Influence of tobacco leaf surface chemicals on germination ofPeronospora tabacina adam sporangia

Abstract

Chromatographic procedures were utilized to isolate and purify components of tobacco cuticular extracts and leaf surface chemicals.In vitro microbial bioassays determined the influence of these leaf surface compounds on germination and germ tube morphology ofP. tabacina sporangia, the tobacco blue mold pathogen, and to a lesser extentAlternaria alternata, the tobacco brown spot pathogen. Exposure to 10 μg/cm(2) of α- and β-duvatrienemonols, sucrose esters, or hydrocarbons did not inhibit germination, whereas germination was significantly decreased bycis-abienol.cis-Abienol did not inhibit sporangial germination when combined with sucrose esters or hydrocarbons at a combined 10 μg/cm(2). Germination of sporangia was completely inhibited by α- and β-duvatrienediols. In contrast to a previous report, α-DVT-diol was more inhibitory than the β isomer. Toxic effects of the DVT-diols were not altered by pH. Diluting the DVT-diols to less than 0.1 μg/cm(2) resulted in a small but significant stimulation of germination. Previously, the DVT-diols had been identified only as inhibitory toP. tabacina. None of the leaf surface chemicals affected germination ofA. alternata conidia.

Use of Several Natural Products from Selected Nicotiana Species to Prevent Black Shank Disease in Tobacco

“…These chemicals have previously shown antifungal, insecticidal, and antibacterial properties (14,19,20,22,29,37,38) but have not been studied for black shank prevention. There are preliminary indications that cis-abienol and phylloplanin have a potential against black shank in laboratory conditions (22).…”

A Review on Bioactivities of Tobacco Cembranoid Diterpenes

“…Tobacco cembranoid diterpenes have good antifungal [12,13,14,15,16,17], antibacterial [18], and antiviral [19,20,21] activities. The antifungal activity of tobacco cembranoid diterpenes was first reported in 1990 [12].…”

Phylloplanins of Tobacco Are Defensive Proteins Deployed on Aerial Surfaces by Short Glandular Trichomes

“…TGST exudate accumulates under the cuticle surrounding the gland and may pass through cuticular striae to migrate down the trichome stalk to disperse widely on the leaf surface, and exudate can accumulate to ;17% of leaf dry weight. Leaf exudate cembratriene diols (a-CBT-diols and b-CBT-diols), labdenediol, sclareol, and sucrose esters, in sufficient amounts, have been reported to inhibit P. tabacina spore germination (Cruickshank et al, 1977;Menetrez et al, 1990;Kennedy et al, 1992). However, resistance is found only in species and cultivars that accumulate high levels of these compounds or when they are applied experimentally.…”