Effect of Tricyclazole on morphology, virulence and enzymatic alterations in pathogenic fungi Bipolaris sorokiniana for management of spot blotch disease in barley

Abstract

Bipolaris sorokiniana synthesizes the 1,8-dihydroxynaphthalene (DHN) melanin via pentaketide pathway and promotes the development of aerial mycelia and conidia. A melanin biosynthesis inhibitor Tricyclazole (TCZ), brought changes when applied at 5-100 μg ml(-1) concentration in the colony morphology, radial growth, mycelia weight, melanin content, antioxidant enzymes (SOD and CAT) and extracellular hydrolytic enzymes (cellulase, pectinase, amylase and protease) in black, mixed and white isolates of B. sorokiniana. A significant alteration was recorded in antioxidant enzymes in black and mixed isolates; however, non-significant alteration was recorded in white isolate. Isolates of B. sorokiniana exposed to 100 µg ml(-1) TCZ showed significantly increased formation of superoxide radical (O 2 (·-) ) and hydrogen peroxide (H2O2)·H2O2 was detected significantly high in hyphae and conidia while, O 2 (·-) was found primarily in the conidia. Microscopic results suggest that TCZ damages not only the cell wall but also the cell membrane. The foliar application of TCZ (25, 50 and 100 µg ml(-1)) decreases the area under disease progress curve, lesion development and spore formation on barley leaves thereby reducing potential for the disease development. In conclusion TCZ influences the pathogenic ability by damaging the cell structure of hyphae and conidia and also alters the antioxidant enzyme levels in B. sorokiniana. TCZ may therefore, works against to pathogen for better management of spot blotch disease in barley infected with B. sorokiniana.

Response of the fungus Pseudocercospora griseola f. mesoamericana to Tricyclazole

“…Recently, Saparrat et al (2009) described that representatives of P. griseola from both gene pools synthesize 1,8-dihydroxynaphthalene (DHN) melanin. These same pigments have already been found in most Ascomycota, such as in Alternaria alternata (Carzaniga et al 2002), Bipolaris oryzae (Moriwaki et al 2004), Bipolaris sorokiniana (Kumar et al 2015), Cladosporium cladosporioides (Llorente et al 2012), Colletotrichum lagenarium, Magnaporthe grisea (Moriwaki et al 2004), Pseudocercospora fijiensis (Beltrán-García et al 2014) and Sporothrix schenckii (Romero-Martinez et al 2000). However, information regarding the pathway of pigment synthesis as well as its localization at the ultrastructural level in P. griseola is lacking.…”

“…Tricyclazole at 100 ppm reduced stratification and deposition of melanin in the hyphal wall of isolate T4, as seen by TEM and CM respectively. Kumar et al (2015) also associated the presence Fig. 7 Hyphae of P.griseola f. mesoamericana isolate T4 from cultures grown on PDA alone (a) and on PDA+100 ppm of tricylazole (b), either nontreated (1) or treated (2) of this inhibitor with morphological changes in the cell walls of hyphae and conidia of the black B. sorokiniana isolates, which also was associated with a lower level of melanization.…”

“…Chattopadhyay et al (2013) and Kumar et al (2015) found that the tricyclazole in the range between 25 and 100 ppm provoked several changes in Bipolaris sorokiniana, such as colony morphology, spore size and number of septa in conidia. Also a decrease in the deposition of electron-dense g r a n ul es i n hy p h a w a l l s w a s f ou n d i n c e l l s o f Trimmatostroma salinum and T. abietis, chlamydospores of Thielaviopsis basicola, and sclerotia of Botrytis cinerea and Sclerotinia sclerotiorum, when they were cultured in a medium with 1-30 ppm of tricyclazole (Wheeler and Stipanovic 1979;van de Sande et al 2007;Butler et al 2009).…”

“…Tricyclazole has been used to control of M. grisea on rice. Recently, it has been demonstrated that this molecule also has fungicide activity against other pathogens of cereals, such as Bipolaris oryzae and B. sorokiniana, Blumeria graminis and Rhynchosporium secalis, as well as Colletotrichum lagenarium and C. lindemuthianum, pathogens of cucumber and beans, respectively (Mares et al 2004;Gupta et al 2013;Kumar and Mukherjee 2013;Kumar et al 2015). Although Saparrat et al (2009) reported the effect of tricyclazole in melanization of Pseudocercospora griseola, there is no additional data on the role this compound might play in the control of ALS.…”

“…Saparrat et al (2009) and Llorente et al (2012) demonstrated that this fungicide reduced growth and melanization both on P. griseola and C. cladosporioides. Furthermore, this compound is used to control plant pathogens such as Magnaporthe grisea, Bipolaris oryzae, B. sorokiniana, Blumeria graminis, Colletotrichum lagenarium, C. lindemuthianum and Rhynchosporium secalis (Mares et al 2004;Kunova et al 2012;Kumar and Mukherjee 2013;Kumar et al 2015).…”