Comparative analysis of sorghum (C4) and rice (C3) plant headspace volatiles induced by artificial herbivory.

Acute stress responses include release of defensive volatiles from herbivore-attacked plants. Here we used two closely related monocot species, rice as a representative C3 plant, and sorghum as a representative C4 plant, and compared their basal and stress-induced headspace volatile organic compounds (VOCs). Although both plants emitted similar types of constitutive and induced VOCs, in agreement with the close phylogenetic relationship of the species, several mono- and sesquiterpenes have been significantly less abundant in headspace of sorghum relative to rice. Furthermore, in spite of generally lower VOC levels, some compounds, such as the green leaf volatile ( Z )-3-hexenyl acetate and homoterpene DMNT, remained relatively high in the sorghum headspace, suggesting that a separate mechanism for dispersal of these compounds may have evolved in this plant. Finally, a variable amount of several VOCs among three sorghum cultivars of different geographical origins suggested that release of VOCs could be used as a valuable resource for the increase of sorghum resistance against herbivores.