Problem of sieve-tube slime

Area of Science:

• Plant Biology
• Plant Physiology
• Cell Biology

Background:

• Sieve tubes are the primary conduits for long-distance transport of photoassimilates in plants.
• The structural integrity and function of sieve tubes are crucial for plant survival and development.
• Previous understanding of sieve tube contents and their role in maintaining function was incomplete.

Purpose of the Study:

• To propose the existence of a stationary, living, filamentous reticulum within functioning sieve tubes.
• To elucidate the role of this reticulum in sieve plate maintenance and pore blockage.
• To describe the characteristics and behavior of the filamentous reticulum and associated slime.

Main Methods:

• Microscopic observation of sieve tube elements.
• Analysis of filament diameter and structure (striations).
• Investigation of slime binding and hydrolysis within sieve tubes across different species.

Main Results:

• A stationary, living, filamentous reticulum (100-150 angstroms in diameter, often striated) is proposed to exist in sieve tubes.
• Filament swelling is suggested as a mechanism to block pores in aged sieve plates after slime loss.
• Slime association with filaments varies: loosely bound in Cucurbita, hydrolyzed and metabolized in other species.

Conclusions:

• The filamentous reticulum is a persistent, integral component of functioning sieve tubes.
• This reticulum plays a vital role in the structural maintenance and functional regulation of sieve plates.
• Understanding this structure provides new insights into phloem transport and sieve tube longevity.