Cytological responses in the hypersensitive reaction in cotyledon and stem tissues of Brassica napus after infection by Leptosphaeria maculans

Abstract

A hypersensitive response (HR) occurs after infection of cotyledon, leaf and stem of Brassica napus cv. Surpass 400 by an avirulent strain of Leptosphaeria maculans. The cotyledon or the sixth true-leaf stages of plants were inoculated with pycnidiospores of L. maculans (strain UWA P11). For the first time in this specific pathosystem and its HR, we report condensation of cytoplasm, shrinkage in cell size and nuclear DNA fragmentation in cotyledon tissues, and in stem tissues, shrinkage and condensation of the cytoplasm, chromatin fragmentation and lobing of the nucleus.

An in vivo root hair assay for determining rates of apoptotic-like programmed cell death in plants

“…In fact, there are numerous examples in plants in which cytoplasm condensation occurs during PCD. These include, leaf morphogenesis in Monstera [20] and lace plant leaves [21], in the final stages of senescence [19,22] or in tissues undergoing the hypersensitive response [23,24]. The lace plant Aponogeton madagascariensis provides in vivo system for studying PCD in real time [25] however in other species the cells undergoing AL-PCD in whole plants are often buried within the tissue and large-scale scoring of individual cells to evaluate changes in cell death rates is not always feasible.…”

White Leaf Spot Caused by Neopseudocercosporella capsellae: A Re-emerging Disease of Brassicaceae

“…Although some pre-invasive host resistance mechanisms are known for N. capsellae, a detailed histopathological study is needed to understand possible post-invasion resistance mechanisms. For instance, hypersensitive reactions (Li et al, 2003) and lignin formation (Sharma et al, 2008) limiting the growth of the pathogen inside the host tissue (Li et al, 2008), have been reported against other Brassica foliar pathogens. Further, the specific details of the biochemical and molecular events occurring on host plant tissues during disease progression in N. capsellae-Brassica spp.…”