Reactions of Grape Rootstocks to Pratylenchus vulnus and Meloidogyne spp.

Five grape rootstocks were inoculated with 0, 100, 1,000, and 10,000 Pratylenchus vulnus. Dogridge and Saltcreek supported low average total numbers of P. vulnus, 136-705/pot, at 12 months after inoculation. Growth of both rootstocks was not affected. Harmony, Couderc 1613, and Ganzin 1 supported high average total numbers, 6-856 times the inoculum levels. Numbers in Harmony continued to increase at all levels but reduced root weight only at the 10,000 level after 12 months. Numbers in Couderc 1613 decreased by 15-30% after 12 months, and root weight was reduced at the 10,000 level. In Ganzin 1, total nematode numbers diminished after 12 months but were still at high levels; growth reduction was proportional to numbers of nematodes added. Meloidogyne incognita, M. javanica, and M. arenaria produced galls and egg masses in Harmony and Couderc 1613 only at 36 C. Galling in Ganzin 1 increased with increasing temperature. Galls in Ganzin 1 at 18 C supported mature females after 90 days. Harmony was resistant to M. incognita in single and concomitant inoculations of P. vulnus and M. incognita. At 250 days after inoculation, total numbers of P. vulnus increased above the inoculum level and the 150-day values; increase was greatest in P. vulnus added singly. Neither nematode species affected growth of Harmony.     

Effect of annual and perennial cropping regimes in microplots on the population density and vertical distribution of Xiphinema diversicaudatum and on soil porosity

Long-term trends in populations of Xiphinema diversicaudatum were measured in two microplot experiments in which annual and perennial crops of seven plant families were grown in monoculture. Numbers of X. diversicaudatum increased under perennial ryegrass, raspberry and strawberry but decreased under hop, spring barley, potato, sugar beet, cabbage, winter wheat and winter beans; these effects probably reflected differences in the inherent host status of the crops. There were fewer X. diversicaudatum at 40–60 cm below annual crops than below perennial crops, and there were differences between perennial crops in nematode vertical distribution. Soil pore space did not limit nematode population density; total pore space was uniformly large under all crops and there was no detectable instability to water slaking. Under ryegrass a greater proportion of soil volume was occupied by pores too small to accommodate X. diversicaudatum, but since ryegrass supported the second largest nematode population, it seems unlikely that this was seriously limiting.     

Effects of the root-lesion nematode Pratylenchus vulnus and the vesicular-arbuscular mycorrhizal fungus Glomus mosseae on the growth of three plum rootstocks

The effects of Pratylenchus vulnus and the endomycorrhizal fungus Glomus mosseae on growth of Myrobalan 605, Marianna 2624 and San Julian 655-2 plum rootstocks were measured under shadehouse conditions in the field for two growing seasons (1990–91). Shoot dry weights were higher in the majority of the vesicular-arbuscular mycorrhizal (VAM) alone inoculated plants after both growing seasons. Root weights of mycorrhizal Myrobalan and Marianna were higher than root weights of the same rootstocks lacking mycorrhizae, inoculated with P. vulnus, and VAM in combination with the nematode. Mycorrhizal Marianna inoculated with the nematode showed a considerably higher final nematode population in relation to non-inoculated VAM treatments. No correlation was found in the number of nematodes per gram of root between mycorrhizal and non-mycorrhizal treatments. P. vulnus adversely affected the mycorrhizal colonization in Marianna, but not in Myrobalan and San Julian. Marianna appears to be more mycorrhizal dependent than the two other rootstocks.     

Host status of some plants for Xiphinema diversicaudatum (Micol.) and their susceptibility to viruses transmitted by this species

Forty plant species were grown in pots containing viruliferous Xiphinema diversicaudatum (Micol.) for 15 wk to assess the host range of the nematode in relation to infection with arabis mosaic (AMV) and strawberry latent ring-spot (SLRV) viruses. Host status for the nematode was determined mainly from changes in total populations, but the presence of eggs in the uteri of females and changes in the numbers of adults provided additional criteria. The nematode multiplied on relatively more woody perennials than on herbaceous crop plants or weeds. Chrysanthemum coronarium was the only plant on which numbers declined significantly below those on the controls. Most plant species became infected with either AMV or SLRV. Neither virus was detected in eight out of thirteen species of trees and shrubs although four were good hosts for the nematode. Galling or distortion of the terminal region of fine feeder roots, associated with X. diversicaudatum feeding, was seen on many of the experimental plants.     

The transmission of strawberry latent ringspot virus by Xiphinema diversicaudatutn (Nematoda)

Strawberry latent ringspot virus (SLRV) was found in diseased rose bushes growing in a glasshouse where the soil contained Xiphinema diversicaudatum (Micol). Adult female, adult male and juvenile X. diversicaudatum all transmitted the virus to cucumber seedlings, and nematodes kept without plants for 32 days after acquiring SLRV later transmitted it. When transferred to fresh plants every 2–4 days for 3 weeks, single nematodes transmitted up to three times; one nematode did not transmit until 19 days after the transfers began. One adult X. diversicaudatum, out of 141 tested, transmitted both SLRV and arabis mosaic virus. In all respects X. diversicaudatum behaved as a vector of SLRV as it does as a vector of arabis mosaic virus.     

Nematodes Attacking Cultivars of Peach in North Carolina

Criconemoides xenoplax and Meloidogyne incognita were the nematode species most frequently associated with peach in North Carolina. Other nematodes often found in high numbers on that crop were Pratylenehus vulnus, Helicotylenchus spp., Trichodorus christiei, Xiphinema amerieanum and Tylenchorhynchus claytoni. P. vulnus and P. penetrans reproduced well on rootstocks of 21 peach cultivars tested in the greenhouse. P. zeae, P. brachyurus, P. coffeae and P. scribneri decreased or increased only slightly in most instances. C. xenoplax increased as much as 330-fold and reproduced on all cultivars tested. In a field experiment with six peach cultivars and moderate numbers of P. brachyurus, P. vulnus, C. xenoplax, and M. incognita, only M. incognita caused significant stunting in 30 months. This nematode increased only on root-knot susceptible cultivars, whereas the other nematodes followed the same patterns observed in the greenhouse. In a second field experiment, seedlings were stunted significantly by high numbers of C. xenoplax during an 18-month period.     

Population Dynamics and Damage Potential of Meloidogyne hapla to Rose Rootstock Species

The relationship between initial population densities (Pi) of Meloidogyne hapla on growth of three rose rootstocks (Rosa corymbifera ‘Laxa’, R. multiflora and R. canina ‘Inermis’) and nematode population development was studied. Each plant species was inoculated with ranges of nematode densities of 0, 0.062, 0.125, 0.25, 0.50, 1, 2, 4, 8, 16, 32, 64 and 128 second‐stage juvenile/g soil and were allowed to grow for 9 weeks. Seinhorst yield model was fitted to total fresh biomass data of the rootstocks. The tolerance limits (T) were 0.04, 0.09 and 0.01 J2/g soil and the minimum yield (m) 0.65, 0.47 and 0.43 for R. corymbifera ‘Laxa’, R. multiflora and R. canina ‘Inermis’, respectively. The reproductive factor (Pf/Pi) was highest at low initial nematode densities for all rootstocks and then decreased to below maintenance level with increasing initial population densities. Root gall severity consistently increased with initial nematode population density. Furthermore, number of root galling showed a strong positive relationship with final nematode population per gram root fresh weight. The relation between Pi and Pf was also fitted to the Seinhorst population model (Pf = (M*Pi)/Pi + M/a). Rosa multiflora supported the population of M. hapla to a maximum population density (M) of 27.53 J2/g soil with an estimated average maximum multiplication rate (a) of 24.39. For R. corymbifera ‘Laxa’ and R. canina, the maximum multiplication rate was 4.34 and 3.62 and the maximum population density 6.08 and 4.78 J2/g dry soil, respectively. Hence, it was demonstrated that all three rootstocks were susceptible to even low initial nematode densities and therefore are considered good hosts for M. hapla.     

The long-term effects of four monocultural regimes on two field populations of the nematodes Xiphinema diversicaudatum and Longidorus spp.

Population density changes of Xiphinema diversicaudatum and several Longidorus spp. were observed under four cultural regimes in long-term field experiments. Numbers of X. diversicaudatum increased under strawberry and, to a lesser extent, ryegrass, but remained more or less unchanged in hop and fallow plots. A mixture of four Longidorus spp. increased in numbers under grass but stayed static, or declined slowly under the other cultural regimes. All changes in population density were slow to occur, taking 3 or 4 yr for differences to become statistically significant. Fluctuations in larval numbers were mainly responsible for overall population changes; numbers of adults showed little difference over 5 yr.     

The geographical distribution of Xiphinema and Longidorus nematodes in the British Isles and Ireland

The distribution of Xiphinema and Longidorus species in the British Isles and Ireland were mapped by means of a computer programme from 5527 records. Longidorus caespiticola, L. elongatus, L. goodeyi and L. leptocephalus were found to be widespread among a wide range of vegetation types, particularly in grassland and arable crops; L. macrosoma and L. profundorum were recorded frequently in southern and central England, and L. attenuatus in East Anglia; L. vineacola was recorded once only in Eire. Paralongidorus maximus was recorded from two localities in eastern Scotland and one in southern England, on each occasion from intensively cultivated ground. Four species of Xiphinema were recorded but only X. diversicaudatum is widespread although apparently with a northerly limit in central Scotland; X. diversicaudatum was equally prevalent in arable crops, grassland and deciduous woodland; X. coxi and X. vuittenezi were recorded from a few scattered localities in England, and the few records for X. mediterraneum were all from Kent, south east England. All species were found in a wide range of soil types but mostly in light soils with a large sand fraction. Many of the species occurred together in mixed populations; L. caespiticola was most frequently associated with X. diversicaudatum and with L. leptocephalus and L. elongatus. X. diversicaudatum also was commonly found with L. goodeyi. Viruses were transmitted in laboratory bait tests in only eighteen of 325 soil samples containing X. diversicaudatum and four of 265 containing L. elongatus.     

Influence of Four Nematodes on Root and Shoot Growth Parameters in Grape

Two grape cultivars, susceptible French Colombard and tolerant Rubired, and four nematodes, Meloidogyne incognita, Pratylenchus vulnus, Tylenchulus semipenetrans, and Xiphinema index, were used to quantify the equilibrium between root (R) and shoot (S) growth. Root and shoot growth of French Colombard was retarded by M. incognita, P. vulnus, and X. index but not by T. semipenetrans. Although the root growth of Rubired was limited by all the nematodes, the shoot growth was limited only by X. index. The R:S ratios of Rubired were higher than those of French Colombard. The reduced R:S ratios of Rubired were primarily an expression of reduction in root systems without an equal reduction in shoot growth, whereas in French Colombard the reduced R:S ratios were due to a reduction in both shoot growth and root growth and to a greater reduction in root growth than shoot growth. All nematodes reproduced equally well on both cultivars. Both foliage and root growth of French Colombard were significantly reduced by M. incognita and P. vulnus. Nematodes reduced the shoot length by reducing the internode length. Accumulative R:S ratios in inoculated plants were significantly smaller than those in controls in all nematode treatments but not at individual harvest dates. Bud break was delayed by X. index and was initiated earlier by P. vulnus and M. incognita. All buds in nematode treatments were less vigorous than in controls.     

Interactions between migratory endoparasitic nematodes and arbuscular mycorrhizal fungi in perennial crops: A review

The root-lesion nematodes are important pests attacking stone and pome fruit crops throughout the world. They play an important role in the development of orchard replant problems. Host resistance toPratylenchus vulnus, the nematode of concern in mediterranean environments, has been difficult to find, and even more, to transmit into commercial rootstocks. Alternative management measures using early mycorrhizal infection that would confer protection against the nematode at a stage when plants are most vulnerable are currently being explored. These measures are considered important, taking into account a widespread change towards production systems that use in vitro material propagated in treated substrates free of mycorrhizal and other beneficial microorganisms. The prophylactic effect against root-lesion nematodes would be linked to mycorrhizal dependency of the host plant. Increase in tolerance would seem to be related to mycorrhiza assisted nutrition rather than to a direct suppressive effect of AM over the root-lesion nematode. InCitrus, Prunus, Malus andCydonia rootstocks, the nematode has shown to have a negative effect over AM colonization in the root.     

Influence of Pratylenchus vulnus and Meloidogyne hapla on the Growth of Rootstocks of Rose

Pratylenchus vulnus is involved in a desease of Rosa noisettiana ''Manetti'' rose rootstock characterized by darkening of roots, death of feeder roots, and stunting of entire plants. The disease is more severe when plants are grown in silt loam soil than when they are grown in sandy loam soil. The nematodes reproduce best in silt loam soil at 20 C. Meloidogyne hapla did not affect the growh of Manetti. Rosa sp. ''Dr. Huey'', Manetti, and R. odorata rose rootstocks were found to be goos hosts for P. vulnus whereas R. multiflora was less suitable. M. hapla reproduced well on R. odorata, Dr. Huey, and R. multiflora, but not on Manetti.     

从日本进境邮寄物中截获伤残短体线虫

【背景】2015年北京出入境检验检疫技术中心植物实验室从日本邮寄进境的鸡爪槭中检出一种短体线虫。【方法】通过采用形态学鉴定、rDNA序列测定及系统进化分析,对该线虫进行鉴定。【结果】将该线虫的形态特征和测计值与已知种群比较,与Pratylenchus vulnus最为接近;系统进化分析表明,其r DNA-ITS区序列特征与P.vulnus序列相似度为99%;系统发育树表明,其与P.vulnus聚为一组,证实该线虫为伤残短体线虫P.vulnus。【结论与意义】伤残短体线虫是一种重要的植物寄生线虫,我国进出境检疫部门曾多次从入境货物中检出该线虫,但从入境邮寄物中检中尚属首次。     

Sites of virus retention in the alimentary tract of the nematode vectors, Xiphinema diversicaudatum (Micol.) and X. index (Thorne and Allen)

Electron microscopy of thin sections of Xiphinema diversicaudatum and X. index fed on plants infected respectively with arabis mosaic and grapevine fanleaf viruses showed that the viruses are retained as a monolayer of particles adsorbed on to the cuticle lining the lumina of the odontophore (stylet extension), anterior oesophagus and oesophageal bulb. During the moult of the nematode the cuticular lining is shed and together with the detached virus particles is ingested into the intestine through the oesophago-intestinal valve; this supports the limited experimental evidence that viruses transmitted by X. diversicaudatum and X. index are not retained through the moult.     

Interaction between the root-lesion nematode Pratylenchus vulnus and the mycorrhizal association of Glomus intraradices and Santa Lucia 64 cherry rootstock

The effects of the interaction between Pratylenchus vulnus and the endomycorrhizal fungus Glomus intraradices on growth and nutrition of Santa Lucia 64 cherry rootstock was studied under microplot conditions during one growing season. Fresh top weight, and stem diameter of mycorrhizal plants and high P treatments with and without P. vulnus were significantly higher than those of non-mycorrhizal plants. The lowest shoot length and fresh root weights were recorded in nematode inoculated plants in low P soil. Mycorrhizal infection did not affect the number of nematodes per gram of root in plants infected with P. vulnus. In the presence of the nematode, internal spore production by G. intraradices was significantly reduced. No nutrient deficiencies were detected through foliar analysis, although low levels of Ca, Mn and Fe were detected in nematode treatments. Mycorrhizal plants achieved the highest values for N, P, S, Fe, and Zn, whereas high P treatments increased absorption of Ca and Mn. Early mycorrhizal infection of Santa Lucia 64 cherry rootstock by G. intraradices confers increased growth capacity in the presence of P. vulnus.     

Effects of the root-lesion nematode Pratylenchus vulnus and the mycorrhizal fungus Glomus mosseae on the growth of EMLA-26 apple rootstock

The interaction between Pratylenchus vulnus and the endomycorrhizal fungus Glomus mosseae on the growth of EMLA 26 apple rootstock was studied under shadehouse conditions in the field during the first 6 months of growth. Fresh top weights, fresh root weights, and shoot lengths of mycorrhizal plants with and without P. vulnus were significantly higher than those of nonmycorrhizal plants. Addition of P to non-mycorrhizal controls had little overall effect. Mycorrhizal treatments with the nematode showed a significantly lower amount of nematodes per gram of root than nonmycorrhizal treatments with P. vulnus. Root colonization by G. mosseae was not affected by the presence of the nematode. No nutrient deficiencies were detected in foliar analyses, although low levels of K, A1, and Fe were detected in nematode treatments. The highest levels of S, Mg, Mn and Zn were detected in P. vulnus inoculated plants. Mycorrhizal plants had the highest levels of N, Na, P, K, and Fe. The importance of early mycorrhizal infection of EMLA 26 apple root-stock in the presence of the nematode is discussed.     

Some effects of oxamyl on the virus-vector nematodes Longidorus elongatus and Xiphinema diversicaudatutn

Oxamyl applied to field soil prevented Longidorus elongatus from acquiring and transmitting tomato black ring virus for at least 6 wk, although numbers of nematodes were not greatly decreased compared with the untreated control. Glasshouse and laboratory tests examined the effects of oxamyl on viruliferous L. elongatus and Xiphinema diversicaudatum. In these tests oxamyl (1.0 ppm) in the soil water largely prevented L. elongatus transmitting virus to bait plants over a period of 1 month. X. diversicaudatum was equally affected by smaller concentrations, 0.1 ppm being sufficient to inhibit virus transmission in one test. Inhibition of virus transmission was associated with a decrease in the number of root tip galls produced by nematode feeding, especially that of X. diversicaudatum. Few nematodes were seriously affected by oxamyl, except at the greatest concentration tested (100 ppm), when numbers of L. elongatus, but not of X. diversicaudatum, were decreased. In vitro-treated viruliferous nematodes protracted their stylets, but their subsequent ability to transmit virus was unimpaired.     

Population Densities of Five Migratory Endoparasitic Nematodes in Carrot Disk Cultures

Numbers of nematodes recovered per culture varied greatly among five species cultured on carrot disks. Radopholus similis and Pratylenchus vulnus showed the highest population densities, with 23,400-fold and 16,600-fold increases, respectively, in 90 days. Final populations of P. thornei and Zygotytenchus guevarai were similar but lower than those of R. similis and P. vulnus. The population of P. neglectus increased 74 times. Species with the greatest reproduction in this study reproduce sexually.     

The expression level of <Emphasis Type="Italic">Rosa Terminal Flower 1</Emphasis> (<Emphasis Type="Italic">RTFL1</Emphasis>) is related with recurrent flowering in roses

We examined the relationship between the recurrent flowering character and the expression patterns of TERMINAL FLOWER 1 (TFL1) homologs in roses, using flower buds of Rosa multiflora, R. rugosa, R. chinensis, and six other rose species and nine rose cultivars. RTFL1 (Rosa TFL1) genes were amplified from rose genomic DNA using a combination of degenerate and gene-specific primers by thermal asymmetric interlaced-PCR and normal PCR, respectively. Their copy numbers in different species were determined by Southern blots. We used real-time PCR to analyze the expression patterns of RTFL1 genes at four developmental stages (pre-sprouting, young, mid-aged, and mature flower buds). Our results show that there are at least three RTFL1 homologs in roses; RTFL1a, RTFL1b, and RTFL1c. The sequences of the homologs were more similar among the same homolog in different species than among the different homologs in the same species. For RTFL1a, we detected two copies in R. multiflora, two copies in R. rugosa, and one copy in R. chinensis. For RTFL1c, we detected one copy in R. multiflora, two copies in R. rugosa, and three copies in R. chinensis. We detected only one copy of RTFL1b in R. chinensis. RTFL1c was expressed at high levels at all four flowering stages in R. multiflora and R. rugosa, which are non-recurrent flowering species, whereas it was barely detected in R. chinensis (a recurrent flowering species) at any stage. These results were further verified in six other non-recurrent flowering species and nine recurrent flowering cultivars. These results suggest that the recurrent flowering habit in roses results from lower expression of RTFL1c, which may be related to recurrent flowering character in roses.     

Increased tolerance to the root-lesion nematode Pratylenchus vulnus in mycorrhizal micropropagated BA-29 quince rootstock

The interaction between Glomus intraradices and the root-lesion nematode Pratylenchus vulnus was studied on micropropagated BA-29 quince rootstock during one growing season. Inoculation with G. intraradices significantly increased growth of plants in low P soil and was more effective than P fertilization at increasing top-plant development. In the presence of the nematode, mycorrhizal plants achieved higher values in all growth parameters measured. P. vulnus caused a significant decrease in the percentage of root length colonized by G. intraradices and fewer internal vesicles were formed within the host roots. Enhanced root mass production accounted for the twofold increase in final nematode population recovered from plants with combined inoculations of pathogen and symbiont. Low levels were found of Al, Fe, Mn and Zn in nonmycorrhizal nematode-infected plants in low P soil. G. intraradices-inoculated plants reached the highest foliar levels of N, Ca, Mg, Mn, Cu and Zn. Mycorrhizal plants infected with P. vulnus maintained normal to high levels of Mn, Cu, and Zn. Inoculation with G. intraradices favours quince growth and confers protection against P. vulnus by improving plant nutrition.