Thermoregulation adaptation of Rheum tanguticum stereostructure leaf
Abstract Background: Leaf is an important plant organ with great variation in shape and size. Leaf size tends to be smaller in plants thrived in the areas of higher elevation and lower annual mean temperature. The Qinghai-Tibetan Plateau is situated at a high altitude of >4,000 m with low annual average temperature. Leaves for most plants species in Qinghai-Tibetan Plateau are small, however, Rheum tanguticum with large leaves is an exception. Here we show that large leaf of R. tanguticum with three-dimensional structure is an ideal solution of thermoregulation with little energy consumption.Results: With increase in age, leaves of R. tanguticum transit from a small oval plane to a large palmatipartite stereostructure. Furthermore, temperature variation of different parts is a distinct character in stereostructure leaves of R. tanguticum. The temperature of regular leaves under strong solar radiation could be much higher than the ambient temperature. However, the stereostructure leaf could lower leaf temperature by avoiding the direct solar radiation and promoting local airflow to prevent serious scorch.Conclusions: Our results demonstrate that the robust three-dimensional leaf structure is a formation for R. tanguticum to adapt to the strong solar radiation and low temperature in Qinghai-Tibetan Plateau through modulation of local temperature in different parts of the large leaves.