Evidence for programmed cell death and activation of specific caspase-like enzymes in the tomato fruit heat stress response.
The tomato (Lycopersicon esculentum) fruit is the best available model to study the stress response of fleshy fruit. Programmed cell death (PCD) plays an important role in stress responses in mammals and plants. In this study, we provide evidence that PCD is triggered in the tomato fruit heat stress response by detection of the sequential diagnostic PCD events, including release of cytochrome c, activation of caspase-like proteases and the presence of TUNEL-positive nuclei. Investigating the time course of these events for 12 h after heat treatment indicated that cytochrome c release and caspase-like protease activation occurred rapidly and were consistent with the onset of DNA fragmentation. In addition, LEHDase and DEVDase enzymes were specifically activated in tomato fruit pericarp during the heat treatment and recovery time. There was no significant activation of YVADase or IETDase proteases. Preincubation of pericarp discs with the broad-spectrum, cell-permeable caspase inhibitor Z-VAD-FMK, suppressed heat-induced cell death measured by trypan blue, accompanied by a decrease in LEHDase and DEVDase activities.
Qu
Gui-Qin
GQ
College of Food Science & Nutritional Engineering, China Agricultural University, No. 17 Qinghua East Road, 100083, Beijing, China. quguiqin2000@sina.com
Liu
Xiang
X
Zhang
Ya-Li
YL
Yao
Dan
D
Ma
Qiu-Min
QM
Yang
Ming-Yu
MY
Zhu
Wen-Hua
WH
Yu
Shi
S
Luo
Yun-Bo
YB
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D045304:Cytochromes c / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D005456:Fluorescent Dyes / Q000378:metabolism; D005638:Fruit / Q000166:cytology / Q000201:enzymology* / Q000378:metabolism; D006358:Hot Temperature; D015151:Immunoblotting; D020287:In Situ Nick-End Labeling; D018551:Solanum lycopersicum / Q000166:cytology / Q000201:enzymology* / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism*; D013997:Time Factors
D000590:Amino Acid Chloromethyl Ketones; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D005456:Fluorescent Dyes; D010940:Plant Proteins; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D045304:Cytochromes c; D020169:Caspases