Involvement of tRNA Bound Cytokinin on the Gall Formation in Zizania

To understand the role of the conjugated forms of cytokininin gall formation, tRNA was extracted and purified from vegetativeand flowering shoots of Zizania, then hydrolysed by RNase T,or acid to release the conjugated forms of cytokinin. The resultsindicated that the level of cw-zeatin riboside fromZizania galltissue was 3 to 5 times higher than that of flowering Zizania,and the cytokinin activity in terms of kinetin equivalence was1.6 times higher in Zizania gall tissue than that of floweringZizania. It was found that higher amounts of cytokinin alsopromote protein synthesis. Due to the difference in levels ofthe conjugated forms of cytokinin between vegetative and floweringZizaniashoots, it is implied that the conjugated form of cytokininmay play an important role during the process of gall formationin Zizania latifolia. Key words: Gall formation, cytokinin, Zizania latifolia, RNA, smut fungus, water oat     

The Effect of Paclobutrazol on Physiological and Biochemical Changes in the Primary Roots of Pea

Primary roots of pea (Pisum sativum L. cv. Taichung No. 11)were treated with 0, 10 and 50 mg dm^–3 paclobutrazol [(2RS,3RS)-1-(4-chlorophenyl)-4, 4-dimethyl-2-(l,2,4-triazol-l-yl)pentan-3-ol]for 1 h at 48 h after germination. Paclobutrazol treatment inhibitedroot extension, promoted swelling (cell expansion was radialrather than longitudinal), and increased cell volume and theactivity of catalase and peroxidase enzymes. Paclobutrazol alsodecreased root respiration and ethylene production. However,under non-stressed conditions, paclobutrazol treatment did notaffect soluble carbohydrate content, water potential, osmoticpotential or water loss. Under osmotic stress with polyethyleneglycol (PEG), paclobutrazol diminished the increase of waterpotential and decreased the rate of water loss caused by theimposed stress, but had no effect on osmotic potential. Catalaseand peroxidase activity were increased in osmotically-stressedroots of treated plants. Key words: Root growth, paclobutrazol, pea, Pisum sativum, water shortage