Premium
Demonstration of Levan and Alginate in Bean Plants ( Phaseolus vulgaris ) Infected by Pseudomonas syringae pv. phaseolicola
Author(s) -
Gross M.,
Rudolph K.
Publication year - 1987
Publication title -
journal of phytopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 60
eISSN - 1439-0434
pISSN - 0931-1785
DOI - 10.1111/j.1439-0434.1987.tb04409.x
Subject(s) - polysaccharide , phaseolus , biology , pseudomonas syringae , virulence , bacteria , microbiology and biotechnology , fructose , pseudomonas , food science , botany , biochemistry , pathogen , gene , genetics
A simple method for the extraction of extracellular polysaccharides (EPS) from plant tissue was developed. The polysaccharides of bacterial and plant origin present in the crude leaf extracts were separated by column chromatography on DEAE‐fractogel, and the bacterial polymers were identified by IR spectroscopy. In extracts from infected leaves as well as in exudates (ooze) from leaf axils, alginate (an acetylated mannuronan) and levan (β‐2,6‐fructofuranan) were detected as the major components amounting up to 80% of the crude extracts. A race‐1 isolate of P. phaseolicola synthesized both levan and alginate in about equal amounts in planta , whereas a race‐2 strain produced EPS composed almost solely of alginate. Extraction of healthy leaves yielded low amounts of complex polysaccharides. These consisted mainly of galactose, arabinose, and galacturonic acid. Neither fructose nor mannuronic acid were detected. Kinetic studies indicated that the main production of bacterial EPS in planta was correlated with the appearance of the water‐soaked symptom in leaves. However, before water‐soaking became apparent, alginate was detected in infected leaves (1, day after inoculation). The high amount of extractable material (ca. 50 mg levan plus alginate per g of dry weight of diseased tissue) suggests that the bacterial EPS is responsible for the typical water‐soaked appearance of lesions after bacterial infection. Since alginate was predominantly synthesized by the more virulent race‐2 isolate, this component of bacterial EPS was suspected to be a decisive factor of virulence of P. phaseolicola. A possible function of alginate during pathogenesis is discussed.