运用聚丙烯酰胺凝胶电泳，对甜瓜属远缘杂种（Cucum is × hytivus Chen & Kirkride）与栽培黄瓜和回交自交群体共46份材料进行了同工酶分析，结果表明：群体内各单株间过氧化物酶酶谱差异较大，根据酶带数目及位置的差异可归为6个类型，反映了群体内的遗传多态性。将回交自交群体与普通栽培黄瓜酶谱相比较时发现，群体比黄瓜新增了4条带；群体的平均酶带数目（7.8）比普通栽培黄瓜（5.0）高出56.0%。与此同时，在酶的活性上群体内也存在很大变异。这说明通过远缘杂交获得的新种对扩大黄瓜的遗传变异，改良黄瓜资源具有巨大的潜力。

甜瓜属种间杂交新种Cucumis hytivus Chen & Kirkbride的光补偿点为11.25μEm-2·S-1，低于以往报道的耐弱光品种长春密刺。弱光处理2周后，新种的叶绿素a和叶绿素b含量增加，叶绿素a/b的值大幅度降低，形态学耐弱光隶属值高达0.946，说明杂交新种耐弱光能力很强。

佛手瓜[Sechium deule (Jacq.) Swartz] 是我国南方一种具有药用价值的特色蔬菜，一个瓜只粒种子，并且其种子脱离果网不能正常革萌发[1]，很难获得足够多的幼根根尖来研究染色体。此外，佛手瓜染色体小且染色能力弱[2]，进一步增加了细胞学研究的难度，使得佛手瓜染色体数目的研究结果仍不统一（2n=26(3)和28[4]）。本文首次利用数量众多的卷须代替根尖作为制片材料，对佛手瓜的染色体数目进行准确鉴定，为进一步开展佛手瓜遗传育种奠定细胞学基础。

利用RAPD（random amplified polymorphic DNA）技术对黄瓜性别特异基因进行分子标记连锁研究。共选取用300个10碱基的随机引物按BSA法对黄瓜性别表型分离群体进行PCR扩增，筛选出5个在全雌和弱雌株基因池（gene pool）中表现多态性的引物。单株检测表明，引物B11具有全雌特异性，在检测的大多数全雌性单株中均可扩增出一条约1000bp的特征带。而在雌雄同株的单株中则未见。因此，将该全雌性特异的片段命名为B11-1000°该标记的获得为黄瓜性别特异基因的分离和克隆奠定了基础。另外，以ACC合酶基因（CS-ACS1）特异上物检测分离群体单株，发现该酶基因存在于所有性型的单株中，不具有性别特异性。

研究了华北型、华南型和西南型黄瓜花粉母细胞的减数分裂行为，发现黄瓜细胞减数分裂的同步性较高，细胞质是同时型分裂。在细胞核分裂的过程中，核仁在前期Ⅰ到中期Ⅰ逐渐消失，在前期Ⅱ再次出现，随后消失；染色体在前期Ⅰ到中期Ⅰ逐渐收缩，变得清晰，至末期Ⅰ解螺旋，变得模糊，在前期Ⅱ再次清晰。不同生态型黄瓜终变期的染色体构型均以环状二价体为主。在前期Ⅰ和前期Ⅱ，西双版纳黄瓜的核仁都相应地比另外两种生态型黄瓜品种的多，在后期Ⅰ还偶尔出现染色体桥，显示了西双版纳黄瓜变种的特殊性。研究还发现寒冷的气候条件下栽培黄瓜都能够形成高频率的多分体，推测其形成很可能与低温逆境有关。

Interspecific hybrids between Cucumis hystrix Chakr. (2n=2x=24) and Cucumis sativus L. (2N=2X=14) were produced by means of F1(2n=19) embryo res-cue and subsequent chromosome doubling. The gybridi-ty was confirmed by genomic in situ hybridization (GISH) and chromosome analysis. The amphidiploid (2n=37) was self-opllinated and backcrossed to cucum-ber resulting in lines with improved crossability to C. sativus. Examination of shape, stainability, and germi-nation rate of pollen grains and yield as a function of mature fruit set per ten pollinated flowers indicated a tendency for increased fertility in BC1S1 progeny when compared to F1 and amphidiploid off spring. Cytogenctic characterization of F1and amphidiploid progeny was performed. Generally normal meioses produces viable pollen grains, and fertilization resulted in partial fertility restoration in amphidiploid progeny. Chromosome anomalies such as "frying-pan trivalent", chromosome lagging and spindle mis-orientation were also observed. In most of the PMCs of the F1 diploid hybrid progeny, 19 univalents were observed at diakinesis and MI. In the amphidiploid, more than 90% of the configurations at MI consisted of the predicted 19 bivalents and less than 5% contained multivalents [trivalents (2.3%) +quadriva-lents (0.3%)], suggesting the presence of preferential pairing, and a distinctive parental genome as well. The chiasmata observed between homoeologous chromo-somes further demonstrated the introgression of the C. hystrix genome into that of C. sativus.

Cucumis hystrix Chakr. (HH, 2n=24), a wild relative of the cultivated cucumber, possesses several potentially valuable disease-resistance and baiotic stress-tolerance traits for cucumber (C. sativus L., CC, 2N=14) improvement. Numerous attempts have been made to transfer desirable traits since the successful interspecific hybridization between C. hystrix and C. sativus, one of which resulted in the production of an allotriploid (HCC, 2n=26: one genome of C. hystrix and two of C. sativus). When this genotype was treated with colchicine to induce polyploidy, two monosomic alien addition lines (MAALs) (plant nos. 87 and 517: 14 CC+1 H, 2n=15) were recovered among 252 viable plants. Each of these plants was morphologically distinct from allotriploids and cultivated cucumbers. Cytogenetic and molecular marker analyses were performed to confirm the genetic eonsti-tution and further characterize these two MAALs. Chro-mosome counts made from at least 30 meristematic cells rom each plant confirmed 15 nuclear chromosomes. In pollen mother cells of plant nos. 87 and 517, seven bivalents and one univalent were observed at diakinesis and metaphase Ⅰ; the frequency of trivalent formation was low (about 4-5%). At anaphase Ⅰ and Ⅱ, stochastic and asymmetric division led to the formation of two gamete classes: n=7 and n=8; however, pollen fertility was relatively high. Pollen stainability in plant no.87 was 86.7% and in plant no.517 was 93.2%. Random amplified polymorphic DNA analysis was performed using 100 random 10-base primers. Genotypes obtained with eight primers (A-9, A-11, AH-13, AI-19, AJ-18, AJ-20, E-19, and N-20) showed a band common to the two MAAL. plants and C. hystrix that was basent in C. sativus, confirming that the alien chromosomes present in the MAALs were derived from C. hystrix. Morphological differences and differences in banding patterns were also observed between plant nos. 87 and 517 after amplifica-tion with primers AI-5, AJ-13, N-12, and N-20, suggest-ing that these plants may contain different C. hystrix chromosomes.

tility restoration through chromosome doubling provide an effective means for investigating genetic relationships among Cucumis spp. In this study, random amplified polymorphic DNA (RAPD) and simple sequence repeat (SSR) markers were used to investigate relationships among C. s. var. sativus L., C. s. var. hardwickii (R.) Alef., C. hystrix interspecific hybrid, 2n=38), C. melo (2n=2x=24) and C. metuliferus Meyer and Naudin (2n=2x=24). A total of 109 SSR bands and 398 RAPD primed sites were used to calculate Jaccard's distance coefficients for cluster analysis using a unweighted pair-group method using an arithmetic averaging (UPGMA) algorithm. The genetic relationships identified using SSR and RAPD markers were highly concordant, such that the correlation between SSR and RAPD genetic distance (GD) estimates was Ⅲγ=0.94. SSR and RAPD analysis of 22 accessions allowed for their grouping into two distinct groups designated as CS and CM. While group CS consisted of 11 C. sativus genotypes, and the C. hytivus and C. hystrix accessions, group CM included six C. melo genotypes and C. metuliferus. The GD values between C. hystrix and C. sativus sacribed by SSR and RAPD matrices were 0.59 and 0.57, respectivelyl These GDs were smaller than those detected between C. hystrix and C. melo (0.87 and 0.70 derived from SSR and RAPD markers, respectively).

Plant materials with different ploidy levels from a series of reciprocal crosses between a wild Cucumis species (Cucumis hystrix Chakr., 2n = 2x = 24) and cucumber (Cucumis sativus L., 2n = 2x = 14) were used to investigate reciprocal differences in morphology, fertility, and DNA characteristics. Diameter of the stem, length of the petiole, and shape and size of the leaves of the hybrids were intermediate when compared with their parents. The length of the internode of the main stem showed maternal transmission in all hybrids, but the branching number and appearance of the first female flower showed paternal transmission. The differences in fertility of reciprocal plants were significant. When C. hystrix was used as the female parent, the diploid (2n = 2x = 19) hybrids set fruit without seeds, whereas the amphidiploid (2n = 4x = 38) plants produced fruits with viable seeds. However, when cucumber was used as the female parent, both tetraploid and diploid hybrid lants were highly sterile and did not set fruits. To further investigate variation in hybrid genomes, 21 arbitrary primers were used for random amplified polymorphic DNA analysis. Reciprocal differences were detected for 15 primers. The banding patterns were different among the four types of hybrids, but there was no significant difference in the total and (or) average numbers of bands observed. We suggest that the differences in random amplified polymorphic DNA banding patterns of the hybrids are probably related to the paternal-and (or) maternal-transmitted morphological characteristics in the reciprocal cross.

A fully fertile in terspecific hybrid (Cucumis hytivus Chen and Kirkbride, 2n=4x=38) between Cucumis hystrix Chakr. (2n=2x=24) and C. sativus L. (2n=2x=14) was previously produced by means of F1 (2n=19) embryorescue and subsequent chromosome doubling. This amphidiploid, a new synthetic species, may serve as a genetic bridge in Cucumis, and thus is a source for broadening the genetic base of C, sativus. The identification and characterization of fertile progeny possessing lower ploidy levels would facilitate bridging among Cucumis species. Putative allotriploids (2n=26) were recovered from C. hytivus × C. sativus matings by means of embryo culture, and experiments were designed to confirm their genetic constitution, describe their morphology, and esgablish an efficient protocol for their micropropapation. Apical and axillary buds of these putative allotriploid plants were used as explants to establish a micropropagation system for subsequent verification and characterization of ploidy, Of the array of micropropagation media tested, the most effective for the induction of adventitious buds (desginated Stage Ⅱ) was a Murashige and Skoog (MS) growth media containing 13.3μM BA+1.1μM NAA or contaning 10μm BA only. The mean number of adventitious buds per explant in the two media was 6.8 and 6.5, respectively. Shoots resultion from adventitius buds produced roots (Stage Ⅲ) in relative abundance (39 of 42, 92.8%) on half-strength MS medium containing 1.0μm IBA. The survivorship of rooted plantlets after acclimatization as assessed by relative production of leaves in plantlets (designated Stage IV) was 91.4% (148 of 162). The chromosome number in putative allotriploid plants as determined in mitotic root tip figures in all plants was 2n=26, the number expected for allotriploids derived from such a mating. An examination of pollen viability in five samples of each plant by cytochemical staining revealed stainability to be<10%. Compared to their parents, the allotriploid genotypes possess a high degree of parthenocarpy (84.8%) as measured by setting fruit in pollen-free conditions. While allotriploid fruit are black-spined and similar to the maternal parent C. hytivus, the dark green leaves typical of allotriploid plants mirrors that of the paternal C. sativus parent.