中国不同地区水稻干尖线虫种群的繁殖特性研究

【目的】明确来自中国不同地区的水稻干尖线虫种群的繁殖特性。【方法】通过室内组织培养的方法,研究来自中国8个省15个种群的水稻干尖线虫,在灰葡萄孢菌上的繁殖力及其繁殖适温。【结果】在灰葡萄孢菌上,供试的15个水稻干尖线虫种群在20℃不能很好繁殖,其中有9个种群的繁殖适温是25℃,6个种群的繁殖适温是30℃;20℃时,繁殖量最大种群的繁殖率是22.2,繁殖量最小种群的繁殖率仅有0.9,有3个种群无雄虫存在;25℃时,繁殖量最大种群的繁殖率是3 523.8,繁殖量最小种群的繁殖率是207.2,只有1个种群无雄虫存在;30℃时,繁殖量最大种群的繁殖率是1 525.0,繁殖量最小种群的繁殖率是6.9,所有种群均有雄虫存在。【结论】来自中国不同地区的水稻干尖线虫种群均能在灰葡萄孢菌上繁殖,种群之间的繁殖力和繁殖适温均存在差异,地理来源较远的种群之间差异较大;在适温条件下,华南地区多数种群的繁殖力大于其他地区,种群繁殖特性与地理来源有一定关系;所有种群均能孤雌生殖,后代均以雌虫为主,但不同种群的雌雄比有较大差异。     

水稻干尖线虫Hsp90基因克隆及在不同逆境、侵染早期和取食过程的表达差异

热激蛋白90(heat shock protein 90,Hsp90)调控生物体的细胞代谢、生长发育和逆境适应等一系列生物过程.本研究通过cDNA末端快速扩增技术(rapid amplification of cDNA ends,RACE)分离获得了一个水稻干尖线虫(Aphelenchoides besseyi)Hsp90基因,命名为Ab-hsp90.Ab-hsp90全长cDNA序列含有69bp的5’非翻译区、编码712个氨基酸2 139 bp的开放阅读框以及137 bp的3'非翻译区UTR.Ab-hsp90DNA序列包含9个外显子和8个内含子.Ab-hsp90蛋白序列与其他植物寄生线虫Hsp90s高度相似,最大似然树显示与植物寄生线虫位于同一进化分支;结构上具有5个保守的Hps90蛋白家族序列标签和特异MEEVD基系,表明Ab-hsp90为胞质型Hsp90.qRT-PCR显示,Ab-hsp90在水稻干尖线虫各个龄期均表达,在卵和成虫表达水平最高.当线虫暴露于干燥、低渗透胁迫以及短时间阿维菌素溶液中时Ab-hsp90均上调表达;Ab-hsp90还受到短时低温(4℃)诱导,在高温(40℃)环境持续高水平表达.在侵染抗感不同的水稻(Oryza sativa)植株时,Ab-hsp90的表达水平具有差异性:在线虫接种抗性水稻72 h内,Ab-hsp90一直高度表达,而在接种感病水稻上Ab-hsp90表达水平显著升高随后下降.取食灰葡萄孢(Botrytis cinerea)的线虫Ab-hsp90在9d内始终高度表达,而胡萝卜(Daucus carota)愈伤组织培养的线虫6d内Ab-hsp90表达上调但此后逐渐下调.这些数据表明,Ab-hsp90可能参与水稻干尖线虫的抗逆适应、早期侵染以及取食行为.本研究有助于拓展植物寄生线虫Hsp90蛋白的功能,为进一步研究线虫与植物互作机制提供了有益借鉴.     

Identification of alternatives for the management of foliar nematodes in floriculture

The foliar nematodes, Aphelenchoides spp, have emerged as important pests of ornamentals in North America during the last decade. Due to the ban on the use of potentially toxic pesticides, there are currently no nematicides registered to manage foliar nematodes on ornamentals. Therefore, we have evaluated a biological [Burkholderia cepacia (syn Pseudomonas cepacia)], two plant products [clove (Syzygium aromaticum) extract and Nimbecidine (azadirachtin)] and twelve chemical pesticides registered for the management of insects, mites, slugs or diseases of ornamentals, against Aphelenchoides fragariae on the most popular ornamental, hosta (Hosta spp), for two consecutive years. We found ZeroTol (270 g liter-1 peroxyacetic acid), currently labeled as a broad-spectrum fungicide/algicide, to be a very potent nematicide that killed 100% of the nematodes in water suspension. It also caused over 70% reduction in A fragariae population in soil and in the leaves without any phytotoxicity. B cepacia caused 67-85% reduction in A fragariae population in leaves and 50% reduction in the soil whereas insecticidal soap caused over 72% reduction in leaves and 61% reduction in the soil. Clove extract and Nimbecidine did not show any potential for the control of A fragariae on hosta. Although all twelve chemical pesticides were effective in reducing the population of A fragariae in the soil 45 days after treatment (DAT), only diazinon 475 g liter-1 EC, trichlorfon 800 g kg-1 SP, ethoprophos 100 g kg-1 GR, oxamyl 100 g kg-1 GR and ZeroTol caused over 70% reduction in nematode population compared with the control. In the leaves, only diazinon EC, trichlorfon SP, insecticidal soap, oxamyl GR and ZeroTol consistently caused over 70% nematode population reduction compared with the control at 45 DAT in both years. Thus, only diazinon EC, trichlorfon SP, oxamyl GR and ZeroTol consistently caused over 70% reduction in nematode population both in soil and leaves. Due to the recent ban by the US Environmental Protection Agency on the use of the first three of these formulations, only ZeroTol would serve as an effective tool to manage foliar nematodes in ornamentals. Although not as effective as ZeroTol in the soil, insecticidal soap is the only other alternative for foliar nematode management.     

香菇菌筒腐烂病研究初报

香菇菌筒腐烂病在福建省的香菇反季节栽培区发生流行，其病原为蘑菇滑刃线虫（Ａｐｈｅｌｅｎｃｈｏｉｄｅｃｏｍｐｏｓｔｉｃｏｌａ）和雅各布滑刃线虫（Ａ．ｊａｃｏｂｉ）．这２种线虫还能侵染凤尾菇、蘑菇、金针菇、猴头菇、竹荪、灰树花、灵芝等菌丝体．清除发病菌筒、冲洗病畦和畦面覆盖地膜能有效防治病害     

Reproduction and Development ofAphelenchoides Besseyi

The mode of reproduction of the Indian population ofAphelenchoides besseyi was studied under different temperatures and on different fungal species used for culturing the nematode. Although parthenogenetic reproduction in this species was recorded on all the fungi tested, the influence of the different fungal species on development and population buildup varied. There was a significant increase in nematode fecundity when one or two males were placed along with single females in the medium, as compared with when no male was introduced. Increasing the number of males further to eight depressed fecundity as compared with the treatment with two males.     

水稻小穗头上的线虫形态特征鉴定

 对水稻生产上较大面积发现的“小穗头”现象，即稻穗长度缩短，籽粒明显减少, 米粒小且米色黑褐，部分籽粒为秕粒，剑叶形态正常，无干尖现象的成因进行了探讨。从水稻品种武育粳3号“小穗头”谷粒中分离到一种滑刃属线虫，百粒线虫数达2014条，单个谷粒带虫量最多可达74条，病穗中谷粒带虫率为92%。经外部形态和内部结构观察表明，虫体侧区具4条侧线，尾尖突为星状，具3~4刺突；雌虫后阴子宫囊短于肛阴距1/2，内无精子，卵母细胞多行排列，为2~4排；雄虫交合刺有一中等发育的缘突。虫体测量数据与Fortuner(1970)所测水稻干尖线虫的原始数据基本相符。因此，将该线虫鉴定为水稻干尖线虫Aphelenchoides besseyi Christie, 1942贝西滑刃线虫。     

水稻干尖线虫生殖方式、生活史及温度对其存活能力的影响及其在水稻中的分布

为了解近年我国水稻主产区水稻干尖线虫Aphelenchoides besseyi种群的生物学特性，并为寻找新的水稻干尖线虫病害防控方法，通过在胡萝卜愈伤组织、灰葡萄孢菌Botrytis cinerea和水稻中培养水稻干尖线虫的方法对其生殖方式、生活史和温度对其存活能力的影响及其在水稻中的分布进行研究。结果表明，在供试的12个水稻干尖线虫种群中，只有G8-315种群可孤雌生殖；在25℃下，水稻干尖线虫在胡萝卜愈伤组织和灰葡萄孢菌上生活史均约为12 d，在水稻苗上生活史约为11 d;-20℃以下低温或42℃以上高温处理12 h，在清水、胡萝卜愈伤组织和灰葡萄孢菌中水稻干尖线虫存活率均显著下降，处理72 h水稻干尖线虫存活率均为0；带虫干燥谷粒在-80、-20和4℃低温保存6个月后，谷粒内水稻干尖线虫存活率均显著低于25℃（对照），其中-80℃保存的谷粒内水稻干尖线虫存活率为0;56、70和80℃高温处理12 h后，2个水稻品种谷粒内水稻干尖线虫存活率均显著下降，80℃处理16 h后2个水稻品种谷粒内水稻干尖线虫存活率均为0；水稻幼苗各部位均可检测出水稻干尖线虫，其中假茎部位水稻干尖线虫数量...