The Formation of Ribulose Diphosphate Carboxylase Protein during Chloroplast Development in Barley

Ribulose 1,5-diphosphate carboxylase is synthesized in barley leaves growing in the dark. Upon illumination there is a marked increase in the rate of synthesis of the enzyme. The specific activity of the enzyme expressed as cpm incorporated into phosphoglyceric acid per μg of fraction I protein, after isolation shows no change either during dark growth or greening. During early stages of illumination of 7 day dark grown leaves with 320 foot-candles the enzymic activity in the water soluble protein fraction of the leaf shows a short term decline after 15 min which lasts for 30 min. Leaves greening at 2 foot-candles show a similar decline which is shifted to a time between the fourth and eighth hr after the onset of illumination.     

Effects of mesophilic and thermophilic composts on suppression of Fusarium root and stem rot of greenhouse cucumber

Three composts were tested for their ability to suppress root and stem rot caused by the soil borne fungal pathogen Fusarium oxysporum f. sp. radicis-cucumerinum (FORC) on cucumber. Two of the composts were prepared from separated dairy solids either by windrow (WDS) or vermicomposting (VMC) while the third, obtained from International Bio-Recovery (IBR), was prepared from vegetable refuse using aerobic digestion. Three sets of potting mixes were prepared by mixing the composts with sawdust at varying ratios, and seeded with cucumber cv. Corona. After 14 days of growth in the greenhouse, inoculum of FORC (20 mL of 5 x 10(6) micro-conidia per mL) was applied to each pot at three different times (14, 21, and 35 days). In unamended inoculated pots, the pathogen caused stunted growth and reduced flowers. Amendment of WDS in the potting mix suppressed these symptoms, while VMC and IBR had no effect. All three composts reduced the FORC colony forming units (cfu) at the end of the experiment (10 weeks). There was a large increase of fluorescent bacteria near the vicinity of roots particularly in WDS amended potting mixes. When water extracts of the composts were plated onto acidified potato dextrose agar (APDA), only IBR contained a potent thermostable inhibitor to FORC. This inhibitor was removed by activated charcoal but was not partitioned into petroleum ether at acid, basic, or neutral pH. Inhibition of FORC by IBR was not due to electrical conductivity or trace elements in the compost. Contrasting effectiveness of the WDS and VMC made from the same waste suggests that composting method can influence the disease suppression properties of the finished compost.     

Arrest of chlorophyll accumulation prior to anthocyanin formation in Euphorbia pulcherrima

Euphorbia pulcherrima Klotz plants exposed to short days (11 h light/13 h dark) for a period of eight weeks, developed flowers and a red canopy consisting of bracts and few true leaves. Plants maintained for three weeks under short day conditions, failed to produce flower primordia or a red canopy in the following 5 weeks in continuous light. Between the 4th and 5th short day week, the youngest leaves began to accumulate anthocyanin and turned red while the apical meristems differentiated into flower primordia. Chlorophyll accumulation ceased at the onset of anthocyanin synthesis and the protein content per unit leaf area declined. mRNA for glutamyl-tRNA^Glu synthetase (EC 6.1.1.17) and glutamyl-tRNA^Glu reductase also declined during this period. Western blot analysis revealed a loss of glutamyl-tRNA^Glu reductase, glutamate 1-semialdehyde (EC 5.4.3.8) and the Mg-chelatase subunits, Olive and CH42, in the last 2 to 4 weeks of the photoperiod.     

Immunoaffinity columns for isolation of abscisic acid in conifer seedlings

Spleen cells of mice immunized with cis, trans (±) abscisic acid (ABA) conjugated to bovine serum albumin (BSA) were fused with myeloma cells to produce hybridomas. Hybridomas secreting antibodies to cis, trans (+) ABA were detected by enzyme-linked immunoassay and injected into the peritoneal cavity of mice to produce ascites fluid. Antibodies purified by size-exclusion chromatography were linked to cyanogen bromide-activated Sepharose beads and used to prepare immunoaffinity columns (IAC). Semi-purified conifer seedling (Douglas-fir [ Pseudotsuga menziesii (Mirb) Franco] lodgepole pine ( Pinus contorta Dougl), cedar ( Thuja plicata D. Don), and spruce [ Picea glauca (Moench) Voss)]) extracts were passed through IAC, washed thoroughly with water and then eluted with methanol. ABA in the methanol eluate was analysed by high performance liquid chromatography with UV detection. UV absorption of extracts before and after purification through IAC indicated an excellent purification of extract by IAC. The identity of the ABA peak was confirmed by gas chromatography-mass spectrometry.     

Nature and bioactivities of endolichenic fungi in Pseudocyphellaria sp., Parmotrema sp. and Usnea sp. at Hakgala montane forest in Sri Lanka

Aim:  The aim of this study was to investigate the nature and bioactivities of endolichenic fungi in three abundant lichens, Pseudocyphellaria sp., Usnea sp. and Parmotrema sp. in the lower elevation of Hakgala montane forest in Sri Lanka.
Methods and Results:  Endolichenic fungal strains, fungi that live asymptomatically in the lichen thallus, much the same way as endophytic fungi live within healthy plant tissues, were isolated from three abundant lichen species, Pseudocyphellaria sp., Usnea sp. and Parmotrema sp., at Hakgala montane forest in Sri Lanka, using the surface sterilization method. Nine endolichenic fungal strains were isolated from Parmotrema sp. and Usnea sp. separately, while 11 endolichenic fungi were recovered from the lichen Pseudocyphellaria sp. Isolation of endolichenic fungus Chrysosporium sp. 2 was common to all three lichen species. Substrate utilization patterns and antifungal activities of eight endolichenic fungal species were evaluated and the results revealed that all the test fungi were able to produce at least one enzyme to utilize the test substrates. Nigrospora sp., Chrysosporium sp. 1 and 2 and Cladosporium sp. showed antifungal activities on growth of some selected plant pathogenic fungi.
Conclusions:  Endolichenic fungal strains (29) were isolated from the lichens Parmotrema sp., Usnea sp. and Pseudocyphellaria sp. in Sri Lanka. Chrysosporium sp. 2 was common in all three lichens. Some of these endolichenic fungal strains showed antifungal activities against common plant pathogenic fungi and they are capable of utilizing the substrates by producing specific enzymes.
Significance and Impact of the Study:  The diversity and prevalence of the endolichenic fungi have not been studied extensively and this is the first report of isolation and identification of endolichenic fungi in lichens available in Sri Lanka.     

Genomic clustering of cyanogenic glucoside biosynthetic genes aids their identification in Lotus japonicus and suggests the repeated evolution of this chemical defence pathway

Cyanogenic glucosides are amino acid-derived defence compounds found in a large number of vascular plants. Their hydrolysis by specific β-glucosidases following tissue damage results in the release of hydrogen cyanide. The cyanogenesis deficient1 (cyd1) mutant of Lotus japonicus carries a partial deletion of the CYP79D3 gene, which encodes a cytochrome P450 enzyme that is responsible for the first step in cyanogenic glucoside biosynthesis. The genomic region surrounding CYP79D3 contains genes encoding the CYP736A2 protein and the UDP-glycosyltransferase UGT85K3. In combination with CYP79D3, these genes encode the enzymes that constitute the entire pathway for cyanogenic glucoside biosynthesis. The biosynthetic genes for cyanogenic glucoside biosynthesis are also co-localized in cassava (Manihot esculenta) and sorghum (Sorghum bicolor), but the three gene clusters show no other similarities. Although the individual enzymes encoded by the biosynthetic genes in these three plant species are related, they are not necessarily orthologous. The independent evolution of cyanogenic glucoside biosynthesis in several higher plant lineages by the repeated recruitment of members from similar gene families, such as the CYP79s, is a likely scenario.