Plant pathogens can be generally divided into two kinds, necrotrophs and biotrophs. Necrotrophs can kill the host cells and feed on the contents, while biotrophs complete their life cycle depending on the living host cells. Microbial necrotrophy is often associated with production of toxins, and necrotrophs are further divided into Host–specific necrotrophs (HSNs) and broad host–range necrotrophs (BHNs) according the toxins they secret. HSNs produce host–specific toxins (HSTs) that is essential for their pathogenicity and virulence and can be recognized by the immune system of theirs hosts. The fungal pathogen Cochliobolus carbonum is archetypical HSN, which produces HC–toxin and limitedly infects the susceptible genotypes, causing the Northern corn leaf spot. There are several broad host–range necrotrophs (BHNs) reported previously, such as the fungal pathogens Sclerotinia sclerotiorum, Alternaria brassicicola, Botrytis cinerea, and Plectosphaerella cucumerina, and the bacterial pathogen Erwinia carotovora. Plant responds to necrotrophs differentially according to the primary determinant of virulence . The attempted infection of plant pathogens, both biotrophs and nerotrophs, can activate plant immune responses, which include complex histological, cellular, biochemical, and molecular events that the pathogen proliferation or disease spread is limited. At the early stages of necrotrophic infections, host cell death is associated with, as well as the production of various secondary metabolites, antimicrobial peptides, and hormones, such as salicylic acid (SA), jasmonate (JA), ethylene (ET), and abscisic acid (ABA). In addition, accumulation of reactive oxygen species (ROS), callose, and some other cell wall modifications are also involved. The kinetics of these responses and the relative abundance and timing may vary but are common responses to different infection.
Citation : Li Wen (2012) Cell Death in Plant Immune Response to Necrotrophs. J Plant Biochem Physiol 1:e103. doi: 10.4172/2329-9029.1000e103
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