Host range study of Argentine Nacobbus aberrans sensu Sher populations and comments on the differential host test

The existence of races within the species Nacobbus aberrans sensu Sher has been confirmed; however, there is no consensus on a consistent system for race determination. Four plant species previously used as differential hosts in some N. aberrans race tests (tomato, pepper, sugarbeet and potato) were tested for susceptibility to seven nematode populations from Argentina. Plants were inoculated with second-stage juveniles and kept under glasshouse conditions at 21 °C for 90 days. The parameters evaluated (root gall index, egg mass index, and reproduction factor) in different nematode populations and plants showed significant differences. The reproductive fitness of the nematode populations differed among the plants that showed some degree of susceptibility. The results showed that N. aberrans comprises populations differing in host preference. Based on the nematode populations’ behaviour on these hosts, two groups were distinguished: i) populations that multiplied on all hosts, ii) populations that did not multiply on potato. The present work contributes to the analysis of criteria for developing a differential host test.     

Biological control of the false root-knot nematode Nacobbus aberrans by Pseudomonas protegens under controlled conditions

The use of antagonistic biological agents, such as fungi and bacteria, offers an economical and safe strategy to manage plant–parasitic nematodes in infested fields. The false root-knot nematode, Nacobbus aberrans, is a damaging parasite of many agronomic and horticultural crops in South and North America. The management of this nematode is challenging and often not profitable for farmers. In greenhouse tests, conducted in Argentina, applications of the strain Pseudomonas protegens CHA0 and its isogenic derivative ARQ1 (used as control) at a rate of 10⁸ cfu ml⁻¹ suppressed infection and reproduction of N. aberrans on tomato roots. However, neither of the strains promoted plant root or shoot growth of the treated plants. Root colonization by the bacteria was assessed by specific PCR–RFLP protocols and fluorescence microscopy. The results obtained in this preliminary study were encouraging and showed the potential of P. protegens CHA0 to be used for the management of the false root-knot nematode on tomato.     

寄生于根结线虫卵囊的绮丽小克银汉霉

从发生根结线虫病害的丝瓜、柑桔、水蜜桃等作物的根上的根结线虫卵囊上分离获得6株绮丽小克银汉霉（Cunning-hamella elegansLendner）。接种试验证实这些分离物可寄生南方根结线虫的卵。     

Evaluation of resistance to root-knot nematode (Meloidogyne incognita) in okra cultivars

The root-knot nematode, Meloidogyne incognita, is one of the major limiting factors affecting plant growth and yield causing an estimated $100 billion loss per year worldwide. Synthetic pesticides, though instantaneously effective, are usually prohibitively expensive, not readily available, may cause hazards to both man and livestock, and inflict injury to the environment. Notable among the alternatives to nematicides is the use of resistant cultivars which are inexpensive and eco-friendly. In the present studies, twelve okra (Abelmoschus esculentus L) cultivars were evaluated for their resistance against M. incognita under field conditions. Ten-day old okra plants of test cultivars were inoculated with 3000 freshly hatched second stage juveniles of M. incognita. The nematode caused reductions in various growth parameters of all the cultivars to varying levels over their respective controls. None of the cultivars was found completely resistant. The cultivar ‘Sharmeeli’ was highly susceptible as >100 galls were recorded on the roots. Sharmeeli also showed maximum reductions in growth among the cultivars evaluated. The cultivars Anmol and Sindha were susceptible with 71–100 galls. The cultivars Sabz Pari, Super Star, PMS-55 and PMS Beauty were moderately susceptible with 31–70 galls and comparatively less reductions in growth. Cultivars Sanam, Dikshah, Arka Anamika, Ikra-1 and Ikra-2 with 11–30 galls were rated as moderately resistant and showed less damage by the nematode as compared to susceptible cultivars and their planting could provide a useful tool to control root-knot nematodes.     

基因工程在植物根结线虫防治中的应用

综述基因工程在植物根结线虫防治中的应用。介绍了利用基因工程获得抗虫植物,实现对根结线虫防治的策略：植物抗体策略,蛋白酶抑制剂策略,抗线虫取食位点策略,抗虫基因的克隆以及RNAi技术的利用等。展望了抗虫基因的克隆和RNAi技术在根结线虫防治方面的研究前景。     

Management of the root-knot nematode Meloidogyne graminicola infesting rice in the nursery and crop field by integrating seed priming and soil application treatments of pesticides

The study evaluates the effects of seed priming (5 g or ml kg⁻¹ seed) and soil application (2 kg or l ha⁻¹) of eight organophosphate pesticides on rice root-knot disease caused by Meloidogyne graminicola. Seed priming (SP) or soil application (SA) of phorate, carbofuran and chlorpyriphos (1000 J₂ of M. graminicola kg⁻¹ soil) suppressed galling in the rice nursery by 92 and 99%, 80 and 88% and 76 and 80%, respectively, over control. Relatively similar decreases in the galling were recorded when this nursery was grown for four months in the sterilized soils in earthen pots. Rice cv. PS-5 grown in naturally infested soil in earthen pots (1000 J₂ kg⁻¹ soil) became stunted, showing chlorotic foliage, and terminal galls developed on the roots. The treatment of SP + SA 15 + 30 days after planting (DAP) with phorate, carbosulfan, and chlorpyriphos significantly suppressed the root-knot development and improved the plant growth of rice over the controls (P ≤ 0.05). The overall effect of the SP + SA 15 DAP treatments was marginally weaker than the SP + SA 15 + 30 DAP treatments but statistically on par. Under field conditions, the greatest decrease in the galling occurred due to SP + SA 15 + 30 DAP of phorate (69−71%) and SP + SA 15 DAP (65−67%) followed by carbosulfan and chlorpyriphos. The yield of rice plants was also highest with phorate (32−36% and 29−34%) over the control during the two years of the study. The soil population of M. graminicola decreased by 58–84% over four months due to the phorate treatments. The study demonstrates that seed priming with phorate effectively controls nematode infections in the nursery and that soil application at 15 DAP (2 kg ai ha⁻¹) prevents root-knot development in an infested field under irrigated conditions. Use of SP + SA 15 DAP may enable to avoid one soil application of phorate in the field.     

六点始叶螨[Eotetranychus sexmaculatus (Riley)]对7种寄主植物的选择性研究

用室内离体叶片饲养方法,研究了分别取食橡胶(Hevea brasiliensis)和7种目前常见的与橡胶间套种的作物[木薯(Manihot esculenta)、甘蔗(Saccharum officinarum)、菠萝(Ananas como sus)、椰子(Cocos nucifera)、杧果(Mangifera indica)、木瓜(Chaenomeles speciosa)和变叶木(Codiaeum variegatum)]后,六点始叶螨(Eotetranychus sexmaculatus)的存活、发育与繁殖情况差异。结果表明,取食木薯、甘蔗、菠萝、椰子和杧果后,六点始叶螨各龄均不能存活;而取食橡胶、木瓜和变叶木叶片后,其幼螨、前若螨、后若螨及卵到成螨的存活率均表现为橡胶(均为100%)变叶木(68%、69%、77%和71%)木瓜(53%、65%、54%和57%),存在显著差异(p0.05);从卵到成螨的发育历期表现为橡胶(12.05 d)变叶木(14.67 d)木瓜(15.61 d),但三者间没有显著差异(p0.05);平均每雌产卵量为橡胶(32.20粒)木瓜(8.00粒)变叶木(7.00粒),橡胶与木瓜和变叶木间存在极显著差异(p0.01);F1代卵孵化率为橡胶(100%)变叶木(97.53%)木瓜(94.42%),仅橡胶与木瓜间存在显著差异(p0.05);后代雌性百分率为橡胶(88.20%)变叶木(75.40%)木瓜(66.30%),三者间存在显著差异(p0.05);成螨寿命为橡胶(19.58 d)木瓜(19.33 d)变叶木(17.00 d),仅橡胶与变叶木间存在显著差异(p0.05)。研究结果表明,木薯、椰子、杧果、菠萝和甘蔗不适于六点始叶螨生存、发育与繁殖,因此为预防六点始叶螨的发生与危害,这5类作物可作为橡胶的间作套种作物;而变叶木和木瓜虽然影响六点始叶螨的发育与繁殖,但六点始叶螨仍可完成世代发育和繁殖,因此其亦为六点始叶螨的嗜好寄主,不适宜与橡胶间作套种。     

不同寄主植物对橡副珠蜡蚧发育和繁殖的影响

研究橡副珠蜡蚧(Parasaissetia nigra Nietner)在香蕉、美人蕉、橡胶树、小叶枇杷、芒果、柑橘、蓖麻、木薯、柠檬、扶桑、木瓜、荔枝、番石榴、垂叶榕等寄主植物上的发育、存活和繁殖情况.结果表明,橡副珠蜡蚧的世代发育时间以在香蕉上的最短(为62.81 d),在垂叶榕上的最长(为120.58 d);世代存活率以在橡胶树上的最高(为67.30%),在垂叶榕上的最低(为6.51%);平均产卵量以在橡胶树上的最多(为801.34粒),在垂叶榕上的最少(为121.86粒);内禀增长率以在橡胶树上的最大(为0.068 1),在垂叶榕上的最小(为0.0146).综合比较橡副珠蜡蚧在14种不同寄主植物上的发育历期、存活率、产卵量及种群特征参数,发现橡胶树、香蕉和美人蕉是橡副珠蜡蚧种群生长发育和繁殖特性最适宜的寄主植物,垂叶榕、番石榴、荔枝和番木瓜是橡副珠蜡蚧的最不适宜寄主植物.     

A study on soil solarization and combined with fumigant application to control Phytophthora crown blight (Phytophthora capsici Leonian) on peppers in the East Mediterranean region of Turkey

Field trials conducted in the pepper growing area ( çel/Turkey) showed that solarization alone and combined with a reduced dose of methyl bromide (40 g/m²), were effective in controlling crown blight disease caused by Phytophthora capsici. Solarization was achieved by covering plots with a clear polyethylene sheet, 0.03 mm thick for 8 weeks. The temperature reached 47 °C and 35 °C at 5 cm and 30 cm soil depth, respectively, an average of 3–8 °C higher than those at equivalent depths in the untreated plots. The average incidence of the disease in solarization plus a reduced dose of methyl bromide, the recommended dose of methyl bromide, solarized and untreated plots in 1991 and 1992 were 17.6 and 13.3%; 20.8 and 16.8%; 24.1 and 19.7%; 39.8 and 42.9%, respectively. All treatments significantly reduced disease incidence.     

以培养学生创新能力为主体的植物生理生化实验教学改革

近年来,生物学相关技术有了长足发展,植物生理生化实验课程中存在的实验内容陈旧、缺乏综合性、设计性以及考核形式单一等问题日显突出。以海南大学植物生理生化实验课程为研究对象,从优化重组教学内容、加强基本实验操作技能、提高学生综合科研素质及培养创新能力和改进实验成绩考核制度等方面进行了一系列改革。通过3年的教改实践,显著提高了学生主动学习植物生理生化课程的兴趣,提高了学生实验操作的能力,促进了学生综合科研素质的提升和创新能力的提高。