J Integr Plant Biol. ›› 1973, Vol. 15 ›› Issue (1): -.

• Research Articles •    

Cytological Studies on the Cold Resistance of Plants--Ultrastructural Changes of the Wheat Cells in the Winter Period

Chien Ling-cheng, Ching Yu-hsiang and Chang Pau-tien   

Abstract: The present work was undertaken with an attempt to study the ultrastructural changes of two wheat varieties which differ from each other in cold resistance. The plants of these two different varieties were cultivated under the same environmental conditions. For comparative studies, materials of these two varieties were collected at the same time and made preparations with the same technique for electron microscopy. The main results obtained are summarized as follows: 1. In the prime stage of tillering, the pores of the nuclear membrane of both the winter and the spring varieties were widely open, while the chromatic and nucleolar materials were observed to traverse the pores into the cytoplasm. When winter arrived, with the temperature dropping the nuclear pores of the hardy winter wheat gradually disappeared, and those of the nonresistant spring wheat, however, remained open. It showed that there must be a close correlation between the behaviour of the nuclear pores and the physiological activities of the plants. The authors have considered that the behaviour of the nuclear pore may have an important bearing on the cessation of the cell division and growth activity and on the causality of the development of cold resistance in wheat plants at low temperature. 2. A phenomenon of zipper-like arrangement of the proplastids occurred in young leaf cells of the hardy wheat in the winter period, but under the same condition no such phenomenon was found in those of the non-resistant variety. 3. As the temperature fell in the late autumn or early winter, the wheat plants were in hardened condition, the mitochondria of the winter wheat increased in size and changed in form, as protrusions and invaginations of various shapes appeared with atendency of the protrusion of one mitochondria inserting into the invagination of the other. The number of the mitochondrial cristae also increased. In the spring wheat, however, there were no such changes in the mitochondria.

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