Correlative Studies of Cell Wall Enzymes and Growth

Abstract

If cell wall hydrolytic enzymes are involv-ed in extension growth, a correlation may be expected between hydrolytic activity of the cell walls and growth rate of the tissue from which the walls are prepared. Epicotyl sections from 0 to 5 mm, 6 to 10 mm, and 11 to 13 mm below the apical hook of pea seedlings (Pisum sativum var. Alaska) have relative growth rates of 100:15:2, respectivelv. The relative fl-glucosidase activities (units/mg wall) Data from several laboratories suggest that glycosidases play a role in wall plasticization, thus permitting cell elongation during extension growth (9). There is evidence that oligosaccharidehydrolyzing enzymes are localized in the walls (1,2,3,7,13,17,19,25) and that these enzymes can hydrolyze cell wall oligosaccharides (12,13, 15,18,25). It becomes important to know whether walllocalized glycosidase activity is correlated with the growth rate of the tissue from which the walls are prepared. Previous studies, mainly employing enzymes extracted from wall preparations (7,13,19,25), report that the amount of glycosidase activity correlates with the growth rate of the tissue from which the walls are prepared. In this current study, highly purified cell walls from Pisum epicotyls were utilized, thus permitting specific activity determinations. We find that (3-glucosidase specific activity is highest in walls from rapidly elongating tissue but that surface sterilized in 1 % sodium hypochlorite for 15 min, soaked in running tap water for 18 hr, and germinated on absorbent paper in covered plastic trays. Germination was in the dark at 25 C and 85c% relative humidity, and seedlings were harvested 84 hr after germination was begun. Growth rates of the seedlings were determined by marking at 2.5-mm intervals and subsequently measuring the spacings. Sequential epicotyl sections were taken from 0 to 5 mm, 6 to 10 mm, and 11 to 15 mm below the apical hook. The sections were either dropped into beakers on Dry Ice immediately after cutting in the case of samples for cell wall preparation by the nonaqueous method, or, in all other cases, they were weighed out in 0.5-g lots and then frozen on Dry Ice as soon as 0.5 g was obtained. The tissue was stored at -80 C until used.Cell Wall Preparation. Cell walls were prepared by homogenization in glycerol and filtration through a glass bead filter, as described by Kivilaan et al. (16). The wall material was dried in an evacuated dessicator over P205, CaCl2, and paraffin at 4 C for 24 to 48 hr. The resultant white powder was stored at -10 C in a sealed jar over CaSO4. Alternatively glycerol was removed from the pelleted walls by water, rather than by solvent washing, as in the Kivilaan procedure. Washing and collection by centrifugation was repeated three times, the cell wall material was collected by filtration, dried over P205 in vacuo, and stored as described above.Aqueous Cell Wall Preparation. Cell walls were also prepared by homogenization of 0.5-g aliquots of frozen tissue sections ground at 0 to 4 C in a 50-ml conical glass hom...

Glycosidases and acid-invertase activities are not correlated with Phaseolus hypocotyl growth

“…It was also involved in autolysis in Cicer arietinum (Dopico et al 1989a). Correlation between g-glucosidase and rate of cell elongation has been reported by Murray and Bandursky (1975). Bucheli et al (1985), working with cotton fibres, related glucanases to growth while Tanimoto (1985) related growth to ot-galactosidase and a-arabinosidase in Pisum sativum.…”

Biochemical Changes Associated with Brassica juncea Seed Development, II: Glycosidases

“…Masuda et al (1985) reported that ␤-galactosidase activity was high in the growing cells and that the activity was related to polysaccharides such as galactan, arabinogalactan, and xyloglucan, which undergo changes during growth. Correlation between ␤-glucosidase and the rate of cell elongation has been reported by Murray and Bandurski (1975); Bucheli et al (1985), working with cotton fibers, related glucanases to growth, and Tanimoto (1985) related growth to ␣-galactosidase and ␣-arabinosidase in Pisum sativum. Thus, the conclusion that these glycosidases are related to the elongation growth (cell wall loosening) and structure of the cell wall has been drawn by several authors.…”

Studies on Acidification of Media by Avena Stem Segments in the Presence and Absence of Gibberellic Acid

“…1). The maximal growth response at pH 5 in these segments is one which appeals to us in that many cell wall hydrolases show maximal enzyme activity at around pH 5 (15,16,18,19). Thus, increase in acidification rates elicited by GA3, resulting in attainment of pH values approximating 5 (compared with pH 5.6 in control segments) could be of major significance in GA3-stimulated growth, especially since GA3 starts to increase cell wall plasticity in the internode base within 60 min (3).…”