| 1 | Structure-guided analysis of Arabidopsis JASMONATE-INDUCED OXYGENASE(JOX)2 reveals key residues for recognition of jasmonic acid substrate by plant JOXs显示文摘The jasmonic acid(JA)signaling pathway is used by plants to control wound responses.The persistent accumulation of JA inhibits plant growth,and the hydroxylation of JA to 12-hydroxy-JA by JASMONATE-INDUCED OXYGENASEs(JOXs,also named jasmonic acid oxidases)is therefore vital for plant growth,while structural details of JA recognition by JOXs are unknown.Here,we present the 2.65Åresolution X-ray crystal structure of Arabidopsis JOX2 in complex with its substrate JA and its co-substrates 2-oxoglutarate and Fe(Ⅱ).JOX2 contains a distorted double-stranded p helix(DSBH)core flanked by a helices and loops.JA is bound in the narrow substrate pocket by hydrogen bonds with the arginine triad R225,R350,and R354 and by hydrophobic interactions mainly with the phenylalanine triad F157,F317,and F346.The most critical residues for JA binding are F157 and R225,both from the DSBH core,which interact with the cyclopentane ring of JA.The spatial distribution of critical residues for JA binding and the shape of the substrate-binding pocket together define the substrate selectivity of the JOXs.Sequence alignment shows that these critical residues are conserved among JOXs from higher plants.Collectively,our study provides insights into the mechanism by which higher plants hydroxylate the hormone JA. | Xin Zhang Dongli Wang Joyce Elberse Linlu Qi Wei Shi You-Liang Peng Robert C.Schuurink Guido Van den Ackerveken Junfeng Liu | 2021 | Molecular Plant2021，14，5： | 2 |
| 2 | Potential Impacts of Proposed Chenglingji Hydraulic Project on Wetlands in Dongting Lake显示文摘Water level fluctuation of is an important ecological character of lakes in monsoon climate zone.It is the key driver to seasonal change of the wetlands and associated habitats,which provide vital inhabiting conditions for different species in summer and winter,or,wet season and dry season.Due the hydrologic regime changes in the recent years after the operation of Three Gorges Dam,in 2012,the government of Hunan province proposed Chenglingji Hydraulic Project,aiming at water level control in dry season at Chenglingji,where the outlet of Dongting Lake located.Through different operations on water retreat process,five scenarios on the water level control from 21 m to 24 m were set in the plan.The potential ecological impacts of the project are under enormous public concern.To analyze potential impacts from different scenarios of water level control on the wetlands,this paper studied the topography of Dongting Lake bed and wetlands in dry season,by using Digital Elevation Model(DEM)and 15 images from HJ satellite and 1 image from Landsat TM.The wetlands at water levels of 19 m to 27 m were analyzed.The study revealed that there were 4 terrain steps on Dongting Lake bed from the West Dongting Lake to East Dongting Lake.Water level control at Chenglingji would increase area of open water in East Dongting Lake and Hengling Lake areas,while its effect on South Dongting Lake and West Dongting Lake areas due to higher terrain was weaker.Particularly,the area percentages of South Dongting Lake area did not change with water level fluctuation,due to its 2 elevation steps.The area percentages of various types of the wetlands in Dongting Lake area during the processes of water level rising and retreating were quite different,even in the relatively close water level interval.The retreating area of open water in autumn was larger than that during the spring flooding.The 23 m was the key water level,a turning point of the area change of the wetlands in Dongting Lake area.Areas of open water,mudflat,meadows and their percentages changed significantly at water levels above 23 meters,with increasing of open water area and shrinking of meadow area,their areas would decrease 30 000 ha.As the key habitats for wintering geese,the area of meadows was from near 70 000 ha to 10 000 ha.Among 5 scenarios,the impact of the scenario at 21 m elevation on wetlands was the weakest.However,water level dropping was still postponed than that of natural hydrological process in the scenarios.It resulted in longer inundation of large area of lakebed at elevation of 22-23 m,increasing habitats for aquatic biodiversity but reducing area of the meadows,where is the key habitat for wintering geese.All the other water level control scenarios would cause large area of inundation of lakebed in dry season and dramatic change of wetlands.To maintain the natural wetlands in Dongting Lake area,the Chenglingji Hydraulic Project should be considered in a more cautious way and further researches were needed on the response of aquatic biodiversity and wintering water birds. | LU Cai SHI Linlu GUAN Lei ZHOU Yan JING Lei LEI Guangchun | 2018 | 湿地科学2018，16，3： | 1 |
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