CHAPTER-2
VARIABILITY AMONG THE ALTERNARIA BRASSICAE ISOLATES
INTRODUCTION
The chapter is mainly concerned with examining the variability among Alternaria brassicae isolates from the oilseed brassicas. Since, the oilseed brassicas are more prone to the fungal attack and thereby, resulting in reduced productivity of the oilseed. Therefore, the present investigation focuses on the studying the features such as morphological, pathological and molecular variability of Alternaria brassicae. The characteristic features of the fungal pathogen Alternaria brassicae is deeply analyzed in this part of chapter and then breeding of fungal resistant oilseed brassicas could be facilitated.
Susceptibility of oilseed brassicas
Breeding of fungal resistant …show more content…
Disea. Plants infected by S. sclerotiorum commonly develop signs of the pathogen, such as white, cottony mycelial growth embedded with black sclerotia that develop on plant surfaces or inside pod and stem tissues (Abawi and Grogan, 1979). The pathogen overwinters in the soil or on crop debris as sclerotia, which under suitable conditions germinate carpogenically to produce apothecia from which ascospores are released (Abawi and Grogan, 1979, Mila and Yang, 2008). Epidemics are initiated by airborne ascospores, originating from apothecia within the field and from external sources (Boland and Hall, 1987, 1988b, Foster et al., 2011, Wegulo et al., 2000). SRC is an economically important disease of carrot, particularly in temperate climates where roots are cold-stored over long periods (Kora et al., 2003). The disease is bicyclic and infects foliage, and occasionally roots, in the field followed by postharvest spread on roots in storage (Kora et al., 2005a). Field epidemics of Sclerotinia diseases of carrot and other crops are associated with canopy closure creating the constant, moist conditions required for carpogenic germination of sclerotia, the production of ascospores and the maintenance of leaf wetness for infection (Boland and Hall, 1987, 1988a, Clarkson et al., 2004, 2007, Kora et al., 2005a, Mila and Yang, 2008). After airborne release and deposition on host tissue, ascospores require a nutrient source to germinate 44 and initiate infection (Lumsden, 1979). Senescent plant tissue serves as a nutrient source for germinating ascospores, such as lodged, senesced leaves of carrot plants along a furrow (Kora et al., 2005a), or senescent petal blossoms in bean (Boland and Hall, 1987) and canola (Turkington et al., 1991). Management of
VARIABILITY AMONG THE ALTERNARIA BRASSICAE ISOLATES
INTRODUCTION
The chapter is mainly concerned with examining the variability among Alternaria brassicae isolates from the oilseed brassicas. Since, the oilseed brassicas are more prone to the fungal attack and thereby, resulting in reduced productivity of the oilseed. Therefore, the present investigation focuses on the studying the features such as morphological, pathological and molecular variability of Alternaria brassicae. The characteristic features of the fungal pathogen Alternaria brassicae is deeply analyzed in this part of chapter and then breeding of fungal resistant oilseed brassicas could be facilitated.
Susceptibility of oilseed brassicas
Breeding of fungal resistant …show more content…
Disea. Plants infected by S. sclerotiorum commonly develop signs of the pathogen, such as white, cottony mycelial growth embedded with black sclerotia that develop on plant surfaces or inside pod and stem tissues (Abawi and Grogan, 1979). The pathogen overwinters in the soil or on crop debris as sclerotia, which under suitable conditions germinate carpogenically to produce apothecia from which ascospores are released (Abawi and Grogan, 1979, Mila and Yang, 2008). Epidemics are initiated by airborne ascospores, originating from apothecia within the field and from external sources (Boland and Hall, 1987, 1988b, Foster et al., 2011, Wegulo et al., 2000). SRC is an economically important disease of carrot, particularly in temperate climates where roots are cold-stored over long periods (Kora et al., 2003). The disease is bicyclic and infects foliage, and occasionally roots, in the field followed by postharvest spread on roots in storage (Kora et al., 2005a). Field epidemics of Sclerotinia diseases of carrot and other crops are associated with canopy closure creating the constant, moist conditions required for carpogenic germination of sclerotia, the production of ascospores and the maintenance of leaf wetness for infection (Boland and Hall, 1987, 1988a, Clarkson et al., 2004, 2007, Kora et al., 2005a, Mila and Yang, 2008). After airborne release and deposition on host tissue, ascospores require a nutrient source to germinate 44 and initiate infection (Lumsden, 1979). Senescent plant tissue serves as a nutrient source for germinating ascospores, such as lodged, senesced leaves of carrot plants along a furrow (Kora et al., 2005a), or senescent petal blossoms in bean (Boland and Hall, 1987) and canola (Turkington et al., 1991). Management of