Hormone Transport and Long Range Signaling

The developmental processes that are controlled by auxin flux

Genetics of Auxin Transport

• AUX1 proteins: components of auxin influx

• PIN proteins: components of auxin efflux machinery

• ABC transporters (ATP binding-cassetle transporters): more auxin transport proteins?

• Other proteins (ROP,PGR er al.,)

IAA Distribution within the Arabidopsis Root Apex.

Plant Cell, 2009, 21: 1621,

using a combination of fluorescence-activated cell sorting (FACS)and precise mass spectrometry–based IAA quantification and biosynthesis measurements

Plant Cell. 2007,19(1):148-62

1 Inhibitors of auxin transport block auxin efflux

TIBA（三碘苯甲酸） ,

NPA（萘基邻氨甲酰苯甲酸） HFCA（羟基氟 -9-羧酸 , 也称形态素） 1-NOA (萘氧乙酸 )

Quercetin （槲皮素） Genistein （金雀异黄素）2 Mutants for auxin transport (aux1,agr, eir1)

3 Cloning genes encoding carriers of auxin transport

Research Methods

(TRENDS in Plant Science 2005,10:170)

ER-localized PIN5 transporter

Tissue-specific and subcellular localization of PINs, PGPs and AUX1

(Biochemical Society Transactions .2007 ， 35,:136-141)

PID can directlyphosphorylate PINs and is localized both apically and basally.

(Current Opinion in Plant Biology 2009, 12:42–48)

PAR proteins

Role of Phosphorylation in Polar Targeting

• A PIN1 sequence-based signal for decision on the PIN1 subcellular localization.

• One of major decision regulators are Ser/Thr protein kinase PID and PP2A.

• The conditional regulation of PIN polarity and directional auxin fluxes by different signalling pathways.

Overview of the subcellular trafficking routes in a polarized plant cell

Plant Physiol. 2008,147:1553-1559

Cite this article as Cold Spring Harb Perspect Biol 2010;2:a001552

Cellular auxin transport.

Role of Secretion and Recycling in Polar Targeting

• The secretion, clathrin (网络蛋白 )-dependent endocytosis (内吞作用 ), and subsequent recycling are important processes in the generation of the PIN polar localization.

Arabidopsis ROOT UVB SENSITIVE2/WEAK AUXINRESPONSE1 Is Required for Polar

Auxin Transport

• weak auxin response1 (wxr1)

• WXR1 is ROOT UV-B SENSITIVE2 (RUS2), a member of the broadly conserved DUF647 domain protein family found in diverse eukaryotic organisms.

• RUS2/WXR1 is required for auxin transport and to maintain the normal levels of PIN proteins in the root.

Plant Cell, 2010. 22: 1749–1761

cytokinins communicate acropetal and systemic long-distance signals,and that structural side chain

variations mediate different biological messages.

Cytokinin as local

and long-distance signals

J Exp Bot, 2008 ,59:75–83,

• Translocation of cytokinin nucleosides is potentially via an equilibrative nucleoside transporter (ENT). Arabidopsis (AtENT1–AtENT8) and rice (OsENT1–OsENT4).

AtENT6 could also participate in cytokinin nucleoside transport with a preference for iP riboside in vascular tissue.

subsets of the purine permease family as a transporter of cytokinin nucleobases.

ENT as transporter ofcytokinin nucleosides

Cytokinins modulate auxin-induced organogenesis (AIO) in plants via regulation of the auxin efflux

PNAS 2009,106 (9): 3609–3614

CTK action is its effect on

auxin distribution

via regulation of expression of auxin efflux

carriers.

Distribution and transport of ACC and ethylene

• ACC is taken up by the roots and transported all over the plant via the xylem

• ethylene diffuses freely in air, but its diffusion in water is at least 4-fold lower than in air, ethylene may accumulate in submerged plants to levels higher than 1ul /L

• Within the canopy, ethylene concentrations are enhanced

GA distribution and transport

• GA taken up by the roots is distributed in the shoot

• The close association of some of the key GA biosynthesis genes with the vascular tissue may be an indication for the use of transport facilities within the plant.

• Transport capacities and rates are different for individual GAs

To grow or not to grow: what can we learn on ethylene–gibberellin cross-talk by in silico gene expression analysis?

(J Exp Bot, 2008, 59: 1–16)

inflorescence stem (black)adult leaves (white)roots (grey).

inflorescence stems (black), flowers (white), juvenile leaves (grey)

adult leaves (white)roots (grey)

shoot apexinflorescence stems

Mutual influences of ethylene and GA on each other’s pathways

5mg/l ethylene 3 h

1 umol/l GA

Shoot branching

• SAM: shoot apical meristem • RAM: root apical meristem

lateral root formation

ABA Transport

(Cell, 2006,126:1023)

ABA 和 ABA-GE在植物茎的再循环和再分配

Intact plant

aao3

ABA is synthesizedmainly in the leaves in response to drought stress and that some of the ABA accumulated in the leavesis transported to the roots.

Plant Cell Physiol. 2009, 50(7): 1201–1214