New Insights in Potato Leaf Freezing by Infrared Thermography

Abstract

Infrared thermography has been widely used to study freezing processes in freezing resistant plants but hardly in freezing susceptible species. Solanum tuberosum leaves get frost killed at −3 °C and are unable to frost harden. The basic nature of frost injury to potato leaves is not clear. By employment of infrared differential thermal analysis (IDTA) in combination with viability assessment, we aimed to clarify the mechanistic relationship between ice formation and frost injury. During controlled freezing of potato leaves two distinct freezing events were detected by IDTA. During the first freezing event, the ice wave propagated via the xylem and spread out within 60 s throughout the whole leaf. When leaves were rewarmed after this freezing event, they did not show any frost injury symptoms. We suggest that this non-lethal first ice wave is restricted to the extracellular space. When leaves remained exposed after this exotherm, a second freezing event with a diffuse freezing pattern without a distinct starting point was recorded. When thawed after this second freezing event, leaves always showed frost damage suggesting intracellular freezing. The freezing behavior of potato leaves and its relation to frost damage corroborates that control of ice nucleation is a key for frost protection.

Freeze dehydration vs. supercooling of mesophyll cells: Impact of cell wall, cellular and tissue traits on the extent of water displacement

“… Note : If something is already known about the species specific freezing behaviour, this is indicated under the point freezing behaviour. a Stegner et al ( 2019 ). b Sakai and Larcher ( 1987 ).…”

“…Mesophyll cells of C. limon were reported to exhibit non‐ideal equilibrium freezing, although results were obtained at lethal freezing temperatures (Anderson et al, 1983 ). In a recent study, S. tuberosum cells could be shown to briefly supercool before they freeze intracellularly around −3°C (Stegner et al, 2019 ). Mesophyll cells of T. fortunei are known to persistently supercool (Larcher et al, 1991 ).…”

In-planta Agrobacterium-mediated Stable hva1 and EPSPS Integration into Potato var. Agria Genome

“…In this study, we used the variety Agria (the predominant cultivated variety in Iran) which based on their previously classed as both frost and drought sensitive [42,43]. Agria seed and tuber was obtained from Seed and Plant Improvement Institute (SPII), Karaj.…”

Ice accommodation in plant tissues pinpointed by cryo-microscopy in reflected-polarised-light

“…Orientation of the polarised light was controlled by the polariser (6) and the analyser (7). Illumination was provided by an external cold light source, which was connected to the microscope with fiber optics (8) the cooled laboratory chest freezer upon completion of a freezing experiment caused intense condensation on the microscope; this was eliminated by rewarming without removing the lid and increasing the temperature with multiple heating pads (total heating power = 49.8 W) attached to the microscopic unit. Controlled rewarming ensured that the temperature of the microscope was always higher than the air inside of the cooling compartment, which completely ruled out condensation effects.…”

“…For the investigation of ice management processes in plant tissues various methods have been employed [1,3]: differential thermal analysis (DTA) [4,5], infrared imaging [6][7][8][9][10][11][12][13][14][15][16][17][18] and in particular infrared differential thermal analysis (IDTA), nuclear magnetic resonance (NMR)/ magnetic resonance imaging (MRI) [1,[19][20][21][22][23], microscopic observations [17,20,[24][25][26][27][28][29][30][31][32][33][34][35][36], indirect observation by freeze-substitution EM [37], cryo-scanning electron microscopy (cryo-SEM) [32,36,38] and X-ray phase contrast imaging [3]. All these approaches differ largely in the obtained resolution, the necessary expenses, time requirements and the gained information: ice is either directly visualised or indirectly detected by measurement of freezing exotherms or assessed by the remaining amount of liquid water.…”