1、OCOOHOCHOGA4OCOOHOCOHHOGA1OCOOHOCHOHOGA34预习提问1：你认为下列赤霉素哪个有生物活性？预习提问2：你能解释下下图中的各种字母缩写的含义吗？预习提问3：从下图所示的试验表现了赤霉素的那些生理作用？CKGA3Characteristic elongated rice seedling caused by bakanaeMacmillan J,Suter PJ.1958.The occurence of gibberellin A1 in higher plants:Isolation from the seed of runner bean(Phaseolu
2、s multiflorus).Naturwiss 45,46.OCOOHOCHOGA1OHent-gibberellane skeleton 赤霉烷骨架赤霉素的种类赤霉素的种类Gibberellin A136C19赤霉素赤霉素C20赤霉素赤霉素C13非羟化赤霉素非羟化赤霉素C13羟化赤霉素羟化赤霉素Biologically active GAs 活性赤霉素的结构特征活性赤霉素的结构特征n3-羟基羟基n1，2不饱和键不饱和键n2，3不饱和键不饱和键OCOOHOCGA7HOOCOOHOCHOGA4OCOOHOCHOGA1OH无活性赤霉素的结构特征无活性赤霉素的结构特征 有2-羟基 有三个羧基COO
3、HCOOHCOOHGA25OCOOHOCHOHOGA8OHOCOOHOCHOGA29OHOCOOHOCHOGA4OCOOHOCOHHOGA1OCOOHOCHOHOGA34OCOOHOCOHGA5活性赤霉素结构的本质Affinity for receptor GID1Ability to form a plex consisting of GID1,GA,and the DELLAd1 d1 WT WT +GA1+GA1Mutants of gibberellin biosynthesisMutants of gibberellin biosynthesisMutants of gibberel
4、lin biosynthesisImportant for regulation of GA biosynthesis/levelsGA biosynthetic enzymes are specifically localized in young,actively growing buds,leaves,and upper internodesGAs are synthesized in shoot and transported to rest of plant via phloemArabidopsis mutantsPea mutantsMaize mutants(1)ent-cop
5、alyl diphosphate synthase(CPS);(2)ent-kaurene synthase(KS);(3)ent-kaurene 19-oxidase(EKO);(4)ent-kaurenoic acid 7 -hydroxylase;(5)GA12-aldehyde synthase;(6)GA 7-oxidase(GA7ox);(7)GA 13-hydroxylase(GA13ox);(8)GA 20-oxidase(GA20ox);(9)GA 3 -hydroxylase(GA3ox);(10)GA 2-oxidase(GA2ox)1、Three Stages of G
6、As Biosynthesis2、Inhibitors of GAs Biosynthesis3、Organ Specificity of GAs Biosynthesis4、Factors affect GAs BiosynthesisBiosynthesis of gibberellinsStage 1 Stage 2Stage 3Stage 3 COOHCOOHCOOHCH2OHCOOHOCOOHOCHOHOOHOCOOHOCHOHOGA8COOHCOOHOHGA15GA53GA34OCOOHOCOCOOHOCOHGA20GA9GA12早期C13非羟化途径早期C13羟化途径OCOOHOC
7、OCOOHOCOHGA1GA4HOHOOCOOHOCOHOCOOHOCOHOCOOHOCOHGA6GA20GA5OOCOOHOCOHGA3HO早期C13羟化途径的一条支路Localization of Gibberellin Biosynthesis发芽发芽茎叶生长茎叶生长花器官分化花器官分化/成熟成熟穗轴穗轴/节间生长节间生长Expression of the GA metabolic genes in various organs of the wild-type rice.Total RNAs were isolated from vegetative shoot apices(1),l
8、eaf sheaths(2),leaf blades(3),stems(4),roots(5),and panicles at flowering time(7),and quantitative RT-PCR was conducted.Histone H3 was used as a control.(A)RNA gel blot analyses of OsGA3ox1 and OsGA3ox2 in various rice organs(cultivar Akibare).Total RNA was isolated from shoot apices(SA),stems(St),l
9、eaf blades(LB),rachis(Ra),unopened flowers(Fl),elongating leaves(EL),young panicles(YP),and shoots(Sh).Blots were hybridized with probes for GA 3-hydrolases(OsGA3ox1,OsGA3ox2).Approximately 10 g of total RNA from each sample was loaded onto the gel and stained with ethidium bromide(rRNA).sd1The leve
10、l of gene expression in each tissue sample,as determined by quantitative PCR,is shown as the number of cDNA copies per 105 copies of UBQ11 cDNA.The organs and developmental stages tested were,from left to right in the graph,12-and 24-h imbibed seeds,2-,5-and 10-day-old seedlings,roots of 5-day-old s
11、eedlings,14-day-old rosettes and the following organs from 35-day-old plants:cauline leaves,stems,flower clusters and siliques.The means of three experiments SE are shown.Mitchum MG,Yamaguchi S,Hanada A,Kuwahara A,Yoshioka Y,et al.2006.Distinct and overlapping roles of two gibberellin 3-oxidases in
12、Arabidopsis development.Plant J.45:80418 Photoperiod regulation of GA1 biosynthesisEnvironmental conditions alter transcription of biosynthesis genesSpinach plants undergo stem and petiole elongation only in long days(LD);AMO=GA biosynthesis inhibitorThe 5-fold increase in GA1 causes growth in spina
13、ch exposed to long daysExpression of a L.temulentum 20-oxidase GA biosynthesis gene.pared with an 8h short day,LD exposure of the leaf(8h SD extended by 9.5h using incandescent lamps)led to a large increase in gene expression.(Semi-quantitative RT PCR assays from Blundell,MacMillan,and King;unpublis
14、hed).In Situ Hybridization Analysis of AtGA3ox1 mRNA.(A)Schematic drawing of a longitudinal section.ale,aleurone;cot,cotyledon;HY,hypocotyl;RA,radicle;SA,shoot apical meristem;SC,seed coat.(B)Schematic drawing of a transverse section.ale,aleurone;cor,cortex;cot,cotyldon;end,endodermis;epi,epidermis;
15、PV,provasculature;SC,seed coat.Biosynthesis and catabolism of gibberellin are carefully regulated during the promotion of seed germination.Effects of GA3 and uniconazol on the expression of OsGA3ox1 and OsGA3ox2 in germinating seeds.Lane 1,control;lane 2,10 M GA3;lane 3,10 M uniconazole.GA3uniconazo
16、lecontrol赤霉素生物合成的控制 生长素的影响KNOX proteins are expressed in the SAM(purple),where they activate CK biosynthesis and repress GA 20-oxidase gene expression and hence GA biosynthesis(GA20ox,gray),thus promoting meristem activity.CK also activates GA2ox(blue)expression,possibly stimulating GA deactivation.
17、These interactions may confine active GA to the leaf(green).KNOX proteins may also activate GA2ox in a CK-independent manner(dashed arrow).Model Depicting Interactions between KNOX Proteins,GA,and CK in the Shoot ApexEUIEUI降解赤霉素的途径降解赤霉素的途径(Zhu&Nomura et al.2006)(Zhu&Nomura et al.2006)(A)and(B)Rice t
18、ransformed with Ubi:GA2ox5 and Ubi:GA2ox6.(C)to(F)Tobacco transformed with Ubi:GA2ox5 and Ubi:GA2ox6.Transgenic plants showed different degrees of dwarfism paredwith the control rice or tobacco transformed with vector only(MS).Photographs of transgenic tobacco were taken at the heading stage(Cand D)
19、The Plant Cell,Vol.20:26032618,October 2008,Wheat plants,cv,Canon,over-expressing a GA 2-oxidase gene,which encodes a gibberellin-catabolising enzyme,in parison with wild-type(on the left).Transgenic plants carrying an antisense construct of 3-hydrolase have a semidwarfPhenotype.(a)In rice the major
20、 active gibberellin involved in shoot elongation is GA1,which is formed by 3-hydrolation of GA20 by GA 3-oxidase(GA3ox).GA1 is turned over to the inactive catabolite GA8 by 2-hydrolation,catalyzed by GA 2-oxidase(GA2ox).(b)Plants transformed with the synthetic geneOsGA3ox2:OsGA2ox1,in which a rice 2
21、-oxidase open reading frame is expressed from the promoter of the shoot-specific OsGA3ox2 gene,have moderate height reduction and normal grain size and numbers.In contrast,plants transformed with OsGA2ox1 expressed from the constitutive actin promoter are severely dwarfed and fail to set grain.Natur
22、e Biotechnology 21,873-874(2003)木葡聚糖转葡糖苷酶木葡聚糖转葡糖苷酶(loglucanendotransglycosylase,XET)Trends in Plant Science,1999.Vol.4,No.5,pp.176-183.赤霉素诱导糊粉层细胞淀粉酶的合成和分泌赤霉素诱导糊粉层细胞淀粉酶的合成和分泌Injecting orchard tree with gibberellin to increase cone production 山口五十磨山口五十磨GibberellinGibberellin Signaling SignalingPhenoty
23、pes of wild-type Arabidopsis and gai,ga1,and the rga mutantsgai=GA-insensitivega1=GA-deficientrga=repressor of ga1RGA is a negative regulator of the GA responserga mutants look like wild typeDomain structure of the RGA or GAI repressor proteinDELLA=aspartic acid(D),glutamic acid(E),leucine(L),leucin
24、e(L),alanine(A)on N-terminus of GAI,RGA,SCR=members of the GRAS familyStructure of the GA3GID1ADELLA plexa,Chemical structures and numbering of GA3 and GA4 that were used in our studies.b,Ribbon representation of the GA3GID1ADELLA plex,with the GAI DELLA domain(pink),the GID1A N-terminal extension(N
25、-Ex,)and the GID1 core domain(light blue).The bound GA3 molecule is represented as a space-filling model with carbon in green and ogen in red.c,As in b,but with a rotation of 90 around a vertical axis.Three N-terminal extension helices a c of GID1A are loosely packed against each other to form a fla
26、t cover on the pocket.Gibberellin-induced DELLA recognition by the gibberellin receptor GID1Kohji Murase,Yoshinori Hirano,Tai-ping Sun&Toshio HakoshimaNature 456,459-463(27 November 2008)Boxed In Binding of gibberellin(gray space-filling structure)within its receptor(green)causes the receptors N-ter
27、minus(purple)to close over the hormone like a lid.Closing the lid provides a platform for binding gene transcription blockers called DELLA(blue).http:/pubs.acs.org/cen/news/86/i48/8648notw1.html A model of GA-regulated GID1DELLA protein interactionsGA functions as an allosteric inducer to enhance GI
28、D1DELLA interactions.GA binding induces a GID1 conformational change in the N-terminal helical switch for DELLA binding,which promotes a conformational transition in the DELLA protein.Thus,GA-activated GID1 functions as a ubiquitylation chaperon that stimulates substrate recognition by the SCF plexG
29、ibberellin-induced DELLA recognition by the gibberellin receptor GID1Kohji Murase,Yoshinori Hirano,Tai-ping Sun&Toshio HakoshimaNature 456,459-463(27 November 2008)SLR1=SLENDER RICE 1Current model of GA signaling during growthposite model for the induction of-amylase synthesis in barley aleurone lay
30、ers by GA A calcium-independent pathway induces-amylase gene transcription;a calcium-dependent pathway is involved in-amylase secretionGibberellin induces growth in Thompsons seedless grapes.The bunch on the left is an untreated control.The bunch on the right was sprayed with GA3 during fruit development.(Sylvan Wittwer/Visuals Unlimited.)http:/
