水稻品种资源91 1A②对稻瘿蚊的抗性鉴定及其遗传分析

 以抗虫品种资源91 1A②为父本,分别与粳桂、TN1、W1263（Gm1）、 IET2911（Gm2）、BG404 1（gm3）、OB677（Gm4）、ARC5984（Gm5）和多抗1号（Gm6）（母本）进行杂交、测交、自交,获得F1、BC1F1、F2群体,对亲本和各个群体进行稻瘿蚊的抗性鉴定,研究91 1A②的抗性基因和遗传规律。结果表明,91 1A②及其与其他品种杂交获得的F1都抗中国稻瘿蚊生物型Ⅳ型,杂交获得的BC1F1和F2对中国稻瘿蚊生物型Ⅳ型的抗虫和感虫植株分离比经χ2测验分别符合1∶3和9∶7,说明91 1A②对中国稻瘿蚊生物型Ⅳ型的抗性受2对显性基因控制。91 1A②所含的2对抗性基因与已知的6个抗性基因Gm1、Gm2、gm3、Gm4、Gm5和Gm6不等位,与其他5个抗性基因Gm7、Gm8、Gm9、Gm10、Gm11(t)也不等位。该抗性基因可能是2对新的抗性基因。     

利用分子标记辅助选择改良水稻恢复系的稻瘿蚊抗性

以含有华南4种稻瘿蚊生物型显性抗性基因Gm6的籼稻材料KG18为供体,三系优质恢复系广恢998为受体,通过杂交、多次回交和自交结合分子标记辅助选择技术,将Gm6基因导入广恢998中。综合目标基因的分子检测、田间农艺性状表现以及遗传背景的回复率,筛选获得6个株系。采用稻瘿蚊生物型1和生物型4对这些改良株系进行人工接虫鉴定,6个改良株系的标葱率为0,表现免疫,而对照标葱率均在98%以上,表现高感;由改良株系组配的杂种F1标葱率在10%～20%,表现中抗。农艺性状分析表明,除1个株系在千粒重方面与对照广恢998有显著差异外,其余改良株系性状与对照无显著差异。     

水稻品种RP1976-18-6-4-2对褐飞虱和稻瘿蚊的抗性评价及其遗传分析

对水稻品种RP1976-18-6-4-2进行褐飞虱和稻瘿蚊的抗性评价及其遗传分析。结果表明,该品种抗褐飞虱生物型Ⅱ、孟加拉型及稻瘿蚊中国Ⅱ型和中国Ⅳ型,它对褐飞虱生物型Ⅱ和孟加拉型的抗性由1对显性基因和1对隐性基因控制;对稻瘿蚊中国Ⅱ型和中国Ⅳ型的抗性由1对显性基因控制。     

Marker-Assisted Selection of Xa21 Conferring Resistance to Bacterial Leaf Blight in indica Rice Cultivar LT2

Bacterial leaf blight of rice (BLB), caused by Xanthomonas oryzae pv. oryzae, is one of the most destructive diseases in Asian rice fields. A high-quality rice variety, LT2, was used as the recipient parent. IRBB21, which carries the Xa21 gene, was used as the donor parent. The resistance gene Xa21 was introduced into LT2 by marker-assisted backcrossing. Three Xoo races were used to inoculate the improved lines following the clipping method. Eleven BC₃F₃ lines carrying Xa21 were obtained based on molecular markers and agronomic performance. The 11 lines were then inoculated with the three Xoo races. All the 11 improved lines showed better resistance to BLB than the recipient parent LT2. Based on the level of resistance to BLB and their agronomic performance, five lines (BC₃F₃ 5.1.5.1, BC₃F₃ 5.1.5.12, BC₃F₃ 8.5.6.44, BC₃F₃ 9.5.4.1 and BC₃F₃ 9.5.4.23) were selected as the most promising for commercial release. These improved lines could contribute to rice production in terms of food security.     

水稻抗稻瘿蚊基因的研究与利用现状

综述了稻瘿蚊(Orscolia oryzae)的生物学特征及其分布、生物类型,重点介绍了抗稻瘿蚊基因的鉴定和定位研究以及应用现状,并对今后抗稻瘿蚊的研究提出了几点建议。     

Improving Rice Blast Resistance by Mining Broad-Spectrum Resistance Genes at Pik Locus

Magnaporthe oryzae is known for its genetic diversity and pathogenic variability, leading to rapid breakdown of resistance in rice. Incorporating multiple broad-spectrum blast resistance genes into rice cultivars would extend disease resistance longevity. Effective resistance breeding in rice therefore requires continual enrichment of the reservoir of resistance genes and alleles. We conducted a large-scale screen of rice blast resistance in about 2 000 rice accessions. Among them, 247 accessions showed at least medium resistance to the natural infection of rice blast and 7 novel Pik alleles were identified from them. Variations in gene sequences were then correlated with the phenotypic trait to enable the identification of favorable alleles. Among the seven novel Pik alleles, the resistant rate of Pik-R0/ME/7017 donors was greater than 80%, and the disease score was less than 3. Through molecular marker-assisted backcross breeding, we successfully transferred the three Pik alleles, Pik-R0/ME/7017, into an elite cultivated line Kongyu 131 to obtain BC₃F₂ lines, which showed enhanced resistance to rice blast compared with the recurrent parent. Assessment of these near-isogenic lines in the greenhouse using 31 isolates of M. oryzae from Heilongjiang Province of China revealed that the resistant levels of the BC₃F₂ lines with Pik-R0/ME/7017 were significantly higher than those of the established cloned resistance genes Pik-m and Pi1. Exploring such alleles will enrich our gene library for resistance to rice blast.     

玉米矮花叶病抗病基因Rscmv1的精细定位

以感病亲本Mo17为轮回亲本、抗病亲本四一为供体亲本,构建近等基因系,对抗病基因Rscmv1进行精细定位。结果表明,在自交系四一中定位了两个抗病基因Rscmv1和Rscmv2,其中Rscmv1是抗源中普遍存在的主要抗病基因。以选育的近等基因系BC4F3、BC4F4和BC4F5为定位群体,在抗病基因区域内开发了9个有多态性的BAC-SSR标记,将Rscmv1定位在BAC-SSR标记A5-1和B2-1之间,其遗传距离分别为0.3 cM和0.6 cM,2个标记之间的物理距离为1.38 Mb。     

Transgressive variants for red pericarp grain with high yield potential derived from Oryza rufipogon × Oryza sativa: Field evaluation, screening for blast disease, QTL validation and background marker analysis for agronomic traits

Five transgressive variants (advanced breeding lines from BC₂F₅ and BC₂F₆ generation) were derived from a cross between the wild relative, O. rufipogon Griff. and O. sativa L. subsp. indica cv. MR219, a popular high yielding Malaysian rice cultivar. The aim of the study was to evaluate the pericarp colour of the grains along with yield potential and to validate quantitative trait loci (QTLs) for agronomic traits. The variants were screened against blast disease. Background marker analysis was also done for the promising variants. The field trials were carried out at a single location (due to containment purposes) over two seasons using randomized complete block design (RCBD) with three replications. A trait-based marker analysis was used to identify QTLs for validation in BC₂F₅ generation. Analysis of variance (ANOVA) showed that the seasonal factors influenced different agronomic traits. Variant G33 produced significantly (p < 0.05) higher yield (5.20 t/ha) than the control, MR219 (4.53 t/ha). Eighteen QTLs for different agronomic traits were identified in BC₂F₂ population in a previous study. Among them 14 QTLs were found in BC₂F₅ population of the present study. The yield of variant G33 was influenced by several QTLs viz. qGPL-1, qSPL-1-2, qSPL-8 and qYLD-4, which were introgressed from the donor parent revealed by background marker analysis using BC₂F₇ generation. Percentage (99%) of red pericarp grain of G33 and G34 in BC₂F₅ and BC₂F₆ generations indicated the stability of pericarp colour which was transferred from the wild relative. Variant G33 showed resistance against two pathotype of blast disease (Magnaporthe oryzae). Among the evaluated variants, G33 could be considered for inclusion in the cultivar development program for red rice with high yield potential and resistance to blast disease. This study demonstrated that the alleles from wild relative could improve the yield and yield related traits through allelic interaction, even though the phenotypic traits were inferior to the recurrent parent.     

Introgression of resistance to reniform nematode (Rotylenchulus reniformis) into upland cotton (Gossypium hirsutum) from Gossypium arboreum and a G. hirsutum/Gossypium aridum bridging line

Gossypium hirsutum L. is the predominant cotton of commerce and all cultivars of this species are susceptible to the reniform nematode, Rotylenchulus reniformis. To introgress resistance to R. reniformis into the tetraploid 2(AD₁) G. hirsutum, a resistant diploid A₂-genome Gossypium arboreum accession (A₂-190) was crossed with a hexaploid 2((AD₁)D₄) bridging line (G 371) to obtain a tetraploid triple-species hybrid. The triple-species hybrid was back-crossed to G. hirsutum and a population of 277 BC₁ individuals was produced. The BC₁s and controls were assayed in growth chambers for resistance to R. reniformis. Fortuitously, the hexaploid bridging line G 371 was also found to be resistant to R. reniformis. The BC₁ segregated 3:1, resistant:susceptible, indicating that resistance was conferred by dominant genes at two different loci, with each originating from a distinct germplasm source. This study demonstrated that it is possible to introgress and pyramid genes for resistance to R. reniformis in G. hirsutum.     

Dissecting Genetic Basis of Deep Rooting in Dongxiang Wild Rice

Deep rooting is an important trait in rice drought resistance. Genetic resources of deep-rooting varieties are valuable in breeding of water-saving and drought-resistant rice. In the present study, 234 BC₂F₇ backcross introgression lines were derived from a cross of Dongye 80 (an accession of Dongxiang wild rice as the donor parent) and R974 (an indica restorer line as the recurrent parent). A genetic linkage map containing 1 977 bin markers was constructed by ddRADSeq for QTL analysis. Thirty-one QTLs for four root traits (the number of deep roots, the number of shallow roots, the total number of deep roots and the ratio of deep roots) were assessed on six rice chromosomes in two environments (2020 Shanghai and 2021 Hainan). Two of the QTLs, qDR5.1 and qTR5.2, were located on chromosome 5 in a 70-kb interval. They were detected in both environments. qDR5.1 explained 13.35% of the phenotypic variance in 2020 Shanghai and 12.01% of the phenotypic variance in 2021 Hainan. qTR5.2 accounted for 10.88% and 10.93% of the phenotypic variance, respectively. One QTL (qRDR2.2) for the ratio of deep roots was detected on chromosome 2 in a 210-kb interval and accounted for 6.72% of the phenotypic variance in 2020. The positive effects of these three QTLs were all from Dongxiang wild rice. Furthermore, nine and four putative candidate genes were identified in qRDR2.2 and qDR5.1/qTR5.2, respectively. These findings added to our knowledge of the genetic control of root traits in rice. In addition, this study will facilitate the future isolation of candidate genes of the deep-rooting trait and the utilization of Dongxiang wild rice in the improvement of rice drought resistance.     

Identification and Genetic Analysis of Fertility Restoration Ability in Dongxiang Wild Rice （Oryza rufipogon）

Two populations of Dongxiang wild rice (Oryza rufipogon), Shuitaoshu and Dongtangshang, were crossed with five male sterile rice lines with different cytoplasmic backgrounds (B06S, Zhenshan 97A, Xieqingzao A, Zhong 9A, and Yuetai A), and the seed setting rate of the F₁ was used to judge the fertility restoration ability in the Dongxiang wild rice. With P₁, F₁, P₂, and F₂ populations as materials, the Akaike's Information Criterion (AIC) was used to identify the major genes affecting quantitative traits, and when the major genes existed, the genetic effects of the major gene and the polygene and their genetic variance were estimated through segregation analysis. The seed setting rates of the F₁ generation varied from 45.98% to 76.57%, suggesting that the Dongxiang wild rice had the fertility restoration ability. One major gene plus polygene mixed inheritance model was the most fitted genetic model for this trait in all the F₂ populations. The heritability values of the major genes varied from 56.63% to 88.29% and those of the polygenes from 2.74% to 30.97%, and the total heritability values were from 63.17% to 94.01%. The major gene inheritance of the combination Zhong 9A/Dongtangshang was controlled by the additive effect without dominant effect, and the other nine combinations were by the completely dominant inheritance.     

Susceptibility to Insecticides and Ecological Fitness in Resistant Rice Varieties of Field Nilaparvata lugens Stl Population Free from Insecticides in Laboratory

A population of rice brown planthopper(BPH) Nilaparvata lugens collected from a paddy field in Hangzhou was successively reared on susceptible rice Taichung Native 1(TN1) in a laboratory free from insecticides for more than 14 generations. The changes in susceptibility to insecticides and ecological fitness on different resistant rice varieties were monitored in each generation. The resistance ratio to imidacloprid sharply declined with the succession of rearing generations without insecticides from 359.94-fold at F1 to 6.50-fold at F14 compared with the susceptible strain, and the resistance ratio to chlorpyrifos was from 9.90-fold at F1 to 5.94-fold at F14. Nymphal duration and weights of newly hatched female adults were significantly affected by rice variety, generation and their interactions, but nymphal survival was significantly affected by the generation only. The ratio of brachypterous adults in males was affected by the generation and generation × variety interaction, whereas no difference was found in females. Nymphal duration extended with increasing generations, and the female nymphal duration was shorter in the susceptible variety TN1 than those in the resistant varieties IR26 and IR36. In addition, the female adult weight in TN1 was higher than those in IR26 and IR36. These results indicated that the resistance of field BPH population to insecticides was reversed after several generations of no-exposure to insecticides, and the ecological fitness in TN1 was higher than those in IR26 and IR36. These findings suggested the rational and reduced use of insecticides in combination with the manipulation of resistant rice varieties would be effective for BPH management.     

Genetic analysis for resistance to the green leafhopper, Nephotettix virescens (Distant), in some cultivars of rice, Oryza sativa L.

The genetics of resistance to green leafhopper Nephotettix virescens (Distant) was studied in 17 cultivars of rice (Oryza sativa L.). Seedlings at the one-leaf stage were infested with second- and third-instar nymphs of green leafhopper. Reactions to seedling injury were recorded 7–8 days after infestation. The reactions of F₁, F₂, and F₃ populations from the crosses of resistant varieties with susceptible parent TN1 revealed that resistance of Tilakkachray, Kalimekri 77-5, and Tilockkachari was governed by two dominant genes and resistance of IR42 was conveyed by a single recessive gene. Single dominant genes govern resistance in the remaining 13 cultivars. Allele tests revealed that a single dominant gene of Segon Perak and one of the two genes of Kalimekri 77-5 are allelic to Glh 1. The single dominant gene of Ernest, Bignou and ARC614 and one of the two genes of each of Tilakkachray, Kalimekri 77-5, and Tilockkachari are allelic to Glh 2. A single dominant gene, which is allelic to Glh 3, conditions resistance in Arai and IR30. The single recessive gene which conveys resistance in IR42 appears to be allelic to glh 4. The allelic relationships of one of the two genes of Tilakkachray and Tilockkachari and single dominant genes of Fulkari 653, Chao Pho Kha, Amoule Borome, Kabero, Aus Murali, IR28 and IR34, with each other and with Glh 5 are not known.     

Improvement of Upland Rice Variety by Pyramiding Drought Tolerance QTL with Two Major Blast Resistance Genes for Sustainable Rice Production

Varalu is an early maturing rice variety widely grown in the rainfed ecosystem preferred for its grain type and cooking quality. However, the yield of Varalu is substantially low since it is being affected by reproductive drought stress along with the blast disease. The genetic improvement of Varalu was done by introgressing a major yield QTL, qDTY_12.1, along with two major blast resistance genes i.e. Pi54 and Pi1 through marker-assisted backcross breeding. Both traits were transferred till BC₂ generation and intercrossing was followed to pyramid the two traits. Stringent foreground selection was carried out using linked markers as well as peak markers (RM28099, RM28130, RM511 and RM28163) for the targeted QTL (qDTY_12.1), RM206 for Pi54 and RM224 for Pi1. Extensive background selection was done using genome-wide SSR markers. Six best lines (MSM-36, MSM-49, MSM-53, MSM-57, MSM-60 and MSM-63) having qDTY_12.1 and two blast resistance genes in homozygous condition with recurrent parent genome of 95.0%-96.5% having minimal linkage drag of about 0.1 to 0.7 Mb were identified. These lines showed yield advantage under drought stress as well as irrigated conditions. MSM-36 showed better performance in the national coordinated trials conducted across India, which indicated that improved lines of Varalu expected to replace Varalu and may have an important role in sustaining rice production. The present study demonstrated the successful marker-assisted pyramiding strategy for introgression of genes/QTLs conferring biotic stress resistance and yield under abiotic stress in rice.     

Seed Length Controlled by Same Locus in Four Different AA GenomeSpecies of Genus Oryza简

To broaden the genetic basis and overcome the yield plateau in Asian cultivated rice, the exploitation and utilization of favorable alleles from rice species with the AA genome has become important and urgent in modern breeding programs. Four different interspecific populations were used to detect quantitative trait locus (QTL) for seed length, including a BC₄F₂ population derived from Oryza glumaepatula crossed with Dianjingyou 1 (a japonica cultivar), a BC₄F₂ population derived from O. nivara crossed with Dianjingyou 1, a BC₇F₁ population derived from a cross between O. longistaminata and RD23 (an indica cultivar), and a BC₈F₁ population derived from a cross between O. glaberrima and Dianjingyou 1. The QTLs for seed length in four different populations were termed as SL-3a, SL-3b, SL-3c and SL-3d, respectively. They had good collinearity and accounted for 49% to 60% of the phenotypic variations. Sequencing data indicated that four QTLs were different alleles of GS3 which were responsible for the seed length variation between O. sativa and its four AA genome relatives. These results will be valuable for confirming the evolution of GS3 and also be helpful for rice breeding.     

Genetic analysis and molecular mapping of a stripe rust resistance gene in wheat–Leymus mollis translocation line M8926-2

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most widespread and destructive diseases of wheat crop worldwide. Growing resistant cultivars is the preferred method of controlling diseases, but only a few effective genes are available. M8926-2, a translocation line developed from interspecific hybridization between Leymus mollis and a common wheat genotype 7182, is highly resistant to the prevalent Chinese Pst races. In order to identify gene(s) for stripe rust resistance, M8926-2 was crossed with susceptible genotype Mingxian 169, and seedlings of parents and F₁, F₂, and F_2:3 progenies were tested with the most prevalent Pst race CYR32 under controlled greenhouse conditions. M8926-2 has a single dominant gene, designated as YrM8926, conferring all-stage resistance to CYR32. Genetic mapping was used to identify molecular markers linked to YrM8926. A linkage group of seven simple sequence repeat (SSR) markers was constructed for YrM8926 using 191 F_2-2 population plants and the gene was located on wheat chromosome 2DS. The wheat-L. mollis translocation line background of M8926-2 and disease assessments indicated that YrM8926 is originally derived from L. mollis. The stripe rust resistance gene and closely linked molecular markers should be useful for pyramiding with other genes to develop wheat cultivars with high-level and long-term resistance to stripe rust.     

转溶菌酶基因水稻回交转育籼型杂交稻亲本

以抗稻瘟病的粳稻中花9号转溶菌酶基因材料D2 1 2与籼型杂交稻两优培九的恢复系9311及不育系培矮64S、汕优63的恢复系明恢63分别杂交和多代回交,进行外源溶菌酶基因的转育。对获得的转育回交后代B39311、B3MH63、B2PA64S和回交自交后代B2F29311、B2F2MH63、B1F2PA64S进行了PCR分析,表明外源基因在回交后代中呈1∶1分离,而在回交的自交后代中呈3∶1分离,证明外源溶菌酶基因是以单拷贝稳定传递给后代的。2003年和2004年对转育后代和测交组合进行了稻瘟病抗性调查,结果表明,转育后代抗性与轮回亲本相比、测交组合抗性与对应杂交稻组合相比都有了较大提高。随着转育回交世代的增加,抗性增强得越明显。研究表明通过回交转育方法将外源溶菌酶基因导入杂交稻亲本是选育抗稻瘟病杂交稻新组合的一条简便有效的途径。     

Genetic Analysis and QTL Mapping of Large Flag Leaf Angle Trait in Japonica Rice

Genetic segregation analysis for flag leaf angle was conducted using six generations of P1,P2,F1,B1,B2 and F2 derived from a cross of 863B(a maintainer line of japonica rice) and A7444(a germplasm with large flag leaf angle).Genotypes and phenotypes of flag leaf angle were investigated in 863B(P1),A7444(P2) and 141 plants in BC1F1(863B/A7444$$$$863B) population.An SSR genetic linkage map was constructed and QTLs for flag leaf angle were detected.The genetic map containing 79 information loci was constructed,which covers a total distance of 441.6 cM,averaging 5.6 cM between two neighboring loci.Results showed that the trait was controlled by two major genes plus polygene and the major genes were more important.Fifteen markers showed highly significant correlations with flag leaf angle based on single marker regression analysis.Two QTLs(qFLA2 and qFLA8) for flag leaf angle were detected by both composite interval method in software WinQTLCart 2.5 and composite interval method based on mixed linear model in QTL Network 2.0.The qFLA2 explained 10.50% and 13.28% of phenotypic variation,respectively,and was located at the interval of RM300 and RM145 on the short arm of chromosome 2.The qFLA8 explained 9.59% and 7.64% of phenotypic variation,respectively,and was located at the interval flanking RM6215 and RM8265 on the long arm of chromosome 8.The positive alleles at the two QTLs were both contributed from A7444.     

Introgression of Gene for Non-Pollen Type Thermo-Sensitive Genic Male Sterility to Thai Rice Cultivars

For the two-line hybrid rice system, pol en sterility is regulated by recessive gene that responds to temperature. The recessive gene controlling thermo-sensitive genetic male sterility （TGMS） is expressed when the plants are grown in conditions with higher or lower critical temperatures. To transfer tgms gene（s） control ing TGMS to Thai rice cultivars by backcross breeding method, a male sterile line was used as a donor parent while Thai rice cultivars ChaiNat 1, PathumThani 1, and SuphanBuri 1 were used as recurrent parents. The BC2F2 lines were developed from backcrossing and selfing. Moreover, the simple sequence repeat （SSR） markers were developed for identifying tgms gene and the linked marker was used for assisting selection in backcrossing. The identification lines were confirmed by pol en observation. The results showed the success of introgression of the tgms gene into Thai rice cultivars. These lines will be tested for combining ability and used as female parent in hybrid rice production in Thailand.