results with other attempts, a total number of 191 green plants was regenerated, 90 for Isly, 74 for Jori, 19 for Cocorit, 7 for Oued Zénati and 1 for Cham1. In a ‘second phase’, permanent regenerating callus lines were obtained through subculture on dif medium. Depending on genotype, 2 to 9 transfers (up to one year for Jori) were performed, giving 507 regenerated plants. From direct regeneration and subcultures, a total of 698 plants were produced, all green and mostly haploid. Fertile doubled haploid plants were obtained, either spontaneously or by colchicine treatment, for all these genotypes. These results are of interest for breeders, who need pure lines for genotypes evaluation and for the creation of improved homozygous varieties.  相似文献   

8.
The use of host resistance (R) genes is considered the most cost‐effective option to control the rice blast disease. The two allelic R genes Pi2 and Pi9 confer very broad‐spectrum resistance against blast isolates collected worldwide. However, the two genes have not yet been widely deployed in rice breeding programmes. Availability of specific markers for them would facilitate incorporating the two R genes into new rice lines through marker‐assisted selection. Herein, we report the development and utilization of a robust and specific marker for the Pi2 and Pi9. This marker was derived from polymorphisms within the target gene, and achieved simultaneously distinguish Pi2 and Pi9 from other alleles through high‐resolution melting of a small amplicon. With the marker, we were able to transfer the Pi2 into an elite restorer line through marker‐assisted backcrossing, successfully obtained effective resistance to blast disease, and we were also able to, respectively, incorporate the Pi2 and Pi9 with two other R genes. As the additive effect, blast resistance in these stacking lines harbouring three R genes were significantly improved.  相似文献   

9.
This research was undertaken to find an efficient tissue culture system and Agrobacterium-mediated genetic transformation method for recalcitrant indica rice cultivars. For this, mature seeds of commercially important indica rice varieties, ASD16, ADT43, IR 64, and Pusa Basmati were cultured on MS and N6 medium supplemented with 2 mg l-1 2, 4-D + 30 g l-1 sucrose. The calli grown in N6 medium showed better friability and embryogenic response. Out of the four varieties tested, ASD16 and IR64 showed better callusing and embryogenic capacity as compared to ADT43 and Pusa Basmati. For genetic transformation studies, embryogenic calli of all the cultivars were co-cultivated with the Agrobacterium tumefaciens strain LBA 4404 harboring the binary vector pCambia 1305.1 with GUS gene. GUS assay was performed for the putative transformed calli and its activity was found to be qualitatively higher in ASD16 and IR64 than the other two varieties. The best responsive ASD16 transformed calli was regenerated and the putative transgenic lines were regenerated. ASD16 transformed calli were confirmed by GUS assay. PCR analysis confirmed the presence of both GUS and HPT genes in ASD16 transgenic lines.  相似文献   

10.
Molecular screening and genetic diversity of major rice blast resistance (R) genes were determined in 32 accessions of rice germplasm from North East and Eastern India with ten gene based single nucleotide polymorphisms and sequence tagged sites (STS) markers, namely z56592, zt56591, k39512, k3957, candidate gene marker, Pita3, YL155/YL87, YL183/YL87, Pb28, 195R-1 which showed close-set linkage to nine major rice blast resistance (R) genes, Piz, Piz-t, Pik, Pik-p, Pik-h, Pita/Pita-2, Pib and Pi9 and one susceptible pita gene. Among the 32 accessions, 13 were positive for Piz gene and six for Piz-t gene. Six accessions were positive for Pik gene, seven for Pik-p and 16 for Pik-h gene. One accession, Atte thima, was positive for three of Pik multiple genes. Out of 32, only two germplasm, Dudhraj and Nepali dhan, were detected with both Pita3 and YL155/YL87 marker for Pita/Pita-2 gene. The Pib gene appeared to be omnipresent and was detected in 31 of 32 germplasm with marker Pb28. The gene specific STS marker, 195R-1, for Pi9 gene produced positive bands in only two germplasm, Kalchatti and Bachi thima. The Uniform Blast Nursery (UBN) analysis showed that out of 32, six germplasm was resistant, ten moderately resistant and 16 germplasm were susceptible. Presence of Piz-t, Pita/Pita-2 and Pi9 gene ensured a resistant reaction in outdoor blast nursery whereas germplasm carrying Pib was susceptible when present alone. Presence of multiple genes, however, contributed to slow blasting resistance in the field. These results are useful in identification and incorporation of resistant genes from the germplasm into elite cultivars through marker assisted selection in rice breeding programs.  相似文献   

11.
Rice blast, caused by the fungal pathogen Magnaporthe oryzae, is one of the most devastating diseases of rice (Oryza sativa) worldwide. Identification and utilization of resistance genes in rice breeding is considered to be an effective and economical method to control this disease. Hanghui 1179 (HH1179) is a new native rice restorer line developed in South China. The hybrids derived from HH1179 show broad-spectrum resistance against rice blast in South China, and a further understanding of the genetic resistance in HH1179 will provide useful information for breeding resistant cultivars. In the present study, we used bulked segregant analysis combined with specific-length amplified fragment sequencing to identify a dominant gene from HH1179 that provides resistance against the rice blast isolate GD13-14. Association analysis indicated that the resistance gene is located on chromosome 6 and we mapped the target gene to a 100.8 kb region (between markers InDel-8 and RM19818) that contains the Pi2/Pi9/Piz/Piz-t/Pi50 gene cluster. Candidate gene prediction and cDNA sequencing indicated that the target resistance gene in HH1179 is Pi2. Our findings will be valuable for resistance breeding with restorer line HH1179.  相似文献   

12.
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   

13.
A traditional Type 3 Basmati rice cultivar grown in India is tall and lodges even under low nitrogen fertilizer dose. In addition to lodging, it is highly susceptible to several diseases and pests including bacterial blight (BB). BB resistance genes (Xa21 and xa13) and a semidwarfing gene (sd-1) were pyramided in Type 3 Basmati from a rice cultivar PR106-P2 using marker-assisted selection (MAS). Foreground selection for BB resistance genes, Xa21 and xa13 and reduced plant height gene, sd-1 was carried on the basis of linked molecular markers pTA248, RG136 and ‘h’, respectively. The BC2F3 progenies with both the BB resistance genes were highly resistant with lower lesion length than either of the genes individually. Background profiling of the selected 16 BC2F3 progenies was done using 95 anchored SSR and 12 ISSR markers. Among the selected 16 BC2F3 progenies, 38-5-2 and 38-5-36 closely clustered along with the recipient parent Type 3 Basmati showing above 85% genetic similarity with the same. Further selection was continued till F5 generation for higher recovery for Type 3 Basmati characteristics. The desirable alleles of intermediate amylose content (wx) and aroma (fgr) loci of Type 3 Basmati were also tracked using the linked SSR markers. The BC2F5 pyramid lines T3-4, T3-5, T3-6 and T3-7 homozygous for the three target genes Xa21, xa13 and sd-1 from the donor parent with wx and fgr alleles of Type 3 Basmati had excellent cooking quality and strong aroma.  相似文献   

14.
A total of 324 Japanese rice accessions, including landrace, improved, and weedy types were used to 1) investigate genetic variations in blast resistance to standard differential isolates, and 2) across the genome using polymorphism data on 64 SSR markers. From the polymorphism data, the accessions were classified into two clusters. Accessions from irrigated lowland areas were included mainly in cluster I, and upland and Indica types were mainly in cluster II. The accessions were classified into three resistance subgroups, A2, B1 and B2, based on the reaction patterns to blast isolates. The accessions in A2 were postulated to have at least two resistance genes Pish and Pik-s, whereas those in B1 had various combinations of the resistance genes Pish, Pia, Pii, Pi3, Pi5(t), and Pik alleles. The B2 accessions were resistant to almost all isolates, and many accessions of cluster II were included, and had Pish, Pia, Pii, Pi3, Pi5(t), certain Pik, Piz and Pita alleles, and unknown genes. The frequencies of accessions of B1 originating in Hokkaido, and those of B2 originating in the Kanto and Tohoku regions were remarkably higher than in the other regions.  相似文献   

15.
The root lesion nematode Pratylenchus thornei is widely distributed in Australian wheat (Triticum aestivum) producing regions and can reduce yield by more than 50%, costing the industry AU$50 M/year. Genetic resistance is the most effective form of management but no commercial cultivars are resistant (R) and the best parental lines are only moderately R. The wild relatives of wheat have evolved in P. thornei-infested soil for millennia and may have superior levels of resistance that can be transferred to commercial wheats. To evaluate this hypothesis, a collection of 251 accessions of wheat and related species was tested for resistance to P. thornei under controlled conditions in glasshouse pot experiments over two consecutive years. Diploid accessions were more R than tetraploid accessions which proved more R than hexaploid accessions. Of the diploid accessions, 11 (52%) Aegilops speltoides (S-[B]-genome), 10 (43%) Triticum monococcum (A m -genome) and 5 (24%) Triticum urartu (A u -genome) accessions were R. One tetraploid accession (Triticum dicoccoides) was R. This establishes for the first time that P. thornei resistance is located on the A-genome and confirms resistance on the B-genome. Since previous research has shown that the moderate levels of P. thornei resistance in hexaploid wheat are dose-dependent, additive and located on the B and D-genomes, it would seem efficient to target A-genome resistance for introduction to hexaploid lines through direct crossing, using durum wheat as a bridging species and/or through the development of amphiploids. This would allow resistances from each genome to be combined to generate a higher level of resistance than is currently available in hexaploid wheat.  相似文献   

16.
Breeding for field resistance to Septoria tritici blotch (STB), caused by Mycosphaerella graminicola (anamorph: Septoria tritici), is the most suitable strategy for controlling this important disease of wheat. Although many Stb genes for resistance to single pathogen isolates have been identified in wheat, knowledge of their efficiency against natural fungal populations is lacking. In a quantitative-trait-locus (QTL) mapping approach in six environments and four locations, field resistance to STB was studied in a doubled-haploid population derived from a cross between the field-resistant cultivar Solitär and the susceptible cultivar Mazurka. After plant height as a disease escape trait was accounted for, five QTL with effects on STB response on chromosomes 5A, 6D and 7D explained 20 % of the genotypic variance; QTL × environment interactions were minor. Field resistance was conferred exclusively by alleles from Solitär, which was previously shown to carry the isolate-specific genes Stb6 and Stb11 as well as minor QTL detected with seven fungal isolates. Surprisingly, neither the Stb6 nor Stb11 isolate-specific genes nor minor QTL previously detected in Solitär were found to be involved in its field resistance. The study suggests that resistance breeding for STB should not rest solely on the deployment of Stb genes. Field tests are indispensable to show their efficacy and durability and to identify genes conferring partial field resistance to STB.  相似文献   

17.
In the present study, we performed the resistance assessment by rice blast inoculation on IRBLta2-Re and IRBLta-CP1, the experimental lines supposed to carry rice blast resistance genes Pita2 and Pita, respectively. The analysis by using 196 rice blast isolates derived from China indicated that the resistance spectrum of IRBLta2-Re was broader than that of IRBLta-CP1. Both IRBLta2-Re and IRBLta-CP1 have the Pita gene by analyzing the functional single amino acid difference of Pita/pita locus. To identify the additional gene in IRBLta2-Re, 1250 F2 individuals from the cross between CO39 and IRBLta2-Re were used as the mapping population. The F2 population was inoculated with the blast isolate 08-T4 which was incompatible to IRBLta2-Re, but compatible to CO39 and IRBLta-CP1. In the phenotypic data analysis, the F2 population segregated in a 3:1 ratio for resistant and susceptible plants, respectively, suggesting that IRBLta2-Re has an additional resistance gene other than Pita, which was tentatively designated Pita3(t) (supposed to be Pita2). To identify the Pita3(t), a total of 50 microsatellite and 12 position specific microsatellite markers distributed by two sides of the Pita gene were selected in the parent polymorphism screening. The results showed that PT4 and PT5 were co-segregated with the target gene. A contig map corresponding to the resistance gene and Pita genes was constructed based on the fine mapping and bioinformatics assay. The resistance gene, Pita3(t), was, thus, assumed to be in an interval of approximately 178 kb which containing a total of 5 NBS–LRR genes, and was about 500 kb away from the Pita gene.  相似文献   

18.
Rice blast (Magnaporthe oryzae) is the most destructive and epidemic disease of rice. Use of host resistance is the best alternative for disease management. The leaf and neck blast resistance of 182 rice breeding lines were assessed for leaf and neck blast and classified relative to a susceptible check-Masuli and resistant check-Laxmi, from greenhouse experiment in 2005 and 2006. The test plants were inoculated with 105 conidial suspension/ml of M. oryzae at 21 days old seedlings for the leaf blast, and at neck base for the neck blast. Among them, for leaf blast, 77 rice lines were resistant, 43 were moderately resistant, 39 were moderately susceptible and 23 were susceptible. While among the selected 31 rice lines evaluated for neck blast, 4 lines were resistant, 4 were moderately resistant, 16 were moderately susceptible and 7 were susceptible. Leaf and neck infection was significant and positively correlated (r = 0.30, P = 0.05). The rice lines, Barkhe 1032, Barkhe 1034, Barkhe 1035, Barkhe 1036, Barkhe 2014, Barkhe 2024, Barkhe 3019, Super 3004 were resistant to leaf blast and Barkhe 1006, Barkhe 1032, Barkhe 1035, Barkhe 3004 were resistant to neck blast. The rice lines with identification # 11, 69, 137, 168, 182 from Masuli × MT4 parentage, and Barkhe 3017 were susceptible to both leaf and neck blast. Progenies of Irradiated Pusa Basmati (IPB), Kalinga III/IR64 (KIII/IR64), and Masuli/IR64 were resistant to both leaf and neck blast. However, most progenies from Masuli/MT4 showed susceptible reaction to both leaf and neck blast. Thus, rice lines form the IPB, KIII/IR64 and Masuli/IR64 will be promising resistant sources for rice blast in breeding programme.  相似文献   

19.
Q. H. Pan    L. Wang    H. Ikehashi    H. Yamagata  T. Tanisaka 《Plant Breeding》1998,117(1):27-31
The Chinese native rice cultivar ‘Maowangu’ expresses a high level of resistance to many races of rice blast (Pyricularia grisea) collected from North China and Japan. ‘Maowangu’ was crossed with 10 Japanese differential cultivars and the susceptible Chinese cultivar ‘Lijiangxintuanheigu’ (LTH). Allelism tests were conducted in the F2 populations with rice blast races. The resistance of ‘Maowangu’ was governed by two dominant genes which were non-allelic to the resistance genes at seven loci: Pi-a, Pi-i, Pi-k, Pi-z, Pi-ta, Pi-b, and Pi-t. To identify the two resistance genes, two F3 lines of ‘Shin 2/Maowangu’ segregating 3R:1S were selected for linkage tests in 1994. One was linked to marker genes C and Amp-3 on chromosome 6 with recombination frequencies of 35.8 ± 6.4% and 42.1 ± 6.2%, respectively, and the other to Amp-1 on chromosome 2 with a recombination frequency of 37.6 ± 6.0%. To confirm these results, two F3 lines of ‘LTH/Maowangu’ were selected for linkage tests in 1995. The one was linked to Amp-3, and other was linked to Amp-1, with recombination frequencies of 36.9 ± 3.1% and 34.3 ± 3.2%, respectively. The two genes on chromosomes 6 and 2 were designated Pi13(t) and Pi14(t), respectively.  相似文献   

20.
M. Gowda    S. Roy-Barman    B. B. Chattoo 《Plant Breeding》2006,125(6):596-599
Blast, caused by Magnaporthe grisea, is the most devastating disease of rice worldwide. In this study, the main objective was to identify and map a new gene for blast resistance, in an indica rice cultivar ‘Tadukan’ against blast fungal isolate B157, using molecular tools. F2 segregating population was derived from ‘CO39’ (susceptible) and ‘Tadukan’ (resistant), and molecular mapping of the blast resistance gene was carried out using simple sequence length polymorphism (SSLP) and amplified fragment length polymorphism (AFLP) methods. Two SSLP markers, RM206 and RM21 and three AFLP markers (AF1: E‐aca/M‐ctt; AF2: E‐aca/M‐cat and AF3: E‐acc/M‐cac2) were identified to be linked to the resistance gene. The co‐segregation analysis using SSLP markers implied that the blast resistance gene designated Pi38 resides on rice chromosome 11.  相似文献   

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