Sources for Heat-Stable Resistance to Southern Root-Knot Nematode （Meloidogyne incognita） in Solanum lycopersicum

Southern root-knot nematode （Meloidogyne incognita） is a major problem in vegetable production in China due to the expansion of plastic tunnel and solar greenhouse. Using resistant cultivars is an effective approach to control the disease. Nine genes, Mi-1 to Mi-9, have been reported and only Mi-1 has been successfully used in tomato breeding. However, Mi-1 is inactive at a temperature above 28~C. In order to identify sources for heat-stable resistance to southern root-knot nematode, 53 genotypes of tomato （Solarium spp.） were inoculated with an isolate of M. incognita in the growth chamber at 28 or 32℃ for initial screening. 28 lines had less than 25 galls and were considered as resistant candidates. The top 60% （16 in total） of resistant candidates obtained from each temperature were subject to re-evaluation at 32~C using the same nematode isolate. Three lines ZN17, ZN 48, and LA0385 showed heat-stable resistance with an average of 10 galls or less per plant. LA0385 is a wild species, while ZNI7 and ZN48 are elite breeding lines. These lines were grown in a greenhouse for two seasons, and also showed high resistance with less than 10 galls per plant. Thus they were considered as good sources for breeding resistance to southern root-knot nematode in tomato.     

Pseudomonas oryzihabitans Suppresses Damage Caused by Root-knot Nematode Meloidogyne javanica on Tomato

Agricultural research made in recent years has found that many bacterial organisms act like biological control agents with minimal impact on the environment. These microorganisms and their toxic metabolites should be included in those which are acceptable to qualify a product as organic or integrated and enjoy all the benefits that entails. Hence, interest in the use of microorganisms as biological agents to protect crop plants against plant parasitic nematodes has been increasing. This study investigated the ability of.Pseudomonas oryzihabitans symbiotically associated with the entomopathogenic nematode Steinernema abbasi as a bioagent against plant parasitic nematodes which infected tomato crop. The bacterium is particularly effective against root-knot nematode in vitro affecting the behavior and mobility of root-knot nematode juveniles. Also, studies in planta demonstrated the efficacy of P. oryzihabitans by preventing tomato root system by invasion of juveniles of Meloidogynejavaniea when bacterial cells were applied to the root system before nematodes. This efficacy is dependent on bacterial cell concentration used and the time of the nematode exposure. However, a better nematode control might be achieved with multiple applications of the biocontrol agent. Furthermore, the results of this study provide evidence that the bacterium P. oryzihabitans produces metabolites, which have nematostatic effects.     

Effects of Two Composted Plant Pesticide Residues, Incorporated with Trichoderma viride, on Root-Knot Nematode in Balloonflower

Plant pesticide residues, such as chinaberry （Melia toosendan） residue and sand cypress （Sabina vulgaris） residue, are pesticidal plant materials discarded after the bioactive ingredient has been extracted with organic solvents. The only option for botanical pesticide residue utilization has been as landfill. Chinaberry residue （CBR） and sand cypress residue （SCR） were collected and composted in Yangling, Shaanxi Province, China. We studied the effects of chinaberry residue compost （CBRC）, CBRC incorporated with Trichoderma viride （CBRCT）, sand cypress residue compost （SCRC）, and SCRC incorporated with T. viride （SCRCv） on the root-knot nematode, Meloidogyne incognita, infesting the balloonflower （Platycodon grandiflorum）. Bioassay results indicated that stock solutions of the CBRCT and SCRCT extracts significantly inhibited egg hatching and caused high larval mortality, followed in degree by the CBRC and SCRC extracts. The CBR and SCR extracts caused very low inhibition of eggs and larvae. Supplementing potting mixtures with these four composts reduced the severity of root galling and increased the proportion of marketable roots. The severity of root galling decreased and the average weight of the marketable roots increased with an increase in all the composts when supplemented at rates from 5 to 30%. CBR- and SCR-supplemented pot soils also inhibited the nematodes, but CBR and SCR applied to the soil had a phytotoxic effect and inhibited balloonflower growth. Supplementing field soil with the composts reduced the severity of root galling and the populations of southern root-knot nematodes in the soil. CBRCT and SCRCT clearly enhanced the average weight of the marketable roots by 30.45 and 26.64%, respectively. Continuous supplementation with CBRCT or SCRCT in the same field significantly enhanced the control of the root-knot nematode, and the populations of nematodes continued to decrease with second inoculations. The populations of total Trichoderma spp. were distinctly enhanced and were maintained at high levels for a long time in the supplemented soils.     

The Importance of the Organic Matter when Extracting Meloidogyne chitwoodi from Soil

 Even very low infections of Meloidogyne chitwoodi can cause heavy damage to some crops.In view of this, the choice of extract ion methods is very important.The number of nematodes kept in the organic fraction plays an important role in the total soil population.It is important to liberate these nematodes in a first step.     

Identification of QTLs for Starch Content in Sweetpotato （Ipomoea batatas （L.） Lam.）

Sweetpotato （Ipomoea batatas （L.） Lam.） breeding is challenging due to its genetic complexity. In the present study, interval mapping （IM） and multiple quantitative trait locus （QTL） model （MQM） analysis were used to identify QTLs for starch content with a mapping population consisting of 202 F1 individuals of a cross between Xushu 18, a cultivar susceptible to stem nematodes, with high yield and moderate starch, and Xu 781, which is resistant to stem nematodes, has low yield and high starch content. Six QTLs for starch content were mapped on six linkage groups of the Xu 781 map, explaining 9.1-38.8% of the variation. Especially, one of them, DMFN 4, accounted for 38.8% of starch content variation, which is the QTL that explains the highest phenotypic variation detected to date in sweetpotato. All of the six QTLs had a positive effect on the variation of the starch content, which indicated the inheritance derived from the parent Xu 781. Two QTLs for starch content were detected on two linkage groups of the Xushu 18 map, explaining 14.3 and 16.1% of the variation, respectively. They had a negative effect on the variation, indicating the inheritance derived from Xu 781. Seven of eight QTLs were co-localized with a single marker. This is the first report on the development of QTLs co-localized with a single marker in sweetpotato. These QTLs and their co-localized markers may be used in marker-assisted breeding for the starch content of sweetpotato.     

Performance of Three Adelphocoris spp.（Hemiptera： Miridae） on Flowering and Non-flowering Cotton and Alfalfa

The genus Adelphocoris（Hemiptera： Miridae） is a group of key insect pests in cotton fields in China that includes three dominant species： A. suturalis（Jakovlev）, A. lineolatus（Goeze） and A. fasciaticollis（Reuter）. Previous field surveys have found that adults of these Adelphocoris species usually move onto specific host plants when the plants enter the flowering stage. To determine the potential trade-offs for this host-plant preference behavior, the performance of these three Adelphocoris spp. on flowering and non-flowering cotton and alfalfa were compared in the laboratory. The results showed that Adelphocoris spp. had significantly higher nymphal developmental and survival rates, along with increased adult longevity and fecundity on flowering cotton and alfalfa than on non-flowering plants of either species. In addition, compared with cotton plants, alfalfa generally promoted better performance of these three Adelphocoris species, especially for A. lineolatus. Simple correlation analysis indicated that female adult longevity was positively correlated to male adult longevity and female fecundity, and female fecundity was positively correlated to nymphal development and survival rates. This study demonstrated a positive correlation between adult preference and offspring/adult performance for all three Adelphocoris species, with no evidence of any trade-offs for this preference for flowering host plants. These findings support the hypothesis that hemimetabolous insects such as mirid bugs have positive adult preference-adult/nymphal performance relationships, which is likely due to the similar feeding habits and nutritional requirements of adults and nymphs.     

Identification and resistant characterization of legume sources against Meloidogyne incognita

Root-knot nematodes(RKNs; Meloidogyne spp.) are becoming a serious problem in legume production. This study identified Vigna genotypes exhibiting resistance to M. incognita(RKN) and characterized the modes of the resistance to M. incognita. In total, 279 accessions from 21 Vigna species were screened for resistance based on a galling index(GI) and an egg mass index(EI). Seven accessions were highly resistant to RKN with GI≤25, namely JP74716(V. mungo var. mungo; cultivated black gram), JP107881(V. nepalensis), JP229392(V. radiata var. sublobata; wild mungbean), Aus TRCF118141(V. unguiculata subsp. unguiculata; cultivated cowpea), Aus TRCF306385(V. unguiculata subsp. unguiculata), Aus TRCF322090(V. vexillata var. vexillata; wild zombi pea) and JP235929(V. vexillata var. vexillata). JP229392 and Aus TRCF322090 were the most resistant accessions having EI values of 18.74 and 1.88, respectively. Continuous culture of M. incognita on both JP229392 and Aus TRCF322090 resulted in a weakness in pathogenic ability for this RKN. The resistance in JP229392 and Aus TRCF322090 to RKN appeared to be antibiosis that was associated with reduced nematode penetration, retardation of nematode development and impeding giant cell formation. The Vigna germplasm resistance to RKN identified in this study could be utilized as gene sources for the development of RKN-resistant Vigna cultivars.     

Evaluation of Essential Oils from Rosemary, Orange, Lavandula and False Yellowhead on Hatching and Motility of Root-Knot Nematode

Essential oils （EOs） from Rosemary, Rosmarinus officinalis （Lamiaceae）, Orange, Citrus sinensis （Rutaceae）, Lavandula, Lavandula angustifolia （Lamiaceae）, False Yellowhead, Dittrichia viscosa （Asteraceae） and their major components were evaluated against root knot nematode, Meloidogyne incognita and Meloidogynejavanica. Second stage juveniles＇ （J2） paralysis and egg hatch inhibition were studied, while pulverized plant parts were tested for nematodes biological cycle arrest. All EOs paralyzed J2 and M. incognita were found more sensitive than M javanica with the EC50/4 days calculated at 250, 3,650 and 4,260 12g/mL for 1）. viscosa, L. angustifolia and R. officinalis, respectively. Similarly, all EOs inhibited nematodes egg hatch and D. viscosa exhibited the highest inhibition on egg hatch （100% inhibition at 5 μg/mL）. A significant influence of constituent terpenes （limonene, 1,8-cineole, linalool, camphor, L-borneol, caryophyllene oxide, β-eudesmol） dose and exposure time was indicated on egg hatch inhibition （56% to 100% at 500 μg/mL and 1,000 μg/mL）, while only β-eudesmol achieved paralysis of J2 and specifically against M. incognita （EC50/1d = 50μg/mL）. Interestingly, the most active botanical species arresting Meloidogyne spp. biological cycle in soil was C. sinensis （EC50 = 2 mg/g） and the most sensitive nematode species was M. javanica. The larvicidal and egg hatch inhibition activity holds promise towards the optimization of artificial terpene mixtures as novel and effective natural nematicides. Complex interactions of primary compounds and subsequent decomposition derivates compose efficacy profile of soil amendments.     

Mycoparasitism of Gliocladium isolates in China Mycoparasitism of Gliocladium isolates in China

During an investigation of mycoparasitic fungi on sclerotia of Sclerotinia sclerotiorum in China, Gliocladium species was consistently encountered and isolated from natural soils collected over the country. Colonization frequencies on sclerotia of S. sclerotiorum by the fungi ranged from 40% to 100% when the sclerotia were introduced into soils and coincubated at 22-24 ℃ for 4 weeks. Identification showed that G. roseum, G. virens and G. catenulatum were the dominant species amon…     

Factorial analysis of the effect of sugarbeet vinasses on agroecological indices in horticultural field

The impact on soil of applying sugarbeet vinasses （V） was analyzed through a field experiment in horticulture greenhouse, arranged in a 23 factorial design. Two levels of three independent variables--application of V, use of polyethylene cover （PC） on the soil. and soil depth （D）---on various dependent variables were studied. Vinasses favoured crop yield and reduced the number of Meloidogyne incognita juveniles in soil. The concentrations ofN. P and K increased with the interaction VxD, with PC also increasing N concentration. The amounts of humic acids and humin decreased with D; fulvic acid concentration increased with V, but decreased with the interaction VxPC. Soil physical factors were improved mainly with D and V. Aromaticity of humic acid-like fractions increased ~＇itb V. In general, V showed significant effects mainly on the topsoil, suggesting low leaching risks. The results indicate that the levels of the independent factors improving a group of variables were not the same that those contributing to another group. Therefore, their best combination should be determined for each scenario to achieve optimum agroecological performance.     

Species and Distribution of Rice Root Nematode in Yunnan Province, China

Rice root nematodes, Hirschmanniella spp. parasitize in the roots of rice and water plant spread widely. Ten species of the genus Hirschmanniella Luc et Goody, 1964 (Nemata:Pratylenchidae) collected from the root of rice in Yunnan Province are reported. They are H. belli, H. caudacrena, H. diversa, H. gracilis, H. imamuri, H. mexicana, H. microtyla,H. mucronata, H. oryzae and H. spinicaudata, including seven species of important pathogenic nematodes of rice and two dominant species H. oryzae and H. imamari. Generally,the trend of species composition pattern is H. oryzae and H. imamari, which is a common composition pattern in the world, but the species composition mode varies with the difference of altitude and latitude. Their distribution relates to altitude and latitude closely, and also to the type of rice, such as indica or japonica rice.     

Evaluation of Chinese rice varieties resistant to the root-knot nematode Meloidogyne graminicola

The root-knot nematode Meloidogyne graminicola, which is distributed worldwide, is considered a major constraint on rice production in Asia. The present study used the root gall index and number of nematodes inside the roots to evaluate resistance/susceptibility to M. graminicola in different subpopulations of Oryza sativa(aus, hybrid aus, indica, hybrid indica, temperate japonica, tropical japonica). Nematode development in highly resistant varieties was also evaluated. Analyses of randomly selected 35 varieties showed the number of M. graminicola nematodes inside the roots correlated very strongly(r=0.87, P≤0.05) with the nematode gall index, and the results from pot and field experiments revealed similar rankings of the varieties for resistance/susceptibility. Among the 136 tested varieties, temperate japonica displayed the highest gall index, followed by tropical japonica, indica, hybrid indica, aus, and hybrid aus. Zhonghua 11(aus), Shenliangyou 1(hybrid aus) and Cliangyou 4418(hybrid indica) were highly resistant to M. graminicola under both pot and field conditions. Further examination of nematode development suggested that compared to susceptible rice, M. graminicola penetrated less often into highly resistant varieties and more frequently failed to develop into females. The promising varieties found in the present research might be useful for the breeding of hybrid rice in China and for the further development of practical nematode management measures.     

Red Palm Weevil,Rhynchophorus ferrugineus （Olivier）： Economic Importance,Biology, Biogeography and Integrated Pest Management

The Red Palm Weevil （RPW）, Rhynchophorus ferrugineus （Olivier）, （Coleoptera, Curculionidae, Rhynchophorinae）, is an invasive species that is originated from Southeast Asia. It has.invaded Middle East and several countries of the Mediterranean Basin during the last three decades where it attacks palm trees. During the last three decades, multiple introductions of RPW to the Middle East, Europe and Caribbean （Island of Curacao, Netherland Antilles）, Lebanon and United States of America （Laguna Beach, Orange County, California） （USA） have occurred and the RPW is now a serious pest of many palm species. Duration of all life parameters varies significantly where the entire life cycle takes about 45 to 298 days. Different artificial diets were developed and were tested for mass rearing of RPW. Control of RPW is difficult due to the concealed nature of the life cycle of the pest. Integrated Pest Management （IPM） strategy has been applied successfully to deal with RPW problem. The IPM strategy consists of various preventive and curative methods; those methods were categorized in nine categories in this review. The main objective of this work was to review the existing knowledge on RPW＇s different aspects, with an ultimate aim of revealing the actual situation of the research on RPW.     

Evaluation of soil flame disinfestation(SFD) for controlling weeds,nematodes and fungi

Soil flame disinfestation(SFD) is a form of physical disinfestation that can be used both in greenhouses and on field crops. Its use for soil disinfestation in different crop growing conditions makes it increasingly attractive for controlling soilborne pathogens and weeds. But little is known about the effect on weeds and soilbrone diseases. This study reports on greenhouses and field crops in China that determined the efficacy of SFD to control weeds, nematodes and fungi. It also determined the impact of SFD on the soil physical and chemical properties(water content, bulk density, NO_3~–-N content, NH_4~+-N content, conductivity and organic matter) in three field trials. A second generation SFD machine was used in these trials. SFD treatment significantly reduced weeds(87.8%) and root-knot nematodes(Meloidogyne incognita)(98.1%). Plant height and crop yield was significantly increased with SFD treatment. NO_3~–-N and NH_4~+-N increased after the SFD treatment, and there was also an increase in soil conductivity. Water content, bulk density and organic matter decreased significantly in the soil after the SFD treatment compared to the control. Soil flame disinfestation is a potential technique for controlling weeds and diseases in greenhouses or in fields. SFD is a non-chemical, safe, environmentally-friendly soil disinfection method.     

Testing of Seedborne Fungi in Wheat Germplasm Conserved in the National Crop Genebank of China

There is a primary understanding of the dominant fungi in wheat seeds conserved in the National Crop Genebank of China （NCGB） and an evaluation of the healthy status of wheat germplasm propagated in different regions. A total of 1 465 wheat accessions were detected for seedbone fungi by blotter, agar plate, and wash tests. By blotter test, 17 genera of fungi, including more than 30 species, were detected in 712 wheat accessions from Shaanxi, Hebei, and Qinghai provinces, China. Alternaria was the most frequently detected in wheat seeds from Shaanxi Province, followed by Rhizopus, Penicillium, Aspergillus, Bipolaris, Cladosporium, Gonatobotrys, Chaetomium, and others. Seedborne fungi in wheat seeds from Hebei Province, with relatively high incidence were Alternaria, Rhizopus, Penicillium, Aspergillus, Bipolaris, Cladosporium, and Fusarium. In the seeds from Qinghai Province, Alternaria, Rhizopus, Bipolaris, Cladosporium, and Trichothecium are important seed-borne fungi. The seed germination was reduced substantially when seeds were infected by Fusarium verticillioides （syn. F. moniliforme）, Bipolaris nodulosa, and Cladosporium herbarum. Eighteen genera and 25 species of fungi were identified in 353 accessions from Shaanxi Province using the agar plate test. The dominant fungi were Alternaria, Aspergillus, Bipolaris, Gonatobotrys, Penicillium, and Fusarium. The smut fungi, Ustilago tritici, was detected by the wash test in 400 accessions, but it was low in incidence in 300 seed samples from Shaanxi Province （1.3%）, and in 100 samples from Hebei Province （2.0%）. Totally 19 genera of fungi were detected in wheat seed samples, and some seedborne fungi were saprophytic and others were biotrophic which could cause seedborne diseases in the field.     

Hydrolytic Enzyme Inhibitors and Necrotic Reactions in Potato Leaves Reduce Reproductive Success of Colorado Potato Beetle

In field and laboratory conditions the reproductive potential （survival at different stages of development） of the Colorado potato beetle has been measured, the dependence of the parameters of insects fertility on varietal features of the feed has been investigated, the food activity of the representatives of insects from four areas of the Southern Urals has been measured, the intensity and time of hypersensitivity reactions on potato leaves has been defined. In laboratory experiments, the level of activity of hydrolytic enzymes in insects and the level of activity of these enzymes inhibitors in the leaves of three potato varieties differing in their resistance to the Colorado potato beetle have been determined. The results show that the insects-representatives of different samples have different food activity in relation to different potato varieties. High mortality rates were revealed at feeding with leaves of potato of the Bashkir variety characterized by a high level of hydrolases inhibitors and relatively rapid development of necrotic reactions after the appearance of eggs laying on the leaves. We suppose that the neerogenetic barrier appearing in the form of necrosis is the major cause of the fetal mortality of insects. The level of the content of inhibitors inactivating larvae digestive enzymes affects the survival of insects at postembryonic stages. The speed of the necrosis emergence, the level of activity of digestive enzymes inhibitors in potato can be considered as criteria for the selection of breeding material for resistance to the Colorado potato beetle.     

Identification of QTLs for Starch Content in Sweetpotato(Ipomoea batatas(L.) Lam.)

Sweetpotato（Ipomoea batatas（L.）Lam.）breeding is challenging due to its genetic complexity.In the present study,interval mapping（IM）and multiple quantitative trait locus（QTL）model（MQM）analysis were used to identify QTLs for starch content with a mapping population consisting of 202 F1 individuals of a cross between Xushu 18,a cultivar susceptible to stem nematodes,with high yield and moderate starch,and Xu 781,which is resistant to stem nematodes,has low yield and high starch content.Six QTLs for starch content were mapped on six linkage groups of the Xu 781 map,explaining 9.1-38.8%of the variation.Especially,one of them,DMFN₄,accounted for 38.8%of starch content variation,which is the QTL that explains the highest phenotypic variation detected to date in sweetpotato.All of the six QTLs had a positive effect on the variation of the starch content,which indicated the inheritance derived from the parent Xu 781.Two QTLs for starch content were detected on two linkage groups of the Xushu 18 map,explaining 14.3 and 16.1%of the variation,respectively.They had a negative effect on the variation,indicating the inheritance derived from Xu 781.Seven of eight QTLs were co-localized with a single marker.This is the first report on the development of QTLs co-localized with a single marker in sweetpotato.These QTLs and their co-localized markers may be used in marker-assisted breeding for the starch content of sweetpotato.     

ISSR-Based Molecular Characterization of an Elite Germplasm Collection of Sweet Potato （Ipomoea batatas L.） in China

To determine the genetic diversity and population structure of sweet potato accessions cultivated in China, and to establish the genetic relationships among their germplasm types, a representative collection of 240 accessions was analyzed using inter-simple sequence repeat （ISSR） markers. The mean genetic similarity coefifcient, Nei’s gene diversity, and shared allele distance of tested sweet potato accessions were 0.7302, 0.3167 and 0.2698, respectively. The 240 accessions could be divided into six subgroups and ifve subpopulations based on neighbor-joining （NJ） clustering and STRUCTURE results, and obvious genetic relationships among the tested sweet potato accessions were identiifed. The marker-based NJ clustering and population structure showed no distinct assignment pattern corresponding to lfesh color or geographical ecotype of the tested sweet potato germplasm. Analysis of molecular variance （AMOVA） revealed small but signiifcant difference between white and orange-lfeshed sweet potato accessions. Small but signiifcant difference were also observed among sweet potato accessions from the Southern summer-autumn sweet potato region, the Yellow River Basin spring and summer sweet potato region and the Yangtze River Basin summer sweet potato region. This study demonstrates that genetic diversity in the tested sweet potato germplasm collection in China is lower than that in some reported sweet potato germplasm collections from other regions. Pedigree investigations suggest that more diverse Chinese sweet potato varieties should be formed by broadening the selection scope of breeding parents and incorporating the introduced varieties into future breeding programs.     

NBS Profiling Identifies Potential Novel Locus from Solanum demissum That Confers Broad-Spectrum Resistance to Phytophthora infestans

Potato late blight, caused by the oomycete pathogen Phytophthora infestans, is the most serious disease of potato worldwide. The adoption of varieties with resistance genes, especially broad-spectrum resistance genes, is the most efficient approach to control late blight. Solanum demissum is a well-known wild potato species from which 11 race-specific resistance genes have been identified, however, no broad-spectrum resistance genes like RB have been reported in this species. Here, we report a novel reisistance locus from S. demissum that potentially confer broad-spectrum resistance to late blight. A small segregating population of S. demissum were assessed for resistance to aggressive P. infestans isolates（race 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, and 11）. This coupled with nucleotide binding site（NBS） profiling analyses, led to the identification of three fragments that linked to the potential candidate resistance gene（s）. Cloning and sequence analysis of these fragments suggested that the identified resistance gene locus is located in the region containing R2 resistance gene at chromosome 4. Based on the sequences of the cloned fragments, a co-segregating sequence characterized amplified region（SCAR） marker, RDSP, was developed. The newly identified marker RDSP will be useful for marker assisted breeding and further cloning of this potential resistance gene locus.