Characterization of six varieties of Cucumis melo L. based on morphological and physiological characters, including shelf-life of fruit

Seventy-two accessions covering six varieties of Cucumis melo were characterized by using 35 morphological characters with emphasis on shelf-life, and the relationships between shelf-life and related characters was investigated. Principal component analysis (PCA) revealed that development period of plant and fruit, size of seed and fruit, shelf-life, stem hair, flesh juiciness, netting, abscission of peduncle, rapid yellowing of epidermis at maturity, Brix value, and color of flesh and epidermis etc. were the principal characters to discriminate melon accessions examined in the present study. According to the scatter diagram, vars. acidulusand makuwa, both of which belong to the Oriental melon, are closely related because of their short growth duration, small seed, thin pericarp and poor shelf-life, while American cantaloupe (var.reticulatus) and European cantaloupe (var. cantalupensis) are rather closely related due to their climacteric fruit with orange flesh, slipped peduncle and rapid yellowing of epidermis at maturity, which is closely related with their shelf-life. PCA also indicated that var. saccharinus was closer to var. inodorus than to the other varieties, due to their requirement of long period for development, large size of seed and fruit, and half- or non-slipped peduncle. Shelf-life of melon fruit was significantly correlated with the following characters: quality of flesh, size of seed and fruit, abscission of peduncle, development periods of plant and fruit, rapid yellowing of epidermis at maturity, Brix value and color of flesh and epidermis. Accessions with good shelf-life were mostly found in vars. saccharinus and inodorus. This revised version was published online in July 2006 with corrections to the Cover Date.     

Molecular marker analysis of genetic variation characterizing a grasspea (Lathyrus sativus) collection from central Italy

Levels of genetic similarity characterizing 20 grasspea (Lathyrus sativus L.) populations collected in central Italy (17 populations in the Marche region and three populations in the Abruzzo region) were analysed with amplified fragment length polymorphism (AFLP) molecular markers. Two main clusters were found: one included large‐seeded populations from farms that were not market‐oriented (named Household populations) and the second, small‐seeded populations, cultivated in market‐oriented farms (named Commercial populations). Relationships among populations collected in different regions were found, although one population of the Abruzzo region was placed between the two main clusters, suggesting a possible further genetic differentiation within this grasspea germplasm collection. Principal component analysis based on AFLP marker frequency was effective in identifying polymorphic markers showing high discriminating ability between clusters H and C. In particular, seven markers showing high positive and three markers with low negative PC1 scores showed an almost cluster‐specific distribution. These results will be useful for enhancing Italian grasspea germplasm use in plant‐breeding programmes and for extending grasspea cultivation within the sustainable agricultural systems of central Italy.     

Combining ability between lines of Cucumis sativus L. and Cucumis sativus var. hardwickii (R.) Alef

Summary Three Cucumis sativus L. (CS) lines adapted to USA growing conditions were used as female parents in crosses to one line each of seven Cucumis sativus var. hardwickii (R.) Alef. (CH) accessions used as male parents to determine the relative combining ability of the CH accessions for six horticultural characters. The 21 F₁ progenies were grown in a randomized complete block design in two locations and evaluated for fruit number, lateral branch number, fruit length, fruit length/diameter ratio, number of female flowering nodes, and days to anthesis. General combining ability (GCA) was significant for all characters in each location. Specific combining ability (SCA) was significant for all characters except days to anthesis in one location and lateral branch number in both locations. Significant location × combining ability interactions were also evident for several characters. Results suggest that CH may be useful for improving fruit yield in commercial cucumber, but that limitations may lie in the attainment of acceptable fruit.Research supported by the College of Agric. and Life Sci., Univ. of Wisconsin, Madison; USDA, ARS, and by funds from Pickle Packers Intl., Inc. Mention of a trademark, proprietary product, or vendor does not constitute a guarantee of warranty of the product by the USDA and does not imply its improval to the exclusion of the other products or vendors that may also be suitable.     

Diversity among landraces of Indian snapmelon (<Emphasis Type="Italic">Cucumis melo</Emphasis> var. <Emphasis Type="Italic">momordica</Emphasis>)

Diversity among 36 snapmelon landraces, collected from 2 agro-ecological regions of India (9 agro-climatic sub-regions), was assayed using RAPD primers, morphological traits of plant habit and fruit, 2 yield-associated traits, pest and disease resistance and biochemical composition (TSS, ascorbic acid, titrable acidity). Typical differences among accessions were observed in plant and fruit characteristics and snapmelon germplasm with high titrable acidity and possessing resistance to downy mildew, Cucumber mosaic virus, Zucchini yellow mosaic virus, Papaya ringspot virus, Aphis gossypii and Meloidogyne incognita was noticed in the collection. RAPD based grouping analysis revealed that Indian snapmelon was rich in genetic variation and region and sub-region approach should be followed across India for acquisition of additional melon landraces. Accessions of var. agrestis and var. momordica clustered together and there was a separate cluster of the accessions of var. reticulatus. Comparative analysis of the genetic variability among Indian snapmelons and an array of previously characterized reference accessions of melon from Spain, Israel, Korea, Japan, Maldives, Iraq, Pakistan and India using SSRs showed that Indian snapmelon germplasm contained a high degree of unique genetic variability which was needed to be preserved to broaden the genetic base of melon germplasm available with the scientific community. N. P. S. Dhillon and Ranjana contributed equally to this work and are considered the first authors.     

黄瓜性别决定的细胞学研究

对黄瓜（Cucumis sativus L.）雄、雌花的细胞学特征进行了研究。黄瓜雄、雌花的发育从花芽原甚至雌蕊原基出现，无明显差异,在雌花中雌蕊原基出现后雌花进一步发育，花芽的中心凹陷发育为下位子房，雄蕊的花药原基中并未分化出小孢子母细胞。开花时，花药体积较小，并由一群形态结构基本一致的小型细胞组成。在雄花中，雌蕊原基出现后，花芽的中心未发生凹陷，在以后的发育过程中，尽管体积有所增大，但至开花时仍未产生柱头、花柱和子房。电镜观察结果显示，早期滞育雄芯细胞的质体具简单的片层结构，不含淀粉粒，线粒体的嵴不明显。开花时，质体内有较大的淀粉粒，线粒体分化出较明显的嵴，高尔基体周围小泡丰富。同样，开花时滞育雌蕊的细胞内质体大量积累淀粉,线粒体的数量较多，有高度分化的峭，高尔基体产生大量小泡。观察结果表明，尽管滞育雄蕊和滞育雌蕊正常的发育途径受阻，但其细胞和某些细胞器仍在发育成熟。     

黄瓜的分子标记和连锁图谱研究进展

黄瓜分子标记和遗传连锁图谱的研究工作相对番茄、小麦等作物比较落后,至今开展的分子标记研究多围绕黄瓜遗传关系分析进行,现有的几张遗传连锁图谱基本是由美国Staub研究小组完成,已被定位在图谱上的同工酶、RAPD、RFLP、SSR、AFLP等标记总数达到300多个,各标记间平均距离达到2.1cM,被整合在一起的遗传基因不足10个(F、B、de、ll、dm)。     

甜瓜种质RAPD体系的优化研究

研究了不同ＤＮＡ提取方法的护增效果。采用Ｌ９（３＾４）正交试验设计,快速、有铲地确定了适合甜瓜的最佳扩增条件（包括ｄＮＴＰ、引物、Ｍｇ＾２＋和ＴａｐＤＮＡ聚合酶等浓度的最佳组合）。并通过试验确定了省时的ＲＡＰＤ－ＰＣＲ反应程序。最终得到了一个重复性好、清晰度高、较理想的甜瓜ＲＡＰＤ技术体系。     

6-BA、NAA和IAA对黄瓜子叶离体培养分化的影响

以‘津春四号’黄瓜(Cucumis stativus)的幼龄子叶为外植体,比较了不同浓度的6-BA、NAA、IAA对其诱导愈伤组织以及对愈伤组织分化不定芽及不定根的影响。结果表明,黄瓜在组织培养再生完整植株时,只需极低浓度的NAA即能诱导大量愈伤组织;在0.05～0.10mg/L浓度范围内随NAA浓度的提高,出愈率提高,愈伤组织增殖加快;MS 6-BA1.0mg/L NAA0.10mg/L为较适宜的愈伤组织诱导培养基;MS 6-BA1.0mg/L IAA0.05～0.10mg/L为较适宜的芽诱导培养基;1/2MS NAA0.5mg/L培养基对生根诱导效果较好。     

分葱对黄瓜、萝卜和白菜的化感作用

以黄瓜(Cucumis sativusL.),萝卜(Raphanus sativusL.)和白菜(Brassica chinensisL.)3种蔬菜作物为受体,通过种子萌发试验及幼苗生长试验,对分葱(Allium fistulosumL.var.caespitosum Makino)根系及其地上部水浸液的化感作用进行了初步研究。结果表明:分葱根系和地上部水浸液对黄瓜、萝卜和白菜具有一定的化感作用。对黄瓜和萝卜的萌发有一定的抑制作用,而对其幼苗生长有一定的促进作用;对白菜的萌发表现为低浓度促进高浓度抑制,而对其幼苗生长有一定的抑制作用。因此,在蔬菜栽培制度中,分葱可与黄瓜和萝卜进行合理的轮作与间套作;但可能不适宜与白菜进行轮作或间套作。