Comparison of microstructure and physiological response of the leaves of six Rosa rugosa genotypes under drought stress

Abstract

Rosa rugosa is a deciduous shrub of the rosa family having ecological, economical, and ornamental values. In this study, the cutting seedlings of wild R. rugosa and five cultivated varieties were treated with polyethylene glycol-6000 (PEG-6000) solution to mimic drought stress. The leaf transpiration rate (Tr), photosynthetic rate (Pn), stomatal conductance (Gs), and the relative water content (RWC) of all genotypes decreased under drought stress. Importantly, the Tr in wild R. rugosa (W) was decreased by 29.42% under 5% PEG treatment, whereas that in other varieties was decreased by 57.63%–74.54%. Similarly, the Pn and Gs of genotype W were significantly higher in W than in other genotypes under 5% PEG treatment. The malondialdehyde (MDA) contents in five cultivated varieties were significantly increased under 5%–10% PEG treatments, and that in W was increased under 15% PEG treatment. In summary, the drought resistance of wild R. rugosa was the strongest, followed by that of ZZ, S, and P, and the drought resistance of ZD and F was the poorest. To explore the adaptation characteristics of R. rugosa leaves to drought stress, the leaf surface and microstructure of six genotypes were observed. The characteristics of the wild leaves such as sunken stomata, developed palisade tissue, and low stomatal density may reduce the water loss, resulting in significantly higher drought tolerance than the other five cultivated varieties. This study elucidated the difference of drought resistance among the six R. rugosa genotypes, and enhanced the understanding of the regulatory mechanisms of drought tolerance.

Keywords

• drought stress
• physiological response
• blade structure
• rosa rugosa