Indole-3-acetic acid biosynthesis in <Emphasis Type="Italic">Aciculosporium take</Emphasis>, a causal agent of witches' broom of bamboo

 Aciculosporium take (Ascomycota; Clavicipitaceae) is a causal agent of witches' broom of bamboo plants. The symptoms of this disease are believed to be induced by plant hormones, particularly auxins. Indole-3-acetic acid (IAA) was identified in cultures of this fungus in an l-tryptophan-supplemented liquid medium. IAA production was confirmed on 30 isolates of A. take from various hosts and locations at levels up to 1 mg/l. The biosynthetic pathway of IAA in A. take culture was examined by analyzing intermediate products and by feeding experiments. The results showed that the indole-3-pyruvic acid pathway (l-tryptophan → indole-3-pyruvic acid → indole acetaldehyde → IAA) was the dominant pathway in A. take. Received: June 3, 2002 / Accepted: July 25, 2002     

Inconspicuous restraint of rice seedling growth by root-infecting fungi in soil of a rice paddy field

 Rice seedling growth, estimated by plant height and root development and discoloration, was better in pasteurized soil than in unpasteurized soil obtained from a flooded rice field. Rice seedlings also grew better in sterilized soil modified by adding roots harvested from the pasteurized soil than in soil modified by adding roots harvested from the unpasteurized soil. The results demonstrate that seedling growth in the rice field soil was inhibited by soil microorganisms, even though no typical symptoms such as seedling blight or damping-off appeared. Pythium aristosporum is suggested to be involved in the inhibition. Thus, it appears that inconspicuous restraint of rice seedling growth could occur in soils of rice paddy fields. Received: May 20, 2002 / Accepted: October 16, 2002 Acknowledgments The authors thank Dr. T. Ichitani, former professor at Osaka Prefectural University, for providing an isolate of Pythium aristosporum for comparison, and Mr. Mitsuaki Sato of Akita Prefectural College of Agriculture for technical assistance.     

‘禅寺丸’甜柿2n花粉形成机制的研究

 以2n花粉发生频率较高的甜柿品种‘禅寺丸’为试材，研究影响2n花粉形成的减数分裂行为。结果表明：2n花粉形成受融合纺锤体(fused spindles)，八字形纺锤体(triangle spindles)及后期Ⅱ染色单体不正常分离(abnormal disorientation of sister chromatid)3种减数分裂行为控制；融合纺锤体及八字形纺锤体形成的2n花粉占2n花粉总数的94.8%，在遗传上等同于FDR(first division restitution，第1次分裂重组)型配子；由姊妹染色单体不正常分离形成的2n花粉在遗传上等同于SDR (second division restitution，第2次分裂重组)型配子。甜柿2n花粉绝大多数为FDR型，因而在倍性育种中有重要的应用价值。     

黄瓜单体异附加系的筛选与观察

 将甜瓜属异源三倍体与栽培黄瓜‘北京截头’杂交，经胚胎拯救获得了两个2n=15 (14C+1H)的单体异附加系，编号分别为02—17和02—39。02一l7植株叶形为戟形，02—39为深陷的掌状形，并且果刺均为白色，不同于异源三倍体的掌状心脏形和黑刺，果形比异源三倍体黄瓜长而更接近普通黄瓜。细胞学研究发现，单体异附加系在终变期和中期I染色体构型主要是由7个二价体和1个单价体构成，出现三价体的频率为4％ ～5％ ，中期Ⅱ不均等分裂形成不同的两极，一极染色体为8条，另一极为7条。RAPD分析证明它们分刖附加了野生种Cucum／s hystrix的染色体。     

温度对稻茎毛眼水蝇实验种群增长的影响

试验结果表明:在17～31℃恒温范围内,稻茎毛眼水蝇的发育速率随温度上升呈逻辑斯蒂曲线趋势。幼虫、蛹存活率、成虫产卵量、种群增长指数随温度的上升呈抛物线趋势。卵孵化率在20～31℃范围内无显著差异,均在92％以上。在17℃和35℃时,孵化率下降至86.67％和76.36％。在35℃时,幼虫不能存活,成虫不产卵。     

猪附红细胞体病的诊断和防治

近年我县发生了一种类似猪瘟症状的疾病 ,表现为高热、嗜睡、全身发红等 ,导致猪群 (特别是仔猪 )大批死亡。经采用注射青霉素、链霉素、磺胺类药、退烧解毒药等治疗 ,效果不理想。特别是在使用磺胺类药物后 ,会加重病情。该病在我县呈蔓延趋势 ,给广大养殖户造成了很大的经济损失。后与省畜牧研究所联合研究 ,根据临床症状、病理剖检、实验室检查等 ,确诊为猪附红细胞体病。经对症下药 ,很快控制了该病的流行和蔓延 ,确保养殖业的健康稳定发展。1流行病学特点本病一年四季均可发生 ,但以夏秋多发。蚊等吸血节肢昆虫可传播该病 ,各种年龄、…     

真空渗入法转pinⅡ基因菜薹外源基因的遗传与表达

 本研究对利用真空渗入法获得的转bar基因及pinⅡ基因菜薹，进行了外源基因的遗传及表达情况分析。结果表明通过该方法获得的转基因植株，外源基因能够稳定遗传。bar基因在 代的分离大部分符合孟德尔遗传规律，但也有不符合的群体；pin II基因在 代中稳定表达，但各个株系之间的表达水平差异较大，因而各个株系的抗虫效果也具有显著差异，即使具有相同外源基因拷贝数的各个株系，其PIN I／蛋白表达量和抗虫效果也具有显著差异。     

‘罗田甜柿’胚乳培养获得十二倍体再生植株

 取‘罗田甜柿’自然授粉后约70 d 的胚乳, 采用不同细胞分裂素和生长素组合进行离体培养。结果表明: 以1/ 2MS (1/ 2N ) + ZT (玉米素) 1.1 mg/ L + 2,4-D 1.0 mg/ L + CH (水解酪蛋白) 1000mg/ L 诱导产生的愈伤组织易获得再生植株; 形态学和细胞学检测确认再生植株中存在2n=12x=180 的个体。该十二倍体植株对中国原产甜柿的遗传改良可能具有潜在的应用价值。     

铺散诸葛菜的组织培养及植株再生

 以铺散诸葛菜的叶柄及叶片为外植体, 研究了不同的再生方式。在6-BA 和NAA 配合使用的MS 培养基上, 叶柄和叶片外植体有高的成芽率, 具有强的器官再生能力。在2,4-D 与6-BA、NAA 结合的培养基上, 叶柄和叶片有较高的愈伤组织诱导率, 在含6-BA 的培养基上也易于分化。叶柄、叶片再生的芽和经愈伤组织分化而得来的芽快速繁殖后, 在生根培养基上形成完整植株。研究表明铺散诸葛菜具有极强的器官分化能力。