Text by Lauri Laanisto
Our PhD student Kaia has published her first first-author paper, which will probably be the cornerstone of her thesis. She has been studying the physiological nooks and crannies of heat stress in plants. What are the specific volatiles emitting under different stress rates and conditions. Black mustard is one of the main components of curry (and also other Indian foods), and we all know or have heard about how hot can it get in India. Especially in the recent years. There was a really bad one just this summer (link). Even though black mustard is considered heat tolerant species, these prolonged heat waves can still cause a lot of damage. So, whenever you feel glucosinolate in the air while near a black mustard field – you´ll now know that the mustard is in trouble!
(Not yet) full citation: Kask, K., Kännaste, A., Talts, E., Copolovici, L., & Niinemets, Ü. (2016). How specialized volatiles respond to chronic, and short‐term physiological and shock heat stress in Brassica nigra. Plant, Cell & Environment. link to full text)(
Brassicales release volatile glucosinolate breakdown products upon tissue mechanical damage, but it is unclear how the release of glucosinolate volatiles responds to abiotic stresses such as heat stress. We used three different heat treatments, simulating different dynamic temperature conditions in the field to gain insight into stress-dependent changes in volatile blends and photosynthetic characteristics in the annual herb Brassica nigra (L.) Koch. Heat stress was applied by either heating leaves through temperature response curve measurements from 20 to 40 °C (mild stress), exposing plants for 4 h to temperatures 25–44 °C (long-term stress) or shock-heating leaves to 45–50 °C. Photosynthetic reduction through temperature response curves was associated with decreased stomatal conductance, while the reduction due to long-term stress and collapse of photosynthetic activity after heat shock stress were associated with non-stomatal processes. Mild stress decreased constitutive monoterpene emissions, while long-term stress and shock stress resulted in emissions of the lipoxygenase pathway and glucosinolate volatiles. Glucosinolate volatile release was more strongly elicited by long-term stress and lipoxygenase product released by heat shock. These results demonstrate that glucosinolate volatiles constitute a major part of emission blend in heat-stressed B. nigra plants, especially upon chronic stress that leads to induction responses.