Start of growing season advanced by 9.4 ± 2.2 and 8.3± 2.0 days during 1982-1999 and 2000-2020 respectively, whereas its end delayed only by 8.2 ± 1.9 days during 2000-2020.Current models project an advance in season start by 8.8 days and a delay in season end by 14.0 days in 2086-2100 relative to 2000-2014 under Shared-Socioeconomic-Pathway 5-8.5. Warming and increasing precipitation are the main climatic drivers of advancing spring phenology (start of vegetative growing season and first flowering) and delaying end of the growing season. The direction and magnitude of responses of phenophases to temperature depend on soil water availability, with greater temperature sensitivity of the start and end of the season under wetter conditions.First flowering date is more sensitive to temperature on the Qinghai-Tibetan Plateau than in Arctic grasslands.The temperature sensitivities of the start and end of the growing season are greater than those of Arctic grasslands, but smaller than those of mid-latitude alpine and subalpine grasslands.

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BackgroundP450 fatty acid decarboxylases represented by the unusual CYP152 peroxygenase family member OleTJE have been receiving great attention recently since these P450 enzymes are able to catalyze the simple and direct production of 1-alkenes for potential applications in biofuels and biomaterials. To gain more mechanistic insights, broader substrate spectra, and improved decarboxylative activities, it is demanded to discover and investigate more P450 fatty acid decarboxylases.ResultsHere, we describe for the first time the expression, purification, and in vitro biochemical characterization of two new CYP152 peroxygenases, CYP-Aa162 and CYP-Sm46Δ29, that are capable of decarboxylating straight-chain saturated fatty acids. Both enzymes were found to catalyze the decarboxylation and hydroxylation of a broad range of free fatty acids (C10–C20) with overlapping substrate specificity, yet distinct chemoselectivity. CYP-Sm46Δ29 works primarily as a fatty (lauric) acid decarboxylase (66.1 ± 3.9% 1-undecene production) while CYP-Aa162 more as a fatty (lauric) acid hydroxylase (72.2 ± 0.9% hydroxy lauric acid production). Notably, the optical spectroscopic analysis of functional CYP-Sm46Δ29 revealed no characteristic P450 band, suggesting a unique heme coordination environment. Active-site mutagenesis analysis showed that substitution with the proposed key decarboxylation-modulating residues, His85 and Ile170, enhanced the decarboxylation activity of CYP-Aa162 and P450BSβ, emphasizing the importance of these residues in directing the decarboxylation pathway. Furthermore, the steady-state kinetic analysis of CYP-Aa162 and CYP-Sm46Δ29 revealed both cooperative and substrate inhibition behaviors which are substrate carbon chain length dependent.ConclusionsOur data identify CYP-Sm46Δ29 as an efficient OleTJE-like fatty acid decarboxylase. Oxidative decarboxylation chemoselectivity of the CYP152 decarboxylases is largely dependent upon the carbon chain length of fatty acid substrates and their precise positioning in the enzyme active site. Finally, the kinetic mode analysis of the enzymes could provide important guidance for future process design.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-017-0894-x) contains supplementary material, which is available to authorized users.