Significant relationships among frost tolerance and net photosynthetic rate, water use efficiency and dehydrin accumulation in cold-treated winter oilseed rapes

Abstract

Five winter oilseed rape cultivars (Benefit, Californium, Cortes, Ladoga, Navajo) were subjected to 30 days of cold treatment (4 °C) to examine the effect of cold on acquired frost tolerance (FT), dehydrin (DHN) content, and photosynthesis-related parameters. The main aim of this study was to determine whether there are relationships between FT (expressed as LT50 values) and the other parameters measured in the cultivars. While the cultivar Benefit accumulated two types of DHNs (D45 and D35), the other cultivars accumulated three additional DHNs (D97, D47, and D37). The similar-sized DHNs (D45 and D47) were the most abundant; the others exhibited significantly lower accumulations. The highest correlations were detected between LT50 and DHN accumulation (r=-0.815), intrinsic water use efficiency (WUEi; r=-0.643), net photosynthetic rate (r=-0.628), stomatal conductance (r=0.511), and intracellular/intercellular CO2 concentration (r=0.505). Those cultivars that exhibited higher Pn rate in cold (and further a significant increase in WUEi) had higher levels of DHNs and also higher FT. No significant correlation was observed between LT50 and E, PRI, or NDVI. Overall, we have shown the selected physiological parameters to be able to distinguish different FT cultivars of winter oilseed rape.

Keywords: ABA; AP; BEN; CA; CAL; COR; COR/LEA; Ci; Cold acclimation; D47, D45, D37 and D35 stand for dehydrin accumulation according to their different molecular masses from protein gel blot analysis (∼97, ∼47, ∼45, ∼37 and ∼35 kD); D97; DHN; Dehydrin; E; FT; Frost tolerance; GS; LAD; LT(50); NAV; NBT/BCIP; NDVI; PCA; PRI; Photosynthesis; Pn; SDS–PAGE; WUE; WUEi; Winter oilseed rape; abscisic acid; alkaline phosphatase; cold acclimation or cold acclimated; cold regulated/late embryogenesis abundant; cultivar Benefit; cultivar Californium; cultivar Cortes; cultivar Ladoga; cultivar Navajo; cultivars; cvs; dehydrin; frost tolerance; internal leaf CO(2) concentration; intrinsic water use efficiency (Pn/GS); lethal temperature for 50% of plants; net photosynthetic rate; nitro-blue tetrazolium/5-bromo-4-chloro-3′-indolyphosphate; normalized difference vegetation index; photochemical reflectance index; principal component analysis; sodium dodecyl sulphate polyacrylamide gel electrophoresis; stomatal conductance; transpiration; water use efficiency (Pn/E).