gybbrellin and its role in plant
DESCRIPTION
deepak yadav --gybbrellinTRANSCRIPT
![Page 1: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/1.jpg)
GibberellinsGAs
![Page 2: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/2.jpg)
![Page 3: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/3.jpg)
![Page 4: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/4.jpg)
a class of plant hormones
affect several important plant processes
eg., seed germination
stem elongation
flowering
male sterility
Gibberellins (GAs)
![Page 5: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/5.jpg)
![Page 6: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/6.jpg)
Gibberellins
1926 Japanese scientist
Gibberella fujikuroi
gibberellin A (terpenoid cpd)
1954, 1955 US and UK scientists
1958 GA1 in higher plant
GAx
1987 synthesis/metabolism
![Page 7: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/7.jpg)
Gibberellins
1991 84 GAs
1995 89 GAs
64 plants, 12 fungi
13 both
1996 more than 100 / 136
1997 genes being cloned
![Page 8: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/8.jpg)
Gibberellic acid (GA3)
End metabolic product in fungi
Plant GA20 GA5 GA3
Commercial
High activity
Slow degradation
Similar to GA1
additional double bond
![Page 9: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/9.jpg)
Gibberellins
GA4 GA7 nonpolar, slowly diffuse
GA9 GA12 precursor
GA29 GA34 deactivated form
Different tissues
Different forms of GA
![Page 10: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/10.jpg)
fungi algae
bacteria
moss fern
gymnosperm
angiosperm
Gibberellins
![Page 11: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/11.jpg)
growing, differentiated tissues
young, developing, expanding leaves
developing seeds/fruit
Gibberellins
![Page 12: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/12.jpg)
elongated internode/petiole
shoot/stem apex
root cap/tip
xylem sap
Gibberellins
![Page 13: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/13.jpg)
Synthesis and Metabolism
Mevalonic acid pathway
in cytosol
Non mevalonic acid pathway
in plastid
![Page 14: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/14.jpg)
Mevalonic acid pathway
![Page 15: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/15.jpg)
![Page 16: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/16.jpg)
In higher plants
from GA12 aldehyde
Early 13-hydroxylation pathway
(GA1)
Non 13-hydroxylation pathway
(GA4)
with GA20oxidase genes:
pathway shifted
GA4 increased / GA1 decreased
![Page 17: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/17.jpg)
GA12 aldehyde: precursor of GA derivatives
by oxidation (C20) and hydroxylation (C13 C3 C2)
![Page 18: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/18.jpg)
Vegetative tissue: conserved synthetic pathway
13-OH pathway to GA20 (C19-GA)
then 3β-OH to GA1
except: arabidopsis and cucumber
non 13-OH pathway to GA4
Reproductive tissue/seed: various pathways
different forms of GA
![Page 19: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/19.jpg)
![Page 20: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/20.jpg)
From mevalonic acid (6C)
GGPP (20C-linear cpd)
ent kaurene (1st specific cpd)
GA12 aldehyde (first GA)
GAx
![Page 21: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/21.jpg)
![Page 22: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/22.jpg)
![Page 23: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/23.jpg)
Isoprene (5C) as basic unit
ent-Gibberellane skeleton
tetracyclic diterpenoid cpd
Gibberellins
![Page 24: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/24.jpg)
2 main types:
C20-GA and C19-GA
GA derivatives by modification of 4 rings
* C20 oxidation: CH3 CH2OH CHO COOH
* Hydroxylation at C2 C3 and C13:
number, position
stoichiometry
* Loss of C20 (C20 to C19 GA)
![Page 25: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/25.jpg)
![Page 26: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/26.jpg)
* 2β-OH: GA20 GA29
GA1 GA8
* C20 oxidation to COOH
GA inactivation
![Page 27: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/27.jpg)
* Conjugation by glucose
Glycosylation:
inactive, storage and transport
Glucose via COOH: GA glycoside
Glucose via OH: GA glycosyl ether
GA inactivation
![Page 28: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/28.jpg)
GA synthesis mutants
Pea na mutant: dwarf
ent-kaurene GA12 aldehyde
Pea le mutant: dwarf
exogenous GA1 tall
exogenous GA20 no response
cloned Le gene:3β hydroxylase
GA20 GA1
![Page 29: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/29.jpg)
Considering 2 locina Le normal ent-kaureneNa le normal GA20
Grafting1. na Le scion
Na le stock tall
2. Na le scionNa Le stock dwarf
Conclusion?
![Page 30: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/30.jpg)
Unlike auxin (acidification)
Increase wall extensibility
Decrease minimum force
for wall extension
GA mechanism in elongation
![Page 31: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/31.jpg)
By (may)
decrease Ca concentration in the wall
increase Ca uptake into the cell
reduce crosslinking of lignin-related cpd
(via peroxidase)
GA mechanism in elongation
![Page 32: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/32.jpg)
GA mechanism in germination
Activate transcription of
α amylase gene
In scutellum and aleurone
![Page 33: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/33.jpg)
GA detection and assay
Bioassay
Easy but not specific
Fractionation
Plant response
Lettuce hypocotyls elongation
Microdrop/dwarf rice
α amylase production
![Page 34: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/34.jpg)
GC-MSSolvent extraction
Chromatography (polarity)
GC (boiling point)
MS (mass)
Identification and quantification
High sensitivity and more specific
![Page 35: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/35.jpg)
Inhibit ent-kaurene synthesis
AMO1618
Cycocel
Inhibit ent-kaurene oxidation
Paclobutrazol Uniconazol
Ancymidol Tetcyclasis
Inhibit later steps by dioxygenases
Bx-1112
LAB1988999
GA inhibitors
![Page 36: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/36.jpg)
Hormone Responses
Perception: receptor
Signal transduction:
second messenger (cAMP, cGMP)
G protein
Ca-Calmodulin
enzyme
transcription factor
![Page 37: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/37.jpg)
At last step
Gene expression
Specific region in promoter
cis element
DNA-binding protein
transcription factor
![Page 38: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/38.jpg)
Exogenous GA / GA inhibitor
GA mutant
Gene identification / Gene cloning
Gene expression / Transformation
GA studies
![Page 39: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/39.jpg)
Enzyme: gene product of multigene family
Each gene with specific pattern of expression
AtGA20ox1: shoot growth
AtGA20ox2: inflorescence development
AtGA20ox3: early seedling development
GA synthesis
![Page 40: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/40.jpg)
Genes controlled by GA, light and daylength
GA: inhibit transcription of GA20oxidase
(GA19 to GA20)
inhibit 3β hydroxylase
promote 2β hydroxylase
At later steps of synthetic pathway
![Page 41: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/41.jpg)
Light: promote conversion of GA1 to inactive GA8
reducing shoot elongation
Negative feedback: reduce production of active GA20 and GA1Daylength (LD): floral initiation
activates GA20oxidase activity
GA53 to GA44
GA19 to GA20
![Page 42: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/42.jpg)
Lettuce: Lactuca sativa seed germination
Red light: activates LsGA3ox1 expression
GA1 increase
Far-red light: inhibits LsGA3ox1
Auxin: promote GA1 production
inhibit deactivation steps to GA29 and GA8
Pea, Pisum sativumIn de-etiolated pea seedling, exposed to red, blue, far red, all reduce GA1 level
![Page 43: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/43.jpg)
Arabidopsis:
seed germination assay
5 complementation groups (56 lines)
ga1 ga2 ga3 ga4 and ga5
all recessive, dwarf, and male sterile
ga1 and ga2 reversed by ent-kaurene
ga3 reversed by ent-kaurenal
GA synthetic mutants
![Page 44: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/44.jpg)
GA1 kaurene synthase (ent-CDP synthase)
GA3 Cyt P450-dependent monooxygenase
GA4 3β hydroxylase
GA5 GA20oxidase
Genes
![Page 45: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/45.jpg)
Pea (sln)
decrease 2β hydroxylase activity
increase active GA
tall plant with light green leaves
![Page 46: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/46.jpg)
Signal transduction mutants
Stature mutants
Decreased response to GA
Increased response to GA
![Page 47: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/47.jpg)
Dwarf
Complete phenocopy of
GA-deficient mutants
No response to exogenous GA
Decreased signaling mutants
![Page 48: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/48.jpg)
Partially / fully dominant
Arabidopsis gai
Maize D8 D9
Wheat Rht1 Rht2 Rht3
Negative regulators
Decreased signaling mutants
![Page 49: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/49.jpg)
Dwarf
Higher level of active GA
and GA20oxidase
Semidominant
Arabidopsis gai mutant
![Page 50: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/50.jpg)
gai1-1
51 bp inframe deletion
loss of 17 amino acid
constitutive repressor
Arabidopsis gai mutant
![Page 51: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/51.jpg)
Arabidopsis gai mutant
intragenic suppressor of gai
loss of function allele
WT phenotype
![Page 52: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/52.jpg)
Maize D8 mutant
Dwarf
Higher level of active GA
6 dominant alleles
with different severity
![Page 53: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/53.jpg)
8 dominant alleles with different severity
Dwarf: prevent lodging
Wheat + N fertilizer: increase yield
increase height
Norin10: dwarf line
2 mutated loci: Rht1 or Rht-B1b (chrs 4B)
Rht2 or Rht-D1b (chrs 4D)
Wheat Rht mutant
![Page 54: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/54.jpg)
All genes cloned:deduced amino acid sequenceGAI / Rht / d8 homologsConserved domains I and II in N terminal
gai mutant: deletion in domain ID8 / Rht: mutation in domain I and/or II
*N terminal essential for GA response*
![Page 55: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/55.jpg)
Similar to WT + GATall by elongated internodes
Arabidopsis spy rgaBarley sln spyRice slrTomato proPea la crys
Recessive / Negative regulators
Increased signal transduction mutants
![Page 56: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/56.jpg)
Arabidopsis rga
Identified by suppression analysis of ga1-3
New mutant: taller
ga1-3 < ga1-3* < WT
new locus: repressor of ga1-3 (rga)
Increased signal transduction mutants
![Page 57: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/57.jpg)
rga: recessive (deletion mutation)
increase stem elongation
reverse ga1-3 delayed flowering time
no effect on GA biosynthesis
RGA: negative regulator
Gene: 82% homology to GAI
especially in N region
Increased signal transduction mutants
![Page 58: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/58.jpg)
Original gai mutant: gain of function
Loss of function allele of GAI ?
Phenotype: normal
Increase paclobutrazol resistance
Low GA = normal height
![Page 59: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/59.jpg)
At least two components inArabidopsis GA signaling pathway
GAI and RGA
homopolymeric Serine / Threonine residue
leucine heptad for protein-protein interaction
putative nuclear localizing signal
![Page 60: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/60.jpg)
slender mutant
recessive
long internodes and narrow leaves
male sterile
increase α-amylase w/o GA
low endogenous GA
resistant to GA synthesis inhibitors
Barley sln
![Page 61: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/61.jpg)
negative regulator
sln x dwarf mutant = sln phenotype
SLN = GAI/RGA homolog
Dominant allele of SLN mutant
Mutation in N terminal
Dwarf barley
![Page 62: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/62.jpg)
slender rice
recessive
phenocopy of barley sln
1 bp deletion in NLS domain
(nuclear localization signal )
Rice slr
![Page 63: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/63.jpg)
frame shift mutation
stop codon
truncated protein
SLR gene = SLN homolog
Modified SLR:
17 aa deletion in DELLA domain
Transformation: dwarf rice
Rice slr
![Page 64: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/64.jpg)
GA signal component
Dicot / Monocot
GAI RGA Rht d8 SLN SLR
Putative transcription repressor
![Page 65: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/65.jpg)
spindly mutant, recessive
paclobutrazol-resistant
long hypocotyls
light green leaves
early flowering
spy ga1-2 = spy phenotypes
spy gai = spy phenotypes
Arabidopsis spy
![Page 66: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/66.jpg)
SPY gene product:
O-GlcNAc transferase
Signaling molecule
Involved in protein-protein interaction
Negative regulator
Arabidopsis spy
![Page 67: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/67.jpg)
Before responses
Expression of GA-regulated genes:
Protein-DNA interaction
Transcription factor
cis elements
![Page 68: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/68.jpg)
Barley: HvGAMyb
Bind specific sequence in
promoter of α-amylase gene
Increase gene expression
Overexpression of HvGAMyb gene
= GA treatment
Transcription factor: GAMyb
![Page 69: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/69.jpg)
Arabidopsis: GAMyb-like genes
AtMyb33 AtMyb65 AtMyb101
Functional homologs of barley GAMyb
Transform barley aleurone with AtMyb33
Activate α-amylase production
![Page 70: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/70.jpg)
Arabidopsis: facultative LD plants
Transfer plants from SD to LD
11x increase of GA1
3x increase of GA4
increase AtMyb33 expression
in shoot apex
shoot apex transition to flowering
![Page 71: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/71.jpg)
Potential target for AtMyb
LFY promoter
LEAFY: meristem-identity gene
Evidence AtMyb binding
to a specific 8-bp sequence
in LFY promoter
![Page 72: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/72.jpg)
cis elements
specific regions in promoter
transcription factor binding site
identified by deletion or
site specific mutagenesis:
gene expression after promoter modification
![Page 73: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/73.jpg)
- amylase box: TATCCAT
- GARE: TAACAA/GA
- Pyrimidine box: C/TCTTTTAC/T
Conserved sequences among
GA-regulated genes
![Page 74: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/74.jpg)
GA and α-amylase production
Perception at membrane receptors
Increase intracellular Ca
Decrease intracellular pH
Increase [CaM]
Increase cGMP
Increase GAMyb transcription
Increase α-amylase activity
Some protein phosphorylation
![Page 75: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/75.jpg)
![Page 76: gybbrellin and its role in plant](https://reader034.vdocuments.us/reader034/viewer/2022051212/5599f0521a28abe01a8b4721/html5/thumbnails/76.jpg)