The rice green semi looper, Naranga aenescens Moore (Lepidoptera: Noctuidae) causes severe damage to rice fields in Eastern Asia and Middle East. We demonstrate that two types of serine proteases are active in the midgut of the third instar larvae of N. aenescens, but trypsin-like proteases are considerably more active than chymotrypsin-like proteases. To develop better control strategies, purification and biochemical characterization of a major trypsin-like digestive protease from the midgut of the third instar larvae of N. aenescens was achieved by gel filtration and anion exchange chromatography. After the final purification step, the enzyme was purified 9.62-fold with a recovery of 16.1% and a specific activity of 4.12 U/mg protein and a molecular mass of approximately 88.5 kDa. Biochemical characterization indicated that the purified protease had highest activity at pH 10 and 30°C and was stable for up to 6 h under those conditions. Divalent cations, especially Ca2+, Mg2+, and Cu2+, increased the enzyme activity and synthetic inhibitors that target trypsin-like activity caused a significant reduction in caseinolytic activity. These data may be used to develop inhibitors that decrease the damage of N. aenescens to rice cultivars in the field.

No abstract

Plants perceive environmental stresses as whole organisms via distant signals conveying danger messages through their vasculature. In parallel to vascular transport, airborne plant volatile compounds, including green leaf volatiles (GLVs), can bypass the lack of vascular connection. However, some small volatile compounds move through the vasculature; such vascular transport is little known about GLVs. Here we illustrate GLV alcohols as solutes move within xylem vessels in Zea mays. We describe GLV alcohols, including Z-3-hexenol and its isomer E-3-hexenol, which is not synthesized in maize, is mobilized through the transpiration stream via xylem vessels. Since transpiration is mediated by stomatal aperture, closing stomata by two independent methods diminishes the transport of GLV alcohol and its isomer. In addition, lower transport of GLV alcohols impairs their function in inducing terpenoid biosynthesis suggesting xylem transport of GLV alcohols plays a significant role in their systemic function. Our study not only shows that GLV alcohols can be transported in the xylem but points to stomatal regulation as a mechanism that climatic factors such as drought, heat, flooding, and high CO levels affect systemic signaling functions of GLVs.

Plants perceive environmental stresses as whole organisms via distant signals conveying danger messages through their vasculature. In parallel to vascular transport, airborne plant volatile compounds, including green leaf volatiles (GLVs), can bypass the lack of vascular connection. However, some small volatile compounds move through the vasculature; such vascular transport is little known about GLVs. Here we illustrate GLV alcohols as solutes move within xylem vessels in Zea mays. We describe GLV alcohols, including Z-3-hexenol and its isomer E-3-hexenol, which is not synthesized in maize, is mobilized through the transpiration stream via xylem vessels. Since transpiration is mediated by stomatal aperture, closing stomata by two independent methods diminishes the transport of GLV alcohol and its isomer. In addition, lower transport of GLV alcohols impairs their function in inducing terpenoid biosynthesis suggesting xylem transport of GLV alcohols plays a significant role in their systemic function. Our study not only shows that GLV alcohols can be transported in the xylem but points to stomatal regulation as a mechanism that climatic factors such as drought, heat, flooding, and high CO levels affect systemic signaling functions of GLVs.