Cytochemistry of developing cotton fibers:: A hypothesized relationship between motes and non-dyeing fibers

Abstract

Developing lint fibers from normally developing seeds and from motes of Upland cotton ( Gossypium hirsutum L. cv Acala SJ2 and cv Acala Maxxa) were compared with respect to cell wall cytochemistry. Fibers from motes (unfertilized ovules or aborted seeds) were used as a model for non-dyeing fibers, a contributor to poor quality textiles. Primary and secondary fiber walls were stained for pectin, cutin, suberin, callose, and cellulose. Up to 25 days post-anthesis (DPA), mote fibers had pectinaceous primary walls with a thin layer of cellulose, indistinguishable from primary walls of normally developing fibers. However, secondary walls in mote fibers had scanty, irregularly deposited cellulose, while secondary walls in normal fibers were well developed with thick cellulosic layers. At 29 DPA and at later stages of development, fibers on normal seeds had well-developed secondary walls, which were proportionally less developed on medium-sized and small motes. Nonetheless, fibers, which varied in diameter and cell wall thickness, were found on all normal seeds, on medium-sized and on small motes; most fiber cell walls were smaller in thickness at the chalazal than at the micropylar end. Regardless of their thickness, fibers on seeds and motes had cellulosic secondary cell walls. As most industrial dyes are specific for cellulose, the paucity of cellulose in mote fibers is consistent with the suggested causal relationship between lack of cellulose and the non-dyeing nature of some fibers. There were indications that immature fibers at the chalazal end of seeds may also contribute to dye imperfections in fabrics.