The anatomy of diseased stems from brooms induced on cocoa (Theobroma cacao) by the fungus Crinipellis perniciosa was examined using the scanning electron microscope, and the amounts of selected cytokinins were measured by immunoassay.
Although the diseased stems were wider in diameter with a lower dry weight:fresh weight ratio than stems of healthy plants, the overall internal organization of tissues remained unchanged, and all the cell types were present. However, the vascular tissue was less differentiated in diseased stems since xylem vessels were absent and the ratio of phloem fibres and sieve tubes to phloem parenchyma was reduced. Cell sizes in diseased stems were larger for all tissues but cell numbers were unchanged except for xylem where fewer cells were seen.
Cytokinins (zeatin, zeatin riboside, isopentenyl adenine and isopentenyl adenosine) were measured in healthy plants and diseased stems at specific stages of disease development. Of these cytokinins only zeatin riboside was present in significantly greater amounts in diseased tissue. The likely role of plant growth regulator balance in stem enlargement and proliferation in witches' broom disease of cocoa is discussed.
The Indian pygmy bat Pipistrellus mimus produced two young per litter, which were altricial at birth. Empirical growth curves were derived by measuring length of forearm, body mass, and length of the total gap of the fourth metacarpal-phalangeal joint. Length of forearm and body mass followed a linear pattern of growth until day 20 and subsequently reached stability. The length of the total gap of the metacarpal-phalangeal joint showed a linear increase up to 20 days, followed by a linear decrease until ca. 80 days when it closed. A quantitative method of estimation of age was derived from values of length of forearm and length of the total gap of the fourth metacarpal-phalangeal joint during the preflight (first 20 days) and postflight stages, respectively. Width of the 95% confidence level was ±0.6 days at a mean length of forearm of 15.1 mm, and it was ±0.9 days at a mean length of the total gap of the fourth metacarpal-phalangeal joint of 2.0 mm. Initiation of flight occurred 21 days after birth. At 33 days of age, young were able to forage on their own. Females experienced their first parturition at the mean age of 112 days. Females of P . . mimus apparently attains sexual maturity within 2 months after birth, which may be the youngest age for sexual maturity in a bat.
The symptoms of witches' broom disease in cocoa, caused by the Basidiomycete fungus Crinipellis perniciosa, are pronounced swelling of the terminal and axillary buds followed in the long term by necrosis of this tissue. The direct effect of C. perniciosa on cocoa cells was examined under controlled conditions by growing primary and secondary phase cultures of the fungus separately and also with callus cultures and with cell suspensions. Both primary and secondary phase mycelium reduced growth of callus cultures by about 47% after one week compared with the controls. However, cell suspensions containing primary phase mycelium showed initial growth double that of the uninfected controls after 5 days, but then growth was reduced below that of the control and particularly when the primary phase became secondary phase mycelium. This change in fungal development coincided with the time that the cell culture reached the stationary growth stage. Cell cultures inoculated with stationary phase mycelium showed the same growth as the control after 5 days but then growth was reduced to 50% of the control after 19 days incubation and remained at this low level subsequently. The inhibitory effect of secondary phase mycelium was examined by incubating callus and cell suspensions with culture filtrate from liquid cultures of the secondary phase. Inclusion of 50% by volume of culture filtrate from the secondary phase in the growth medium for callus and cell suspensions, respectively, resulted in a reduction in growth of the plant tissue cultures. Addition of fungal culture filtrates also led to loss in potassium and loss of viability of cell suspensions and of isolated cells as represented by protoplasts. The necrotrophic mode of the secondary phase may be achieved through the production of phytotoxins acting on the host cell membrane.
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