Resistance analysis of the rice variety Huaidao 5 against root-knot nematode Meloidogyne graminicola

Meloidogyne graminicola has emerged as one of the most destructive plant-parasitic nematodes affecting rice(Oryza sativa)production worldwide.Resistance to M.graminicola in rice could be the most effective option for its management.However,sources of germplasm with resistance to M.graminicola in rice remain limited.Here,we describe the root attraction,gall formation and genetic analysis of the resistance to M.graminicola in the rice variety Huidao 5.A nematode attraction assay showed that second-stage juveniles(J2s)of M.graminicola were attracted at the root tip of Huaidao 5 within 8 h without a significant reduction in attraction compared to the susceptible rice variety Nanjing 9108.Microscopic observation of the infection revealed that the J2s invaded root tissues 12 h after inoculation,but their subsequent movement to the root tip was hindered in Huaidao 5,resulting in decreased nematode number compared to Nanjing 9108.Additionally,we used the soil and hydroponic culture systems to simulate upland and flooding conditions in the paddy fields respectively,and found that gall number was significantly reduced,and nematode development was clearly suppressed in Huaidao 5.To investigate the genetic basis of this resistance,cross breeding was performed between the Huaidao 5 and Nanjing 9108 varieties.There was no reduction in the resistance of the F_(1) offspring to M.graminicola in the greenhouse or field trials,suggesting that a dominant gene could control resistance in Huaidao 5.In summary,this study provides a detailed characterization of a novel source of resistance to M.graminicola in rice,which is of great potential for use in crop breeding.

Determination of Nematicidal Effects of Some Biopesticides against Root-Knot Nematode （Meloidogyne incognita） on Kiwifruit

The aim of this study was to determine the nematicidal effects of some biopesticides againist root-knot nematodes （RKNs） （Meloidogyne incognita） on Bruno type kiwifruit seedlings. Research was conducted in the Atattirk Central Horticultural Research Institute （ACHRI, Yalova, Turkey） greenhouse during 2013-2014. Biopesticides observed in this study were： sesame oil （Devalone EC）, castor oil （Ricinus communis）, Myrothecium verrucaria （M. verrucaria strain AARC-0255, Inferno DF）, Glomus spp. （Endomycorrhizal fungi, Endo Roots Soluble SP） and Paecilomyces lilacinus （Entomopathogenic fungi, P. lilacinus strain PL1, Bionematon SL）. Nematicide Nemacur EC 400 （fenamiphos） was used as treated control （TC） and trials were set up as randomized parcel design （RPD） with seven characters and 10 replicates. Reproduction ratio was determined according to scale values in trial applications and second stage juvenile （J2） populations of M. incognita in soil. The results showed that the best nematicidal effects against RKNs were determined in castor oil （77.92% in 2013 and 73.61% in 2014） and P. lilacinus （61.03% in 2013 and 55.55% in 2014）.

Efficiency of Some Plant Essential Oils on Root-Knot Nematode Meloidogyne incognita

During the last few decades, researchers have been in the search for environmental friendly ways to cope with agricultural pests, instead of using chemical pesticides. The use of essential oils has a high potential to become an alternative control strategy against plant parasitic nematodes. This study was conducted to determine the toxicity of 10 essential oils （Artemisia absinthium, Citrus bergamia, Eucalyptus citriodora, Hypericum perforatum, Lavandula officinalis, Mentha arvensis, Ocimum basilicum, Piper nigrum, Thymus serpyllum and Zingiber officinale） against the second stage juveniles of the root-knot nematode Meloidogyne incognita. The aqueous solutions of these essential oils have been applied to the second stage juveniles in three different concentrations （1%, 3% and 5%） at four different application time intervals （12, 24, 48 and 72 h）. The interactions between the variables have been examined with repeated measure analysis of variance （ANOVA）. This showed that the interactions of essential oil-time and essential oil-concentration were statistically significant, and it is concluded that L. officinalis, A. absinthium, P. nigrum, C. bergamia and M. arvensis have the most toxic effect in all concentrations and times, respectively.

RNAi of <i>MiASB</i>caused high mortality of <i>Meloidogyne incognita</i>juveniles and inhibited the nematode disease

The southern root-knot nematode, Meloidogyne incognita, is one of the most prevalent and damaging plant-parasitic nematodes in the world and causes serious damages to agricultural production. We cloned a mitochondrial ATP synthase b subunit gene fragment of M. incognita (MiASB) based on the nematode genomics prediction. By soaking in the MiASB dsRNA solution, the hatching of RNAi treated eggs was reduced by 60% compared to negative control and by 64% compared to untreated control. Mortality of RNAi treated second stage juvenile (J2) was 8.6 times higher than that of negative control and 26 times higher than the untreated control. Inoculating the RNAi treated egg masses and J2 to tomato seedlings showed the pathogencity was significantly reduced. For the RNAi treated egg masses, the amount of root galls on silence treated seedlings was reduced by 92% compared to that on the negative control seedlings, and reduced by 93% compared to that on untreated control seedlings. For the treated J2, the amount of root galls on silence treated seedlings was reduced by 83% and 86% compared to negative and untreated control seedlings, respectively. The study revealed the MiASB silence had a positive effect on prevention and control of root-knot nematode disease, and also showed that the MiASB may be involved in the pathogenesis of nematode, which provided new ideas and ways to the research of nematode pathology and nematode disease control.

侵染江苏猕猴桃的北方根结线虫(Meloidogyne hapla)形态学描述和分子特征分析

根结线虫病长期以来对猕猴桃安全生产造成了严重威胁。调查发现江苏省连云港市部分猕猴桃种植园根结线虫病发生普遍,组织切片可见根部出现根结线虫诱导的特异的巨细胞。形态学观察和分子检测结果显示,尽管与其他群体存在一定差异,但仍确定本次分离自猕猴桃的根结线虫(种群编号:CN43)为北方根结线虫(Meloidogyne hapla)。基于内转录间隔区(ITS)和COⅡ-16S序列构建的遗传进化树显示,CN43分离群体与已知的北方根结线虫位于同一进化分支,而与其他种类的根结线虫明显区分开来。以ITS序列构建的中接网络将34个北方根结线虫分离群体划分为10个单倍型,其中CN43属于最大的单倍型群组;然而,单倍型分析不能确定各分离群体在地理分布上的关联性。综上,本研究首次报道了北方根结线虫在中国猕猴桃上的侵染和发生,其分离群体的形态学描述和分子特征分析可为揭示猕猴桃根结线虫的种群多样性和种间变异提供参考。

Effect of Pleurotus ostreatus on Dynamics of Meloidogyne arenaria Population and Control Effectiveness

The control effects and application methods of Pleurotus ostreatus on the peanut root-knot nematode disease, Meloidogyne arenaria, were systematically studied in the greenhouse. Results of pot experiments showed that P. ostreatus could effectively reduce the 2nd-instar population density in the soil, and the larva reduced by 80% compared with the control. P. ostreatus could markedly lower the infecting number of the peanut root-knot nematodes, the nematode density inside the root knots declined by 40.00% -82.64%, and the peanut root knots also reduced by 86.96% - 94. 03%. The fungus could defer the initial infection of M. arenaria to the roots, the epidemic rate of the peanut root-knot nematode disease was significantly cut down, and the increase of root-knot changed from the way of Logistic curve in the control to the way of linear curve in the treatment. The final control effectiveness was about 80%. The results of pot trial also indicated that the control effectiveness is closely related to the application time and the amount of this fungus. The key factor affecting control effectiveness was the application time of P. ostreatus in the soil and the suitable time was 20 days before sowing.

Biochar from grape pomace,a waste of vitivinicultural origin,is effective for root-knot nematode control

Root-knot nematodes(RKNs)are obligate endoparasites that feed on their host plants to complete its life cycle,representing a major threat to agriculture and economy worldwide.The development of new management strategies becomes essential as effective chemical nematicides are progressively being restricted.Hence,we analysed grape pomace-derived biochars,pyrolysed at 350℃(BC350)and 700℃(BC700),focusing on their potential for RKN control.The thermal treatment of grape pomace caused an increase in the concentration of carbon and plant macro-and micronutrients,which were largely present in a water-soluble form.Synchrotron radiation-based Fourier transform infrared microspectroscopy data showed a general loss of carboxylic functional groups during pyrolysis,partially contributing to the alkalinisation of both biochars,mostly in BC700.Scanning electron microscopy coupled with energydispersive X-ray spectroscopy analysis revealed a highly porous structure filled with different crystals composed of elements such as K,Ca,Mg,P,Si or Al,which could be a suitable environment for the growth of microorganisms.Biochar-derived aqueous extracts showed phytotoxicity to tomato seedlings at high concentrations,and disappeared upon dilution,but no toxic effect was observed on the nematode’s infective stage.However,the infective and reproductive traits of a Meloidogyne javanica population in tomato were significantly reduced(i.e.egg masses and eggs per plant)in washed-biochar-treated soil in pots(0.75%;BC350W).Therefore,the large amount of grape waste generated after wine production can be transformed into a valuable product such as biochar,effective for RKNs control,thus reducing the waste management problem and contributing to a circular economy.

花生抗北方根结线虫病SSR标记研究

本研究利用抗、感北方根结线虫病的花生品种为亲本配制杂交组合"花育22号×D099",以其F2分离群体为研究材料,采用SSR技术和BSA分析方法,获得了与花生北方根结线虫病抗性基因连锁的2个SSR分子标记S32-380和S89-140,标记与抗病基因间的遗传距离分别为4.421cM和7.404cM。该分子标记的建立将为开展花生抗北方根结线虫病的分子标记辅助选择育种奠定基础。

花生对北方根结线虫病抗性遗传规律的研究

用对花生根结线虫病表现抗性和感病的材料进行杂交,并将杂交得到的F1代种子及F1代自交得到的F2代种子种植在病圃内,调查植株的抗感病性,结果显示,F1代植株全部表现为感病,F2代抗病植株与感病植株的分离比率为1∶3,符合遗传分离规律。初步认为,亲本花生抗病材料的抗性是受一对隐性基因控制。

苏云金芽孢杆菌晶体蛋白对北方根结线虫生物测定方法的建立和杀虫效果评价(英文)

A bioassay procedure was developed to assess the toxicity of Bacillus thuringiensis crystal protein against Meloidogyne hapla,a root-knot nematode,under laboratory conditions.Reproducibility and precision of the bioassay results were optimal when forty 2nd stage juveniles were incubated in the dissolved crystal protein solution at 25℃,pH9.0 for 7 days.The juveniles were stained with 1% KMnO4 for 2 hours or methylene blue solution for 1 hour to distinguish living and dead ones.By the bioassay procedure,the LC50 value of strain YBT-1532 crystal protein against M.hapla was determined as 0.304±0.086 mg/mL(LC50±1.96SE).Moreover,the strain YBT-1532 showed toxicity to Caenorhabditis elegans,a free-living nematode.All results indicated that YBT-1532 is a toxic strain to plant-parasitic nematode,and has the potential to control plant-parasitic nematode.

一年蓬根结线虫病的病原线虫鉴定

2021年11月在陕西省汉中市佛坪县采集到有明显根结症状的一年蓬植株样品,从其根部分离得到根结线虫雌虫,观察会阴花纹,并利用特异性引物扩增和ITS序列系统进化分析进行分子生物学鉴定。结果显示,根结线虫雌虫的会阴具有较为明显侧线,尾端具有刻点,与北方根结线虫相似。利用北方根结线虫特异性引物对分离到的线虫DNA进行扩增,能够得到610bp的特异性扩增条带。系统进化分析显示分离到的线虫ITS序列与NCBI数据库中已报道的北方根结线虫相应序列聚为一支。一年蓬根结线虫病在我国为首次报道,而侵染佛坪县一年蓬的根结线虫为北方根结线虫。