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1.
The 32R rice genotype is resistant to sheath blight disease (ShB), with a high-yield potential. We examined effects of temperature on the plant responses of 32R in comparison with those of the ShB-susceptible rice genotype (29S) and Nipponbare (Nb, a Japonica standard cultivar). The seedlings at the 4th leaf stage of rice genotypes were exposed to 14/14, 19/14, 25/20, 31/26, 37/32 and 37/37 °C (day/night) for 5, 10 and 15 days. The dry weight, leaf area, photosynthesis, contents of ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) and chlorophyll contents were examined. The dry weight showed lower in 32R than in 29S and Nb at a low temperature, and total dry weight correlated strongly with root dry weight and leaf area. The relative growth rate (RGR) correlated strongly with the net assimilation rate (NAR). Rubisco, chlorophyll contents and the photosynthetic rates were limited at a low temperature and showed lower in 32R than in 29S and Nb. The strong correlations between Rubisco and the rates of maximum photosynthesis and initial slope were found in 32R, but not found in 29S and Nb. In addition, RGR and NAR of 32R correlated positively with Rubisco. These suggest that 32R contains traits of cold-sensitive genotypes that are related to limiting Rubisco at a low temperature, thus diminishing photosynthesis and limiting plant growth. Differences of growth among 32R, 29S and Nb were discussed in the relation of genotypes.  相似文献   

2.
A field study was undertaken to ascertain the effects of elicitors viz. benzothiadiazole (BTH) and salicylic acid (SA) on defense related enzymes viz. peroxidase, phenylalanine ammonia lyase, superoxide dismutase, chitinase and β-1,3-glucanase, and phenols in rice (Pusa Basmati I) plants. First foliar spray of BTH (50 mg/kg) and SA (50 mg/kg) was done at the maximum tillering stage and inoculation with Rhizoctonia solani was carried 24 h after elicitor treatment. Elicitors were further sprayed at every growth stage. Time course analysis showed peak accumulation of defense related enzymes and phenols in the rice leaves treated with BTH and SA, and accumulation was the highest at the flowering stage. Higher enzymatic activity was observed in elicitor treated plants inoculated with R. solani. Compared to the untreated control plants, application of elicitors before R. solani inoculation significantly elicited the defense related enzymes and phenols. Moreover, application of elicitors had a positive effect on yield and disease reduction. It is suggested that pretreatment of rice leaves with BTH and SA could be used to enhance the level of protection against sheath blight and to improve rice yield in the fields.  相似文献   

3.
Laetisaria arvalis, a soil-inhabiting basidiomycete, reducedRhizoctonia solani infection of white potato. A greenhouse study that monitored population levels of both fungi showed that soil infested withL. arvalis suppressed the growth ofR. solani after eight wks. Populations ofL. arvalis andR. solani increased after 11 wks. when both fungi were infested simultaneously and whenL. arvalis was introduced to soil previously infested withR. solani. Five years of field studies showed that variousL. arvalis seed treatments and soil amendments reducedR. solani infection of stems and stolons and sclerotial formation on tubers equal to the standard chemical treatment of pentachloronitrobenzene (PCNB) + thiabendazole. No relationship was shown between populations ofL. arvalis andR. solani in field plot soils, but native or wild strains ofL. arvalis were shown to be present at detectable levels in field soils.  相似文献   

4.
MicroRNAs(miRNAs) are about 22 nucleotides regulatory non-coding RNAs that play versatile roles in reprogramming plant responses to biotic and abiotic stresses. However, it remains unknown whether miRNAs confer the resistance to necrotrophic fungus Rhizoctonia solani in rice. To investigate whether miRNAs regulate the resistance to R. solani, we constructed 12 small RNA libraries from susceptible and resistant rice cultivars treated with water/pathogen at 5 h post inoculation(hpi), 10 hpi and 20 hpi, respectively. By taking the advantage of next-generation sequencing, we totally collected 400–450 known mi RNAs and 450–620 novel miRNAs from the libraries. Expression analysis of mi RNAs demonstrated different patterns for known and novel miRNAs upon R. solani challenge. Thirty-four mi RNA families were identified to be expressed specifically in rice, and most of them were involved in plant disease resistance. A particular Kyoto Encyclopedia of Genes and Genomes(KEGG) pathway analysis result revealed that a great majority of target genes of regulated miRNAs belonged to the pathway of plant-pathogen interaction. Moreover, miR444 b.2, miR531 a, mir1861 i, novel_miR1956 and novel_miR135 conferred response to R. solani infection confirmed by Northern blot. Our global understanding of miRNA profiling revealed that the regulation of mi RNAs may be implicated in the control of rice immunity to R. solani. Analysis of the expression of miRNAs will offer the community with a direction to generate appropriate strategies for controlling rice sheath blight disease.  相似文献   

5.
The aims of this study were to develop new bioformulations using Trichoderma harzianum, Trichoderma asperellum, and Talaromyces flavus and some organic and inorganic carriers and evaluate their effects against Rhizoctonia solani, the fungal causal agent of sugar beet seedling damping-off disease. Selected fungal isolates were first re-cultured and maintained on potato dextrose agar (PDA) culture medium. Antagonistic effects of eight isolates of the above-mentioned antagonistic fungi were then evaluated against R. solani, through volatile metabolites and non-volatile metabolites production mechanisms under laboratory conditions. In volatile and non-volatile metabolite experiments, five and seven isolates caused significant reduction in R. solani growth respectively. Based on the results of laboratory experiments, the most effective antagonistic isolates (one isolate from each species) were selected for development of nine bioformulations using peat, rice bran and talc as carriers. The effectiveness of developed bioformulations was then evaluated in controlling sugar beet damping-off disease in a greenhouse experiment where sugar beet seeds were coated with bioformulations and were sown in pasteurized field soil pre-inoculated with R. solani. Results of the greenhouse experiment 60 days after sowing showed that all bioformulations increased the number of healthy seedlings significantly (compared to the untreated control) with different rates. According to the results, the most effective bioformulation was Talc-T. harzianum followed by Peat-T. flavus, Talc-T. flavus and Rice bran-T. harzianum. In general, in both laboratory and greenhouse experiments, T. flavus was the most effective fungal antagonist followed by T. harzianum and T. asperellum. Based on the results of this study it is concluded that Trichoderma and Talaromyces employing different mechanisms might be potential biocontrol agents for controlling R. solani-induced sugar beet damping-off disease.  相似文献   

6.
Summary The viability of five pathogens was decreased by treatment with hot water when tested in vitro.Polyscytalum pustulans was most sensitive andRhizoctonia solani least sensitive. Potato tubers were exposed to 55°C for 5 min in a commercial continuous hot water treatment plant using naturally contaminated seed tubers and tubers which had been inoculated by dipping in comminuted cultures. The frequency of eyes colonised byP. pustulans, Helminthosporium solani, andR. solani was reduced to virtually zero and the effect persisted on tubers subsequently stored at 4°C and at 15°C for up to 16 wk. Results withColletotrichum coccodes were inconclusive. Treatment suppressedPenicillium spp. which, however, rapidly recolonised the eyes during storage, leading to higher contamination levels in the treated than in the untreated tubers. With tubers inoculated withPhoma foveata, good control was achieved when the incubation period before treatment was 10 d but not when the period was 42 d.  相似文献   

7.
《Plant Production Science》2013,16(1):134-138
Abstract

A total of 32 rice genotypes carrying different dwarf or semi-dwarf genes were inoculated with the fungus Fusarium moniliforme Sheldon or treated with 50 mg l-1 GA3 in order to select resources resistant to rice bakanae disease from the dwarf materials. The length of the elongated seedlings was measured, and the percentage of death of the seedlings after transplanting to field was also counted. A significant correlation was found between the length of the seedling treated with GA3 and disease injury by bakanae fungus. Rice materials carrying dwarf gene such as sd1 were not only sensitivity to GA3 but also susceptive to rice bakanae disease. Materials carrying dwarf gene d1 were insensitive to GA3 but susceptive to bakanae. On the other hand, all materials carrying d29, sd6 or sdq(t) genes showed resistance to bakanae. The present study indicated that dwarf and semi-dwarf rice materials might be useful resources for improvement of bakanae resistance in rice breeding programs.  相似文献   

8.
Thirteen fungi were isolated from mouldy shelled melon seeds. The fungi more frequently isolated included species ofMucor (11.25%),Rhizopus (13.75%),Aspergillus (36.25%),Macrophoma (2.50%),Penicillium (8.75%),Alternaria (5.00%),Fusarium (8.75%),Botrytis (6.25%),Torula (3.75%) andGeotrichum (3.75%). Healthy, shelled melon seeds inoculated withFusarium solani for 7 or 14 days caused increases in the free fatty acid (f.f.a.) content of the healthy seeds from an initial value of 1.06% to 2.19% after 7 days and 4.23% after 14 days. Similar results were obtained when other fungal isolates were used as inocula butFusarium solani effected the greatest increase in the f.f.a. content followed byAspergillus niger andPenicillium notatum. The fungi also caused decreases in the crude protein from 35.51% to 25.16%, crude fibre from 4.30% to 1.35% and total carbohydrate content from 4.28% to 3.01% of the seeds after 14 days infection. Aflatoxin was detected (0.20µg/g) in the infected seeds being sold in the markets and also from seeds inoculated with spores (0.40µg/g) ofA. flavus and (0.50µg/g) from a mixture of spores of variousAspergillus strains after incubation for 14 days.  相似文献   

9.
Inoculation withAlternaria solani andUlocladium consortiale caused significantly more severe infection of tubers than inoculations ofA. solani alone.U. consortiale, when inoculated alone, caused no significant tuber infection. Infection resulting from a plug-type inoculation was significantly greater than that from a flap-type inoculation.  相似文献   

10.
《Plant Production Science》2013,16(3):345-350
Abstract

The activity of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is a major limitation of photosynthetic CO2 assimilation in C3 plants. In order to find useful Rubisco for improvement of photosynthesis in rice under elevated CO2, we analyzed the catalytic turnover rate (kcat) of Rubisco in Poaceae including C3 alpine plants, C3 cold-resistant plants and C4 plants. Rubisco in these plants showed 1.1- to 2.8-fold higher kcat than that in rice. However, the most of high kcat Rubisco also showed a higher km for CO2 (Kc) than that of rice, indicating that increase in kcat led to decrease in the affinity for CO2. Rubisco in Festuca ovina, Phleum pratense and Sorghum bicolor showed relatively high kcat to Kc. Although the kcat of Rubisco in F. ovina and P. pratense was not so high (1.5-1.6 fold relative to rice), the Kc was comparable to that in rice and the amino acid sequence of RbcL shared higher identity to that in rice than that in S. bicolor. By contrast, Rubisco of S. bicolor showed considerably high kcat (2.5-fold relative to rice), which is considered to be the most important factor for improvement of photosynthesis. In our estimation, the expression of high kcat Rubisco of F. ovina and S. bicolor in rice could significantly enhance CO2 assimilation at Ci of 50 Pa, the level assumed to be reached by the middle of this century.  相似文献   

11.
XIAO Guo-ying 《水稻科学》2009,16(3):235-239
In addition to weed control in direct seeding field of hybrid rice, herbicide resistance genes were used by Chinese scientists to increase and identify the purity of hybrid seeds, and to realize the mechanization of hybrid seed production. The elite restorer lines, such as Minghui 63, R752, T461, R402, D68 and E32 were transformed directly with herbicide resistance genes, in which D68 and E32 are restorer lines of two-line system and the others are of three-line system. Because almost all of important restorer lines are indica varieties and are recalcitrant in transformation, many herbicide resistant near-isogenic restorer lines were developed by sexual hybridization of indica and japonica varieties and backcross with indica restorer lines later, such as Ce 64, Minghui 63, Teqing, Milyang 46, R402 and 9311, in which 9311 is a restorer line of two-line system. The elite photoperiod-sensitive/thermo-sensitive genic male sterile lines, such as Pei'ai 64S, P88S, 4008S and 7001S, were transformed with herbicide resistance genes. A few herbicide resistant male sterile lines were developed through sexual hybridization and subsequently systemic selection, such as Bar1259S, Bar2172S, 05Z221A and 05Z227A. With the employment of herbicide resistant male sterile lines or herbicide resistant restorer lines, a few herbicide resistant hybrid rice combinations were developed, such as Xiang 125S/Bar 68-1 and Pei'ai 64S/Bar 9311. Based on herbicide resistance, the research was marching on to investigate the parental lines of hybrid rice with insect resistance, drought tolerance, etc.  相似文献   

12.
The soil-borne pathogen Rhizoctonia solani AG 8 causes major yield losses in wheat (Triticum aestivum. L) production worldwide. Plant tissues of Brassicaceae species contain glucosinolates that are hydrolyzed in the presence of the enzyme myrosinase into products with pesticidal properties. Growth chamber studies were conducted to determine the effect of the Brassicaceae seed meals (SMs) from Brassica juncea, Brassica napus and Sinapis alba on the suppression of the R. solani AG 8 infection of winter wheat. Pasteurized sandy soils were amended with intact and denatured SMs of rape seed and mustard at a rate of 0.5% by soil weight. Regardless of the glucosinolate type and content, all intact and denatured Brassicaceae significantly reduced the infection of winter wheat seedlings by R. solani AG 8 compared to the un-amended control. However, soils amended with S. alba SMs had the lowest severity of Rhizoctonia root rot relative to other amended soils. Phytotoxicity arising from the use of Brassicaceae SMs was observed particularly in soils amended with high glucosinolate-containing SMs. These studies demonstrate that Brassicaceae SMs can be used to manage disease caused by R. solani AG-8. However, future studies will need to focus on strategies for diminishing the crop growth-reducing effects associated with Brassicaceae SM amendment to fully maximize these fungicidal benefits.  相似文献   

13.
Two tillage practices, chisel plowing (30 cm) and deep moldboard plowing (22 cm), and five rotation crops (oats, lupine, buckwheat, broccoli and peas) were studied for their effects on the soil population ofRhizoctonia solani AG-3 and on Rhizoctonia disease on potato. All rotation crops were harvested except buckwheat, which was treated as a green manure crop. Chisel plowing significantly reduced (p = 0.05) the incidence and severity of stem lesions on potato caused byR. solani AG-3. In 1990, oats after moldboard plowing significantly increased disease when compared to other crops and broccoli after chisel plowing decreased disease severity. Soil populations ofR. solani AG-3 were significantly lower with chisel plowing. No interactions between tillage and rotation crops were observed. Rhizoctonia solani Kühn is a soil inhabiting plant pathogen found worldwide that affects many plant species including white potato (Solanum tuberosum L.).R. solani attacks potato at one or more stages in development resulting in distinct disease symptoms (25) often termed the Rhizoctonia disease complex of potato. In Maine, only strains AG-3 and AG-5 ofR. solani (4, 5) have been identified as attacking potato and causing four distinct types of symptoms: 1) black scurf (sclerotia) on tubers, 2) stem cankers, 3) aerial tubers and top rosetting, and 4) killing of sprouts. Crop rotation has been reported to reduce the incidence and severity ofR. solani on potato, but no single rotation method controls completely or to a high degree of reliability (11, 23, 24, 26). Deep moldboard plowing has been shown to reduce diseases caused byR. solani andSclerotium rolfsii Sacc. in crops other than potatoes (2, 7, 15, 19, 20). However, Gudmestadet al. (6) reported that deep moldboard plowing increased the severity ofR. solani on stems and stolons of potatoes. The reduction of diseases caused byR. solani andS. rolfsii by moldboard plowing is attributed to low inoculum densities in the upper soil layer by the burial of sclerotia to depths where germination and infection were prevented (14, 15, 19, 20). However, disking to a depth of 5–7 cm did not affect disease as the inoculum remained in the root zone (14, 15). Gurkin (7) states that the rationale for deep moldboard plowing is to promote decay of organic matter, remove organic matter from the infection court and to bury the sclerotia below the infection court. Cultural control techniques are largely preventive and are designed to reduce the quantity or the activity of inoculum by means of crop rotation, tillage practices, green manure crops, etc. (22). This study was conducted to determine individual effects and possible interactions of deep moldboard plowing versus chisel plowing in various rotation crops on the presence ofR. solani AG-3 in the soil and on the incidence of Rhizoctonia disease complex of potato.  相似文献   

14.
Summary A two year field experiment was conducted twice to assess effects of chemical soil disinfection at planting and methods of harvesting potatoes on stem infection withRhizoctonia solani in the subsequent year. In the first year of the experiments seven methods. including one with soil disinfection at planting, were applied in August. In the following year,R. solani stem and stolon infection (disease severity) on potato plants were assessed in June. Soil treatment at planting with pencycuron resulted in lowest disease severity in the following year. Compared with chemical haulm killing and haulm pulling. immature-crop-harvesting also resulted in a lower disease severity, but only when black scurf was scarce on tubers at harvest in the preceding year.  相似文献   

15.
Silver scurf, caused byHelminthosporium solani, is an important disease of table stock and processing potatoes, for which few management strategies exist. Two hundred-twelve accessions of tuber-bearingSolarium species were screened for their response toH. solani. Tubers were inoculated in the laboratory with a spore suspension, incubated for 1 mo, and evaluated for infection using the number of conidiophore groups per square millimeter of sporulating tuber surface. Tubers with relatively low sporulation in the laboratory were retested using natural inoculum present in potato storages and assessed for infection. There were significant differences (P < 0.05) between accessions with both methods of inoculation. Some accessions ofSolanum demissum, S. chacoense, S. acaule, S. stoloniferum, S. oxycarpum, andS. hondelmannii consistently demonstrated low sporulation in laboratory and storage, suggesting partial resistance. Both methods of inoculation, laboratory and storage, were found to be correlated (ranging from r = 0.582,P= 0.006; to r = 0.925,P < 0.003).  相似文献   

16.
Abstract

The effect of porous hydrated calcium silicate (PS) application on the resistance of rice plants ( Oryza sativa L.) to rice blast (Pyricularia olyzae) was evaluated. Experiments were conducted in Andisol at the experimental farm of Tohoku University from 1993 to 1995. The blast infection in the PS plot was much less than that in the control plot. On the other hand, slag (commercial slag silicate fertilizer) used in our experiment had no effect on blast infection. The number of silicified bulliform cells, the main invasion site for rice blast, was increased 320-980% by PS application, but only 80% by commercial slag. These results imply that PS application is effective in preventing fungal infection through silicification of bulliform cells. The number of silicified bulliform and trichome cells increased exponentially with increasing content of the silicon in the leaf blade, whereas the number of silicified short cells, which are smaller than bulliform cells and trichomes, had no relation to the silicon content in the rice leaf blade. We may conclude that the application of porous hydrated calcium silicate for rice plants is effective in increasing rice blast resistance because PS increase the number of silicified bulliform cells.  相似文献   

17.
K. Scholte 《Potato Research》1989,32(3):367-376
Summary The effects of soil-borneRhizoctonia solani on yield and quality of potato were studied by an extensive individual plant sampling procedure. From 1983 to 1986, stem canker and stolon pruning were examined in 10 768 plants growing on a sandy soil. Tuber yield and quality and haulm yield per plant were also recorded. The degree of attack byR. solani depended on the cropping frequency of potato. Severe and very severe stem and stolon attacks decreased fresh yield, dry matter yield and dry matter content of tubers and increased the number of deformed and small tubers, whereas the effect on haulm yield and stem number was small. Potato cultivars differed in susceptibility toR. solani, but yield response did not differ significantly between cultivars at the same levels of stem and stolon infection.  相似文献   

18.
Summary Samples of a sandy soil and a marine clay soil sterilized by steam were put in 55-1 containers insulated with polystyrene and placed outdoors on a brick pavement. Sandy soil was infested singly or in all possible combinations with root-knot nematodes (Meloidogyne spp.) and the fungiRhizoctonia solani andVerticillium dahliae, and the marine clay soil was infested with the root-lesion nematodePratylenchus neglectus and the same fungi to evaluate the effects of these organisms on the yield of potato. The experiments were carried out from 1983 to 1986. Tuber yield was reduced by single infestations of theMeloidogyne spp. andV. dahliae but not significantly byR. solani orP. neglectus. A three-factor interaction: nematode ×R. solani × V. dahliae was found in both experiments.R. solani andV. dahliae showed significant synergistic effects when soil was infested with theMeloidogyne spp. orP. neglectus.  相似文献   

19.
Field and laboratory studies were conducted in 1985–1986 to evaluate the relative severity ofRhizoctonia solani damage among 26 clones and five potato (Solanum tuberosum) cultivars. A test with true potato seeds showed that resistance toR. solani could be identified in two years. One highly resistant line was identified by this method. Moderate degrees of resistance were found in lines from the USDA Potato Breeding Program (BARC) with russet types producing a higher percentage of highly resistant lines than round whites. A laboratory test revealed that apical sprout damage (nipping) was variable within and between lines and that it was an important phase of disease development to measure when determining resistance because of its effects on the resulting plant growth and production of marketable tubers. It was also determined that to accurately define resistance toR. solani in potato, all phases of the disease must be evaluated to insure against resistance “breakdown” at some point in plant development.  相似文献   

20.
Streptomyces philanthi RM-1-138, isolated from the rhizosphere soil of chili pepper in southern Thailand, was investigated for its antagonistic activity against phytopathogenic fungi. In dual culture on glucose yeast-malt extract (GYM) agar plates, this strain suppressed the mycelial growth of all seven plant pathogenic fungi tested (Rhizoctonia solani PTRRC-9, Pyricularia grisea PTRRC-18, Colletotrichum gloeosporioides NBCRSR-3, Colletotrichum capcisi NBCRSR-15, Ganoderma boninense NBCRSR-26, Fusarium fujikuroi PTRRC-16 and Bipolaris oryzae PTRRC-36) with an 82.2–89.2% inhibition and that was most pronounced on R. solani PTRRC-9. Heat treatment of the culture filtrate from growing R. solani PTRRC-9 at 40 °C, 60 °C, 80 °C, and 100 °C for 30 min and 121 °C for 15 min had no negative effect on the inhibitory activity against R. solani PTRRC-9 tested on both solid and liquid culture. The effective dose (>80% inhibition) of culture filtrate in liquid culture was at 5.0% (v/v) while it was at 10% (v/v) on the solid medium. This effectiveness was similar to those of the four chemical fungicides tested. The effect of S. philanthi RM-1-138 against R. solani PTRRC-9 was investigated using SEM and TEM. The compounds produced by S. philanthi RM-1-138 induced alterations to the cell-wall structure of R. solani PTRRC-9, that resulted in the loss of cytoplasm materials by partial lysis. The greenhouse experiment revealed that using either the culture filtrate or the autoclaved culture filtrate from S. philanthi RM-1-138 effectively suppressed rice sheath blight disease by up to 65.6 and 60.8%, respectively.  相似文献   

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