Dieback-affected papaya plants were characterized by a discoloration of the contents of laticifers, while the anatomy of sieve elements was healthy in appearance until the necrotic stages of the disorder were reached. Laticifer discoloration was not always associated with the presence of phytoplasma in affected tissue, as judged by polymerase chain reaction (PCR) using primers based on the 16S rRNA gene and 16S-23S intergenic spacer region. Phytoplasma DNA was detected in a range of plant tissues, including roots, but not in mature leaves which would act as photoassimilate sources. As plants recovered from a dieback period, the extent of the distribution of both laticifer discoloration and phytoplasma DNA decreased. Phytoplasma cells were not observed in transmission electron microscopy studies of mature sieve elements of dieback-affected leaf, stem, or fruit tissue from plants at various stages of symptom expression, although PCR tests indicated the presence of phytoplasma DNA. Membrane-bound structures, similar in shape and size to phytoplasma cells but interpreted as autophagic vesicles or latex vesicles in immature laticifers, were observed within vacuoles of cells in phloem tissue in leaves displaying tissue breakdown in the form of a water-soaked appearance to veins (“X-Y” patterning). In contrast, phytoplasmas were readily observed in papaya leaves displaying symptoms of yellow crinkle. We conclude that phytoplasma cells are present in very low titer in dieback-affected tissues and that, while the plant appears to limit proliferation of the dieback-associated pathogen, this defense strategy is ultimately unsuccessful because it is associated with a rapid decline of the papaya plant.
Proteases with characteristic stabilities are considered attractive candidates for industrial catalysis. In the present study, a potent bacterial strain KT004404, an inhabitant of hydrothermal vents, was isolated and characterized for protease production. Initial screening indicated that this strain produced a hydrolytic zone of 30 mm 16S rRNA-based identification revealed that our isolate was a strain of Bacillus subtilis. Optimum reaction condition for maximum protease production was determined as 55 °C, pH 6, 1 % inoculum size and malt extract as primary growth substrate supplemented with 1 % dextrose. Yield of the enzyme was increased up to 7.53 folds with a specific activity of 55.125 U/mg after gel filtration chromatography. SDS-PAGE analysis confirmed the size of protease as 28.24 kDa. Purified enzyme retained its catalytic activity over a broad range of temperature (5 to 65 °C) and pH [5-8]. Addition of metal ions shown to have a stimulatory effect on catalytic properties while EDTA inhibited the efficiency of the enzyme confirming it as a metalloprotease. Protease exhibited excellent stability and activity in the presence of anionic surfactants, solvents, and detergents. The results of dehairing and destaining experiments suggested that the protease produced by B. subtilis KT004404 could be used in leather and textile industries with ecological benefits.
Nitrogen fixation in legume root nodules is believed to be supported by the supply of photosynthate of the current photoperiod. However, in peanut nodules, prolonged periods of darkness or detopping do not disrupt nitrogen fixation for at least 48 h. During this period, nodule oleosomes (lipid bodies) have been shown to decrease in number within the infected cells, and it has been suggested that lipids from oleosomes are mobilized to maintain the energy and carbon requirements of the nitrogen-fixing nodules. We present morphological evidence, at the ultrastructural level, for the utilization of oleosomes during photosynthate stress. The biochemical status of the nodule has also been assessed and correlated with ultrastructure. For comparison cowpea nodules were used that totally lacked oleosomes. In peanut nodules leghemoglobin and total protein remained unchanged along with integrated ultrastructure on nodule cells for 48 h, whereas in cowpea a decline in proteins with ultrastructural damage became apparent within a very short period of photosynthate stress. In peanut nodules empty or partially empty oleosomes were taken as evidence for their utilization during the stress period. Key words: N2 fixation, photosynthate stress, lipid bodies, catalase, malate synthase, peanut nodule, β-oxidation.
Gerbera (Gerbera jamesonii L.) plants with phyllody symptoms (green flower) were observed in Central Queensland, Australia. Leaves and flowers from both symptomatic and asymptomatic healthy plants were examined by transmission electron microscopy (TEM). The presence of pleomorphic bodies similar to phytoplasma was observed exclusively in diseased plants. Polymerase chain reaction (PCR) with phytoplasmaspecific primers confirmed the presence of phytoplasma DNA in the infected plants. Further DNA sequencing analysis of the PCR product revealed high homology with other phytoplasma DNA in the database. Based on phylogenetic analysis of 16S rRNA the gerbera phyllody phytoplasma was grouped under Peanut witchesÕ broom as described by Lee et al. (1998). The results of TEM, PCR and sequencing analysis clearly indicate phytoplasmal association with phyllody disease of gerbera.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.