Date of Award:

5-1974

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Plants, Soils, and Climate

Department name when degree awarded

Plant Science

Committee Chair(s)

W. F. Campbell

Committee

W. F. Campbell

Committee

D. R. Walker

Committee

T. F. Emery

Committee

H. P. Stanley

Abstract

This study was conducted to gain a better understanding of the seasonal changes of Gleason Elberta peach flower buds at the cellular level. Peach buds were obtained from the Howell Experiment Station in Ogden, Utah. Samples were collected at weekly intervals from October 25th, 1971 to March 29th, 1972. When a killing frost precluded further sampling, the buds were preserved by standard electron microscopic techniques. Thin sections (500 to 700 A) of the cells around the ovarious cavity were examined with a Zeiss EM-9S-2A electron microscope.

From October 25th, 1971 to January 3rd, 1972, more heterochromatin than euchromatin was in the nucleus. After January 3rd, 1972, no heterochromatin patches were observed. Nucleopores were not observed until March 7th, 1972.

Proplastids looked very similar to mitochondria until November 22nd, 1971 when the alignment of the transparent part of proplastids became apparent around the envelope. The number of lipid droplets increased and reached a maximum level near December 6th, 1971 then leveled off. A few short cisternae of rough endoplasmic reticulum (RER) were found only in the sample collected on October 25th. From October 25th throush December 27th, short tubular smooth endoplasmic reticulum (SER) was observed near the cell membrane region and only a few Golgi bodies were found, scattered in the cytoplasm. They were in a pre-maturation stage. Starting from December 27th Golgi bodies were in a maturation stage, long sheetlike rough endoplasmic reticulum was noted and lysosomes, presumably pinched from Golgi bodies, were also observed.

On February 22nd, the number of mitochondria as well as Golgi bodies and Golgi vesicles had increased. The number of mitochondria was further increased on February 29th. On March 7th, amyloplasts presumably developed from proplastids were observed.

The results of this work revealed that polysaccharide metabolism was in progress from October 25th to December 27th as indicated by the presence of SER. The presence of lysosomes starting on December 27th suggested that the cell was undergoing intracellular digestion. The increased number of mitochondria and the Golgi bodies observed on February 22nd revealed an increased rate of respiration and the progression of cell wall metabolism respectively. The presence of nucleopores on March 7th would enhance exchange of information between the nucleus and the cytoplasm.

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