基于GISH的甘蔗与斑茅F1染色体遗传与核型分析

斑茅在甘蔗育种的利用是现代甘蔗育种种质创新的热点,育种者期望把斑茅中优异的特性通过杂交渗透到甘蔗中。甘蔗与斑茅的F1是斑茅利用研究的难点也是基础。本研究利用基因组原位杂交技术(GISH)分析甘蔗与斑茅的F1染色体构成和核型,探讨甘蔗与斑茅F1染色体的遗传行为。GISH结果表明,甘蔗与斑茅杂交F1的染色体众数68~69条,其中40条来自甘蔗热带种Badila,28~29条来自海南斑茅,未发现有染色体的交换或易位现象。参试材料大部分染色体都属于中部着丝点(m)的染色体,少数为近中部着丝点(sm),YCE95-41核型属2B型,其余的核型都为1B型。甘蔗与斑茅的染色体按n+n的方式传递给F1,本研究结果为斑茅种质在甘蔗育种中的利用及其杂交后代染色体细胞遗传研究提供参考依据。     

滇蔗茅杂交F_1双抗SCSMV和SrMV鉴定与评价

以我国蔗区甘蔗花叶病的2种主要病原甘蔗条纹花叶病毒分离物(SCSMV-JP1,Gen Bank登录号JF488064)和高粱花叶病毒分离物(Sr MV-HH,Gen Bank登录号DQ530434)为接种毒源,采用人工切茎接种和RT-PCR检测相结合的方法,于2015-2016年2次对由热带种路打士与滇蔗茅云滇95-19杂交获得的41份滇蔗茅杂交F_1及亲本进行了双抗SCSMV和Sr MV鉴定与评价。结果表明,41份滇蔗茅杂交F_1及亲本中,对SCSMV表现1级高抗到3级中抗的有23份,占53.49%,4级感病到5级高感的有20份,占46.51%;对Sr MV表现1级高抗到3级中抗的有31份,占72.09%,4级感病到5级高感的有12份,占27.91%。综合分析结果显示,10份滇蔗茅杂交F_1对SCSMV和Sr MV均表现1~2级抗病,占23.26%,其中云09-604、云09-607、云09-619、云09-633、云09-656、云滇95-19等6份滇蔗茅杂交F_1对2种病毒均表现为1级高抗,占13.95%。研究结果明确了41份滇蔗茅杂交F_1及亲本对甘蔗花叶病2种主要致病病原的抗性,筛选出10份双抗SCSMV和Sr MV的滇蔗茅杂交F_1,为深入开展抗甘蔗花叶病育种提供了优良抗源种质和参考依据。     

斑茅割手密复合体杂交利用过程野生特异基因遗传分析

揭示斑茅割手密复合体在杂交利用过程中的斑茅、割手密野生特异基因在各世代的遗传规律,为利用斑割复合体创制甘蔗育种新亲本提供理论依据。利用AFLP-PCR分子标记结合毛细管电泳技术对斑割复合体在杂交利用过程中的斑茅、割手密野生特异基因在各世代的传递动态进行分析,并研究它们之间的遗传关系。29对AFLP引物组合共扩增出3695个位点,多态性比例为97.89%。斑茅和割手密对斑割复合体的遗传贡献率分别为43.96%和56.04%。斑茅特异位点在F1、BC1和BC2 3个世代的平均遗传率分别为8.25%、1.90%和0.63%,割手密特异位点在F1、BC1和BC2 3个世代的平均遗传率分别为16.98%、2.40%和0.21%,特异遗传物质均呈逐代减少趋势。比较不同世代甘蔗栽培种亲本遗传到后代的特异位点比率,F1的GT02-761特异位点比率最高,BC1的GT05-2743特异位点比例平均高达92.75%,BC2的ROC23遗传率最低,为49.09%,FN39遗传率最高,达94.32%。聚类分析结果表明斑割复合体偏向父本遗传,斑割复合体杂交后代偏向甘蔗栽培种遗传,与分子遗传关系分析结果一致。研究表明,经过3代的遗传重组,斑割复合体后代的遗传物质与斑割复合体相比已发生了很大的改变;研究明确了斑茅、割手密2个亲本在3个世代的遗传贡献规律,为进一步的杂交选育提供理论支持。     

甘蔗与斑茅割手密复合体杂交后代的分子标记鉴定

为有效利用甘蔗野生种质拓宽甘蔗遗传基础,本研究利用甘蔗与斑茅割手密复合体进行杂交,同时应用序列相关扩增多态性(SRAP)和微卫星(SSR)分子标记技术鉴定其后代。两种分子标记鉴定结果相互印证表明:3个杂交组合的后代中,经表型鉴定含斑茅血缘的34个后代为真杂种。该真杂种后代为进一步综合利用斑茅、割手密的优异基因改良甘蔗品种提供了优良的创新种质。     

玉米抗甘蔗花叶病毒分子标记开发

由甘蔗花叶病毒引起的玉米矮花叶病是我国黄淮海地区玉米生产的重要病害,开发抗矮花叶病基因分子标记是开展抗病分子标记辅助育种的基础。本文基于玉米6．00-6．01区域的“一致性抗甘蔗花叶病毒QTL区间”寻找抗病基因的功能保守域,依据序列多态性开发出抗病分子标记InDel-130和InDel-110,在已知抗性的102份玉米自交系中进行验证。通过分析标记抗病带型和感病带型中的抗病和感病自交系数目,卡平方测验表明标记InDel-130在供试自交系中与抗病性的表现独立无关．而标记InDel-110与甘蔗花叶病毒抗性高度相关,为共显性标记,可用于玉米抗甘蔗花叶病毒种质筛选和分子标记辅助育种。     

黑穗病菌侵染早期的甘蔗生理生化响应差异

由黑粉菌(Sporisorium scitamineum)引起的甘蔗黑穗病能导致甘蔗产量和甘蔗糖分的严重损失,研究抗、感甘蔗基因型在病原菌侵染初期的生理生化变化,对基于生理生化综合分析开发抗病育种的辅助选择技术具有重要意义。采用经田间抗性鉴定为抗病(YZ03/258)和感病(FN39)的甘蔗基因型各1个,测定并分析了蔗芽人工针刺接种甘蔗黑穗病菌后,早期(0~7 d)生理生化响应及其与抗病性的关系。结果表明,病原菌胁迫后,甘蔗抗、感基因型的过氧化物酶(POD)活性均持续上升,但抗病基因型增幅大、持续时间长,表明POD在甘蔗防御黑穗病菌的侵染中起保护作用;在接种0~1 d时,抗病基因型的过氧化氢酶(CAT)活性较感病基因型上升时间快,暗示该阶段CAT可能与抗病性密切相关;超氧化物歧化酶(SOD)和抗坏血酸过氧化物酶(APX)的变化趋势相同,即接种0~1 d,抗、感基因型中的酶活性变化不明显,3 d时感病基因型相对高于同期抗病基因型,但接种后期(7 d)抗病基因型的酶活性急剧上升且高于感病基因型,表明SOD和APX在甘蔗应答黑穗病菌胁迫中可能存在协同表达作用;β-1,3-葡聚糖酶活性的变化与抗病性的关系不明显。此外,丙二醛(MDA)含量测定结果显示,抗、感基因型在病原菌侵染0~3 d MDA快速积累,说明细胞膜脂出现过氧化,且感病基因型MDA含量更高意味着其生物膜受损害程度更高。     

斑茅割手密复合体(GXAS07-6-1)及其与甘蔗F_1的GISH分析

斑茅割手密复合体(GXAS07-6-1)是广西蔗茅属斑茅和广西甘蔗属割手密的属间杂种,聚集了双亲的优点。本研究利用基于Alu-like的PCR鉴定方法对GXAS07-6-1及甘蔗与GXAS07-6-1的3份F_1材料进行真实性鉴定,基于基因组原位杂交技术(GISH)对父本GXAS07-6-1及其3份F_1染色体组成及核型进行分析。研究结果表明:3份F_1材料为GXAS07-6-1的真杂种;父本GXAS07-6-1的染色体众数为62条,其中30条来自蔗茅属斑茅,32条来自甘蔗属割手密,核型分类属于1B,其染色体按"n+n"方式传递;GXASF_108-2-17、GXASF_108-2-22、GXASF_108-2-32的染色体数目为78~80条,其中69~71条来自甘蔗属,9~11条来自蔗茅属斑茅,3份F_1的核型分类分别属于2B、1B、1B,染色体传递方式均为"n+n"。父本GXAS07-6-1及3份F_1材料中均未发现有染色体的交换或易位现象。甘蔗与斑割复合体杂交,蔗茅属斑茅染色体在亲子间传递过程存在丢失现象。     

玉米抗甘蔗花叶病毒分子标记开发

由甘蔗花叶病毒引起的玉米矮花叶病是我国黄淮海地区玉米生产的重要病害,开发抗矮花叶病基因分子标记是开展抗病分子标记辅助育种的基础。本文基于玉米6.00-6.01区域的“一致性抗甘蔗花叶病毒QTL区间”寻找抗病基因的功能保守域,依据序列多态性开发出抗病分子标记InDel-130和InDel-110,在已知抗性的102份玉米自交系中进行验证。通过分析标记抗病带型和感病带型中的抗病和感病自交系数目,卡平方测验表明标记InDel-130在供试自交系中与抗病性的表现独立无关,而标记InDel-110与甘蔗花叶病毒抗性高度相关,为共显性标记,可用于玉米抗甘蔗花叶病毒种质筛选和分子标记辅助育种。     

甘蔗优良品种材料抗高粱花叶病毒鉴定与评价

采用生长期人工切茎接种和RT-PCR检测相结合方法,于2011—2012年2次对国家甘蔗体系近年选育的49份优良新品种(系)和19份云蔗系列优良中间材料进行由高粱花叶病毒(SrMV-HH,GenBank登录号DQ530434)引起的甘蔗花叶病的抗性鉴定与评价。结果表明,49份优良新品种(系)中,1级高抗到3级中抗的有29份,占59.18%。其中粤甘40号、粤甘42号、粤糖55号、云蔗03-194、云蔗99-596、云瑞06-189、桂糖30号、德蔗03-83、闽糖01-77等9份材料表现1级高抗,占18.37%;福农0335、柳城05-129、粤糖96-86、云蔗01-1413、云蔗03-258、云蔗06-80、桂糖02-351等7份材料表现2级抗病,占14.29%。19份云蔗系列优良中间材料中,1级高抗到3级中抗的有13份,占68.42%。其中云蔗04-622、云蔗05-197、云蔗06-267、云蔗05-194、云蔗06-160、云蔗07-2384、云瑞05-704等7份材料表现1级高抗,占36.84%;云蔗06-362表现2级抗病,占5.26%。研究结果为深入开展甘蔗抗花叶病育种,选育和推广优良抗病品种,有效防控甘蔗花叶病提供了科学依据和优良抗源材料。     

29份云南甘蔗创新种质的SSR遗传多样性分析和指纹图谱构建

该研究以16份甘蔗骨干亲本为参照,对29份云南甘蔗创新种质进行SSR指纹图谱构建和遗传多样性分析,以明确创新种质与16份亲本间的遗传基础和多样性水平。结果表明:6对引物共扩增出104条带,其中101条为多态性条带,多态性条带比例为97.25%;45份材料的遗传相似性系数为0.235 3~0.891 3,平均值为0.563 3;其中16份甘蔗骨干亲本的遗传相似性系数为0.301 6~0.755 6,甘蔗创新种质与甘蔗骨干亲本的特异条带比例为14∶1,涵盖了割手密、大茎野生种、斑茅和滇蔗茅等基因源。根据骨干亲本间的相似性系数范围,在相似性系数为0.43处,可将种质分为6大类群,亲缘关系相对较远,适宜作为种质间的杂交利用。通过引物区分效率分析,6对引物扩增的多态信息量为0.967 9~0.975 8,其中MSSCIR21引物区分效率最高,利用MSSCIR21和SMC1047HA引物组合构建了云南甘蔗创新种质标准指纹图谱,在相似性系数为0.85处即可区分所有种质,图谱的鉴别准确率为100%,每份资源都有唯一的指纹图谱,可将29份创新种质和16份骨干亲本区分鉴别出来。该研究能够为后续杂交利用、种质鉴定和知识产权保护提供依据。     

DNA Marker Transmission and Linkage Analysis in Populations Derived from a Sugarcane (Saccharum spp.) x Erianthus arundinaceus Hybrid

Introgression of Erianthus arundinaceus has been the focus of several sugarcane breeding programs in the world, because the species has desirable traits such as high biomass production, vigour, ratooning ability and good resistance to environmental stresses and disease. In this study four genetic maps were constructed for two intergeneric populations. The first population (BC₁) was generated from a cross between an Erianthus/Saccharum hybrid YC96-40 and a commercial sugarcane variety CP84-1198. The second population (BC₂) was generated from a cross between YCE01-116, a progeny of the BC₁ cross and NJ57-416, a commercial sugarcane cultivar. Markers across both populations were generated using 35 AFLP and 23 SSR primer pairs. A total of 756 and 728 polymorphic markers were scored in the BC₁ and BC₂ populations, respectively. In the BC₁ population, a higher proportion of markers was derived from the Erianthus ancestor than those from the Saccharum ancestor Badila. In the BC₂ population, both the number and proportion of markers derived from Erianthus were approximately half of those in the BC₁ population. Linkage analysis led to the construction of 38, 57, 36 and 47 linkage groups (LGs) for YC96-40, CP84-1198, YCE01-116, and NJ57-416, encompassing 116, 174, 97 and 159 markers (including single dose, double dose and bi-parental markers), respectively. These LGs could be further placed into four, five, five and six homology groups (HGs), respectively, based on information from multi-allelic SSR markers and repulsion phase linkages detected between LGs. Analysis of repulsion phase linkage indicated that Erianthus behaved like a true autopolyploid.     

Inheritance of Fusarium wilt resistance introgressed from Solanum aethiopicum Gilo and Aculeatum groups into cultivated eggplant (S. melongena) and development of associated PCR-based markers

The two eggplant relatives Solanum aethiopicum gr. Gilo and Solanum aethiopicum gr. Aculeatum (=Solanum integrifolium) carry resistance to the fungal wilt disease caused by Fusarium oxysporum f. sp. melongenae, a worldwide soil-borne disease of eggplant. To introgress the resistance trait into cultivated eggplant, the tetraploid somatic hybrids S. melongena + S. aethiopicum and S. melongena + S. integrifolium were used. An inheritance study of the resistance was performed on advanced anther culture-derived androgenetic backcross progenies from the two somatic hybrids. The segregation fitted a 3 resistant (R): 1 susceptible (S) ratio in the selfed populations and a 1R:1S ratio in the backcross progenies for the trait derived from S. aethiopicum and S. integrifolium. These ratios are consistent with a single gene, which we designated as Rfo-sa1, controlling the resistance to Fusarium oxysporum f. sp. melongenae. The allelic relationship between the resistance genes from S. aethiopicum and S. integrifolium indicate that these two genes are alleles of the same locus. Bulked Segregant Analysis (BSA) was performed with RAPD markers on the BC₃/BC₅ resistant advanced backcross progenies, and three RAPD markers associated with the resistance trait were identified. Cleaved Amplified Polymorphic Sequences (CAPSs) were subsequently obtained on the basis of the amplicon sequences. The evaluation of the efficiency of these markers in predicting the resistant phenotype in segregating progenies revealed that they represent useful tools for indirect selection of Fusarium resistance in eggplant.     

Introgression of genes from Oryza officinalis Well ex Watt to cultivated rice,O. sativa L.

Summary Sterile AC hybrids between cultivated Oryza sativa (AA) and a distant wild species, O. officinalis (CC), were backcross to O. sativa. Most of the BC₁ progenies were allotriploid (AAC), a few were hypotriploid. AAC progenies were again backcrossed to O. sativa. BC₂ progenies consisting of disomic or aneuploid individuals were examined for the presence of O. officinalis traits. Eleven different traits from O. officinalis were identified in these progenies. Segregation data in the subsequent generations suggest that these traits are monogenic in nature. Two of these genes — for resistance to BPH and WBPH — are of value in rice improvement. The extremely low recovery of recombinant progenies is in agreement with the very low amount of pairing between A and C genomes. Because of this restricted recombination, the genotype of the recurrent parent was reconstituted after two backcrosses only. Thus, the BC₂ progenies look remarkably similar to O. sativa. Most of them are stable and fertile and also interfertile with other O. sativa breeding lines. Some of the BPH-and WBPH-resistant progenies are comparable in yield to the best O. sativa parents and are being evaluated as varietal possibilities.     

Transfer of bacterial blight and blast resistance from the tetraploid wild rice Oryza minuta to cultivated rice,Oryza sativa

Summary Oryza minuta J. S. Presl ex C. B. Presl is a tetraploid wild rice with resistance to several insects and diseases, including blast (caused by Pyricularia grisea) and bacterial blight (caused by Xanthomonas oryzae pv. oryzae). To transfer resistance from the wild species into the genome of cultivated rice (Oryza sativa L.), backcross progeny (BC₁, BC₂, and BC₃) were produced from interspecific hybrids of O. sativa cv IR31917-45-3-2 (2n=24, AA genome) and O. minuta Acc. 101141 (2n=48, BBCC genomes) by backcrossing to the O. sativa parent followed by embryo rescue. The chromosome numbers ranged from 44 to 47 in the BC₁ progeny and from 24 to 37 in the BC₂ progeny. All F₁ hybrids were resistant to both blast and bacterial blight. One BC₁ plant was moderately susceptible to blast while the rest were resistant. Thirteen of the 16 BC₂ progeny tested were resistant to blast; 1 blast-resistant BC₂, plant 75-1, had 24 chromosomes. A 3 resistant: 1 susceptible segregation ratio, consistent with the action of a major, dominant gene, was observed in the BC₂F₂ and BC₂F₃ generations. Five of the BC₁ plants tested were resistant to bacterial blight. Ten of the 21 BC₂ progeny tested were resistant to Philippine races 2, 3, and 6 of the bacterial blight pathogen. One resistant BC₂, plant 78-1, had 24 chromosomes. The segregation of reactions of the BC₂F₂, BC₂F₃, and BC₂F₄ progenies of plant 78-1 suggested that the same or closely linked gene(s) conferred resistance to races 2, 3, 5, and 6 of the bacterial blight pathogen from the Philippines.     

Transfer of a dominant gene for powdery mildew resistance and DNA from Hordeum bulbosum into cultivated barley (H. vulgare)

Summary In an attempt to transfer traits of agronomic importance from H. bulbosum into H. vulgare we carried out crosses between four diploid barley cultivars and a tetraploid H. bulbosum. Eleven viable triploid F₁ plants were produced by means of embryo rescue techniques. Meiotic pairing between H. vulgare and H. bulbosum chromosomes was evidenced by the formation of trivalents at a mean frequency of 1.3 with a maximum of five per cell. The resulting triploid hybrids were backcrossed to diploid barley, and nine DC₁ plants were obtained. Three of the BC₁ plants exhibited H. bulbosum DNA or disease resistance. A species specific 611-bp DNA probe, pSc119.2, located in telomeres of the H. bulbosum genome, clearly detected five H. bulbosum DNA fragments of about 2.1, 2.4, 3.4, 4.0 and 4.8 kb in size present in one of the BC₁ plants (BC₁-5) in BamHI-digésted genomic Southern blots. Plant BC₁-5 also contained a heterozygous chromosomal interchange involving chromosomes 3 and 4 as identified by N-banding. One of the two translocated chromosomes had the H. bulbosum sequence in the telomeric region as detected using in situ hybridization with pSc119.2. Two other BC₁ plants (BC₁-1 and BC₁-2) were resistant to the powdery mildew isolates to which the barley cultivars were susceptible. Seventy-nine BC₂ plants from plant BC₁-2 segregated 32 mildew resistant to 47 susceptible, which fits a ratio of 11, indicating that the transferred resistance was conditioned by a single dominant gene. Reciprocal crosses showed a tendency towards gametoselection that was relative to the resistance. Mildew resistant plant BC₁-2 also had a 1-kb H. bulbosum DNA fragment identified with a ten-base random primer using polymerase chain reaction (PCR). Forty-three BC₁ plants, randomly sampled from the 79 BC₁ plants, also segregated 2320 for the presence versus absence of this 1-kb H. bulbosum DNA fragment, thereby fitting a 11 ratio and indicating that the PCR product originated from a single locus. The 1-kb DNA fragment and disease resistance were independently inherited as detected by PCR analysis of bulked DNA from 17 resistant and 17 susceptible plants as well as by trait segregation in the 43 individual plants. The progenies produced could serve as an important resistant source in plant breeding. This is the first conclusive report of the stable transfer of disease resistance and DNA from H. bulbosum to H. vulgare.     

Development of monosomic alien addition lines and introgression of genes from Oryza australiensis Domin. to cultivated rice O. sativa L.

Oryza australiensis, a diploid wild relative of cultivated rice, is an important source of resistance to brown planthopper (BPH) and bacterial blight (BB). Interspecific hybrids between three breeding lines of O. sativa (2n=24, AA) and four accessions of O. australiensis (2n=24, EE) were obtained through embryo rescue. The crossability ranged from 0.25% to 0.90%. The mean frequency of bivalents at diakinesis/metaphase I in F₁ hybrids (AE) was 2.29 to 4.85 with a range of 0–8 bivalents. F₁ hybrids were completely male sterile. We did not obtain any BC₁ progenies even after pollinating 20,234 spikelets of AE hybrids with O. sativa pollen. We crossed the artificially induced autotetraploid of an elite breeding line (IR31917-45-3-2) with O. australiensis (Acc. 100882) and, following embryo rescue, produced six F₁ hybrid plants (AAE). These triploid hybrids were backcrossed to O. sativa. The chromosome number of 16 BC₁ plants varied from 28 to 31, and all were male sterile. BC₂ plants had 24–28 chromosomes. Eight monosomic alien addition lines (MAALs) having a 2n chromosome complement of O. sativa and one chromosome of O. australiensis were selected from the BC₂ F₂ progenies. The MAALs resembled the primary trisomies of O. sativa in morphology, and on the basis of this morphological similarity the MAALs were designated as MAAL-1, -4, -5, -7, -9, -10, -11, and -12. The identity of the alien chromosome was verified at the pachytene stage of meiosis. The alien chromosomes paired with the homoeologous pairs to form trivalents at a frequency of 13.2% to 24.0% at diakinesis and 7.5% to 18.5% at metaphase I. The female transmission rates of alien chromosomes varied from 4.2% to 37.2%, whereas three of the eight MAALs transmitted the alien chromosome through the male gametes. BC₂ progenies consisting of disomic and aneuploid plants were examined for the presence of O. australiensis traits. Alien introgression was detected for morphological traits, such as long awns, earliness, and Amp-3 and Est-2 allozymes. Of the 600 BC₂ F₄ progenies 4 were resistant to BPH and 1 to race 6 of BB. F₃ segregation data suggest that earliness is a recessive trait and that BPH resistance is monogenic recessive in two of the four lines but controlled by a dominant gene in the other two lines.     

Development of four tobacco cytoplasmic male sterile sources using in vitro techniques

In the present paper are summarized our results on obtaining tobacco male sterile forms through interspecific hybridization. The wild species Nicotiana velutina, N. benthamiana, N. maritima, N. paniculata were used as cytoplasm donors and N. tabacum as the donor of the nucleus. Completely sterile hybrids from these combinations were obtained whose sterility was overcome through the use of tissue culture. Stem parenchyma grown in vitro on MS medium was used for inducing callus, and for organogenesis and rooting. The regenerants obtained were mixoploid. Male sterile plants were obtained in BC₁P₂ progenies from the combinations between N. velutina × N. tabacum, N. benthamiana × N. tabacum and in R₂ progenies from N. maritima × N. tabacum and N. paniculata × N. tabacum. The observed male sterility was preserved in BC₁P₂-BC₇P₂ progenies and was identified as cytoplasmic male sterility (CMS) because it was inherited only throuth the female parent.     

Unexpected Inheritance Pattern of Erianthus arundinaceus Chromosomes in the Intergeneric Progeny between Saccharum spp. and Erianthus arundinaceus

Erianthus arundinaceus is a valuable source of agronomic traits for sugarcane improvement such as ratoonability, biomass, vigor, tolerance to drought and water logging, as well as resistance to pests and disease. To investigate the introgression of the E. arundinaceus genome into sugarcane, five intergeneric F₁ hybrids between S. officinarum and E. arundinaceus and 13 of their BC₁ progeny were studied using the genomic in situ hybridization (GISH) technique. In doing so, we assessed the chromosome composition and chromosome transmission in these plants. All F₁ hybrids were aneuploidy, containing either 28 or 29 E. arundinaceus chromosomes. The number of E. arundinaceus chromosomes in nine of the BC₁ progeny was less than or equal to 29. Unexpectedly, the number of E. arundinaceus chromosomes in the other four BC₁ progeny was above 29, which was more than in their F₁ female parents. This is the first cytogenetic evidence for an unexpected inheritance pattern of E. arundinaceus chromosomes in sugarcane. We pointed to several mechanisms that may be involved in generating more than 2n gametes in the BC₁ progeny. Furthermore, the implication of these results for sugarcane breeding programs was discussed.     

三倍体观赏百合与二倍体食用龙牙百合的杂交分析

为探讨异源三倍体百合与龙牙百合(BB)的杂交亲和性,实现观赏百合与食用百合的种质融合与创新,该研究以三倍体百合Triumphator(LLO)作母本,龙牙百合为父本,采用常规授粉与切柱头授粉,利用基因组荧光原位杂交(GISH)技术分析母本及子代的基因组成。结果显示:(1)通过常规授粉和切柱头授粉共获得17个发育良好的果实,通过胚抢救共获得了40株幼苗,且常规授粉的出苗率明显比切柱头授粉的高。(2)对随机选取的8个子代进行GISH分析,所鉴定的后代均为非整倍体,染色体数目为26～32条,其中东方百合基因组(O)染色体数目为2～8条,铁炮百合(L)与龙牙百合(B)基因组染色体始终为24条。(3)通过GISH技术无法区分铁炮百合与龙牙百合的染色体,亲本与子代均无重组现象。研究表明,龙牙百合与铁炮百合亲缘关系较近,龙牙百合作父本与三倍体百合Triumphator杂交可获得非整倍体,实现了观赏百合与食用百合的种质融合,为培育赏食兼用百合奠定了基础。     

Inheritance of resistance to the two-spotted spider mite from L. pimpinellifolium (Jusl.) Mill. accession ‘TO-937’

The two-spotted spider mite (Tetranychus urticae Koch) is an important pest of tomato (Lycopersicon esculentum Mill.) crops in temperate regions as this spider mite has a very large capacity for population increase and causes severe tomato yield losses. There is no described tomato cultivar fully resistant to this pest, although resistant accessions have been reported within the green-fruited tomato wild species L. pennellii (Corr.) D’Arcy and L. hirsutum Humb. & Bonpl. We observed a L. pimpinellifolium (Jusl.) Mill. accession, ‘TO-937’, which seemed to be completely resistant to mite attacks and we crossed it with the susceptible L. esculentum cultivar. ‘Moneymaker’ to obtain a family of generations consisting of the two parents, the F₁, the F₂, the BC₁ to L. esculentum, and the BC₁ to L. pimpinellifolium. This family was evaluated for mite resistance in a polyethylene greenhouse using an experimental design in 60 small complete blocks distributed along 12 double rows. Each block consisted of five F₂ plants in one row and one plant of each of the two parents, the F₁, the BC₁ to L. esculentum, and the BC₁ to L. pimpinellifolium in the adjacent row. Plants at the 10–15 leaf stage were artificially infested by putting on them two pieces of French bean leaf heavily infested with T. urticae. After two months, evaluations of infestation were made by visual observation of mite nets and leaf damage. Plants that were free of signs of mite reproduction on the top half were considered as resistant, plants with silky nets only on their basal leaves, intermediate, and plants with mite reproduction on both basal and top canopies were scored as susceptible. Dominance for resistance appeared because all the ‘To-937’, BC₁ to L. pimpinellifolium, and F₁ plants were resistant. Not all ‘Moneymaker’ plants behaved as susceptible because 35% of plants were intermediate. In the BC₁ to L. pimpinellifolium and the F₂, most plants were scored as resistant, only 7 % BC₁ and 3 % F₂ plants were intermediate, and a single F₂ plant (0.3 %) was susceptible. With these figures, resistance seemed to be controlled by either four or two genes according to whether segregation in the BC₁ or in the F₂, respectively, were considered. These results could in part be explained because of appearance of negative interplot interference due to the high frequency of resistant genotypes within most of the generations. Therefore, the family was evaluated again but using a different experimental design. In the new experiment, 16 ‘TO-937’, 17 ‘Moneymaker’, 17 F₁, 37 BC₁ to L. pimpinellifolium, 38 BC₁ to L. esculentum, and 125 F₂ plants were included. Each of these test plants was grown besides a susceptible ‘Moneymaker’ auxilliary plant that served to keep mite population high and homogeneous in the greenhouse. Negative interplot interference was avoided with this design and all the ‘TO-937’, F₁, and BC₁ to L. pimpinellifolium plants were resistant, all ‘Moneymaker’ test plants were susceptible, and 52 % BC₁ to L. esculentum and 25 % F₂ plants were susceptible, which fitted very well with the expected for resistance governed by a single dominant gene. The simple inheritance mode found will favour sucessful introgression of mite resistance into commercial tomatoes from the very close relative L. pimpinellifolium.