瓜类枯萎病菌遗传多样性和亲缘关系的SRAP分析

尖孢镰刀菌可造成不同瓜类的枯萎病.为明确不同寄主、不同地区的瓜类枯萎病菌菌株间的遗传多样性及亲缘关系,采用相关序列扩增多态性(SRAP)分子标记技术,对来源于不同地区、不同寄主的95株尖孢镰刀菌的基因组DNA进行多态性扩增.以筛选出的19对引物共扩增出238条带,多态性比率为100%,平均每对引物扩增出12.5个位点和12.5个多态性位点;尖孢镰刀菌苦瓜专化型共扩增出166条带,其中145条为多态性条带,多态性比率为87.4%,平均每对引物扩增出8.7个位点和7.7个多态性位点,说明尖孢镰刀菌的遗传变异较为广泛.瓜类枯萎病菌株间的遗传相似系数范围为0.68～0.99,样品间的平均Nei遗传多样性指数和Shannon指数分别为0.2390和0.3718.在遗传相似系数为0.74时,可将供试的95株尖孢镰刀菌划分为苦瓜、黄瓜、西瓜、甜瓜4个专化群.在SRAP聚类树中,同一寄主的尖孢镰刀菌聚在一个分支上,其中尖孢镰刀菌苦瓜专化型菌株间的遗传相似系数范围为0.78～0.99,Nei遗传多样性指数为0.1811,平均Shannon指数为0.2750,表明尖孢镰刀菌苦瓜专化型的遗传变异较大,且菌株的聚群与地理来源存在相关性.     

Evidence for the origin of chayote,sechium edule (Cucurbitaceae)

Sechium edule (Jacq.) Sw. (Cucurbitaceae), a one-seeded squash most popular in Latin America, is cultivated worldwide in tropical and subtropical climates. In the past, a Mexican center of origin for chayote has been inferred mainly from linguistic data, but to use this argument correctly, relevant indigenous terms should be interpreted. Evidence from historical documents indicates pre-Columbian Aztecs used chayote in Mexico, but the lack of documentation from other countries does not constitute proof that the plant was absent. Chayote’s center of genetic diversity suggests it was first domesticated in Mexico and Central America, but this variation could have been secondarily derived. However inconclusive these three lines of evidence are, they do converge on the same conclusion supported by new botanical evidence. Chayote’s closest wild relative,S. compositum, from Mexico and Guatemala, and two potentially ancestral forms of chayote recently discovered outside cultivation in Mexico, demarcate Mexico and Guatemala as the most likely center of origin for this ancient crop. S. edule (Cucurbitaceae) es una calabaza de una semilla muy popular en América Latina, cultivada en los trópicos y subtrópicos mundialmente. La información linguistica sugiere a México como el centro de origen del chayote, pero para usar fuente de información se deben interpretar correctamente datos completos provenientes de fuentes indígenas apropiadas. El uso del chayote por los Aztecas precolombinos en México se mantiene como otra fuente de evidencia aún inconclusa por falta de documentación histórica proveniente de otros paises, aunque o tampoco constituye prueba de su ausencia. El centro de diversidad genética sugiere que el chayote fue originalmente domesticado en México y Centro América, pero esta variación podria haber sido secundariamente derivada. Tan inconclusas como son estas tres fuentes de evidencia, convergen con resultados favorecidos por nueva evidencia botánica. La especie silvestre más cercana al chayote,S. compositum, descubierta recientemente en México, sugiere a México y Guatemala como centros de origen para esta cosecha de antigua origen.

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Presented at the Symposium on New Perspectives on the Origin of Neotropical Crops, twenty-ninth annual Meeting, Society for Economic Botany; symposium organized by Peter K. Bretting.     

天然甜味剂罗汉果的研究与应用

本文综述了广西特产药用植物罗汉果的化学成分和药理研究,其甜味成分的甜度与结构关系及提取分离方法和应用。     

中国大陆葫芦科一归化属--野胡瓜属

报道了中国大陆葫芦科—归化属—野胡瓜属。     

Micropropagation for recovery of Cucumis hystrix

A micropropagation protocol that allows for the efficient cloning of C. hystrix was developed using 1 mm shoot-tip explants prepared from plants grown in the greenhouse. Establishment of Stage I cultures was greatest (83%) when shoot tips were cultured in modified MS (Murashige and Skoog, 1962) medium containing (per liter) 30 g sucrose, 0.1 g myo-inositol, and 5 g Agargel plus 1.7 M indole-3-butyric acid (IBA), 0.5 M kinetin and 0.3 M gibberillic acid (GA₃) (IKG). Benzyladenine (BA, 5 M) proved best for Stage II shoot proliferation. Over 35 shoots were obtained per vessel (five shoots per vessel) when explants were cultured in medium containing BA. Less than 10 shoots were obtained per vessel when kinetin (0.5–5 M) and IKG were used. Stage II cultures established from 1 cm shoot tips obtained from Stage I shoots produced more shoots (1.3-fold) than single node explants. Rooting and plantlet acclimatization were best when shoots greater than 1.5 cm were incubated in MS medium containing 0.5 M naphthalene acetic acid (NAA). Higher NAA concentrations stimulated rooting but inhibited shoot elongation and reduced the ability of plantlets to survive acclimatization to ambient conditions. Plantlet height influenced acclimatization. Over 72% of plantlets survived acclimatization if they were at least 4.6 cm when transferred to soilless growing medium.     

Ethylene plays a dual role in sex determination and fruit shape in cucurbits

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