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Vegetation responses to rising atmospheric CO2 levels can significantly affect water availability (defined as precipitation minus evapotranspiration (ET)). While this effect has long been recognized and assessed for the mean state, its influence on interannual variability, which is more closely associated with extreme events, has yet to be comprehensively quantified. In this study, our primary focus is to evaluate the impacts of ET by plant physiology (denoted as ETPhy) on the mean and interannual variability of water availability under elevated CO2 using multiple CO2 sensitivity experiments from the coupled model intercomparison project phase 6. We show that the contribution of vegetation physiological effects to the mean water availability varies among regions, while it consistently contributes to variability by about 33%. Considering CO2 physiological effects alone, ETPhy exerts a more significant influence on the mean state than on variability, particularly in humid regions. Consequently, ETPhy contributes less than 5% to the variability of water availability in humid regions under rising CO2, whereas it accounts for about 20% of the mean state. This distinction could be attributed to the different mechanisms governing the mean and variability of ETPhy. Specifically, evaporation from CO2 physiological forcing is the most critical contributor to the variability of ETPhy in most regions while showing minimal impacts on the mean state. Our findings identify the divergent effects of ETPhy on the mean state and interannual variability of water availability under elevated CO2, as important in future climate projections. Plain Language Summary: Rising atmospheric CO2 concentrations impacts on vegetation physiological processes are expected to change the evapotranspiration (ET) by plant physiology (denoted as ETPhy), allowing for altering the mean and the interannual variability of water availability (defined as precipitation minus ET). Using an ensemble of Earth system model simulations, this study reveals that the impacts of CO2 physiological effects on the mean of water availability are region‐specific, but with a nearly consistent contribution to its interannual variability. Combined with the impact of ETPhy on the mean and variability of water availability resulting from CO2 physiological forcing, ETPhy typically contributes less than 5% to the variability of water availability in humid regions under rising CO2, whereas it accounts for about 20% of the mean state. This discrepancy could arise from the different mechanisms governing the mean and variability of ETPhy. These results underscore the importance of accounting for the effects of ETPhy in response to increasing CO2 in altering the mean and the interannual variability of regional water resources. Key Points: The effects of CO2 vegetation responses contribute variably in space to mean annual water availability but uniformly to variabilityThe evapotranspiration (ET) from CO2 physiological forcing (ETPhy) shows more impacts on the mean of water availability than its variabilityThe evaporation from CO2 physiological forcing plays an important role in the variability of ETPhy but has weak effects on the mean [ABSTRACT FROM AUTHOR]

The yeast expression system, Pichia pastoris, is one of the most robust and versatile expression systems in biotechnology and molecular biology, generally considered as a safe host for heterologous protein expression, especially for producing cellulases and xylanases at the industrial level. Despite the high recombinant protein expression rate, the potential of the P. pastoris expression system has still not been fully explored. Cultivation of P. pastoris under optimized conditions greatly relies on the strain and is associated with certain problems such as promoter strength, sensitivity to methanol, and oxygen demand. To address these issues, different genetic engineering strategies have been employed. Advancements in promoter engineering, optimization of gene dosage and codon usage, recombinant plasmid engineering using CRISPR/Cas9 system, and directed evolution strategies have proven beneficial to the yield of cellulase expression levels. This study will systemically review recent progress in various genetic engineering strategies to enhance cellulase and xylanase expression in the P. pastoris expression system. The utilization of alcohol oxidase 1 promoter (pAOX1), methanol‐free system, and recombinant plasmid engineering for improved production of these enzymes are highlighted. Additionally, we discuss the recent advancements in the P. pastoris expression system toolbox for improved cellulase and xylanase production, thus providing a deep insight into how P. pastoris is becoming the indispensable platform for heterologous protein production. © 2023 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]