Quantification of Infection by Alternaria cassiae Using Leaf Immuno-Autoradiography and Radioimmunosorbent Assays

The severity of fungal infection is usually estimated visually as a rating of injury. A more quantitative method was needed to ascertain the effect of additives used to enhance the virulence of mycoherbicidal preparations. A sensitive and accurate serological method is presented for quantitative measurement of Alternaria cassiae infection of Cassia obtusifolia. An antiserum was prepared against a homogenate of mycelium of A. cassiae. A fast and simple procedure of leaf immuno-autoradiography was developed for the visualization of A. cassiae mycelium on inoculated leaves. A radioimmunosorbent assay (RISA) was developed for quantification of the extent of fungal infection. As little as 1. 6 ng/ ml dry weight equivalent of mycelium could be detected by RISA. There was a linear relationship between the logarithm of the RISA values and the logarithm of fungus concentration up to 300 ng/ml. Reduced sensitivity of the assay was pronounced in extracts containing 400 μ g/ml or more fresh weight of leaves. There was 30–40 % cross-reactivity of the antiserum with two other species of Alternaria, as well as with Monilinia fructicola, and almost no reactivity was found with three other fungi tested.     

Multistage disruption of protoplasts by dikegulac

Dikegulac (2,3:4,6 di-o-isopropylidine-2-keto-I-gulonate) is a growth regulator used to differentially kill terminal apices, and it analogously inhibits basic metabolic functions in dividing cells, but not stationary cells, in suspension culture. This report demonstrates an analogous situation in isolated tobacco protoplasts. At the lowest concentrations, dikegulac partially suppresses division of the protoplasts. Higher concentrations are required to produce visual cytoplasmic damage to the protoplasts, which probably first occurs at the level of the plasmalemma, as the vacuoles can be released intact. Later, tonoplast disruption occurs.Abbreviation FDA fluorescein diacetate     

Morphogenesis in Trichoderma: Action spectrum of photoinduced sporulation

Summary An action spectrum for photoinduced sporulation (conidia formation) in Trichoderma viride is presented. The detectable quantum efficiency was between 350 and 550 nm with peaks near 380 and 440 nm with a minimum at about 400 nm. Essentially no sporulation occurred at 254 nm or from 525 to 1100 nm. The half maximum response is reached with 6.6·10^-10 Einstein/cm² at 447 nm.     

Catabolism of single ring aromatic acids by four Aspergillus species

Four species of the genus Aspergillus, viz A. fumigatus, A. japonicus, A. niger and A. terreus, decarboxylated, demethoxylated and ring-cleaved aromatic compounds but to different extents. Decarboxylation of vanillate occurred before ring-cleavage, which preceded the release of 14CO2 from the methoxyl group. A large proportion of labelled carbon from the ring of ferulate and vanillate was found in particulate or trichloracetic acid precipitable material of homogenized fungal mycelium. The four Aspergillus species contained vanillate-inducible protocatechuate-3,4-dioxygenase and catechol-1,2-dioxygenase activities.     

The twin terrors – a biological solution

Drug-related crime and international drug trafficking are undercut by biotechnology - the use of aerially applied pathogens and insects against narcotic plants in this biothriller novel.     

Effects of dikegulac, a new growth regulator, on RNA syntheses in Spirodela

The effects of dikegulac sodium on plastid RNA syntheses werestudied, as dikegulac induces the formation of yellow misshapenleaves. It depressed uridine incorporation into both plastidand cytoplasmic ribosomal RNAs of axenically cultured Spirodela(duckweed). With short labeling time (1 hr) dikegulac specificallysuppressed the synthesis of a plastid 1.2 ? 10⁶ MW RNA species,as well as nonspecifically depressing incorporation. With longerlabeling time (24 hr), the incorporation into mature plastidrRNAs was suppressed to a greater extent than that into cytoplasmicrRNAs. The inhibitions of uridine incorporation caused by dikegulacare probably indirect and a reflection of its effect on othergrowth parameters. (Received September 25, 1976; )     

Recent advances in the biocontrol of Orobanche (broomrape) species

Parasitic broomrapes (Orobanche spp.) are majoruncontrolled weeds in the Mediterranean regions of Europe and the NearEast causing major losses to vegetable, grain legume, and sunflowercrops. Selective herbicides alone cannot provide persistent, season-longcontrol of these parasites, and much methyl bromide is used for theircontrol, where affordable. Thus they are excellent targets forbiocontrol. The recent progress by the COST 816 Orobancheworking group in this area is reviewed herein. Natural infestation bythe fly Phytomyza orobanchia of seed capsules of Orobanchecrenata parasitising faba bean halved Orobanche seedproduction while inundative releases of adults reduced it to 5%of viable seeds. The fungi Fusarium arthrosporioides E4a andF. oxysporum E1d, as well as strains of bacteria were isolatedfrom diseased, juvenile, Orobanche flower stalks. They arepathogenic to O. aegyptiaca, O. crenata and O. ramosaon most vegetable crops. A F. oxysporum f. sp.orthoceras was specifically pathogenic to O. cumana onsunflowers. All were used in various experiments with a modicum ofsuccess. Methods were developed to formulate isolated mycelia, whichcould eventually allow the use of transgenic hypervirulent pathogens inasporogenic (deletion) mutants (as a failsafe against spread).Mycotoxins were also isolated from different Fusarium and otherfungal species that kill Orobanche, and are being consideredfor direct use, or to augment other strategies. All threeFusarium spp. used have been transformed with gusand/or gfp genes allowing tracing their movement in theenvironment, and opening the way to future transformations tohypervirulence.     

Solar pasteurization of straw for nutritional upgrading and as substrate for ligninolytic organisms

Summary Solar digesters were designed to wet pasteurize straw. Microbial levels were reduced, precluding competition with ligninolytic organisms. The pasteurization treatment alone increased the available cellulose by 20–40%. Ligninolytic organisms produced biomass with 6–8% protein on pasteurized wheat straw.