Genetic divergence among inbred lines in Cucurbita moschata from China

Knowledge of genetic divergence among inbred lines is essential for cross breeding. The objectives of this study were to (1) analyze the level and character of genetic diversity in C. moschata accessions, and (2) classify the genetic divergence among inbred lines in C. moschata to assist in selection of parent genotypes for genetic improvement. Twenty agronomic characters were investigated and rich diversities were demonstrated among 39 inbred lines of C. moschata from China. Various degree correlations among these characters made it possible to summarize the diversities of the twenty characters into 3 major principal components: leaf, fruit and flesh quality factor. Forty-one inbred lines of pumpkin were clustered into four groups based on principal component data, which is more distinct for classification that based on the original data of the 20 characters. However, parent inbred lines whose hybrids displayed significant heterosis in fruit weight, soluble solid and fruit shape were located in different clusters or sub-clusters based on standardized original data. It was suggested that genotypes in the same clusters may represent members of one heterotic group.     

籽用美洲南瓜白粉病病原菌生理小种鉴定及抗性遗传分析

利用形态学和分子生物学的方法对内蒙古不同地区籽用美洲南瓜白粉病病原菌种类进行鉴定，并采用国际通用的13 个甜瓜生理小种鉴别寄主和鉴别标准体系，对不同地区白粉病菌的生理小种进行鉴定。对20 份籽用美洲南瓜种质的抗病性进行鉴定，并采用苗期人工接种的方法对籽用美洲南瓜六世代群体进行抗性统计分析，开展白粉病抗性遗传研究。形态学鉴定结果表明，籽用美洲南瓜白粉病病菌具有成串的椭圆形分生孢子，具有纤维状体。系统发育树鉴定结果表明该白粉病菌ITS 序列与GenBank 中已公布的瓜类单囊壳白粉菌（Podosphaera xanthii）的序列聚在一个分枝，确定内蒙古地区白粉病菌为单囊壳白粉菌P. xanthii。初步确定内蒙古地区籽用美洲南瓜白粉病存在4 个生理小种，分别为小种4、小种2F 和小种1，还有1 个未知的小种。种质抗性鉴定结果表明，20 份籽用美洲南瓜种质中有7 份抗病种质，4 份中抗种质，1 份高抗种质。内蒙古地区籽用美洲南瓜抗白粉病基因由1 对主效隐性单基因控制。     

Relationship between field and cage assessments for resistance to red pumpkin beetle in summer squash

Summary Significant differences in resistance to the red pumpkin beetle were observed among summer squash lines in both field and cage experiments. Broad sense heritability estimates were 0.87 and 0.78 for field and cage assessments respectively. Significant positive rank (r_s=0.96) and phenotypic (r_p=0.76) correlations were observed. Cage evaluation of red pumpkin beetle resistance may be used with confidence in selection programmes of red pumpkin beetle resistance.     

裸仁南瓜种皮发育研究进展

裸仁南瓜是南瓜中的一种自然突变类型,其种皮在发育过程中因缺乏木质素和纤维素逐渐退化成一层薄膜。裸仁南瓜营养丰富,方便食用和加工,是优异的种质资源,国内外市场需求旺盛,其种皮形成机制复杂,对其深入研究有助于解决生产难题和促进裸仁南瓜籽产业发展。笔者综述了近年来国内外裸仁南瓜种皮发育相关基础研究取得的最新进展与成果,包含南瓜籽主要营养成分研究、南瓜种皮分类、种皮形态学研究、相关酶分析、育种研究、种皮颜色研究、基因定位研究等。分析了目前裸仁南瓜种皮发育相关基础研究中存在的问题以及今后研究的重点和难点,以期为裸仁南瓜育种及种皮发育的深入研究提供理论和实践依据。     

巨型艾美耳球虫gam82基因核酸疫苗的构建与免疫原性分析

以重组质粒pGEM-T-gam82为模板,构建巨型艾美耳球虫gam82基因核酸疫苗.采用MTT法与ELISA对该核酸疫苗接种鸡体后淋巴细胞增殖与抗体水平的变化进行检测,结果显示,该核酸疫苗具有一定的免疫原性.     

巨型艾美球虫重组蛋白Gam82-Y和重组质粒pcDNA-gam82的免疫保护效果研究

为研究巨型艾美球虫NT株重组蛋白Gam82-Y和重组质粒pcDNA-gam82对鸡的免疫保护效果,本研究以平均增重、相对增重率及卵囊减少率等作为评价指标,检测结果显示:中剂量重组蛋白佐剂组(0.5 mg-FCA)和中剂量重组蛋白组(0.5 mg)的免疫保护力均低于卵囊免疫组(p＜0.05),但比其他各免疫组高(p＜0.05);重组质粒(pcDNA-gam82)免疫组的平均增重、相对增重率、卵囊减少率等方面与重组蛋白免疫组相同,两者均优于未免疫攻虫组(p＜0.05),但仍未能够达到卵囊免疫组的免疫保护水平(p＜0.05).     

Improved shoot regeneration due to prolonged seed storage

Regeneration in vitro from cotyledon explants of commercial squash (Cucurbita pepo L.) cultivars is generally efficient on Murashige and Skoog [Murashige, M., Skoog, F., 1962. A revised medium for rapid growth and bioassays with tobacco tissue cultures. Physiol Plant. 15, 473–497] medium augmented with 4.4 μM benzyladenine. However, cotyledon explants from certain seed batches of cultivars Bareqet and Ma’yan could regenerate only buds, leaf primordia or very small shoots with storage for up to 2 years at 4 °C. Seed storage of cultivars Bareqet and Ma’yan at 4 °C for 6–8 years resulted in significant increases in shoot regeneration, shoot growth and explant growth, returning to the normal range of values for C. pepo. For example, for cv. Bareqet shoots regenerated per explant increased from 0.4 after storage for 2 years to 1.21 after storage for 8 years; shoot length increased from a mean of less than 2 mm after storage for 2 years to 22 mm after storage for 8 years. Additionally, the final explant fresh weight of cv. B increased from 181 mg after storage for 2 years, to 1389 mg after storage for 8 years. Similar responses were observed for seedling-derived explants of cv. Ma’yan following storage’ for 2–7 years. However, total regeneration (number of explants regenerating buds, leaf primordia or shoots) was not affected by prolonged storage for either cultivar. This is the first report of stimulation of in vitro shoot regeneration of a seedling-derived organ caused by prolonged seed storage. Moreover, the great improvement in regeneration due to long-term seed storage provides a new mechanism for the understanding of non-repeatability of plant tissue culture results.     

Colonisation and histological changes in muskmelon and autumn squash tissues infected by <Emphasis Type="Italic">Acremonium cucurbitacearum</Emphasis> or <Emphasis Type="Italic">Monosporascus cannonballus</Emphasis>

Muskmelon (Cucumis melo cv. Temprano Rochet) and autumn squash (Cucurbita maxima) seedlings were inoculated either with Acremonium cucurbitacearum or Monosporascus cannonballus, two of the soil-borne fungi implicated in ‘melon collapse’. Inoculation was achieved in two different ways: by growing the plants in pots containing infested soil to study the histological changes produced in the infected tissues using light microscopy and by growing seedlings in Petri dishes together with fungal colonies in order to observe the colonisation of the plant tissues using scanning electron microscopy. Both muskmelon and autumn squash roots infected with A. cucurbitacearum showed a suberised layer in the epidermis and the outermost layers of the parenchymatic cortex, but these symptoms developed earlier in the muskmelon plants. Muskmelon plants infected by this fungus also presented hypertrophy and hyperplasia, which led to a progressive separation of the vascular bundles in the lower stems of the affected plants. This response was not observed in autumn squash during the study. On the other hand, few histological changes were observed in tissues infected with M. cannonballus and only a slight increase in the size of cortical intercellular spaces was noted in the lower stems of muskmelon plants, and infected autumn squash tissues remained free of these symptoms throughout the study. The scanning electron microscope observations revealed that both fungi were able to colonise the tissues of the two host plants which were studied. A. cucurbitacearum colonised the epidermis and cortex of both muskmelon and autumn squash. The hyphae grew both inter- and intracellularly, and the density of the colonisation decreased within the endodermis. The same colonisation of host plants was observed as a result of M. cannonballus infection. The xylem vessel lumina of both muskmelon and autumn squash showed hyphae and tylose formation as a result of both fungal infections. However, non-fungal structures were detected in the hypocotyl vascular tissues. The present study demonstrates that both fungi are capable of infecting the tissues of a species which is resistant (autumn squash) and a species which is susceptible (muskmelon) to melon collapse.     

处红柚选育及其生物学特性观察初报

通过对浙江丽水市柚类资源的调查,从果实品质、结果性能、树势、抗性等方面制定了选优标准,经预选、初选、复选筛选出处红柚优良单株,并经遗传稳定性检验和生物学特性观察认为,处红柚外观漂亮、易剥、果肉红色、少籽、可食率高、酸甜可口、水分充足,成熟期早、适应性强、病虫害少、抗寒性好、座果性能好,遗传稳定性高,综合性状优良,适宜浙江丽水及生态条件类似地区推广栽培.     

柚皮柠檬苦素的提取及其杀虫活性研究

为了探究柚皮中柠檬苦素的最佳提取工艺及其杀虫活性,采用正交试验对柚皮中柠檬苦素的提取工艺进行优化,利用得到的柠檬苦素对夹竹桃蚜虫、吹绵蚧和菜蝽喷雾进行杀虫试验。结果表明：超声波提取法、二氯甲烷和丙酮水浴提取法从10 g柚皮中提取到的柠檬苦素分别是0.9700、1.5860、1.6000 g;二氯甲烷水浴提取法对柚皮中的柠檬苦素提取率为6.08%。10 mg/mL的柠檬苦素能将供试害虫全部杀死,0.625 mg/mL的柠檬苦素依然有较高的杀虫活性。回流法提取柚子皮中的柠檬苦素时,最佳提取工艺是：二氯甲烷为提取溶剂,液料比为1:12,回流提取2次,每次2 h,温度50℃;得到的柠檬苦素对3种供试害虫有较强的杀虫活性。