Joseph F. Worley

The Influence of Light Intensity on the Internodal Response of Intact Bean Plants to Brassins

The response of pinto bean (Phaseolus vulgaris L.) plants to a single application of brassins (10 μg) in the second-internode assay was determined under high-intensity (2,000 ft-c = 21.5 klux) and low-intensity (100 ft-c = 1.08 klux) cool-white fluorescent light in a controlled environment. Under high light, maximum elongation of the second internode was reached in 4 days in both the lanolin controls and the brassin-treated plants. After 4 days of high light, second internodes treated with brassins were five times longer than those of controls. Under low light, however, brassin-treated internodes were nearly 10 times longer than those of controls after the same length of time, and the controls and the treated internodes continued to elongate for 10 days. Under both low and high light, brassins induced not only elongation but also a marked thickening of the treated internode. Under low light, radial increase was caused predominantly by cell enlargement in the cortical and phloem tissues, whereas under high light, the increase in stem diameter was caused by cell division in the pith. These findings demonstrate that light plays a major role in determining the response of bean plants to brassin treatment.

Intracellular Transport Apparatus of Phloem Fibers

Rotational streaming of cytoplasm occurs in the form of longicellular currents in immature and relatively mature fibers of bean stems. Plastids carried by these currents move continuously on their rotational course from one end of the cell to the other in relatively straight lines. A distance of approximately 2 millimeters, the average length of the fibers, is covered in about 3 minutes (3.6 cm per hour). The same type of streaming occurs in immature phloem fibers that develop within 24 hours after bean seeds are planted and before the plants appear above the soil surface. Rotational streaming also occurs in xylem fibers of bean stems and in cells which appear to be fibers in stems of young cucumber, tomato, sunflower, and flax.

6-d-glucopyranosyl fatty acid esters from Brassica napus pollen

6-d-Glucopyranosyl esters of palmitic, oleic, linoleic and linolenic acids were identified in Brassica napus (rape) pollen. These esters are inactive as plant growth promoters in the bean second-internode bioassay.