外源NO对NaCl胁迫下黄瓜(Cucumis sativus L.)幼苗生长和谷胱甘肽抗氧化酶系统的影响

采用营养液水培,研究了外源一氧化氮(NO)对黄瓜(Cucumis sativusL.)幼苗生长和叶片谷胱甘肽抗氧化酶系统的影响。结果表明,正常生长条件下添加NO能促进黄瓜幼苗生长,而添加NO信号传递途径关键酶鸟苷酸环化酶(cGC)抑制剂亚甲基蓝(MB-1)显著抑制了黄瓜幼苗的生长;添加NO显著缓解了盐胁迫对黄瓜幼苗生长的抑制,提高了叶片谷胱甘肽还原酶(GR)活性、脱氢抗坏血酸还原酶(DHAR)活性、抗坏血酸过氧化物酶(APX)及还原型谷胱甘肽(GSH)、抗坏血酸(ASA)含量,降低了氧化型谷胱甘肽(GSSG)含量,提高了GSH/GSSG,对单脱氢抗坏血酸还原酶(MDAR)活性无显著影响;NaCl胁迫下添加NO的同时添加MB-1抑制了GR活性的提高,GSH和ASA含量、GSH/GSSG均降低,GSSG含量提高,但对MDAR、APX和DHAR活性无显著影响,表明NaCl胁迫下NO对GR活性、GSH和ASA含量、GSH/GSSG的调节可能是通过cGC介导的,对MDAR无明显的调节作用,对DHAR、APX的调节还存在其它途径。

Interspecific Hybridization between Cucumis ssp. Plants and SRAP Analysis of Hybrids

To understand the inter-hybridization between Cucumis ssp.plants,we used 150 melon varieties as female parents to cross with Cucumis metuliferus and Cucumis anguria.Only melon accessions V2 and V129 set fruits,but seeds from fruits V2（V129）×C.metuliferus were abortive.A few of seeds from the bottom of fruit V2（V129）×C.anguria were fertile.Sequence-related amplified polymorphism（SRAP）molecular markers were used to analyze the progenies of inter-specific hybridization between C.anguria and melon V129.One pair primer（E14/M2）was found effective in amplification on male parent characteristic bands from the hybrids,suggesting that some DNA exchange had happened between C.anguria and melon V129.This study provided data for analyzing the mechanism of inter-hybridization between Cucumis plants.

采后河套蜜瓜(Cucumis melo cv.Hetao)软化的生理生化研究

采后河套蜜瓜贮存中，呼吸强度和内源乙烯含量均发生跃变，并都在采后６ｄ达到最大值，分别为７６．６ｍｇＣｏ２ｋｇ－１ｈ－１和１８．５５ｎｍｏｌｍｌ－１．可溶性固形物在采后４ｄ达到最大值１２．８％，至采后６ｄ前基本维持这一含量，表明此时果实品质最佳．对直接软化因素细胞膜透性、淀粉含量及淀粉酶活力、组织含水量、果胶层降解酶ＰＧ及β－半乳糖苷酶活力等的研究表明，ＰＧ和β－半乳糖苷酶对细胞壁果胶层的破坏及组织含水量降低引起膨压降低，是河套蜜瓜采后软化的重要因素．组织膜透性变化，对采后８ｄ前果实软化影响较小；

来自甜瓜属(Cucumis melo L.)6个变种部分品种货架期差异比较

对甜瓜属6个变种的13个材料的货架期及相关因素进行了测定比较。结果表明,来自var.saccharinus和inodorus的5个品系表现出乙烯释放速率和鲜样质量损失率很低,货架期显著优于其它变种的材料。var.reticulatus虽然乙烯释放量较低,但由于果肉软化,其货架期短于var.inodorus。var.cantalupensis,makuwa和acidulus货架期短。相关性分析显示货架期还与果实发育期及果实质量存在高度相关,而果实表面的网纹结构与乙烯释放速率、鲜样质量损失速率及货架期并无显著的相关性。

河套蜜瓜Cucumis melo CV Hetau成熟期中某些生理生化过程的变化

对河套密瓜成熟过程中生长速率、呼吸强度以及内源乙烯含量变化的研究表明：该种甜瓜属呼吸跃变型果实，从开花到成熟约为３８ｄ；呼吸跃交出现之前乙烯开始产生，其含量升高先于呼吸跃变．可溶性精含量在成熟过程中不断增高，在呼吸峰值时达到最大，淀粉含量出现一个由积累到降解的变化．此外也研究了瓜硬度、色泽和可溶性固形物的变化．

Preliminary Study on the Adaptability of Cucumis hystrix Chakr. under Aluminum Salt Stress

[Objective] The study was carried out to research the adaptability of Cucumis hystrix Chakr.under aluminum salt stress.[Method] Using Cucumis hystrix Chakr.and three cultivated cucumbers as tested materials,the change of physiological indexes including POD activity,SOD activity,electrolyte leakage and the content of malondialdehyde（MDA）,proline（Pro）content and soluble sugar were studied.[Result] The POD activity,SOD activity,proline content and soluble sugar content of Cucumis hystrix were higher than these of cultivated cucumbers,while electrolyte leakage and MDA content were lower,and it showed that Cucumis hystrix had better adaptability under aluminum salt stress.[Conclusion] Our study could lay a foundation for the improvement of cultivated cucumber by using the excellent characteristics of Cucumis hystrix.

河套蜜瓜(Cucumis melo L cv Hetau)子叶的组织培养和再生植株研究

切取在ＭＳ培养基中生长５ｄ的河套蜜瓜子叶，在ＭＳ＋ＮＡＡ１＋ＢＡ０．１的培养基中予培养３ｄ后转入芽诱导培养基（ＭＳ＋ＺＴ６）诱导生芽，待芽长２ｃｍ左右转入ＭＳ＋ＩＢＡ０．５诱导生根，１０ｄ后再转入沙质土壤的营养缶本中成苗，整个成苗过程约需６０～７０ｄ，再生植株诱导率可达５５％。

厚皮甜瓜(Cucumis melo var.reliculatus)的快速繁殖

以厚皮甜瓜 (Cucumismelovar.reliculatus)西薄洛托带腋芽茎段为外植体进行离体快速繁殖研究。结果表明 :在MS +BA 0 .5～ 1 .0mg/L +IAA 0 .1mg/L的培养基上利于诱导形成丛生芽 ,芽的月增殖系数达到 1 1以上 ;在 1 /2MS +IAA 0 .5mg/L培养基上并经暗处理 3d最易生根 ,生根率 90 % ;在蛭石 :草炭土 =1 :1 (体积比 )基质中移栽驯化效果好。试管植株定植大田后种性不变 ,生长和结果习性优于种子苗。

Spectrin-like Protein in the Phloem of Cucumis sativus

Spectrin-like protein has been found in a variety of plant cells. In this study, electron microscopic observation of immuno-gold labelled preparations from the leaf petiole of cucumber ( Cucumis sativus L.) shows that it also exists in the sieve element-companion cell (SE-CC) complex, being widely distributed in P-protein filaments and sieve element reticulum (SER), in the cytoplasm and mitochondrial membrane of companion cell (CC) and in the branched plasmodesmata between sieve element (SE) and CC as well. The results suggest that this protein could be synthesized in CC and transferred to SE through plasmodesmata. Western blotting showed that spectrin-like protein existed in the protein of phloem exudate of cucumber, and its molecular weight was about 260 kD.

哈密瓜(Cucumis melo L.)致腐真菌的鉴定

研究从哈密瓜表面分离出引起其腐败的菌株A和菌株B,并采用显微镜形态学观察、表型特征和分子生物学三种方法对其进行鉴定。结果发现菌株A可利用碳源包括杏苷、糊精、D-半乳糖、D-葡萄糖酸、麦芽糖、肝糖、L-鼠李糖、L-山梨糖、L-乳酸等72种碳源,其ITS rDNA序列与尖孢镰刀菌甜瓜转化型(Fusarium oxysporum f.sp.melonis)的同源性为99%,分支长度为0.00。菌株B可利用碳源包括L-阿拉伯糖、D-果糖、丙三醇、蔗糖和木糖醇等54种碳源,其ITS rDNA序列与链格孢菌(Alternaria alternata)的同源性为100%,分支长度为0.00。因此,推断菌株A为尖孢镰刀菌甜瓜转化型,菌株B为链格孢菌。

Current status of genetic transformation technology developed in cucumber(Cucumis sativus L.)

Genetic transformation is an important technique for functional genomics study and genetic improvement of plants. Until now, Agrobacterium-mediated transformation methods using cotyledon as explants has been the major approach for cucumber, and its frequency has been up to 23%. For example, significantly enhancement of the transformation efficiency of this plant species was achieved from the cotyledon explants of the cultivar Poinsett 76 infected by Agrobacterium strains EHA105 with efficient positive selection system in lots of experiments. This review is to summarize some key factors influencing cucumber regeneration and genetic transformation, including target genes, selection systems and the ways of transgene introduction, and then to put forward some strategies for the increasing of cucumber transformation efficiency. In the future, it is high possible for cucumber to be potential bioreactor to produce vaccine and biomaterials for human beings.

Inheritance of Powdery Mildew Resistance in Cucumber (Cucumis sativus L.) and Development of an AFLP Marker for Resistance Detection

Cucumber powdery mildew is one of the most destructive diseases of cucumber throughout the world. In the present study, inheritance of powdery mildew resistance in three crosses, and linkage of resistance with amplified fragment length polymorphism （AFLP） markers are studied to formulate efficient strategies for breeding cultivars resistant to powdery mildew. The joint analysis of multiple generations and AFLP technique has been applied in this study. The best model is the one with two major genes, additive, dominant, and epistatic effects, plus polygenes with additive, dominant, and epistatic effects （E-l-0 model）. The heritabilities of the major genes varied from 64.26% to 97.82%, and susceptibility was incompletely dominant for the two major genes in the three crosses studied. The additive effects of the two major genes and the dominant effect of the second major gene were high, and the epistatic effect of the additive-dominant between the two major genes was the highest in cross I . In cross II, the absolute value of the additive effect, dominant effect, and potential ratio of the first major gene were far higher than those of the second major gene, and the epistatic effect of the additive-additive was the highest. The genetic parameters of the two major genes in cross III were similar to those in cross II. Correlation and regression analyses showed that marker E25/M63-103 was linked to a susceptible gene controlling powdery mildew resistance. The marker could account for 19.98% of the phenotypic variation. When the marker was tested on a diverse set of 29 cucumber lines, the correlation between phenotype and genotype was not significant, which suggested cultivar specialty of gene expression or different methods of resistance to powdery mildew. The target DNA fragment was 103 bp in length, and only a small part was found to be homologous to DNA in the other species evaluated, which indicated that it was unique to the cucumber genome.

Asynchronous meiosis in Cucumis hystrix–cucumber synthetic tetraploids resulting in low male fertility

Interspecific hybridization and allopolyploidization contribute to the improvement of many important crops. Recently, we successfully developed an amphidiploid from an interspecific cross between cucumber(Cucumis sativus, 2n = 2x = 14) and its relative C. hystrix(2n = 2x = 24) followed by chemical induction of chromosome doubling. The resulting allotetraploid plant was self-pollinated for three generations. The fertility and seed set of the amphidiploid plants were very low. In this study, we investigated the meiotic chromosome behavior in pollen mother cells with the aid of fluorescence in situ hybridization, aiming to identify the reasons for the low fertility and seed set in the amphidiploid plants. Homologous chromosome pairing appeared normal, but chromosome laggards were common, owing primarily to asynchronous meiosis of chromosomes from the two donor genomes. We suggest that asynchronous meiotic rhythm between the two parental genomes is the main reason for the low fertility and low seed set of the C. hystrix–cucumber amphidiploid plants.

Cytogenetic Analysis of the Primary Amphidiploid Derived from Interspecific Hybridization in Cucumis and Its Selfed Progenies

Studies on the reproduction and cytogenetic characterization of a primary amphidiploid Cucumis species C. hytivus Chen and Kirkbride (2n = 4x = 38) indicated that a more comprehensive cytogenetic analysis of this species and its first selfed progeny would increase its potential utility in cucumber improvement. With tendrils used as source materials for mitotic analysis, chromosome numbers in all selfed progenies were 2n = 38, confirming chromosomal stability in this synthetic amphidiploid species. Detailed meiotic processes were described by comparing the primary and the selfed amphidiploids. Meiotic abnormalities, such as chromosome lagging, unequal separation, chromosome multi-polarization and polyads were observed frequently in all amphidiploid plants except for the selfed no.8, in which meiosis was arrested prior to metaphase Ⅰ. Generally, the frequency of multivalents was higher and the configurations were more complex in the selfed progenies, demonstrating a more extensive genetic exchange between cucumber and C. hystrix Chakr. Genome separation between cucumber and C. hystrix was observed through prophase Ⅰ to anaphase Ⅰ in both generations of the amphidiploids. Consequently, in addition to n = 19, a new gamete with n = 7 was produced, which was confirmed by the chromosome counts 2n = 14 in the backcrossing progenies from cucumber × amphidiploid mating. Fertility varied among the selfed amphidiploid plants. The selfed plant no.1 was found to have an improved fertility (e.g., pollen staining ability 40.8% and 25.6 seeds per fruit) and then was used as source germplasm in further introgression and gene exchange experiments.

Breeding melon(Cucumis melo)with resistance to powdery mildew and downy mildew

Melon(Cucumis melo L.)production is often restricted by a plethora of pests and diseases,including powdery mildew and downy mildew caused respectively by the fungal species Podosphaera xanthii/Golovinomyces orontii and oomycete species Pseudoperonospora cubensis.Many efforts have been directed on identification of resistant sources by screening(wild)melon germplasm.In the current review,we summarized such efforts from various publications of the last 50 plus years.Resistance to powdery mildew has been identified in 239 melon accessions and downy mildew resistance in 452 accessions of both C.melo and the wild relative species C.figarei.Among the resistance sources,C.melo var.cantalupensis accessions PMR 45,PMR 5,PMR 6,and WMR 29 as well as C.melo var.momordica accessions PI 124111,PI 124112,and PI 414723 have been considered as the most valuable germplasm because multiple resistance genes have been identified from these accessions and are widely used in melon resistance breeding.Further genetic mapping in a number of resistant sources has enabled identification of 25 dominant genes,two recessive genes and seven QTLs conferring powdery mildew resistance,as well as eight dominant genes and 11 QTLs for downy mildew resistances.Based on the reported sequences of associated markers,we anchored physically(many of)these genes and QTLs to chromosomes of the melon cv.DHL92 genome.In addition to presenting a comprehensive overview on powdery mildew and downy mildew resistance in(wild)melon germplasm,we suggest strategies aiming at breeding melon with durable and broad-spectrum resistance to pathogens and pests.

Telomere-to-telomere genome assembly of melon(Cucumis melo L.var.inodorus)provides a high-quality reference for meta-QTL analysis of important traits

Melon is an important horticultural crop with extensive diversity in many horticultural groups.To explore its genomic diversity,it is necessary to assemble more high-quality complete genomes from different melon accessions.Meanwhile,a large number of QTLs have been mapped in several studies.Integration of the published QTLs onto a complete genome can provide more accurate information for candidate gene cloning.To address these problems,a telomere-to-telomere(T2T)genome of the elite melon landrace Kuizilikjiz(Cucumis melo L.var.inodorus)was de novo assembled and all the published QTLs were projected onto it in this study.The results showed that a high-quality Kuizilikjiz genome with the size of 379.2 Mb and N50 of 31.7 Mb was de novo assembled using the combination of short reads,PacBio high-fidelity long reads,Hi-C data,and a high-density genetic map.Each chromosome contained the centromere and telomeres at both ends.A large number of structural variations were observed between Kuizilikjiz and the other published genomes.A total of 1294 QTLs published in 67 studies were collected and projected onto the T2T genome.Several clustered,co-localized,and overlapped QTLs were determined.Furthermore,20 stable meta-QTLs were identified,which significantly reduced the mapping intervals of the initial QTLs and greatly facilitated identification of the candidate genes.Collectively,the T2T genome assembly together with the numerous projected QTLs will not only broaden the high-quality genome resources but also provide valuable and abundant QTL information for cloning the genes controlling important traits in melon.

Genome-wide characterization of graft-transmissible mRNA-coding P450 genes of cucumber(Cucumis sativus L.)

P450(cytochrome P450)is a supergene family,which is involved in various metabolic pathways in plants.Based on previous study,we found some of cucumber P450 mRNAs were systemic mobile in cucumber/pumpkin grafts.However,the reason that why P450 mRNAs were endorsed as signaling,and what specific motif(s)did they harbored is not clear yet.Here,we first identified 221 CsaP450 genes in cucumber genomewide level.Combining with graft-transmissiblemRNAs datasets in cucumber,we elucidated 15mobile-CsaP450-coding genes,of which 5 and 10 belonged to A-type and non-A type respectively.Compared with Arabidopsis and pumpkin(Cucubit moschata)graft-induced-transmissible P450 mRNAs,a phylogenetic treewas constructed and divided into eight clans by usingmultiple-sequence alignment.Gene ontology(GO)enrichment and Kyoto Encyclopedia of Genes and Genomes(KEGG)annotations indicated that the expression patterns of the mobile-mRNA-coding CsaP450 genes in different tissues of cucumber was specifically enriched in oxidoreductase activity and secondary metabolic pathways.The structures and motifs of these 15 mobile-mRNA-coding CsaP450 genes and their types of regulatory elements told that the proportion of CU-rich motifs was higher than nonmobile-mRNA-coding CsaP450 genes.The integrated analysis of mobility direction and mRNA abundance of 15 mobilemRNA-coding CsaP450 genes allowed to conclude that there was rarely relationship between them.The study provided a new insight into the relationship between the motifs and functional characterization of mobile-mRNA-coding P450 genes of cucumber in genome-wide levels.

Effect of Low Concentration of Yttrium on Physiological Characteristics of Cucumber (Cucumis Sativus L.)

There is no doubt that rare earth elements stand an important position among the essential elements of plant growth and it is long time since they are first used as plant growth promoters. Given their effects on microstructure, most reports are focused on the toxicology rather than promotion. Using cucumis sativus L. (Jin Chun No.5) as experiment material, we try to find out the nutritional effects of low Y3+ concentrations on cucumber seedlings′ leaves. The present paper suggests that the rare earth elements act as micronutrients at low concentrations while they give rise to toxicity at high concentration. Benefits defeat toxicity with concentration ranging from 5 to 25 μmol·L-1. Through careful study, at the Y(NO3)3 concentration of 10 μmol·L-1 the content of chlorophyll as well as the activities of SOD, Cu-Zn SOD and the POD are the highest. It indicates 10 μmol·L-1 is the optimum concentration of yttrium for promoting the cucumber growth.

Cytological Analyses on Development of Male and Female Gametophytes in an Interspecific Hybrid F_1 from Cucumis hystrix Chakr. × Cucumis sativus L.

An interspecific hybrid F1 of Cucumis hystrix Chakr. x Cucumis sativus L. （NC4406） was used to establish the developmental sequence and to characterize the male and female gametophytes at cytological level for further understanding of the phylogenic relationship and the mechanism of fertility or sterility in the interspecific hybrid F1 The development of male and female gametophytes was studied through meiotic analysis and paraffin section observation technique, respectively. Meanwhile, the fertility level was assessed through hybrid F1 backcrossing to cultivated cucumber 4406. Variable chromosome configurations were observed in the pollen mother cells （PMCs） of hybrid F1 at metaphase Ⅰ , e.g., univalents, bivalents, trivalents, quadravalents, etc. At anaphase Ⅰ and Ⅱ, chromosome lagging and bridges were frequently observed as well, which led to the formation of polyads and only a partial number of microspores could develop into fertile pollen grains （about 23.3%）. Observations of the paraffin sections showed numerous degenerated and abnormal embryo sacs during the development of female gametophytes, and only 40% of the female gametophytes could develop into normal eight-nuclear megaspore. On an average, 22.8 and 6.3 seeds per fruit could be obtained from the reciprocal backcross. The interspecific hybrid F1 of C. hystrix x NC4406 was partially fertile; however, the meiotic behaviors of hybrid F1 showed a high level of intergenomic recombination between C. hystrix and C. sativus chromosomes, which indicated that it plays an important role for introgression of useful traits from C. hystrix into C. sativus.

Cloning and Sequence Analysis of Lipoxygenase Gene cDNA from Cucumber Fruit (Cucumis sativus L.)

Lipoxygenases are nonheme-iron-containing dioxygenases that catalyze the hydroperoxidation of unsatrated fatty acids containing a cis, cis-1,4-pentadiene structure producing hydroperoxy acids with conjugated dienes.