Localization and Nature of Phenolase in Sugar-beet Leaves

Phenolase activity has been found in chloroplast, mitochondrial,and soluble fractions of homogenates prepared from sugar-beetleaves. The phenolases present in the three fractions have differentcatecholase/cresolase ratios and respond differently to inhibitors.The chloroplasts contain about half the cresolase activity ofa leaf homogenate, whereas the bulk of the catecholase activityis present in the soluble fraction. The findings are discussed in relation to the possible modeof action of catecholase and cresolase.     

Changes Induced by Salinity to the Anatomy and Morphology of Excised Pea Roots in Culture

Ann. Bot. 57, 811–818, 1986     

Relation Between the Anatomy of the Testa, Water Permeability and the Presence of Phenolics in the Genus Pisum

The seed coats of Pisum elatius, P. fulvum and P. humile areimpermeable to water while those of P. sativum and P. humilex P. sativum are permeable. The anatomical structure of theseed coats and the location of phenolics and quinones in thecells is described. The barriers to permeation of water in theimpermeable seeds are the continuous, very hard, pectinaceouslayer of the caps of the palisade cells and the presence ofquinones in either the palisade or osteosclereid cells, in acontinuous layer of these cells. In water permeable seeds thecaps are looser and quinones discontinuous or absent in palisadeor osteosclereid cells. Pisum, testa, water permeability, quinones, phenolics, palisade cells, osteosclereids, pectinaceous caps     

Fruit differentiation, palynology, and systematics in Pterocephalus Adanson and Pterocephalodes, gem now (Dipsacaceae)

The single-seeded fruits of the Dipsacaceae are enclosed by four fused bracts forming an epicalyx. A detailed study of the epicalyx morphology and anatomy of nearly all of the approximately 30 species of Pterocephalus s.L, together with other floral, palynological and karyological data, suggest only loose relationships and convergent similarities (homoplasies) between the core of the taxa (Pterocephalus s.s.), ranging from south-west and central Asia (P gedrosiacus, P. afghanicus) to Macaronesia (e.g. P. dumetorum) east Africa (P. frutescens) and southeast Asia (P. hookeri, P. bretschneideri and P. siamensis). The latter are separated as a new genus: Pterocephalodes. Pterocephalus S.S. lacks floral bracts, has numerous feathery calyx bristles and 5-merous corollas, and is apparently monophyletic. Its species demonstrate the gradual development of a hyalie corona, a diaphragma and other specialized epicalyx structures. These and other features allows the recognition of a relatively plesiornorphic, very widespread and paraphyletic basal group of perennial species (epicalyx type I), two more apomorphic perennial groups (epicalyx types II and III), and two most advanced groups (epicalyx types IV and V) with one perennial and two annual species. Pterocephalodes has floral bracts and 4-merous corollas, also appears to be monophyletic, and is limited to the eastern Himalaya and south-west China. It shares with Pseudoscabiosa the lack of a diaphragma in some of its species as well as the origin of a feathery pappus and of a corona. Thus, all three genera allow an insight into the evolutionary processes of fruit differentiation in the Dipsacaceae family.     

Pectolytic Activity by the Haustorium of the Parasitic PlantOrobancheL. (Orobanchaceae) in Host Roots

The possible involvement of enzymes in the penetration of intrusivecells of the parasitic angiospermOrobancheinto host root tissueswas studied using cytochemical and immunocytochemical methods.Pectin methyl esterase (PME) was detected, with specific antibodies,in the cytoplasm and cell walls ofOrobancheintrusive cells andin adjacent host apoplast. Depletion and chemical changes ofpectins in host cell walls were shown by histochemical stainingwith PATAg, which detects carbohydrates that are sensitive toperiodic acid, especially pectins, and with the monoclonal antibodiesJIM 5 and JIM 7 that label pectins with low and high rates ofesterification, respectively. Galacturonic sequences with lowrates of esterification were more abundant in host cell wallsadjacent to the parasite, which is consistent with pectin de-methylationby PME release from the parasite. Pectins were absent in middlelamellae and in host cell walls neighbouring mature intrusivecells of the parasite, consistent with further degradation ofpectins by other enzymes. These results provide the first directevidence for the presence and activity of a pectolytic enzymein the infection zone of the haustorium of a parasitic angiosperminsitu.Copyright 1998 Annals of Botany Company Broomrape;Orobanche; parasitic weed; haustorium; pectin methyl esterase; pectin; cell wall.     

The Activity of Organic Acids as Germination Inhibitors and its Relation to pH

The germination inhibitory activity of organic acids relatedto coumarin was investigated. The activity was found to be unrelatedto the nature of the side chain carrying the carboxyl group.Little or no relation between structure and activity existed.pH was found to be of secondary importance on the activity ofthe acids. Synergism between buffers and the acids exists insome cases. Moreover, the use of buffers in studying germinationinhibition was found to be unnecessary, due to the powerfulbuffering action of the seeds, and impermissible due to verymarked secondary effects of the buffers themselves and theireffect on germination.     

LOCALIZATION AND REACTIONS OF A PHEROMONE DEGRADATIVE ENZYME ISOLATED FROM AN INSECT ANTENNA

A fluid isolated from chemosensory sensilla on the antennaeof males and females of the cabbage looper, Trichoplusia ni(Hübner), was fractionated by gel filtration. Enzymaticdegradation of the pheromone was associated with 2 distinctgroups of fractions. The first group contained membrane fragments,vesicles, and membrane-bound enzyme or insoluble enzyme aggregates.The second group of fractions contained solublilized enzyme.Because of the method of isolating the ‘sensillum liquor’by breaking the tips of the hairs, membranes from chemoreceptorcell dendrites should greatly predominate. In general, 3 isomersand the saturated analog of the pheromone were hydrolyzed morerapidly than the pheromone. ^*Mention of a proprietary product in this paper does not constitutean endorsement of this product by the U. S. Department of Agriculture.