Can wild relatives of sorghum provide new sources of resistance or tolerance against Striga species?

Summary The genus Striga contains some of the most noxious parasitic plants, which have a devastating impact on cereal production in Africa; of most importance are Striga hermonthica and Striga asiatica . Complete resistance to infection by Striga species does not exist in cultivated cereals. Of great interest is the possibility that wild relatives of cereals may provide a genetic basis for resistance or tolerance to infection and may be of enormous value for the development of resistant crops. A wild relative of cultivated sorghum, Sorghum arundinaceum , demonstrated tolerance to infection by S. asiatica , with little impact of S. asiatica on host growth or grain production compared with the detrimental impact of the parasite on cultivated sorghum. Infection by S.hermonthica , however, had a significant influence on host performance for both wild and cultivated sorghum. Differences in host:parasite responses may be explained by the timing of parasite attachment and differences in host specificity for these two Striga species.     

山西菜田捕食性食蚜蝇优势种及其对菜蚜的控制效果

对山西菜田捕食性食蚜蝇优势种及对菜蚜的控制效果进行了研究，菜田常见捕食性食蚜蝇有黑带食蚜蝇，大灰食蚜蝇，斜斑鼓额食蚜蝇，野食蚜蝇，四条小食蚜蝇，短翅细腹食蚜蝇6种，以黑带食蚜蝇种群数量最大，平均占全年发生总量的36.3%，通过对食蚜蝇产卵量，卵化率，幼虫期捕食量和羽化率测试，筛选出的黑带食蚜蝇，大灰食蚜蝇，斜斑鼓额食蚜蝇幼虫对菜蚜均有较强的捕食能力，其中黑带食蚜蝇为山西菜田菜蚜捕食性食蚜蝇优势种，用黑带食蚜蝇三龄幼虫对菜蚜进行防治试验，结果以1：180防效最佳，72h后控制效果达93.5%。     

转 Bt基因抗虫棉对棉大卷叶螟抗性的研究

:转Bt基因抗虫棉对棉铃虫有很好的抗性,对棉大卷叶螟(SyleptaderogataFabricius)的抗性未见报道。作者研究表明,棉大卷叶螟在棉田为聚集分布型,低龄幼虫有集中为害习性;抗虫棉对其有很好的抗性,平均虫株率为2.2%,较常规棉中棉所12降低96.6%;百株虫量为133.8头,较常规棉降低88.4%。     

云南特有野生果树资源及其分布特点

 云南有各类野生果树资源约500 余种, 其中云南特有的164种, 分属35科54属, 多为热带、亚热带果树和浆果类果树, 形成滇南—滇东南、滇西—滇西北和滇中—滇东北3个特有野生果树集中分布中心。这些果树资源用途广泛, 优异性状明显, 有待深入研究和综合开发利用。     

黄瓜雌雄株性别苗期化学鉴别方法

应用BTB(溴麝香草酚蓝 )法、NADH(还原辅酶Ⅰ )法和TTC(氯化三苯基四氮唑 )法对黄瓜雌雄株进行了苗期鉴别 ,结果表明 :雌、雄株提取液加入BTB液后雌株转色快于雄株 ,反应后 5h(小时 )内在 6 30nm处雌、雄株吸光值差异最大 ,是鉴别黄瓜雌、雄株的最佳时期。雌、雄株NADH含量和TTCH含量差异显著。BTB法、NADH法和TTC法鉴别雌雄株其差异显著概率均为极显著 ,BTB法和TTC法对雌、雄株混合群体的鉴别正确率均为 10 0 % ,二者可应用于黄瓜雌、雄株苗期鉴别。而NADH法对混合群体的鉴别正确率仅 71.4%。     

Microscopic detection of reactive oxygen species generation in the compatible and incompatible interactions of Alternaria alternata Japanese pear pathotype and host plants

 Reactive oxygen species (ROS) generation was examined in the interaction of Alternaria alternata Japanese pear pathotype and host plants using three methods: nitro blue tetrazolium (NBT) method for microscopic detection of O₂ ⁻, diaminobenzidine (DAB) methods for microscopic detection of H₂O₂, and cerium chloride methods for ultrastructural detection of H₂O₂. ROS generation was detected by NBT and DAB methods at appressoria on leaves of susceptible cultivars and heat-shocked leaves of resistant cultivars but not in leaves of resistant cultivars. Ultrastructural detection by the cerium chloride method identified ROS generation at cell walls of appressoria and penetration pegs in susceptible, resistant leaves and heat-shocked leaves. These differences in the ultrastructural and microscopic data in resistant areas were due to the restriction of ROS generation in limited areas, the side facing the plant surface, of appressoria and penetration pegs. Therefore, ROS generation was apparently induced regardless of the resistance or susceptibility of the cultivar with the difference being in the volumes generated. After evaluating the pathological role of ROS generation in fungal structures, such generation was found to be associated with early penetration of cell walls in pear plants. Additionally, ROS generation in plants was also found in degrading pectin layers near infected hyphae and in plasma membrane modification sites in susceptible leaves but not in resistant leaves. ROS generation in susceptible leaves might be accompanied with plasma membrane damage, although the role of ROS generation in the pectin layers is not clear. ROS generation in both fungal and plant cells during their interaction was likely associated with the expression of susceptibility. Received: June 3, 2002 / Accepted: July 31, 2002     

转基因水稻对稻瘟病的抗性研究

 采用苗期初筛、复筛、抗谱测定和田间自然诱发试验等不同鉴定方法,对经分子检测证明已整合有碱性几丁质酶基因和β-1,3-葡聚精酶基因的22个转化系的转基因水稻植株进行稻瘟病抗性鉴定研究,筛选出对稻瘟病的抗性比原种对照七丝软占有明显提高的一系列转基因水稻品系,其中表现高抗的有来自F4-9转化株系的7个品系。高抗材料的R7代品系,经室内抗谱测定及田间病圃试验结果,仍然表现高抗稻瘟病。本研究通过转基因技术,成功地将优质感病品种改良成高抗品系,研究结果证明了利用基因工程手段培育抗病水稻新品种是一个非常有希望的育种途径。     

外来入侵种的危害与防治对策

外来入侵种对当地的自然生态系统结构和功能以及生物多样性都有着深远的影响,而且可能对地方的生态环境和经济造成严重危害。四川已经成为遭受外来入侵种威胁的省份之一,全省现有20多个外来入侵种。为了防止外来入侵种的泛滥,应当建立外来物种的引入评价机制,慎重进行有意引种;加强口岸管理,防止外来入侵种通过贸易途径无意引入,同时采取措施控制已经产生危害的外来入侵种。     

甘肃河西地区盐碱地野生药用植物资源

甘肃河西地区盐碱地野生药用植物资源丰富,主要有50种,隶属于21科40属。针对当地农业生产状况,应合理开发利用盐生药用植物资源。     

半自然条件下几种赤眼蜂及品系对亚洲玉米螟卵寄生能力比较

在半自然条件(田间网罩)下,将人工饲养的玉米螟卵按4、8、16块/株3个处理分别固定在网罩内的玉米植株中上部叶片上,然后每网罩分别引入供试赤眼蜂20头,24 h后更换玉米螟卵块,连续3 d。7 d后调查供寄生的玉米螟卵被寄生率及羽化率。结果表明:在半自然条件下广赤眼蜂伊朗1-1品系虽寄生能力高于其他供试品系,但到第2、3天明显降低;玉米螟赤眼蜂北京6-2-2品系每天均维持一个较平稳的寄生能力,产卵量在时间上的分配比较分散,并在第2、3天显示出比其他品系较高的寄生潜能。广赤眼蜂伊朗1-1品系的卵块寄生数量可随卵块密度的增加而增加,而其他品系则在各处理密度下,寄生数量基本没有变化;从卵粒寄生率看,广赤眼蜂伊朗1-1和吉林1-2两个品系的寄生数量随卵块密度的增加而大幅度提高,其他品系增加幅度较小。