scholarly journals New Approaches to Selecting Resistance or Tolerance to SDS and Fusarium Root Rot

2017 ◽  
Vol 1 (1) ◽  
pp. 10-17 ◽  
Author(s):  
Jiazheng Yuan ◽  
Rabia Bashir ◽  
Graciela Salas ◽  
Hemlata Sharma ◽  
Ali Srour ◽  
...  

Fusarial rots are a significant problem worldwide affecting roots (and sometimes fruits) of most major crops including soybean, maize and wheat. Cultivar variation in partial resistance or tolerance is widespread and significant. Different cultivars of the soybean [Glycine max (L.) Merr.] have both resistance/tolerance to the leaf scorch known as Sudden Death Syndrome (SDS) and to the infection and root rot by the causal organism, Fusarium virguliforme (ex. F. solani f. sp glycines) hence the syndrome is composed of two diseases (1-3). Thirteen loci have been identified from analysis of 7 different crosses (2). Using new strains and new methods resistance loci in ‘Hartwig’ and ‘Forrest’, resistant cultivars clearly showed two loci underlie root resistance (lower LG G and D2) and four to eleven loci underlie leaf scorch resistance, depending on the cross made(eg, C2, F, I and upper G in ExF). Transcript abundance analysis of roots in response to F. virguliforme shows an orthologous set of transcripts accumulate during infection of resistant soybean cultivars and Arabidopsis thaliana that include the pathways leading to phenylpropanoid metabolism and its control, guanyl cylase a common second messenger and several transcription factors. Guanyl cyclase is also implicated in resistance in maize. In root disease resistance the genes implicated were known to be stress related. Therefore, A. thaliana is partially resistant and can be used to test both transgenes and mutants in candidate genes. Trangenics show fine maps to BACs have isolated some genes. For example, by fine mapping in NILs candidate genes underlying the controlling loci programming root resistance was a multi-stress resistance protein (lower G; Rfs1). For leaf scorch (Rfs4) an ascorbate peroxidase (C2) has been targeted. Also, Rfs2, a receptor like kinase (G) has been used to generate stable transgenic soybeans. Identification of the genes and loci conferring SDS resistance has provided options to breed improved cultivars with resistance to SDS.

1951 ◽  
Vol 4 (3) ◽  
pp. 211
Author(s):  
GC Wade

The disease known as white root rot affects raspberries, and to a less extent loganberries, in Victoria. The causal organism is a white, sterile fungus that has not been identified. The disease is favoured by dry soil conditions and high soil temperatures. It spreads externally to the host by means of undifferentiated rhizomorphs; and requires a food base for the establishment of infection. The spread of rhizomorphs through the soil is hindered by high soil moisture content and consequent poor aeration of the soil.


Plant Disease ◽  
2014 ◽  
Vol 98 (9) ◽  
pp. 1273-1273 ◽  
Author(s):  
X.-M. Luo ◽  
J.-L. Li ◽  
J.-Y. Dong ◽  
A.-P. Sui ◽  
M.-L. Sheng ◽  
...  

China is the world's largest producer country of coptis (Coptis chinensis), the rhizomes of which are used in traditional Chinese medicine. Since 2008, however, root rot symptoms, including severe necrosis and wilting, have been observed on coptis plants in Chongqing, southwestern China. Of the plants examined from March 2011 to May 2013 in 27 fields, 15 to 30% were covered with black necrotic lesions. The leaves of infected plants showed wilt, necrotic lesions, drying, and death. The fibrous roots, storage roots, and rhizomes exhibited brown discoloration and progressive necrosis that caused mortality of the infected plants. Infected plants were analyzed to identify the causal organism. Discoloration of the internal vascular and cortical tissues of the rhizomes and taproots was also evident. Symptomatic taproots of the diseased coptis were surface sterilized in 1% sodium hypochlorite for 2 min, rinsed in sterile distilled water for 2 min, and then air-dried in sterilized atmosphere/laminar flow. Small pieces of disinfested tissue (0.3 cm in length) were transferred to petri dishes containing potato dextrose agar (PDA) supplemented with 125 μg ml–1 streptomycin sulfate and 100 μg ml–1 ampicillin, and incubated for 5 days at 25°C with a 12-h photoperiod. Four distinct species of fungal isolates (HL1 to 4) derived from single spores were isolated from 30 plants with root rot symptoms collected from the study sites. To verify the pathogenicity of individual isolates, healthy coptis plants were inoculated by dipping roots into a conidial suspension (106 conidia/ml) for 30 min (15 plants per isolate), as described previously (1). Inoculated plants were potted in a mixture of sterilized quartz sand-vermiculite-perlite (4:2:1, v/v) and incubated at 25/18°C and 85 to 90% relative humidity (day/night) in a growth chamber with a daily 16-h photoperiod of fluorescent light. Plants dipped in sterile distilled water were used as controls. After 15 days, symptoms similar to those observed in the field were observed on all plants (n = 15) that were inoculated with HL1, but symptoms were not observed on plants inoculated with HL2, HL3, and HL4, nor on control plants. HL1 was re-isolated from symptomatic plants but not from any other plants. Morphological characterization of HL1 was performed by microscopic examination. The septate hyphae, blunt microconidia (2 to 3 septa) in the foot cell and slightly curved microconidia in the apical cell, and chlamydospores were consistent with descriptions of Fusarium solani (2). The pathogen was confirmed to be F. solani by amplification and sequencing of the ribosomal DNA internal transcribed spacer (rDNA-ITS) using the universal primer pair ITS4 and ITS5. Sequencing of the PCR product revealed a 99 to 100% similarity with the ITS sequences of F. solani in GenBank (JQ724444.1 and EU273504.1). Phylogenetic analysis (MEGA 5.1) using the neighbor-joining algorithm placed the HL1 isolate in a well-supported cluster (97% bootstrap value based on 1,000 replicates) with JQ724444.1 and EU273504.1. The pathogen was thus identified as F. solani based on its morphological and molecular characteristics. To our knowledge, this is the first report of root rot of coptis caused by F. solani in the world. References: (1) K. Dobinson et al. Can. J. Plant Pathol. 18:55, 1996. (2) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell Publishing, Oxford, 2006.


2018 ◽  
pp. 583-591
Author(s):  
Yi Chen Lee ◽  
M Javed Iqbal ◽  
Victor N Njiti ◽  
Stella Kantartzi ◽  
David A. Lightfoot

Soybean (Glycine max (L.) Merr.) cultivars differ in their resistance to sudden death syndrome (SDS), caused by Fusarium virguliforme. Breeding for improving SDS response has been challenging, due to interactions among the 18-42 known resistance loci. Four quantitative trait loci (QTL) for resistance to SDS (cqRfs–cqRfs3) were clustered within 20 cM of the rhg1 locus underlying resistance to soybean cyst nematode (SCN) on Chromosome (Chr.) 18. Another locus on Chr. 20 (cqRfs5) was reported to interact with this cluster. The aims here were to compare the inheritance of resistance to SDS in a near isogenic line (NIL) population that was fixed for resistance to SCN but segregated at two of the four loci (cqRfs1 and cqRfs) for SDS resistance; to examine the interaction with the locus on Chr. 20; and to identify candidate genes underlying QTL. Used were; a NIL population derived from residual heterozygosity in an F5:7 recombinant inbred line EF60 (lines 1-38); SDS response data from two locations and years; four segregating microsatellite and 1,500 SNP markers. Polymorphic regions were found from 2,788 Kbp to 8,938 Kbp on Chr. 18 and 33,100 Kbp to 34,943 Kbp on Chr. 20 that were significantly (0.005 < P > 0.0001) associated with resistance to SDS. The QTL fine maps suggested that the two loci on Chr. 18 were three loci (cqRfs1, cqRfs, and cqRfs19). Candidate genes were inferred.  An epistatic interaction was inferred between Chr. 18 and Chr. 20 loci. Therefore, SDS resistance QTL were both complex and interacting.


2016 ◽  
Vol 5 (1) ◽  
pp. 32
Author(s):  
Supriadi Supriadi ◽  
E.M. Adhia ◽  
D. Wahyuno ◽  
S. Rahayuningsih ◽  
N. Karyani ◽  
...  

Brown root rot disease is a major constraint on cashew plantation in Pekat District, West Nusa Tenggara. Its causal agent has not been characterized. This paper describes efforts to study the pathogen, distribution and loss. Field study was conducted in Pekat District in 2003. Laboratory  experiments to isolate and test the causal agent were conducted in the Indonesian Spices and Medicinal Crops Research Institute, Bogor.  Research results showed that the disease was found widespread in several villages in Pekat District, such as Pekat, Beringin Jaya, Sorinomo, and Nangamiro. Total number of died cashew trees was 1,075 equals to 5,106 kg kernel yield lost, worth Rp20.5 million. Infected trees showed leaf yellowing and defoliation leading to die. The lateral and taproots near collar were encrusted with gravel, earth, and brown mycelia sleeves. The fungus produced arthrospores and brown pigmentation on agar medium containing 0.05% gallic acid. An isolate of the fungus induced typical disease symptoms following inoculation on 5 month-old cashew seedlings. These results indicated that the causal agent of mass decline of cashew in Pekat District is Phellinus noxius. In field, the fungus also infects a barrier tree (Lannea coromandelica [Houtt.] Merr.) (Anacardiaceae), locally known as kedondong pagar or kayu bantenan.


2016 ◽  
Vol 6 ◽  
Author(s):  
Marta Francisco ◽  
Mahmoud Ali ◽  
Federico Ferreres ◽  
Diego A. Moreno ◽  
Pablo Velasco ◽  
...  

2020 ◽  
Vol 42 (4) ◽  
pp. 560-571
Author(s):  
Paul N. Okello ◽  
Kristina Petrovic ◽  
Asheesh K. Singh ◽  
Brian Kontz ◽  
Febina M. Mathew

2018 ◽  
Vol 19 (1) ◽  
pp. 46-53 ◽  
Author(s):  
David A. Marburger ◽  
Jaime F. Willbur ◽  
Maria E. Weber ◽  
Jean-Michel Ané ◽  
Medhi Kabbage ◽  
...  

Lipo-chitooligosaccharides (LCOs) are signal molecules produced by plant root endosymbionts and have been identified, formulated, and marketed as growth-promoting adjuvants for soybean (Glycine max [L.] Merr.). Experiments were conducted under controlled environmental conditions to characterize the effects of foliar LCO applications on early symptom development of sudden death syndrome (SDS), caused by Fusarium virguliforme, and Sclerotinia stem rot (SSR), caused by Sclerotinia sclerotiorum. Treatment factors for the SDS experiment included two soybean cultivars (Sloan and CH2105R2), two inoculation levels (noninoculated control and inoculated), and two LCO applications (control and foliar LCO application), whereas two experimental soybean lines (91-38 and 91-44) and two LCO applications (water control and foliar LCO application) were used in the SSR experiment. The LCO application did not significantly influence SDS root symptom severity or early-season growth characteristics. However, on the susceptible line (P = 0.01) and with LCO application (P = 0.03), significantly larger SSR lesions developed compared with the nontreated control and resistant line. These results suggest foliar-applied LCOs have a limited effect on early root symptom development caused by F. virguliforme but increase stem symptom development caused by S. sclerotiorum.


1991 ◽  
Vol 71 (1) ◽  
pp. 175-176
Author(s):  
G. R. Ablett ◽  
W. D. Beversdorf

RCAT Persian is a mid-late Maturity Group I soybean [Glycine max L. (Merr.)] cultivar with excellent yield potential, good lodging tolerance and resistance to most races of phytophthora root rot caused by Phytophthora megasperma f. sp. glycinea (Pmg) found in Ontario. Key words: Soybean, cultivar description


2014 ◽  
Vol 40 (3) ◽  
pp. 185-187
Author(s):  
E. A. Semenova ◽  
L. K. Dubovitskaya ◽  
S. A. Titova

1943 ◽  
Vol 21c (8) ◽  
pp. 235-248 ◽  
Author(s):  
A. A. Hildebrand ◽  
L. W. Koch

During the summer of 1942 sugar beets growing in an experimental plot at the Harrow laboratory were destroyed by a root rot of a type that apparently has been reported only once previously on this host in North America. Wilting of the foliage first attracts attention to affected plants, the roots of which show, externally, grayish-brown discoloured areas and, internally, fairly sharply-delimited, grayish to coffee-coloured lesions, affected tissues being more or less spongy in consistency. The causal organism, found to be a wound parasite, has been identified as Rhizopus arrhizus Fischer. The effect of temperature on the growth in culture and on the pathogenicity of this fungus and of representatives of the species, R. oryzae and R. nigricans, has been studied. It has been found that R. arrhizus and R. oryzae are relatively high temperature organisms, showing optimum growth at about 34° to 36 °C., and each capable of infecting and destroying artificially injured sugar beets most rapidly between 30° and 40 °C. R. nigricans, also a wound parasite is, on the other hand, a relatively low temperature organism showing optimum growth in culture at about 24° and displaying highest infection capability at about 14° to 16 °C.


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