scholarly journals Impact of Cruciferous Phytoalexins on the Detoxification of Brassilexin by the Blackleg Fungus Pathogenic to Brown Mustard

2010 ◽  
Vol 5 (6) ◽  
pp. 1934578X1000500
Author(s):  
M. Soledade C. Pedras ◽  
Ryan B. Snitynsky

The biotransformation of brassilexin, a potent phytoalexin produced by brown mustard (Brassica juncea L.), in the presence of various cruciferous phytoalexins was investigated. An important group of isolates of the fungal species Leptosphaeria maculans (Laird 2 and Mayfair 2), which is virulent to brown mustard, but not to canola, was used in this investigation. Brassilexin was detoxified by the fungus, but none of the phytoalexins seemed to affect substantially the rate of brassilexin detoxification; after 12 h of incubation, the amounts of brassilexin remaining in culture were as low as in controls, except in co-incubations with cyclobrassinin and sinalexin, which afforded intermediates that in solution oxidized spontaneously to brassilexin.

2011 ◽  
Vol 6 (5) ◽  
pp. 1934578X1100600
Author(s):  
M. Soledade C. Pedras ◽  
Paulos B. Chumala

The phytotoxins and other metabolites produced by isolates L2/M2 of the fungal species Leptosphaeria maculans under different culture conditions, together with those of two new, but related isolates are disclosed. The common metabolic characteristics suggest a phylogenetic similarity between these isolates with potential to become widespread in mustard growing areas.


2021 ◽  
Author(s):  
A. P. Van de Wouw ◽  
J. L. Scanlan ◽  
S. J. Marcroft ◽  
A. J. Smith ◽  
E. M. Sheedy ◽  
...  

Genome ◽  
2006 ◽  
Vol 49 (1) ◽  
pp. 30-41 ◽  
Author(s):  
J A Christianson ◽  
S R Rimmer ◽  
A G Good ◽  
D J Lydiate

Blackleg disease of crucifers, caused by the fungus Leptosphaeria maculans, is a major concern to oilseed rape producers worldwide. Brassica species containing the B genome have high levels of resistance to blackleg. Brassica juncea F2 and first-backcross (B1) populations segregating for resistance to a PG2 isolate of L. maculans were created. Segregation for resistance to L. maculans in these populations suggested that resistance was controlled by two independent genes, one dominant and one recessive in nature. A map of the B. juncea genome was constructed using segregation in the F2 population of a combination of restriction fragment length polymorphism (RFLP) and microsatel lite markers. The B. juncea map consisted of 325 loci and was aligned with previous maps of the Brassica A and B genomes. The gene controlling dominant resistance to L. maculans was positioned on linkage group J13 based on segregation for resistance in the F2 population. This position was confirmed in the B1 population in which the resistance gene was definitively mapped in the interval flanked by pN199RV and sB31143F. The provisional location of the recessive gene controlling resistance to L. maculans on linkage group J18 was identified using a subset of informative F2 individuals.Key words: blackleg, B genome, phoma, recessive resistance.


2009 ◽  
Vol 4 (9) ◽  
pp. 1934578X0900400 ◽  
Author(s):  
M. Soledade C. Pedras ◽  
Yang Yu

The metabolites produced by the fungal species Leptosphaeria maculans and L. biglobosa under different culture conditions, together with their phytotoxic activities are reviewed. In addition, the biosynthetic studies of blackleg metabolites carried out to date are described and suggestions for species reclassification are provided.


2001 ◽  
Vol 41 (1) ◽  
pp. 71 ◽  
Author(s):  
R. K. Khangura ◽  
M. J. Barbetti

Canola crops were monitored throughout the Western Australian wheatbelt during 1996–99 to determine the incidence and severity of crown cankers caused by the blackleg fungus (Leptosphaeria maculans). All crops surveyed had blackleg. The incidence of crown canker was 48–100%, 15–100%, 9–94% and 48–100% during 1996, 1997, 1998 and 1999, respectively. The mean incidence of crown cankers statewide was 85, 63, 55 and 85% in 1996, 1997, 1998 and 1999, respectively. The severity of crown canker (expressed as percentage disease index) ranged between 30 and 96%, 3 and 94%, 5 and 78% and 21 and 96% during 1996, 1997, 1998 and 1999, respectively. These high levels of blackleg can possibly be attributed to the accumulation of large amounts of infested canola residues. In 1999, there were effects of variety, application of the fungicide Impact, distance to last year’s canola residues and rainfall on the incidence and severity of blackleg. However, there were no effects of sowing date or region on the disease incidence or severity once the other factor effects listed above had been considered. In 1995, an additional survey of 19 sites in the central wheatbelt of Western Australia assessed the survival of the blackleg fungus on residues from crops grown in 1992–94. The residues at all sites carried blackleg. However, the extent of infection at any particular site varied from 12 to 100% of stems with the percentage of stems carrying pseudothecia containing ascospores varying between 7 and 96%. The high levels of blackleg disease found in commercial crops are indicative of significant losses in seed yields, making it imperative that management of blackleg be improved if canola is to remain a viable long-term cropping option in Western Australia.


1977 ◽  
Vol 17 (86) ◽  
pp. 445 ◽  
Author(s):  
N Thurling ◽  
LA Venn

The responses of 53 cultivars of the rapeseed species Brassica napus and Brassica campestris to infection by three different populations of the blackleg fungus, Leptosphaeria maculans, were examined in a controlled environment. Significant variation in disease development was observed between cultivars as well as between fungal populations which had been derived from diseased stubble collected at widely separated sites in Western Australia. A large proportion of the cultivars tested were either susceptible or only slightly resistant to infection by each of the three fungal populations whereas only one cultivar, Zollerngold, was highly resistant to all fungal populations. Several other cultivars, however, were resistant to one population and susceptible or slightly resistant to the other two. In these cases, marked interactions between host and parasite were evident, some cultivars being substantially more resistant than others to infection by spores from a particular population.


2009 ◽  
Vol 89 (2) ◽  
pp. 337-340 ◽  
Author(s):  
G. Rakow ◽  
J. P. Raney ◽  
D. Rode ◽  
J. Relf-Eckstein

Brown condiment mustard (Common Brown) has about 10% lower grain yield than oriental condiment mustard (yellow seeded), which both belong to the same species [Brassica juncea (L.) Czern.]. Yield improvements in brown condiment mustard are therefore of great importance. The Saskatoon Research Centre of AAFC initiated a condiment brown mustard improvement program in 1996 applying pedigree selection of single plants from the condiment brown mustard cultivar Blaze, which resulted in the selection and registration of the cultivar Centennial Brown. Centennial Brown yielded 3.2% more grain than the landrace Common Brown, on average over 81 location years in 9 yr of condiment mustard Co-op tests (1999–2007) and was well adapted to the mustard-growing areas of the Canadian prairies. Support for registration was based on 6 yr of Co-op tests. Centennial Brown had the same maturity (91 d) and was 5 cm taller (116 cm) than Common Brown. It had 1.5% lower fixed oil (36.6%) and 1.2% greater protein content (30.0%) compared with Common Brown. It had 0.4 g heavier seed (2.96 g 1000 seed-1) than Common Brown. Centennial Brown had 0.9 mg g seed-1 greater allyl glucosinolate content than Common Brown (9.15 mg g seed-1). Green seed counts were low in Centennial Brown (0.64%) compared with Common Brown (0.79%). This was confirmed in chlorophyll content measurements, 4.76 mg kg-1 for Centennial Brown and 5.24 mg kg-1 for Common Brown. Centennial Brown was resistant to blackleg disease [Leptosphaeria maculans (Desm.) Ces. et de Not.] and highly susceptible to the B. juncea races of white rust [Albugo candida (Pers.) Kuntze], equal to Common Brown. Centennial Brown will quickly replace Common Brown in the market place because of its increased grain yield and much superior seed quality. Key words: Brassica juncea (L.) Czern., cultivar description, grain yield, seed quality


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