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Although many studies have reported the negative effects of elevated O 3 on plant physiological characteristics, the influence of elevated O 3 on below-ground processes and soil microbial functioning is less studied. In this study, we examined the effects of elevated O 3 on soil properties, soil microbial biomass, as well as microbial community composition using high-throughput sequencing. Throughout one growing season, one-year old seedlings of two important endemic trees in subtropical China: Taxus chinensis (Pilger) Rehd. var. chinensis, and Machilus ichangensis Rehd. Et Wils, were exposed to charcoal-filtered air (CF as control), 100 nl l -1 (E100) or 150 nl l -1 (E150) O 3 -enriched air, in open top chambers (OTCs). We found that only higher O 3 exposure (E150) significantly decreased soil microbial biomass carbon and nitrogen in M. ichangensis, and the contents of organic matter were significantly decreased by E150 in both tree species. Although both levels of O 3 exposure decreased NO 3 -N in T. chinensis, only E150 increased NO 3 -N in M. ichangensis, and there were no effects of O 3 on NH 4 -N. Moreover, elevated O 3 elicited changes in soil microbial community structure and decreased fungal diversity in both M. ichangensis and T. chinensis. However, even though O 3 exposure reduced bacterial diversity in M. ichangensis, no effect of O 3 exposure on bacterial diversity was detected in soil grown with T. chinensis. Our results showed that elevated O 3 altered the abundance of bacteria and fungi in general, and in particular reduced nitrifiers and increased the relative abundance of some fungal taxa capable of denitrification, which may stimulate N 2 O emissions. Overall, our findings indicate that elevated O 3 not only impacts the soil microbial community structure, but may also exert an influence on the functioning of microbial communities., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Numerous studies have documented the negative effects of ozone (O 3 ) on tree species in growing season, however, little is done in non-growing season. Three evergreen tree species, Phoebe bournei (Hemsl.) Yang (P. bournei), Machilus pauhoi Kanehira (M. pauhoi) and Taxus chinensis (Pilger) Rehd (T. chinensis), were exposed to non-filtered air, 100 nmol mol -1 O 3 air (E1) and 150 nmol mol -1 O 3 air (E2) in open-top chambers in subtropical China. In the entire period of experiment, O 3 fumigation decreased net photosynthesis rate (Pn) through stomatal limitation during the transition period from growing to non-growing season (TGN), and through non-stomatal limitation during the period of non-growing season (NGS) in all species tested. Meanwhile, O 3 fumigation reduced and delayed the resilience of Pn in all species tested during the transition period from non-growing to growing season (TNG). O 3 fumigation significantly decreased chlorophyll contents during NGS, whereas no obvious injury symptoms were observed till the end of experiment. O 3 fumigation induced increases in levels of malondialdehyde, superoxide dismutase, total phenolics and reduced ascorbic acid, and changes in four plant endogenous hormones as well in all species tested during NGS. During NGS, E1 and E2 reduced Pn by an average of 80.11% in P. bournei, 94.56% in M. pauhoi and 12.57% in T. chinensis, indicating that the O 3 sensitivity was in an order of M. pauhoi > P. bournei > T. chinensis. Overall, O 3 fumigation inhibited carbon fixation in all species tested during NGS. Furthermore, O 3 -induced physiological activities also consumed the dry matter. All these suggested that elevated O 3 , which is likely to come true during NGS in the future, will adversely affect the accumulation of dry matter and the resilience of Pn during TNG in evergreen tree species, and further inhibit their growth and development in the upcoming growing season., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Taxus spp. are ancient gymnosperms that produce a unique secondary metabolite, namely, taxol, an anticancer drug. JAZ proteins are key regulators of the JA signaling pathway, which control taxol biosynthesis. However, the JAZ proteins of Taxus spp. are poorly studied. In this work, nine JAZ genes from Taxus chinensis were identified using our previous transcriptome data and named as TcJAZ1-TcJAZ9. Of these nine TcJAZ proteins, eight contain Jas and TIFY domains, and the Jas domain of TcJAZ6 is incomplete. Most TcJAZs and PsJAZs are not related to AtJAZs and OsJAZs. Phylogenetic analysis divided all JAZ proteins from Arabidopsis thaliana, Oryza sativa, Picea sitchensis, and T. chinensis into eight subgroups; gymnosperms JAZs were classified into subgroups V-VIII, and angiosperm JAZs were categorized into subgroups I-V. Three motifs of subgroups VI-VIII were identified in gymnosperm JAZs, indicating that gymnosperm JAZ proteins exhibit a different evolutionary process from those of angiosperms. The expression patterns of nine TcJAZs showed that TcJAZ2/3/8 was a key regulator, indicating their important roles in T. chinensis. Results revealed that gymnosperm JAZs differ from angiosperm JAZs in terms of molecular structure. Three novel conserved motifs were found in TcJAZs and PsJAZs. This study provides a basis for research on JA regulatory system in Taxus spp. and for elucidating the significance of JA signaling pathway to land plants., (Copyright © 2017. Published by Elsevier B.V.)

Plant cell cultures constitute eco-friendly biotechnological platforms for the production of plant secondary metabolites with pharmacological activities, as well as a suitable system for extending our knowledge of secondary metabolism. Despite the high added value of taxol and the importance of taxanes as anticancer compounds, several aspects of their biosynthesis remain unknown. In this work, a genomewide expression analysis of jasmonate-elicited Taxus baccata cell cultures by complementary DNA-amplified fragment length polymorphism (cDNA-AFLP) indicated a correlation between an extensive elicitor-induced genetic reprogramming and increased taxane production in the targeted cultures. Subsequent in silico analysis allowed us to identify 15 genes with a jasmonate-induced differential expression as putative candidates for genes encoding enzymes involved in five unknown steps of taxane biosynthesis. Among them, the TB768 gene showed a strong homology, including a very similar predicted 3D structure, with other genes previously reported to encode acyl-CoA ligases, thus suggesting a role in the formation of the taxol lateral chain. Functional analysis confirmed that the TB768 gene encodes an acyl-CoA ligase that localizes to the cytoplasm and is able to convert β-phenylalanine, as well as coumaric acid, into their respective derivative CoA esters. β-phenylalanyl-CoA is attached to baccatin III in one of the last steps of the taxol biosynthetic pathway. The identification of this gene will contribute to the establishment of sustainable taxol production systems through metabolic engineering or synthetic biology approaches., (© 2015 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.)