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1.
Jutta Ludwig-Müller Astrid Schuller 《European journal of plant pathology / European Foundation for Plant Pathology》2008,121(3):291-302
The clubroot disease of cruciferous crops is caused by an obligate biotrophic protist, Plasmodiophora brassicae. The disease is characterized by the development of large root galls accompanied by changes in source-sink relations and
the hormonal balance within the plant. Since the disease is difficult to control, it is of high economic interest to understand
the events leading to gall formation. In this review we will give an overview on the current knowledge of changes brought
about in the host root by this obligate biotrophic pathogen. Emphasis will be on the regulation of changes in plant hormone
homeostasis, mainly auxins and cytokinins; the possible role of secondary metabolites, especially indole glucosinolates, in
gall formation and auxin homeostasis will be discussed. Also, results from mutant analysis and microarrays using the model
plant Arabidopsis thaliana are presented. 相似文献
2.
Giorgio Gambino Rosalina Vallania Ivana Gribaudo 《European journal of plant pathology / European Foundation for Plant Pathology》2010,127(4):557-570
In grapevine, somatic embryogenesis is particularly effective in eliminating several important virus diseases. However, the
mechanism whereby regenerated somatic embryos are freed of the viruses is not clear. The distribution of Grapevine fanleaf virus (GFLV), Grapevine leafroll-associated virus-3 (GLRaV-3) and Grapevine virus A (GVA) in embryogenic callus of grapevine was investigated by in situ hybridization using digoxygenin-labelled oligonucleotide probes. Four months after culture initiation, in callus originated
by GFLV-infected explants we observed a mosaic of infected and uninfected cells, with high concentrations of viruses in some
cell groups in peripheral zones of the callus. In addition some abnormal somatic embryos showed a high hybridization signal.
In callus originated by GVA- and GLRaV-3-infected explants the viruses were concentrated in few cells surrounded by areas
of virus-free cells. The two viruses were generally localized in different clusters of cells inside the callus and the levels
of infection were lower than those observed in GFLV-infected callus. No virus was detected in callus nor in somatic embryos
after 6 months of culture. The results highlight the difficulties of some viruses at stably invading callus tissues and the
differential ability of GFLV to spread in the callus cells compared to the phloem-limited viruses. 相似文献
3.
Chunyu Li Shi Chen Cunwu Zuo Qingming Sun Qian Ye Ganjun Yi Bingzhi Huang 《European journal of plant pathology / European Foundation for Plant Pathology》2011,131(2):327-340
Fusarium oxysporum f. sp. cubense (Foc) is the causal pathogen of Fusarium wilt of banana. To understand infection of banana roots by Foc race 4, we developed a green fluorescent protein (GFP)-tagged transformant and studied pathogenesis using fluorescence microscopy
and confocal laser scanning microscopy. The transformation was efficient, and GFP expression was stable for at least six subcultures
with fluorescence clearly visible in both hyphae and spores. The transformed Foc isolate also retained its pathogenicity and growth pattern, which was similar to that of the wild type. The study showed
that: (i) Foc race 4 was capable of invading the epidermal cells of banana roots directly; (ii) potential invasion sites include epidermal
cells of root caps and elongation zone, and natural wounds in the lateral root base; (iii) in banana roots, fungal hyphae
were able to penetrate cell walls directly to grow inside and outside cells; and (iv) fungal spores were produced in the root
system and rhizome. To better understand the interaction between Foc race 4 and bananas, nine banana cultivars were inoculated with the GFP-transformed pathogen. Root exudates from these cultivars
were collected and their effect on conidia of the GFP-tagged Foc race 4 was determined. Our results showed that roots of the Foc race 4-susceptible banana plants were well colonized with the pathogen, but not those of the Foc race 4-resistant cultivars. Root exudates from highly resistant cultivars inhibited the germination and growth of the Fusarium
wilt pathogen; those of moderately resistant cultivars reduced spore germination and hyphal growth, whereas the susceptible
cultivars did not affect fungal germination and growth. The results of this work demonstrated that GFP-tagged Foc race 4 isolates are an effective tool to study plant–fungus interactions that could potentially be used for evaluating resistance
in banana to Foc race 4 by means of root colonization studies. Banana root exudates could potentially also be used to identify cultivars in
the Chinese Banana Germplasm Collection with resistance to the Fusarium wilt pathogen. 相似文献
4.
Phap Q. Trinh Wim M. L. Wesemael Sy T. T. Nguyen Chau N. Nguyen Maurice Moens 《European journal of plant pathology / European Foundation for Plant Pathology》2011,130(1):45-57
The pathogenicity and reproductive fitness of Pratylenchus coffeae and Radopholus arabocoffeae from Vietnam on coffee (Coffea arabica) seedlings cv. Catimor were evaluated in greenhouse experiments. The effect of initial population densities (Pi = 0, 1, 2,
4, 8, 16, 32, 64, 128, and 256 nematodes per cm3 soil) was studied for both species at different days after inoculation (dai). The data were adjusted to the Seinhorst damage
model Y = m + (1-m).zPi-T. Tolerance limit (T) for P. coffeae was zero for the height and the diameter of the coffee plants. For the diameter, the T-value for R. arabocoffeae was 25.6 for 30 and 60 dai and 12.8 for 90 and 120 dai. After 4 months T was zero. The low tolerance limits indicate that
Arabica coffee is highly intolerant to both nematode species. At the end of the experiment (180 dai), all plants were infected
and most were dead when inoculated with R. arabocoffeae at initial densities of 32, 64, 128 and 256 nematodes/cm3 soil. For P. coffeae plant death was already observed at the lowest inoculation densities. Growth of coffee was reduced at all inoculation levels
for both species. Pratylenchus coffeae and R. arabocoffeae caused intense darkening of the roots, leaf chlorosis and a strong reduction of root and shoot growth. It was observed that
P. coffeae mainly destroyed lateral roots rather than tap roots, whereas R. arabocoffeae reduced tap root length rather than the lateral roots. At the lowest inoculum densities, the reproduction factor of P. coffeae was 2.38 and 2.01 for R. arabocoffeae, indicating that arabica coffee is a host for both species. Plant growth as expressed by shoot height and shoot and root
weight measured 60 dai was negatively correlated with nematode (both species) density as expressed by the geometric mean of
nematode numbers at 30 and 60 dai. 相似文献
5.
6.
Fusarium head blight in small grain cereals has emerged as a major problem in the Nordic countries. However, the impact of
this disease in oats has been less investigated than in other cereals. For this reason we have studied the infection process
(the optimal time of infection and infection pathways) of Fusarium graminearum in oats and its subsequent effects on kernel infection, deoxynivalenol (DON) content and germination capacity. In a field
experiment the oat cultivar Morton was spray-inoculated at different developmental stages, and the highest kernel infection
and DON content and lowest germination percentage were observed when inoculation took place at anthesis. Field grown oats
affected by a natural Fusarium head blight epidemic and spray-inoculated field and greenhouse oats were used to study the
infection pathway. Results showed that the fungus entered primarily through the floret apex into the floret cavity, where
it could infect via the internal surfaces of the palea, lemma and caryopsis. Both visual symptoms and fungal infections started at the apical
portions of the florets and progressed to the basal portions. Hyphae of F. graminearum grew more profusely on the anthers than on other floret parts during initial stages of infection. Disease development within
the oat panicle was slow and is primarily by physical contact between adjoining florets, indicating that the long pedicels
give Type II resistance in oats. 相似文献
7.
Nicolas Desoignies Celine Stocco Claude Bragard Anne Legrève 《European journal of plant pathology / European Foundation for Plant Pathology》2011,131(1):27-38
The understanding of the molecular biology of Polymyxa betae, the protist vector of Beet necrotic yellow vein virus, remains limited because of the obligate nature of this root endoparasite and the limited data on the genome of Beta vulgaris, its most common host plant. The aim of this work was to assess the infection of P. betae in Arabidopsis thaliana in order to learn more about the P. betae genome and its interaction with the host. The susceptibility of a set of ecotypes of various origins to a monosporosorus
and aviruliferous isolate of P. betae was analyzed in a series of bioassays conducted under controlled conditions. P. betae was detected in roots of A. thaliana using light microscopy and PCR. The infection severity was relatively low in this species compared with B. vulgaris, but the different stages of the life cycle were present. The phenotype of P. betae in A. thaliana root cells differed from the phenotype in B. vulgaris: the spore-forming phase was more prevalent in comparison with the sporangial phase, and the sporosori contained a lower number
of spores. The compatible interaction between P. betae and A. thaliana obtained after the inoculation of zoospores and optimal conditions for the development of P. betae provide a new model system that can be used to improve the knowledge on the P. betae genome and on the mechanisms of the spore-forming phase of P. betae. 相似文献
8.
Fatma F. Abdel-Motaal Soad A. El-zayat Yuki Kosaka Magdi A. El-Sayed Rumi Kashima Yukie Maeda Mortada S. M. Nassar Shin-ichi Ito 《Journal of General Plant Pathology》2010,76(2):102-111
The antifungal activities of hyoscyamine and scopolamine, major alkaloids extracted from the desert plant Hyoscyamus muticus, against two rice pathogens, Magnaporthe oryzae and Rhizoctonia solani, were studied. The minimum inhibitory concentration of hyoscyamine that resulted in distinctive inhibition (MIC50) was 1 μg/ml for both fungi. Exposure to hyoscyamine caused the leakage of electrolytes from the mycelia of both fungi. Hyoscyamine
(>1 μg/ml) irreversibly delayed or inhibited conidial germination and appressorium formation in M. oryzae grown on polystyrene plates. Hyoscyamine effectively inhibited the attachment of conidia to the surface of rice (Oryza sativa) leaves and inhibited appressorium formation on the leaves. A high concentration of scopolamine (1000 μg/ml) also delayed
or inhibited conidial germination in M. oryzae, but conidial germination was restored after washing the conidia with water. Antifungal activity of hyoscyamine was reduced
by scopolamine. Magnaporthe oryzae infection was significantly suppressed (by >95%) in leaves of intact rice plants treated with hyoscyamine (10 μg/ml). Moreover,
10 μg hyoscyamine/ml significantly reduced the disease severity index for sheath blight to ≤0.2, when compared with the disease
index of control plants (>7.0). Hyoscyamine (>20 μg/ml) completely inhibited sclerotial germination and development of R. solani by delaying the initiation, maturation, and melanization of the sclerotia. These results suggest that tropane alkaloids may
be useful for controlling blast and sheath blight diseases of rice and for studying the mechanisms that regulate conidial
germination in M. oryzae and sclerotial germination and development in R. solani. 相似文献
9.
Domenico Rongai Claudio Cerato Luca Lazzeri 《European journal of plant pathology / European Foundation for Plant Pathology》2009,124(4):613-619
This study examines the effects of a vegetable fungicide on sugar beet powdery mildew (Erysiphe betae) and cucumber powdery mildew (Erysiphe cichoracearum). The formulations consisting of a dispersion of Brassicaceae meal in vegetable or mineral oils on infected leaves of sugar beet, reared in the greenhouse, and of musk melons cultivated
under plastic tunnels, were tested in comparison to each oil taken separately. Both formulations containing Brassicaceae meals, caused 94% of conidia to be distorted while for the untreated group only 2% were distorted. Furthermore, the leaf
area infected by E. betae was 56% for untreated plants and 2.7 and 9.9% respectively, for plants treated with meal containing mineral and vegetable
oil. Vegetable oil considered separately or with Brassicaceae meals showed no phytotoxicity, while the formulations based on mineral oil showed a significantly lower fresh and dry weight
on tomato plants. The low level or absence of phytotoxicity of plants treated with vegetable oil formulations suggests that
to improve the efficacy of powdery mildew control, they could be used mixed with sulphur. The efficiency of the vegetable
formulations in the powdery mildew control observed during these trials encourages further investigation on other parasitic
fungi and foliar pathogens. 相似文献
10.
The apple rust mite Aculus schlechtendali (Nal.) (Acari: Eriophyidae), is a main pest in apple-growing areas in Ankara, Turkey, and chemical control applications have
some limitations. Entomopathogenic fungi have a potential for biological control of mites. In this study, an entomopathogenic
fungus, Paecilomyces lilacinus (Thom) Samson (Deuteromycota: Hyphomycetes), was first isolated from the mite cadavers on Japanese crab apple leaves and
pathogenicity of the fungus was observed in different inoculum densities and relative humidities. The pathogen caused up to
98.22% mortality of the mite population. The effects of some fungicides on the entomopathogenic fungus were determined in
in vitro studies. Carbendazim, penconazole and tebuconazole were the most effective fungicides on mycelial growth of P. lilacinus, with EC50 values under 3 μg ml−1. In spore germination tests, captan, mancozeb, propineb were the most effective fungicides, followed by tebuconazole, penconazole,
nuarimol and chlorothalonil. Sulphur could not inhibit the conidia germination totally at 5,000 μg ml−1. Copper oxychloride and fosetyl-al prevented conidia formation at concentrations above 1,000 μg ml−1. 相似文献
11.
The effects of some fungicides used against citrus diseases, on mycelial growth and conidial germination of Isaria farinosa (Holmsk.) Fries [Sordariomycetes: Hypocreales] and also on the pathogenicity of the fungus on citrus mealybug, Planococcus citri (Risso), were determined. Systemic fungicides such as tebuconazole, penconazole and nuarimol were the most effective as regards
both conidial germination and mycelial growth. Protective fungicides such as captan, chlorothalonil, mancozeb and propineb
inhibited conidial germination at between 1 and 5 μg ml−1 concentration, but captan, chlorothalonil and propineb did not inhibit the mycelial growth at 5,000 μg ml−1. Mancozeb inhibited mycelial growth between 2,500 and 5,000 μg ml−1. Sulphur and copper oxychloride did not inhibit the fungus even at very high concentrations. Sulphur, copper oxychloride,
fosetyl-al, chlorothalonil and carbendazim did not decrease the mortality percentage caused by I. farinosa. Tebuconazole, penconazole and mancozeb were the most effective and respectively reduced the mortality from 83% to 33%, 28%
and 30% in the ovisacs, from 81% to 29%, 27% and 29% in the 1st instar larvae, and from 84% to 34% in the adult females. 相似文献
12.
Susan J. Sprague Barbara J. Howlett John A. Kirkegaard 《European journal of plant pathology / European Foundation for Plant Pathology》2009,125(2):189-202
The infection of above-ground tissues of Brassica napus by Leptosphaeria maculans is well understood. However, root infection (root rot) under field conditions, the development of root rot over time and
its relationship to other disease symptoms caused by L. maculans has not been described. A survey of B. napus crops was conducted in Australia to investigate the incidence and severity of root rot. Additionally, the pathway of root
infection was examined in field experiments. Root rot was present in 95% of the 127 crops surveyed. The severity and incidence
of root rot was significantly correlated with that of crown canker; however, the strength of this relationship was dependent
on the season. Root rot symptoms appeared before flowering and increased in severity during flowering and at maturity, a pattern
similar to crown canker suggesting that the infection of the root is an extension of the crown canker phase of the L. maculans lifecycle. All isolates of L. maculans tested in glasshouse experiments caused root rot and crown canker in B. napus and Brassica juncea. In the field, the main pathway of root infection is via invasion of cotyledons or leaves by airborne ascospores, rather
than from inoculum in the soil. Root rot was present in crops in fields that had never been sown to B. napus previously, in plants grown in fumigated fields, and in glasshouse-grown plants inoculated in the hypocotyl with L. maculans. 相似文献
13.
Manuela Branco Conceição Boavida Nicolas Durand José Carlos Franco Zvi Mendel 《Phytoparasitica》2009,37(1):51-54
The Eucalyptus gall wasp Ophelimus maskelli (Hymenoptera: Eulophidae) and its parasitoid Closterocerus chamaeleon (Hymenoptera: Eulophidae) were observed for the first time in Portugal, in 2006 and 2007, respectively. Data on the distribution
of O. maskelli in Portugal, differences in the susceptibility of two host species, Eucalyptus globulus and Eucalyptus camaldulensis, and parasitism by C. chamaeleon are given. 相似文献
14.
Ahmed A. Kheder Yasunori Akagi Hajime Akamatsu Konomi Yanaga Nitaro Maekawa Hiroshi Otani Takashi Tsuge Motoichiro Kodama 《Journal of General Plant Pathology》2012,78(1):30-38
The tomato pathotype of Alternaria alternata (A. arborescens) produces the dark brown to black pigment melanin, which accumulates in the cell walls of hyphae and conidia. Melanin has
been implicated as a pathogenicity factor in some phytopathogenic fungi. Here, two genes of the tomato pathotype for melanin
biosynthesis, ALM1 and BRM2-1, which encode a polyketide synthetase and a 1,3,8-trihydroxynaphthalene (THN) reductase, respectively, have been cloned and
disrupted in the pathogen. The gene-disrupted mutants, alm1 and brm2-1, had albino and brown phenotypes, respectively. The wild-type and the mutants caused the same necrotic lesions on the leaves
after inoculation with spores. These results suggest that melanin is unlikely to play a direct role in pathogenicity in the
tomato pathotype A. alternata. Scanning electron microscopy revealed that the conidia of both mutants have much smoother surfaces in comparison to the
wild-type. The conidia of those mutants were more sensitive to UV light than those of the wild-type, demonstrating that melanin
confers UV tolerance. 相似文献
15.
Erika Valéria Saliba Albuquerque Poliene Martins Costa Ana Cristina Meneses Mendes Gomes Marcilene Santos Antonio Alves Pereira Michel Nicole Diana Fernandez Maria Fatima Grossi-de-Sa 《European journal of plant pathology / European Foundation for Plant Pathology》2010,127(3):365-373
Root-knot nematodes (RKN) are obligate parasite species of the genus Meloidogyne that cause great losses in Arabica coffee (Coffea arabica L.) plantations. Identification of resistant genotypes would facilitate the improvement of coffee varieties aiming at an
environmental friendly and costless nematode control. In this work, the C. arabica genotype ‘UFV 408-28’ was found to be resistant to the most destructive RKN species M. incognita. Pathogenicity assays indicated that the highly aggressive populations of M. incognita races 1, 2 and 3 were not able to successfully reproduce on ‘UFV 408-28’ roots and displayed a low gall index (GI = 2). An
average reduction of 87% reduction of the M. incognita population was observed on ‘UFV 408-28’ when compared to the susceptible cultivar ‘IAC 15’. By contrast, ‘UFV 408-28’ was
susceptible to the related species M. exigua and M. paranaensis (GI = 5 and 4, respectively). Histological observations performed on sections of UFV408-28 roots infected with M. incognita race 1 showed that nematode infection could be blocked right after penetration or during migration and establishment stages,
at 6 days, 7 days and 8 days after infection (DAI). Fluorescence and bright field microscopy observations showed that root
cells surrounding the nematodes exhibited HR-like features such as accumulation of phenolic compounds and a necrotic cell
aspect. In the susceptible ‘IAC 15’ roots, 6 DAI, feeding sites contained giant cells with a dense cytoplasm. Necrotic cells
were never observed throughout the entire infection cycle. The HR-like phenotype observed in the ‘UFV 408-28’—M. incognita interaction suggests that the coffee resistance may be mediated by a R-gene based immunity system and may therefore provide new insights for understanding the molecular basis of RKN resistance
in perennial crops. 相似文献
16.
Plant-induced germination of Plasmodiophora brassicae resting spores was studied in a laboratory experiment. Spore reaction was analysed in nutrient solution with exudates from
growing roots of different plant species – one host plant (Brassica rapa var. pekinensis) and four non-host plants (Lolium perenne, Allium porrum, Secale cereale and Trifolium pratense) – and in controls with distilled water and nutrient solution. It was found that root exudates from L. perenne stimulated spore germination more than exudates from the other plants, including those from the host plant. The effect could
not be explained by differences in the nutritional composition of the solutions due to differential uptake of the plant species,
or by differences in root activity, measured as exudation of soluble sugars. This is the first time such a separation of factors
has been done in analysing the influence of plants on P. brassicae germination. Although stimulation of P. brassicae resting spore germination is not restricted to the presence of host plants, it seems to vary depending on the plant species. 相似文献
17.
Hua Li Xintian Ge Shiue Han Krishnapillai Sivasithamparam Martin John Barbetti 《European journal of plant pathology / European Foundation for Plant Pathology》2011,129(2):221-232
Differences in Hyaloperonospora parasitica development and plant tissue responses were compared for 10 cruciferous hosts (including both resistant and susceptible genotypes),
3 leguminous and 1 graminaceous non-host species. Cotyledons, or true leaves in the case of Triticum aestivum and Pisum sativum, were studied at 2, 8, 24 h and 3, 5, 7 days post inoculation (dpi). The high levels of zoosporangial germination observed
on all species tested, as well as on glass slides, suggested that inhibition of germination did not play a significant role
in distinguishing host versus non-host resistance. During the early stages of infection, at spore germination and host penetration, there was no evidence
of a clear-cut difference between Brassica host species which displayed a hypersensitive, partially resistant or susceptible reaction compared with non-host species.
Haustoria formation was the key infection phase for the establishment of biotrophy. Across all tested species, haustoria were
initiated inside the epidermal cells. However, there were significant differences in the frequency and timing of haustorial
formation and the final size of haustoria among the tested species at early infection stage. Fully developed haustoria were
never observed in Raphanus raphanistrum, Triticum aestivum, Lupinus angustifolius nor Trifolium subterraneum. Instead, the haustorium development appears to abort in the penetrated epidermal cells of these species. Although haustoria
were formed in the epidermal and mesophyll cells of Sinapsis alba and Pisum sativum, subsequent hyphal growth and/or continued haustoria formation were rare or few, respectively. Hypersensitive reaction was
the key resistance response observed among the host and non-host resistant species tested. It is noteworthy that, in the initial
stages of pathogenesis, there was no differentiating point that separated the non-host species from those that were hosts. 相似文献
18.
Dolar Pak Ming Pei You Vincent Lanoiselet Martin J. Barbetti 《European journal of plant pathology / European Foundation for Plant Pathology》2018,151(4):927-936
Pyricularia oryzae (rice blast) conidial development at pre-penetration stage determines success or otherwise of infection inside the rice host plants. Studies on conidial germination and growth on the leaf surface in commercial rice (Oryza sativa) report differently, dependent upon host type and level of blast resistance. Although wild rice (O. australiensis) is known to be an alternative host of blast, the interaction between P. oryzae conidia and wild O. australiensis on its leaf surface has not been previously studied. We found significant (P?<?0.001) differences in conidial development between two blast isolates with different virulence in terms of conidial germination, germ tube growth and appressoria formation on both wild and cultivated rice. Conidial germination at 6 h post-inoculation (hpi) for the virulent isolate was significantly (P?<?0.001) delayed. Germ tubes of the avirulent isolate conidia grew significantly (P?<?0.001) faster and with significantly (P?<?0.001) longer germ tubes than from virulent conidia. Appressoria development for the virulent isolate was significantly (P?<?0.001) faster at its later growth stages of 12 and 18 hpi when approximately 100% of germ tubes formed appressoria. In contrast, formation rate of appressoria for the avirulent isolate was significantly (P?<?0.001) slower and only reached 76% of germ tubes forming appressoria. Appressoria formation on O. australiensis was significantly (P?<?0.001) greater than the formation on O. sativa for both virulent and avirulent P. oryzae at 12 hpi, a clear indication that host type influences the extent of appressoria formation. 相似文献
19.
Hiroshi KAMIUNTEN Takeharu NAKAO Shiomi OSHIDA 《Journal of General Plant Pathology》2000,66(3):219-224
Bacterial gall on trunks and twigs of cherry trees (Prunus × yedoens, Someiyoshino) was found in Miyazaki and Saga prefectures, Japan. The surface of young galls are relatively smooth and light
brown, but they become rough and dark brown. Characteristics of the bacterium isolated from galls on trunks or twigs are similar
to those of Pseudomonas syringae pathovars, i.e., pv. actinidiae, pv. daphniphylli, pv. dendropanacis, pv. Morsprunorum, pv. myricae, pv. rhaphiolepidis, pv. syringae and pv. tremae. This bacterium produced galls on cherry and apricot, but not on 66 other species of plants belonging to 39 families. From
these results, this bacterium was classified as a new pathovar of Pseudomonas syringae, and the name Pseudomonas syringae pv. cerasicola, pv. nov., is proposed. Strain M9501(ICMP 13926) was designated as the pathotype strain.
Received 10 September 1999/ Accepted in revised form 24 December 1999 相似文献
20.
Ting-Fang Hsieh Hung-Chang Huang R. Scott Erickson 《European journal of plant pathology / European Foundation for Plant Pathology》2010,127(4):579-584
Studies were conducted in the laboratory and greenhouse to determine the distribution of Erwinia rhapontici in plants arising from naturally infected seeds of pea or artificially inoculated seeds of bean and wheat, and whether the
pathogen is transmitted to the subsequent generation of seeds. Infected seeds were planted in pots of Cornell mix in the greenhouse,
and sampled at specified intervals throughout the plant growth cycle (seedling stage, elongation stage, flowering stage, seed
formation stage, and maturity). Plating of surface sterilized lateral roots, tap roots, basal stems, mid-stems, apical stems,
petioles, pods, and seeds of pea and bean, and of lateral roots, sub-crown internodes, basal stems, mid-stems, apical stems,
peduncles, glumes, and seeds of wheat revealed that the bacterial pathogen spread from infected seeds to the lower parts of
the plant tissues, but failed to spread further to the seeds produced on these plants. The study concludes that E. rhapontici did not establish systemic infection throughout the plants. Possible mechanisms of infection of seeds are discussed. 相似文献