Germination and seedling growth of pechay (Brassica pekinensis c.v. Behi Czern L.) in the presence of cadmium and buthionine sulfoximine.

Date

3-1997

Degree

Bachelor of Science in Biology

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Bonifacio T. Mercado

Abstract

This study describes the germination and seedling growth responses of pechay (Brassica pekinensis c.v Behi Czern L) to the presence of sublethal concentrations of cadmium, in combination with buthionine sulfoximine (BSO), a known phytochelatin synthesis inhibitor In terms of IS, (defined as the concentration of cadmium which caused a SO % decrement in elongation of either the root or the hypocotyl), the results indicated an to of approximately 0 09 mM CdCI7 for the root. This value was brought down to 0 07 mM and 0 05 mM Cda, in the presence of 15 uM and 25 uM BSO, respectively On the other hand, the hypocotyl cells appeared less sensitive to the metal, with an I% of more than 0.15 mM CdC12 (the highest concentration used), which however is slightly lowered to approximately 0 125 mM in the presence of the BSO Seed germination remained high ( 9 Cr/o ) even at the highest CdCl1 concentration used, but was markedly decreased in the presence of 25 uM BSO The sensitivity of root tip cells to the metal relative to the hypocotyl cells is probably due to the interplay of at least two factors namely, the developmental age of the cells involved and the known immobility of cadmium. The root tip cells are mostly meristematic, rich in cytoplasm and with no conspicuously developed vacuoles In contrast, the hypocotyl cells are more mature and some are even well differentiated, and highly vacuolated. Cadmium, being immobile, tends to accumulate in the roots and bind with the proteins, which in the absence of phytochelatin (because of BSO) further increased the phytotoxicity of the metal. When the cadmium concentration is increased, a portion of the metal is moved to the hypocotyl, some of which binds with the cytoplasm but most probably becomes sequestered in the vacuoles. The inhibitory effect of the metal on the root and hypocotyl elongation is amply supported by the results of the mitotic index determination The results also suggests that increased cell division does not lead to growth if it is not accompanied by cell elongation.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

Thesis

Document Type

Thesis

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