Abstract

BackgroundThe leaf is an important plant organ, and how it will respond to future global warming is a question that remains unanswered. The effects of experimental warming on leaf photosynthesis and respiration acclimation has been well studied so far, but relatively little information exists on the structural and biochemical responses to warming. However, such information is very important to better understand the plant responses to global warming. Therefore, we grew Arabidopsis thaliana at the three day/night temperatures of 23/18°C (ambient temperature), 25.5/20.5°C (elevated by 2.5°C) and 28/23°C (elevated by 5°C) to simulate the middle and the upper projected warming expected within the 21st century for this purpose.ResultsThe 28/23°C treatment significantly reduced the life span, total biomass and total weight of seeds compared with the other two temperatures. Among the three temperature regimes, the concentrations of starch, chlorophyll, and proline were the lowest at 28/23°C, whereas the total weight of seeds, concentrations of chlorophyll and proline, stomatal density (SD), stomatal conductance (gs), net CO2 assimilation rate (A) and transpiration rate (E) were the highest at 25.5/20.5°C. Furthermore, the number of chloroplasts per cell and mitochondrial size were highest at 25.5/20.5°C and lowest at 28/23°C.ConclusionsThe conditions whereby the temperature was increased by 2.5°C were advantageous for Arabidopsis. However, a rise of 5°C produced negative effects, suggesting that lower levels of warming may benefit plants, especially those which belong to the same functional group as Arabidopsis, whereas higher levels of warming may produce negative affects. In addition, the increase in A under moderately warm conditions may be attributed to the increase in SD, chlorophyll content, and number of chloroplasts. Furthermore, starch accumulation in chloroplasts may be the main factor influencing chloroplast ultrastructure, and elevated temperature regulates plant respiration by probably affecting mitochondrial size. Finally, high SOD and CAT activities may enable plants grown at elevated temperatures to exhibit relatively high tolerance to temperature stress, thus alleviating the harmful effects of superoxide anion radicals and hydrogen peroxide.

Highlights

  • The leaf is an important plant organ, and how it will respond to future global warming is a question that remains unanswered

  • Stomatal and photosynthetic characters Compared with ambient temperature, the stomatal density (SD) on the adaxial and abaxial surfaces at elevated temperature I was significantly increased by 24% and 29%, respectively

  • The results of this warming experiment using Arabidopsis, a small annual herb with short life cycle, may be useful for predicting how plants, especially those belonging to the same functional group as Arabidopsis, respond to an increasing air temperature

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Summary

Introduction

The leaf is an important plant organ, and how it will respond to future global warming is a question that remains unanswered. Atmospheric concentrations of greenhouse gases such as CO2, CH4, and N2O have increased dramatically since the beginning of the industrial revolution due to fossil fuel combustion, deforestation and land development; together, these probably led to a rise in ground-level air warming is expected to have profound effects on plant physiology and growth, structure and function of plant populations, species distributions, and probabilities of extinction [6,7] This change in plants may result in complex impacts on vegetation and biodiversity, leading to terrestrial ecosystem consequences [8,9]. Experiments on the effects of global warming on leaf growth and development will provide a better understanding of the mechanism of plant responses to global warming at the community level

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