| dc.description.abstract | Extensin is one member of a class of hydroxyproline-rich glycoproteins present in a wide variety of plants and algae [1]. Cell walls of higher plants usually contain small quantities of extensins. Their usually low level is strikingly increased in response to wounding [2,3,4], infection [5,6, 7], elicitor treatment [8,9], and under tissue culture conditions [1 0]. A number of reports,cited in [1 ], have suggested that this accumulation of the glycoprotein may act as a defense mechanism of the plant to disease. Isolation of extensins is a prerequisite to clearly understanding their roles. This step, however, is particularly difficult due to the high insolubility of the glycoprotein. Recent progress in the isolation has been accomplished either by direct elution of a precursor from carrot root and tomato cell walls with a salt solution [11 ,4] or by solubilizing intact extensins from a homogenate of potato tubers and tobacco callus at very acidic pH [12, 13]. In addition to hydroxyproline-rich glycoprotein (HRGP)-extensin precursors, these procedures have led to the solubilization of hydroxyproline-rich arabinogalactan proteins. The objectives of this research were as follows: 1) To isolate extensins from callus cultures of susceptible and resistant cultivars of Gossypium hirsutum (cotton). 2) To determine several biochemical parameters such as amino acid content, hydroxyproline content and carbohydrate content. 3) To relate the differences in the biochemical parameters such as amino acid content and hydroxyproline content to the resistance of the plant to the bacterial pathogen, Xanthomonas campestris pv . malvacearum. | |
