Phosphorous fertilization alleviates drought effects on Alnus cremastogyne by regulating its antioxidant and osmotic potential

Akash Tariq,Lin Zhang,Zilong Li,Aiping Zhang,Tan Xue,Wenkai Chen,Olusanya Abiodun Olatunji,Xiaogang Wu,Dan Huang,Feng Sun,Corina Graciano,Dagang Song,Kaiwen Pan

doi:10.1038/s41598-018-24038-2

Akash Tariq, Lin Zhang + Show 11 more

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https://doi.org/10.1038/s41598-018-24038-2

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Alnus cremastogyne, a broad-leaved tree endemic to south-western China, has both commercial and restoration importance. However, little is known of its morphological, physiological and biochemical responses to drought and phosphorous (P) application. A randomized experimental design was used to investigate how drought affected A. cremastogyne seedlings, and the role that P applications play in these responses. Drought had significant negative effects on A. cremastogyne growth and metabolism, as revealed by reduced biomass (leaf, shoot and root), leaf area, stem diameter, plant height, photosynthetic rate, leaf relative water content, and photosynthetic pigments, and a weakened antioxidative defence mechanism and high lipid peroxidation level. However, the reduced leaf area and enhanced osmolyte (proline and soluble sugars) accumulation suggests drought avoidance and tolerance strategies in this tree. Applying P significantly improved the leaf relative water content and photosynthetic rate of drought-stressed seedlings, which may reflect increased anti-oxidative enzyme (superoxide dismutase, catalase and peroxidase) activities, osmolyte accumulation, soluble proteins, and decreased lipid peroxidation levels. However, P had only a slight or negligible effect on the well-watered plants. A. cremastogyne is sensitive to drought stress, but P facilitates and improves its metabolism primarily via biochemical and physiological rather than morphological adjustments, regardless of water availability.

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Global climate models predict alterations in inter- and intra-annual precipitation in many regions of the world[1]
Irrespective of the P application, there was a significant reduction in leaf biomass (38.29%), shoot biomass (65.73%), leaf area (50.32%) and stem diameter (24.88%) of A. cremastogyne under drought stress compared with well-watered conditions
Our result showed that biomass and growth of A. cremastogyne was significantly reduced under drought stress when compared with well-watered growing conditions, which may be explained by associated leaf area and stem diameter reductions (Table 1)

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Global climate models predict alterations in inter- and intra-annual precipitation in many regions of the world[1]. CO2 inhibition leads to excess excitation energy and electron fluxes to O2, which results in photo-oxidative damage of the cell components through an over-generation of reactive oxygen species (ROS), and eventually photo-inhibition[5]. Complex ROS scavenging enzymatic (superoxide dismutase [SOD], peroxidase [POD], catalase [CAT], etc.) and non-enzymatic antioxidant systems, such as low-molecular mass antioxidants (glutathione, ascorbate, carotenoids), are involved in managing excessive energy to alleviate oxidative stress under drought conditions[9]. These enzymatic components may directly scavenge ROS or produce a non-enzymatic antioxidant. A response or tolerance to drought stress varies with plant species, stress intensity and growth stage[11]

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