Cell Wall Degrading Enzymes in Cuscuta reflexa and Its Hosts

Pectin degrading enzymes, hemicellulose degrading enzyme andcellulose degrading enzymes were studied in Cuscuta reflexaRoxb., its susceptible hosts, Brassica campestris L., Cocciniaindica W. & A. Datura innoxia Mill, Helianthus annuus L.,Holoptelea indica Planch, Lantana camara L., Medicago sativaL., Manihot utilissima Pohl, Petunia hybrida X Hort exvilm,Pisum sativum L., Phaseolus vulgaris L. and Solanum nigrum L.and non-susceptible plants Ipomoea batata Lam. and Solanum tuberosumL. Pectin esterase and polygalacturonase were present in higheramounts in Cuscuta parasitic on P. vulgaris and S. nigrum, whichneeded more time for haustorial establishment. Exo-l, 4-ß-D-glucosidaseactivity was found in Cuscuta but could not be detected in itshosts. Xylanase and cellulase activity of host plants increasedwhile cellobiase activity decreased as a result of infectionby the parasite. Higher pectin esterase, polygalacturonase,xylanase and exo-l, 4-ß-D-glucosidase activities inthe haustorial region of the parasite is likely to bring aboutthe lysis of the cell wall of the host plant and thus facilitatethe penetration of the parasite haustoria into the host sieveelement, which is necessary for the transport of nutrients betweenthe host and the parasite. Key words: Cell wall degrading enzymes, Cuscuta reflexa     

Gibberellin-like Substances in Immature Seeds of Guava (Psidium guajava L.)

From immature seeds of guava fruits, Psidium guajava, L. eightgibberellin-like substances designated X1, X2, X3, X4, X5, X6,X7, and X8 were isolated. Chemical and biological evidence ledto the tentative identification of X1, X2, X3, X4, X5, X6, andX7 as gibberellins A₆, A₅, A₁, A₃, A₇, A₉, and A₄ respectively.Support for such identification was obtained from paper chromatography,thin-layer chromatography, gradient elution column chromatography,and the lettuce hypocotyl test. The compound X8 has not beenidentified chemically.     

Studies on the Separation of Gibberellins on Silicic Acid and Celite Columns

Studies carried out on the separation of gibberellins A1, A3,A4, A7, and A, on silicic acid: celite columns employing twodifferent gradient elution systems showed that they can be separatedclearly from one another on inactivated silicic acid and celitecolumns but not on activated silicic acid and celite columns.     

Changes in Cytokinin Activity during Seed Germination in Rice (Oryza sativa L.)

Cytokinin activity was determined in dry mature rice seeds,in endosperm and embryo tissues 24, 48 and 72 over imbibitionand in radicles 96 h after germination. Cytokinins with chromatographicproperties similar to zeatin, zeatin riboside, zeatin glucosideand zeatin riboside glucoside were datected in embryo and endosperm,but only the latter two were detected in mature seeds. Cytokininactivity was low during early toges of germination. Qualitativeand quantitative changes in cytokinins were observed in bothembryo and endosperm. The presence of higher cytokinin activityin the endosperm than in the embryo during the first 24 h aftergermination suggests that the endosperm may supply cytokininsuntil the embryo is able to synthaize its own cytokinins. Thepossible significance of high cytokinin glucoside activity inthe embryo early during germination and high cytokinin activityin the radicle during the later stages is discussed. Oryza sativa L., rice, cytokinin, germination, seed     

Studies on Endogenous Cytokinins in Guava (Psidium guajava L.)

The natural occurrence of cytokinins was examined in seededand seedless fruits of guava (Psidium guajava L.). Five differentcytokinins were isolated and three of them were tentativelyidentified as zeatin, zeatin riboside and zeatin nucleotide.Quantitative differences in cytokinin content were observedin the two types of fruits. Psidium guajava L., guava, cytokinin