title: Time-course of programmed cell death during leaf senescence in Eucommia ulmoides.
abstract: Leaves of Eucommia ulmoidesOliv. harvested between April to November were examined for programmed cell death (PCD) during growth and senescence. Leaves developed in April, becoming fully expanded in late May, remaining unchanged until November when they started to dehisce. Falling leaves retained a green color. Our results showed that (1) mesophyll cells gradually reduced their nuclei from September to November, (2) positive TUNEL signals appeared on the nuclei from August, (3) ladder-like DNA fragmentation occurred in September and October, and (4) a 20-kDa Ca(2+)-dependent DNase appeared in these same months. In fallen leaves, intact mesophyll cell nuclei could not be detected, but a few cells around the vascular bundle had nuclei. Therefore, (1) programmed cell death (PCD) of leaf cells occurred in the leaves of E. ulmoides, (2) the progress of mesophyll cell PCD lasted for more than 2 months, and (3) PCD of leaf cells was asynchronous in natural senescing leaves.
authors.affiliation: College of Life Sciences, Peking University, Beijing 100871, P.R. China.
authors.forename: Jing
authors.initials: J
authors.lastname: Cao
authors.forename: Feng
authors.initials: F
authors.lastname: Jiang
authors.lastname: Sodmergen
authors.forename: Keming
authors.initials: K
authors.lastname: Cui
mesh_terms: D017209:Apoptosis / Q000235:genetics / Q000502:physiology*; D002118:Calcium / Q000494:pharmacology; D053938:DNA Fragmentation / Q000235:genetics / Q000502:physiology; D003851:Deoxyribonucleases / Q000187:drug effects / Q000378:metabolism; D031283:Eucommiaceae / Q000235:genetics / Q000502:physiology*; D020287:In Situ Nick-End Labeling; D008856:Microscopy, Fluorescence; D018515:Plant Leaves / Q000235:genetics / Q000502:physiology*; D013997:Time Factors
chemical_list: D003851:Deoxyribonucleases; D002118:Calcium