Varietal similarities and differences in the polycyclic isopentenoid composition of sorghum

The intraspecific similarities and differences among the various polycyclic isopentenoids (sterols and pentacyclic triterpenes) which occur in leaf tissue and surface wax from three varieties of flowering Sorghum bicolor; G499 GBR, BOK 8 and IS 809, have been determined. The three varieties exhibited differences in phenotypic characters (e.g. shoot height) and pest resistance. While sterol and pentacyclic amyroid compositions were similar in the three varieties, significant differences were evident in the qualitative distribution of the migrated hopanoids. One variety, IS 809, which is phenotypically short and resistant, contained a single migrated hopanoid, sorghumol Alternatively, the other two varieties, both phenotypically tall and one-G 499 GBR-resistant, the other-BOK 8-susceptible, contained a mixture of four Δ⁹⁽¹¹⁾-migrated hopanoids, i.e. sorghumol and three of its stereoisomers, and the Δ⁵⁽⁶⁾-migrated hopanoid simiarenol. While ketones corresponding to the Δ⁹⁽¹¹⁾-migrated hopanoids were detected in the three varieties, the ketone of the Δ⁵⁽⁶⁾-migrated hopanoid was apparently absent. In contrast to other graminaceous plants, the predominant C-3 derivatives did not include the C-3 methyl ethers, but did include esters and polar conjugates. Significant differences apparent in amounts of pentacyclic triterpenes were not apparent in the total amount of sterols extracted from the leaves (including surface wax) of the three varieties. Since S. bicolor varietal differences occurred only among the migrated hopanoids (found in mature leaves) it would appear that pentacyclic triterpenes, unlike sterols, have greater applicability as chemotaxonomic indices for intraspecific relationships in sorghum.     

Effects of light and temperature on the composition of epicuticular wax of barley leaves

The amount of wax/cm² on expanding primary leaves of Bonus barley depends on both the photo- and thermoperiods in which the seedlings are grown. With a temperature cycle of 15–10°, transfer of dark grown leaves to the light stopped leaf expansion and after 24 hr yielded 2·5 times more wax/cm² than is characteristic for light grown leaves. This demonstrates that wax synthesis and extrusion is not directly correlated with leaf expansion. The relative amounts of the wax classes formed by the decarboxylation pathways (< 1%), the reductive pathways (89%) or only by elongation (10%) are the same in light and dark. Within the reductive pathways, however, light stimulates aldehyde formation. Both environmental parameters can strongly influence the chain length composition of the wax classes. In the light one chain length or one group of chain lengths dominates a given wax class. In the dark two prominent chain lengths or groups thereof are found. The major chain length in these two groups differs by two or more carbons.     

Ultrasonic mate calling in the lesser wax moth

ABSTRACT. The lesser wax moth, Achroia grisella (Fabricius) (Pyralidae: Galleriinae), uses an altrasonic communication system for mate calling The male produces a 100 kHz sound by striking its tegula with the forewing. This calling sound induces virgin females to orient toward males. Although the pheromone released from the male's wing glands may stimulate kinesis in females, it does not elicit orientation. Female moths are attracted toward synthetic 40 and 72 kHz sounds which simulate the pulse length and repetition rate of the male's calling signal.     

p-Hydroxybenzaldehyde as a major constituent of the epicuticular wax of seedling Sorghum bicolor

p-Hydroxybenzaldehyde is present in concentrations up to 30% in the wax of Sorghum bicolor seedlings. It is highly deterrent to locusts, reducing their normal feeding by 90%.