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.

Integrated management of African rice gall midge (AfRGM) (<i>Orseolia oryzivora,</i>Harris and gagné), weeds and diseases of lowland rice

Studies were conducted during the 2001 and 2002 cropping years at Edozhigi and Sachi in the Southern Guinea Savannah of Nigeria to study the effect of following rice with another crop on the next rice crop. There were twelve treatments consisting of poor, good and excellent weed management and pesticidal applications against (AfRGM and diseases set up in a randomized complete block design, in twelve plots in 3 replicates. Results showed that rice treated with gramular isazofos at 0.75 kg a.i. ha–1 and benomyl at 1.0 kg/ha at 20 and 40 days after transplanting (DAT), with good weed management and a follow up crop after rice reduced AfRGM occurrence and disease incidence with a consequent increase in yield of the next rice crop. In 2001 infestation of rice by ARGM was more at Sachi than Edozhigi, while in 2002 there was low ARGM occurrence at the two locations. Brown leaf spot was high at the two locations in the two years of the trial while leaf blast was checked by the integrated control methods used in the study. Higher yields were (1.7 - 11.9 t·ha) from treated-well weeded plots that were cropped to cowpea after the 2001 rice harvest Ludwigia decurens, Sphanoclea geylanica Cyperus difformis and Lepllocidia chinensis were the widely occurring weed species at Edozhigi site while Cyperus difformis, Ipomea mvolucrata, F. awuata and Firnbristylis litoralis were weed species prevalent at Sachi site. The rice nematode, hirschmanniella sp. was recorded at the Sachi site along with other nematodes but was absent at the Edozhigi site. The net benefit farmers would derive for following this rice-dry-season crop sequence vary from US$ 172 - 427 and US$ 175 - 265 ha–1 at Sachi and Edozhigi respectively.

Suberin Biopolymer in Rice Root Exodermis Reinforces Preformed Barrier Against Meloidogyne graminicola Infection

Exploration of novel genetic resources against root-knot nematode(RKN)is necessary to strengthen the resistance breeding program in cultivated rice,and investigations on the role of genotype-specific root anatomy in conferring a structural barrier against nematode invasion are largely underexplored.Here,we reported a highly-resistant rice germplasm Phule Radha that conferred remarkably lower RKN parasitic fitness in terms of reduced penetration and delayed development and reproduction when compared with susceptible cultivar PB1121.Using histological and biochemical analyses,we demonstrated that an enhanced suberin deposition in the exodermal root tip tissue of Phule Radha compared to PB1121 can effectively form a penetrative barrier against RKN infection,and this preformed barrier in the control tissue did not necessarily alter to a greater extent when challenged with RKN stress.Using qRT-PCR analysis,we showed that a number of suberin biosynthesis genes were greatly expressed in the exodermis of Phule Radha compared to PB1121.In sum,the present study established the role of rice exodermal barrier system in defense against an important soil-borne pathogen.

不同种植方式对水稻根结线虫病发生危害的影响

水稻根结线虫病是严重危害水稻生产的主要病害之一,目前尚无成本低且安全有效的防控方法。本研究通过田间小区试验评价了直播、移栽和直播前撒施0.2 kg/667 m 210%噻唑膦颗粒剂(GR)3种种植方式下水稻根结线虫病发生及危害情况。结果表明,与直播相比,移栽田移栽后25 d水稻根结线虫的抑制率达到94.26%,根结指数为1.97,与直播前撒施0.2 kg/667 m 210%噻唑膦GR化学药剂处理组无显著差异;移栽后55 d水稻根结线虫的抑制率为58.56%。同时,移栽田移栽后25 d和55 d根结线虫2龄幼虫虫口减退率分别达到77.63%和72.22%。此外,移栽田水稻株高与根长均高于直播处理组及直播前撒施10%噻唑膦GR处理组;产量比直播处理组增加26.34%,直播处理组产量和直播前撒施10%噻唑膦GR处理组没有显著差异。因此,在水稻根结线虫病发生严重的田块采用移栽方式种植,可显著抑制根结线虫的发生为害,是一种安全、有效的防控措施。

光合细菌菌剂与噻唑膦协同使用对水稻根结线虫病防治研究

水稻根结线虫病近年来对我国的水稻生产造成了严重危害。探索低成本、高效安全的水稻根结线虫病防治方法对减少其危害具有极其重要的意义。本研究通过田间小区试验评价了光合细菌微生物菌剂与噻唑膦协同使用对水稻根结线虫病的防治效果及对水稻生产的影响。结果显示,利用光合细菌微生物菌剂1 L/667m^(2)与10%噻唑膦GR 0.10 kg/667m^(2)协同作用能显著降低稻田拟禾本科根结线虫2龄幼虫种群密度,减少发病株率与根结指数,35 d和70 d对水稻根结线虫病的防治效果分别达到76.94%和89.99%,与10%噻唑膦GR 0.15 kg/667m^(2)单剂处理在发病株率以及70 d防治效果、虫口减退率等不存在显著差异。利用光合细菌微生物菌剂与噻唑膦协同使用后,可减少噻唑膦药剂对水稻生长产生的抑制作用,增加作物产量,其增产率达到19.48%,显著高于10%噻唑膦GR 0.15 kg/667m^(2)单剂的使用效果。试验表明通过光合细菌微生物菌剂与噻唑膦协同应用,能减少化学杀线剂的使用,降低线虫抗药性的产生和环境污染的风险。此外,通过联合使用还能解决微生物杀线剂速效性差、防效较低等缺点,不失为一种高效绿色的水稻根结线虫病防治方法。

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.

水稻根结线虫病的病原鉴定及同源性分析

水稻根结线虫病是水稻生产过程中重要病害之一。本研究通过形态学与分子生物学技术对采集的10个水稻根结线虫种群进行鉴定,结果表明,10个水稻根结线虫种群均为拟禾本科根结线虫(Meloidogyne graminicola)。本研究中对1MSY和10MDZ种群进行同源性分析,结果显示,1MSY和10MDZ根结线虫种群与相同种或属内相近种的同源性较高,而与不同属的不同种之间的同源性相对要低。水稻根结线虫病病原与亲缘关系的明确为开展水稻抗病育种和该病防治提供了科学依据。

20%咪鲜胺·噻唑膦·戊唑醇悬浮剂对水稻种传病害防治效果

[目的]筛选新的水稻种子处理剂配方。[方法]通过室内毒力测定和田间小区试验。[结果]联合毒力测定结果表明,当咪鲜胺和戊唑醇复配比例为2∶1时,抑制水稻恶苗病菌菌丝生长表现为增效作用。噻唑膦对水稻干尖线虫的LC_(50)值为50.3513 mg/L。田间试验结果表明,20%咪鲜胺·噻唑膦·戊唑醇悬浮剂400~100 mg/L浸种或1∶250药种比拌种,对水稻恶苗病和干尖线虫病具有良好的防效。[结论]20%咪鲜胺·噻唑膦·戊唑醇悬浮剂可作为新型种子处理剂防治水稻种传病害。

湖南平江县水稻根结线虫病发生调查及病原种类分子鉴定

本研究对湖南平江地区23个乡(镇)的水稻根结线虫病进行了取样调查。结果表明,从安定镇上黄村、龙门镇居委会、福寿山镇洞下村、三市镇宦田村和加义镇小岩村等5个采样点发现了水稻根结线虫的为害。通过对根结线虫rDNA-ITS进行扩增、测序和比对,其序列和Genbank中的拟禾本科根结线虫的相似性为99.9%,采用特异性引物扩增确定其结果。据此,在湖南平江地区首次发现水稻根结线虫,并鉴定为拟禾本科根结线虫。