TY - JOUR

T1 - Wheat cultivars selected for high Fv/Fm under heat stress maintain high photosynthesis, total chlorophyll, stomatal conductance, transpiration and dry matter

AU - Sharma, Dew Kumari

AU - Andersen, Sven Bode

AU - Ottosen, Carl Otto

AU - Rosenqvist, Eva

PY - 2015

Y1 - 2015

N2 - The chlorophyll fluorescence parameter Fv/Fm reflects the maximum quantumefficiency of photosystem II (PSII) photochemistry and has been widely usedfor early stress detection in plants. Previously, we have used a three-tieredapproach of phenotyping by Fv/Fm to identify naturally existing genetic variationfor tolerance to severe heat stress (3 days at 40∘C in controlled conditions)in wheat (Triticum aestivum L.). Here we investigated the performance of thepreviously selected cultivars (high and low group based on Fv/Fm value) interms of growth and photosynthetic traits undermoderate heat stress (1 week at36/30∘C day/night temperature in greenhouse) closer to natural heat waves inNorth-Western Europe. Dry matter accumulation after 7 days of heat stresswaspositively correlated to Fv/Fm. The high Fv/Fm group maintained significantlyhigher total chlorophyll and net photosynthetic rate (PN) than the low group,accompanied by higher stomatal conductance (gs), transpiration rate (E) andevaporative cooling of the leaf (ΔT). The difference in PN between the groupswas not caused by differences in PSII capacity or gs as the variation in Fv/Fmand intracellular CO2 (Ci) was non-significant under the given heat stress. Thisstudy validated that our three-tiered approach of phenotyping by Fv/Fm performedunder increasing severity of heat was successful in identifying wheatcultivars differing in photosynthesis under moderate and agronomically morerelevant heat stress. The identified cultivars may serve as a valuable resourcefor further studies to understand the physiological mechanisms underlying thegenetic variability in heat sensitivity of photosynthesis.

AB - The chlorophyll fluorescence parameter Fv/Fm reflects the maximum quantumefficiency of photosystem II (PSII) photochemistry and has been widely usedfor early stress detection in plants. Previously, we have used a three-tieredapproach of phenotyping by Fv/Fm to identify naturally existing genetic variationfor tolerance to severe heat stress (3 days at 40∘C in controlled conditions)in wheat (Triticum aestivum L.). Here we investigated the performance of thepreviously selected cultivars (high and low group based on Fv/Fm value) interms of growth and photosynthetic traits undermoderate heat stress (1 week at36/30∘C day/night temperature in greenhouse) closer to natural heat waves inNorth-Western Europe. Dry matter accumulation after 7 days of heat stresswaspositively correlated to Fv/Fm. The high Fv/Fm group maintained significantlyhigher total chlorophyll and net photosynthetic rate (PN) than the low group,accompanied by higher stomatal conductance (gs), transpiration rate (E) andevaporative cooling of the leaf (ΔT). The difference in PN between the groupswas not caused by differences in PSII capacity or gs as the variation in Fv/Fmand intracellular CO2 (Ci) was non-significant under the given heat stress. Thisstudy validated that our three-tiered approach of phenotyping by Fv/Fm performedunder increasing severity of heat was successful in identifying wheatcultivars differing in photosynthesis under moderate and agronomically morerelevant heat stress. The identified cultivars may serve as a valuable resourcefor further studies to understand the physiological mechanisms underlying thegenetic variability in heat sensitivity of photosynthesis.

U2 - 10.1111/ppl.12245

DO - 10.1111/ppl.12245

M3 - Journal article

VL - 153

SP - 284

EP - 298

JO - Physiologia Plantarum

JF - Physiologia Plantarum

SN - 0031-9317

IS - 2

ER -