A novel approach for isolation of volatile chemicals released by individual leaves of a plant in situ

A glass chamber designed specifically for collecting volatile chemicals fro m individual leaves of a plant in situ is described. The effectiveness of t he chamber was demonstrated by collecting volatile chemicals from single le aves of two plant species, potato (Solanum tuberosum) and broad bean (Vicia faba), before and after mechanical damage. The glass chamber, in conjuncti on with thermal desorption, enables reduction of the entrainment time and t hereby allows the monitoring of compounds released by leaf damage in succes sive 5-min periods. An intact broad bean leaf, in the middle of the day, pr oduces small amounts of the green leaf volatiles (E)-2-hexenal and (Z)-3-he xen-1-ol. However, during the first 5 min after mechanical damage, large am ounts of (Z)-3-hexenal, (E)-2-hexenal, and (Z)-3-hexen-1-ol are produced. T he decline in production of (Z)-3-hexenal and (E)-2-hexenal is fast, and af ter 10 min, these compounds reach very low levels. (Z)-3-Hexen-1-ol shows a n increase for the first 10 min and then a gradual decline. An intact potat o leaf, in the middle of the day, produces very small amounts of the sesqui terpene hydrocarbons P-caryophyllene and germacrene-D. After being damaged, the profile of released volatiles is different from that of broad bean. In potato, damage is associated with release of large amounts of green leaf v olatiles and sesquiterpene hydrocarbons. Compounds such as (Z)-3-hexenal, ( E)-2-hexenal, and (Z)-3-hexen-1-ol are released in high amounts during the first 5 min after damage, but after 10 min, these drop to very low levels. High release associated with damage is also observed for beta-caryophyllene , (E)-beta-farnesene, germacrene-D, and beta-bisabolene. The highest level is reached 5 min after damage and 15 min later, these compounds drop to low levels. The significance of compounds released after plant damage is discu ssed.