Spectrum and inheritance of resistance to the root-knot nematode Meloidogyne hapla in Rosa multiflora and R. indica

The spectrum and inheritance of resistance to the root‐knot nematode Meloidogyne hapla was studied in the diploid species Rosa multiflora and R. indica. The host suitability of seven rose rootstocks, namely five R. multiflora (K2, K1, Floradale, CE63 and CE65) and two R. indica (CE35 and Maroc) clonal accessions, was evaluated using four geographic isolates of M. hapla. Plants grown under greenhouse conditions were tested at high and durable inoculum pressure of nematodes and rated for nematode infestation five months after inoculation on a 0–5 gall index. Different host suitabilities to M. hapla were demonstrated depending on the nematode isolates: in R. multiflora, the clone K2 had a resistant (R) response to all isolates; the clone K1 ranged from intermediate (I) (isolate ‘Canada’) to resistant (other isolates), Floradale was shown to be intermediate, whereas CE63 and CE65 were moderate to good hosts (H). In R. indica, both rootstocks were good to excellent hosts for the isolate Canada but resistant to all three other isolates, thus expressing an isolate‐specific resistance. A study on the genetics of resistance in R. multiflora to the M. hapla isolate Canada was then conducted using an incomplete diallel cross involving all previous clones except Floradale. A total of 120 hybrid individuals belonging to several progenies representing the cross combinations R × I, R × H, I × H and H × H were evaluated. Individuals of each progeny generally ranged into a monomodal distribution that suggests polygenic inheritance of resistance. In the family Rosaceae, the differences in the resistance genetics to the meiotic species M. hapla and to the mitotic species, M. arenaria, M. incognita and M. javanica are discussed in relation to the reproductive status of the nematodes.     

Genetic resistance to root-knot nematode (Meloidogyne javanica) in eggplant (Solanum melongena)

A germplasm collection of 39 eggplant Solanum melongena genotypes and one accession of S. torvum was evaluated for resistance to the root-knot nematode (Meloidogyne javanica) by using controlled greenhouse tests. Different degrees of resistance to the disease caused by this nematode species were observed among the genotypes tested. Complete resistance (no nematode egg mass formation up to 7 weeks after inoculation) was detected in one accession belonging to domesticated S. melongena species. Good levels of incomplete resistance were also observed in some commercial eggplant genotypes. This is apparently the first report of a source of complete resistance to M. javanica within the S. melongena gene pool and our finding could greatly facilitate the incorporation of this trait into commercial eggplant cultivars. S. torvum, previously described as resistant to several root-knot nematode species (including M. javanica, M. arenaria, and M. incognita) was also confirmed as a source of resistance to this Brazilian population of M. javanica. Therefore, S. torvum can be considered as one of the most promising sources of broad-spectrum resistance genes against root-knot nematodes. Broad-spectrum resistance is of paramount importance for breeding programmes focused on the development of cultivars for tropical and subtropical areas of the world where multiple infestation of soils with distinct Meloidogyne species is a very common feature.     

Genetic variation and response to selection for resistance to root-knot nematodes in oil radish (Raphanus sativus ssp. oleiferus)

Based on a preliminary screening of a collection of cruciferous crops, such as oilseed rape (Brassica napus L. ssp. oleifera Metzg.), oil radish (Raphanus sativus L. ssp. oleiferus DC.), and yellow mustard (Sinapis alba L.), some plants within the oil radish varieties showed resistance to the root-knot nematodes Meloidogyne hapla Chitwood and M. incognita (Kofoid & White) Chitwood. Resistance tests of S₁ progeny of these selected genotypes revealed a quantitative nature of resistance to M. hapla. Only a few resistant individuals were found, but a significant effect of selection was observed. In contrast, the progenies of plants resistant to M. incognita showed a very low number of egg masses, suggesting that this resistance may be conferred by dominant major gene(s). The results indicate that resistance of oil radish to root-knot nematodes may be effective and may thus provide new possibilities for the management of M. hapla and M. incognita.     

评价黑龙江省主栽马铃薯品种及重要育种材料对北方根结线虫的抗性

根结线虫(Meloidogyne spp.)是一种寄主范围广泛,危害马铃薯的重要的植物寄生线虫。本研究选用黑龙省主栽马铃薯品种和部分育种材料共28份进行温室盆栽试验以明确其对北方根结线虫病害的抗感反应,随机区组设计,5次重复。结果表明,北方根结线虫在这28份材料上都能繁殖,且繁殖系数(RF)均大于1(1.53~37.90)。白头翁、会-2和红参的繁殖系数分别为2.41、2.02和1.53,与青薯3号(36.93)和608 Kennebec(37.9)差异显著(P0.05);线虫在参试的马铃薯植株根上繁殖的卵块数量范围为每克鲜重26.6~217.4个,根据卵块数量分级,白头翁(3级)为抗病材料;植株上的虫瘿指数(Galling Index)范围为1.5~6.8,根据虫瘿指数评价,白头翁(1.8)、会-2(1.5)和红参(2.2)为抗病材料。综合块茎评价结果在参试的28份材料中白头翁是较抗北方根结线虫的材料,会-2和红参的根部对北方根结线虫具有一定的耐病性,可作为培育抗病品种资源,感病材料青薯3号和608 Kennebec可作为筛选材料的感病对照。     

Evaluation and verification of resistance to Meloidogyne hapla Chitwood in a Cannabis germplasm collection

A collection of Cannabis accessions was evaluated for resistance to the root-knot nematode Meloidogyne hapla Chitwood in a seedling test. After inoculation with a larval suspension, significant variation was found for the number of galls and egg masses on the seedling roots. These parameters were considered as estimates for nematode infection and larval multiplication, respectively. A subset of the tested accessions was grown on a naturally infested arable field to study the relation between the test results and host characteristics in the field. The ranking order of accessions for the number of galls in the seedling test agreed well with that for the number of root galls on juvenile plants in the field. Therefore the test provides a useful indication for nematode infection. The number of egg masses in the seedling test and the population density of Meloidogyne measured in post-treatment soil samples of the field trial, showed a comparable ranking of accessions. Differences between accessions in the field were however smaller and not statistically significant.     

Inheritance of the resistant reaction of the lettuce cultivar `Grand Rapids' to the southern root-knot nematode Meloidogyne incognita (Kofoid & White) Chitwood

Resistance to the southern root-knot nematode Meloidogyne incognita Chitwood would be an important attribute of lettuce Lactuca sativa L. cultivars adapted to both protected and field cultivation in tropical regions. `Grand Rapids' and a few other cultivars are reported to be resistant to this nematode. In this paper, we studied the inheritance of the resistant reaction of `Grand Rapids' (P₂) in a cross with a standard nematode-susceptible cultivar Regma-71 (P₁). F₁(Regina-71 × Grand Rapids) and F₂ seed were obtained, and inoculated along with the parental cultivars with different races of M. incognita to evaluate nematode resistance. Broad sense heritability estimates for the number of galls and of egg masses per root system, gall size and gall index were generally in the order of 0.5 or higher. Class distributions of these variables over generations P₁, P₂, F₁ and F₂ were in agreement with simulated theoretical distributions based on monogenic inheritance models. F₃ families were obtained from randomly sampled F₂ plants and tested for reaction to the nematode. The frequency ratio of homozygous resistant, segregating and homozygous susceptible F₃ families did not differ from the 1:2:1 ratio expected from monogenic inheritance. M. incognita resistance appears to be under control of a single gene locus. The Grand Rapids allele (for which the symbol Me is proposed) is responsible for the resistant reaction, and shows high (though incomplete) penetrance, variable expressivity and predominantly additive gene action. This revised version was published online in July 2006 with corrections to the Cover Date.     

拟南芥蔗糖转运蛋白(SUTs)的功能研究进展

蔗糖是光合产物在植物体内贮藏、运输的主要形式.植物蔗糖转运蛋白对蔗糖的装载、运输、卸出与分配过程起着不可替代的作用.本文详细介绍了拟南芥9个蔗糖转运蛋白家族成员的功能、分类、表达定位以及动力学特性等方面的研究进展.     

Molecular markers linked to the Aegilops variabilis-derived root-knot nematode resistance gene Rkn-mn1 in wheat

Aegilops variabilis no. 1 is the only known source of resistance to the root‐knot nematode Meloidogyne naasi in wheat. Previous studies showed that a dominant gene, Rkn‐mn1, was transferred to a wheat translocation line from the donor Ae. variabilis. Random amplified polymorphic DNA (RAPD) analysis was performed on the wheat cultivar ‘Lutin’, on Ae. variabilis, on a resistant disomic addition line and on a resistant translocation line. For genetic and molecular studies, 114‐117 BC₃F₂ plants and F₃‐derived families were tested. Five DNA and one isozyme marker were linked to Rkn‐mn1. Three RAPD markers flanking the Rkn‐mn1 locus were mapped at 0 cM (OpY16_‐1065), 0.8 cM (OpB12_‐1320) and 1.7 cM (OpN20_‐1235), respectively. Since the Rkn‐mn1 gene remained effective, its introduction into different wheat cultivars by marker‐assisted selection is suggested.     

马铃薯不同品种(系)和稻、薯轮作模式对根结线虫病的防治效果

根结线虫病是马铃薯连作减产的主要原因之一。为研究根结线虫病的农艺防治措施,本文开展了品种抗性评价、稻、薯轮作和土壤淹水下的线虫消减动态研究。抗性评价试验表明, 18个品种(系)中没有筛选到同时抗南方根结线虫和爪哇根结线虫的材料,品系1002-1和品种丽薯6号相对抗性较好,青薯9号和合作88相对敏感。马铃薯根结线虫发病土壤中可同时检测到卵、幼虫和成虫等不同形态。水旱轮作试验表明,经一茬水稻栽培可使土壤中根结线虫虫态完全消失,再种植马铃薯也不再发生根结线虫病,且马铃薯有效产量显著提高,青薯9号、合作88和丽薯6号的单株有效产量较对照分别提高50.5%、43.7%和26.0%,差异均极显著, 1002-1单株有效产量与对照差异不显著。由此可见,稻、薯轮作根结线虫防治效果明显。为进一步探索水旱轮作的防治机制,观察了土壤淹水进程中各种虫态消减动态。结果表明,在淹水过程中,根结线虫的卵、幼虫和成虫不同虫态此消彼长,要淹水60 d以上,土壤中才检测不到所有形态虫体。水早轮作中水稻生长期淹水时间足够长,满足防治线虫的淹水条件。因此结合抗病品种选用进行稻、薯轮作是防治马铃薯根结线虫病既绿色环保又可持续有...     

The sea beet source of resistance to multiple species of root-knot nematode

Development of commercially available host-plant resistance to Meloidogyne spp. is essential to sugarbeet (Beta vulgaris L.) root-knot nematode resistance breeding. Reactions of seedlings from resistant crosses and hybrid derivatives were evaluated against juvenile (J2) inoculations in the greenhouse. The noncultivated sea beet [B. vulgaris ssp. maritime (L.) Arcang] source of resistance is effective against the four economically important root-knot nematodes, i.e., M. incognita Races 1, 2 and 4 (Race 3 not tested), M. Javanica, M. arenaria Races 1 and 2, and M. hapla. In monoxenic culture, M. arenaria inoculations resulted in the most galling, and M. hapla, the least. Species combinations induced higher rates of infection. Different races of the same Meloidogyne species caused similar galling. Preliminary inoculation studies indicated that resistance was also effective to M. Chitwoodi and M. fallax. The trait of resistance to multiple Meloidogyne species may be valuable in developing sugarbeet, and possibly transgenic lines of other crops, resistant to root-knot nematode. This revised version was published online in July 2006 with corrections to the Cover Date.     

New data on the specificity of the root-knot nematode resistance genes Me1 and Me3 in pepper

Root‐knot nematodes, Meloidogyne spp., cause severe damage on solanaceous crops, including tomato and pepper. The objective of this study was to test whether nematodes virulent against the tomato Mi resistance gene were able to overcome the Me1 and Me3 resistance genes from pepper. For that purpose, a collection of 22 Meloidogyne arenaria, Meloidogyne incognita and Meloidogyne javanica isolates, avirulent or virulent against the Mi gene, was assembled. The reproduction of each isolate was evaluated on both susceptible and resistant tomato and pepper genotypes in a growth chamber. The Me1 resistance gene controlled all the avirulent and Mi‐virulent nematodes tested, and therefore appears promising for pepper breeding. In contrast, one M. arenaria and two M. incognita virulent isolates were shown to overcome the pepper Me3 resistance gene. These results encourage the testing of a large number of Meloidogyne isolates to evaluate the plant‐nematode interaction, which could have important consequences for the use and management of resistance genes in the field with respect to specificity and durability of the resistance.     

Variation in forage grasses as hosts of the root-knot nematode Meloidogyne naasi (Franklin) and selection for resistance in ryegrass

Summary Reactions of 13 grasses to Meloidogyne naasi varied with species; ryegrasses, fescues and their hybrids were generally susceptible and cocksfoot and timothy resistant. Marked variation in host resistance levels occurred between genotypes within cultivars.Selection of single plants, followed by tests on replicate tillers, identified resistant and susceptible genotypes in both Italian and perennial ryegrass cultivars. Resistant plants had few nematode-induced galls and fewer females and eggs than susceptibles. There was more or less continuous variation, with many genotypes intermediate between extremes of resistance and susceptibility. Selected resistant and susceptible genotypes are of use in assessing variation in nematode populations and as controls for breeding and selection programmes.     

拟南芥尿黑酸叶绿醇转移酶(HPT)基因启动子的分离及表达特性分析

尿黑酸叶绿醇转移酶（HPT）是催化生育酚生物合成分支途径中的关键酶,催化叶绿醇焦磷酸（phytyl-PP）与尿黑酸（HGA）缩合生成生育酚的前体。从拟南芥中分离HPT基因的启动子序列946 bp,构建了该启动子与GUS嵌合的重组载体,通过农杆菌介导转化拟南芥,取正常生长条件下的拟南芥转基因植株进行GUS组织化学染色,结果表明,在HPT启动子的驱动下,GUS基因主要在转基因拟南芥的根中高表达,在成熟叶片、花丝、雌蕊中也有一些表达,而在茎、根尖、花药、种荚及发育的种子中则未表达,可见该启动子为根优势表达启动子。     

Exploiting natural genetic diversity and mutant resources of Arabidopsis thaliana to study the A. thaliana–Plasmodiophora brassicae interaction

Clubroot, caused by the obligate biotroph Plasmodiophora brassicae Woron., is one of the most damaging diseases of Brassica crops in the world. Because the pathogen can infect all the Brassicaceae, including Arabidopsis thaliana, possible advantages have been found by identifying sources of resistance to P. brassicae in this model plant. Fifty‐seven ecotypes of A. thaliana, including the INRA Arabidopsis core collection, were assessed for resistance to clubroot disease. Ecotypes Burren (Bur‐0), Tsu (Tsu‐0) and Kaunas (Kn − 0) were identified as partially resistant to P. brassicae isolates eH and/or Ms6. Fifteen Arabidopsis mutant lines known for certain physiological processes potentially involved in the host‐pathogen interaction were evaluated for their resistance/susceptibility to P. brassicae. Mutant axr3‐1 appeared to be less susceptible than the wild type Columbia, supporting the hypothesis of the involvement of the auxin pathway in the development of clubs.     

氮离子注入对拟南芥的生理影响初步研究

以拟南芥菜为研究对象,对低能氮离子注入对拟南芥干种子的萌发力、苗体生长形态性状的影响及过氧化物同工酶酶活性和酶谱变异情况进行了研究和探讨。结果表明,发芽率-剂量曲线呈“马鞍型”特性;离子注入对拟南芥菜生长有抑制作用,营养器官的损伤率-剂量关系为先降后升的趋势,并且剂量间各性状差异极显著;离子注入后过氧化物同工酶酶活性在一定剂量范围内增强,酶谱的变异体现在谱带强弱的变化而不是谱带增减上,初步探讨了各性状表现与POD酶活变化的关系。     

拟南芥高亲和性钾转运体AtHAK5参与植物根对盐胁迫及ABA的反应

为研究在不同逆境,如低钾、低钙、NaCl及ABA胁迫下,对拟南芥高亲和性钾转运体基因AtHAK5表达的影响,在对含有promoter AtHAK5：GUS融合基因的拟南芥转基因植株进行组织化学染色基础上进行Real time RT-PCR检测。结果表明,这些逆境条件可以引起拟南芥AtHAK5基因表达量的上调。同时在对拟南芥Col-0和AtHAK5缺失突变体athak5表型对比分析,发现AtHAK5参与植物根对盐胁迫及ABA的反应。     

Inheritance of resistance to the peach root‐knot nematode (Meloidogyne floridensis) in interspecific crosses between peach (Prunus persica) and its wild relative (Prunus kansuensis)

The peach root‐knot nematode, Meloidogyne floridensis (MF), infects majority of available nematode‐resistant peach rootstocks which are mostly derived from peach (Prunus persica) and Chinese wild peach (P. davidiana). Interspecific hybridization of peach with its wild relative, Kansu peach (P. kansuensis), offers potential for broadening the resistance spectrum in standard peach rootstocks. We investigated the inheritance of resistance to MF in segregating populations of peach (‘Okinawa’ or ‘Flordaguard’) × P. kansuensis. A total of 379 individuals from 13 F₂ and BC₁F₁ families were challenged with a pathogenic MF isolate “MFGnv14” and were classified as resistant (R) or susceptible (S) based on root galling intensity. Segregation analyses in F₂ progeny revealed the involvement of a major locus with a dominant or recessive allele determining resistance in progeny segregating 3R:1S and 1R:3S, respectively. Testcrosses with a homozygous‐susceptible peach genotype (‘Flordaguard’ or ‘UFSharp’) confirmed P. kansuensis as a source of new resistance and the heterozygous allelic status of P. kansuensis at the locus conferring resistance to MF. We propose a single‐locus dominant/recessive model for the inheritance of resistance.     

Characteristics of the Incomplete Resistance of Hordeum chilense to the Root-Knot Nematode Meloidogyne naasi Franklin — Description of a Newly Conceived Test to Detect the Resistance

We are able to describe, due to some assays conducted under field conditions, the different ways the root-knot nematode of cereals was affected in some amphiploid plants carrying the resistance of a wild Hordeum sp. This resistance arises in one of three ways: (i) a reduction in the establishment of the infective juvenile stages in the root, (ii) a delay and/or a cessation of development of the parasite occurring at the J2 or swelling-J2 stage, (iii) an altered fecundity of the females. These three actions efficiently control the multiplication of the nematode, resulting in few females at the end of growing period of the crop. A new test was developed for early screening of the resistance under controlled conditions. Based on the analysis of the gall rating and the contents of five young galls from each plant, the response of a line can be seen within 16 days, while preserving the viability of the plants to continue their growth.     

拟南芥植物型PEPC基因人工小RNA表达载体的构建与遗传转化

磷酸烯醇式丙酮酸羧化酶（PEPC）是植物中具有多种生理功能的酶。为探索拟南芥中植物型PEPC基因对模式植物拟南芥脂肪酸含量以及抗逆性等方面的影响,本文构建了同时敲除拟南芥Atppc1、Atppc2和Atppc3基因的人工小RNA（amiRNA）植物表达载体pFGC-amiAtppc123,经根癌农杆菌EHA105介导,用花序浸染法转化拟南芥,成功获得转基因植株。RT-PCR半定量分析表明人工小RNA在转化植株中成功进行了超量表达。该试验为分析拟南芥脂肪酸含量以及抗逆性方面提供了基础材料。     

异源表达棉花S-腺苷甲硫氨酸脱羧酶(Gh SAMDC1)基因提高了拟南芥抗盐能力

以转GhSAMDC1基因拟南芥研究了过量表达GhSAMDC1基因对拟南芥幼苗抗盐能力的影响,以及内源多胺、过氧化氢(H2O2)、丙二醛(MDA)、叶绿素含量(Chl)、离子渗透率、抗氧化酶(SOD、CAT、POD)活性和表达量在盐胁迫下的变化。结果表明,过量表达GhSAMDC1基因能够减少拟南芥内源腐胺(Put)含量,增加亚精胺(Spd)和精胺(Spm)含量。盐胁迫下,转基因株系亚精胺合酶(AtSPDS1、AtSPDS2)和精胺合酶(AtSPMS)基因表达量明显高于野生型,Spd和Spm含量进一步增加,H2O2、MDA、Chl以及离子渗透率显著降低;与野生型相比,过氧化物酶(POD)活力无明显差异,但超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活力明显增加,其表达水平与活力变化趋势基本一致。因此,盐胁迫下,GhSAMDC1基因通过提高Spd和Spm合成相关基因的表达,增加了转基因株系Spd和Spm含量,Spd和Spm直接或间接提高抗氧化系统相关酶的活力,通过清除H2O2等活性氧的方式提高拟南芥的抗盐能力。