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Regulation of polar auxin transport in grapevine fruitlets (Vitis vinifera L.) and the proposed role of auxin homeostasis during fruit abscission.
BMC Plant Biol. 2016 10 28; 16(1):234.BP

Abstract

BACKGROUND

Indole-3-acetic acid (IAA), the most abundant auxin, is a growth promoter hormone involved in several developmental processes. Auxin homeostasis is very important to its function and this is achieved through the regulation of IAA biosynthesis, conjugation, degradation and transport. In grapevine, IAA plays an essential role during initial stages of berry development, since it delays fruitlet abscission by reducing the ethylene sensitivity in the abscission zone. For this reason, Continuous polar IAA transport to the pedicel is required. This kind of transport is controlled by IAA, which regulates its own movement by modifying the expression and localization of PIN-FORMED (PIN) auxin efflux facilitators that localize asymmetrically within the cell. On the other hand, the hormone gibberellin (GA) also activates the polar auxin transport by increasing PIN stability. In Vitis vinifera, fruitlet abscission occurs during the first two to three weeks after flowering. During this time, IAA and GA are present, however the role of these hormones in the control of polar auxin transport is unknown.

RESULTS

In this work, the use of radiolabeled IAA showed that auxin is basipetally transported during grapevine fruitlet abscission. This observation was further supported by immunolocalization of putative VvPIN proteins that display a basipetal distribution in pericarp cells. Polar auxin transport and transcripts of four putative VvPIN genes decreased in conjunction with increased abscission, and the inhibition of polar auxin transport resulted in fruit drop. GA3 and IAA treatments reduced polar auxin transport, but only GA3 treatment decreased VvPIN transcript abundance. When GA biosynthesis was blocked, IAA was capable to increase polar auxin transport, suggesting that its effect depends on GA content. Finally, we observed significant changes in the content of several IAA-related compounds during the abscission period.

CONCLUSIONS

These results provide evidence that auxin homeostasis plays a central role during grapevine initial fruit development and that GA and IAA controls auxin homeostasis by reducing polar auxin transport.

Authors+Show Affiliations

Departamento de Genética Molecular y Microbiología, Pontificia Universidad Católica de Chile, Alameda 340, PO Box 114-D, Santiago, Chile.Departamento de Genética Molecular y Microbiología, Pontificia Universidad Católica de Chile, Alameda 340, PO Box 114-D, Santiago, Chile.Departamento de Genética Molecular y Microbiología, Pontificia Universidad Católica de Chile, Alameda 340, PO Box 114-D, Santiago, Chile.Departamento de Genética Molecular y Microbiología, Pontificia Universidad Católica de Chile, Alameda 340, PO Box 114-D, Santiago, Chile.Departamento de Genética Molecular y Microbiología, Pontificia Universidad Católica de Chile, Alameda 340, PO Box 114-D, Santiago, Chile.Department of Horticulture, Oregon State University, Corvallis, OR, 97331, USA.Department of Horticulture, Oregon State University, Corvallis, OR, 97331, USA.Departamento de Genética Molecular y Microbiología, Pontificia Universidad Católica de Chile, Alameda 340, PO Box 114-D, Santiago, Chile. parce@bio.puc.cl.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

27793088

Citation

Kühn, Nathalie, et al. "Regulation of Polar Auxin Transport in Grapevine Fruitlets (Vitis Vinifera L.) and the Proposed Role of Auxin Homeostasis During Fruit Abscission." BMC Plant Biology, vol. 16, no. 1, 2016, p. 234.
Kühn N, Serrano A, Abello C, et al. Regulation of polar auxin transport in grapevine fruitlets (Vitis vinifera L.) and the proposed role of auxin homeostasis during fruit abscission. BMC Plant Biol. 2016;16(1):234.
Kühn, N., Serrano, A., Abello, C., Arce, A., Espinoza, C., Gouthu, S., Deluc, L., & Arce-Johnson, P. (2016). Regulation of polar auxin transport in grapevine fruitlets (Vitis vinifera L.) and the proposed role of auxin homeostasis during fruit abscission. BMC Plant Biology, 16(1), 234.
Kühn N, et al. Regulation of Polar Auxin Transport in Grapevine Fruitlets (Vitis Vinifera L.) and the Proposed Role of Auxin Homeostasis During Fruit Abscission. BMC Plant Biol. 2016 10 28;16(1):234. PubMed PMID: 27793088.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Regulation of polar auxin transport in grapevine fruitlets (Vitis vinifera L.) and the proposed role of auxin homeostasis during fruit abscission. AU - Kühn,Nathalie, AU - Serrano,Alejandra, AU - Abello,Carlos, AU - Arce,Aníbal, AU - Espinoza,Carmen, AU - Gouthu,Satyanarayana, AU - Deluc,Laurent, AU - Arce-Johnson,Patricio, Y1 - 2016/10/28/ PY - 2016/04/15/received PY - 2016/10/04/accepted PY - 2016/10/30/pubmed PY - 2017/8/16/medline PY - 2016/10/30/entrez KW - Auxin homeostasis KW - Fruitlet abscission KW - Grapevine KW - IAA KW - PIN efflux facilitators KW - Polar auxin transport SP - 234 EP - 234 JF - BMC plant biology JO - BMC Plant Biol VL - 16 IS - 1 N2 - BACKGROUND: Indole-3-acetic acid (IAA), the most abundant auxin, is a growth promoter hormone involved in several developmental processes. Auxin homeostasis is very important to its function and this is achieved through the regulation of IAA biosynthesis, conjugation, degradation and transport. In grapevine, IAA plays an essential role during initial stages of berry development, since it delays fruitlet abscission by reducing the ethylene sensitivity in the abscission zone. For this reason, Continuous polar IAA transport to the pedicel is required. This kind of transport is controlled by IAA, which regulates its own movement by modifying the expression and localization of PIN-FORMED (PIN) auxin efflux facilitators that localize asymmetrically within the cell. On the other hand, the hormone gibberellin (GA) also activates the polar auxin transport by increasing PIN stability. In Vitis vinifera, fruitlet abscission occurs during the first two to three weeks after flowering. During this time, IAA and GA are present, however the role of these hormones in the control of polar auxin transport is unknown. RESULTS: In this work, the use of radiolabeled IAA showed that auxin is basipetally transported during grapevine fruitlet abscission. This observation was further supported by immunolocalization of putative VvPIN proteins that display a basipetal distribution in pericarp cells. Polar auxin transport and transcripts of four putative VvPIN genes decreased in conjunction with increased abscission, and the inhibition of polar auxin transport resulted in fruit drop. GA3 and IAA treatments reduced polar auxin transport, but only GA3 treatment decreased VvPIN transcript abundance. When GA biosynthesis was blocked, IAA was capable to increase polar auxin transport, suggesting that its effect depends on GA content. Finally, we observed significant changes in the content of several IAA-related compounds during the abscission period. CONCLUSIONS: These results provide evidence that auxin homeostasis plays a central role during grapevine initial fruit development and that GA and IAA controls auxin homeostasis by reducing polar auxin transport. SN - 1471-2229 UR - https://www.unboundmedicine.com/medline/citation/27793088/Regulation_of_polar_auxin_transport_in_grapevine_fruitlets__Vitis_vinifera_L___and_the_proposed_role_of_auxin_homeostasis_during_fruit_abscission_ L2 - https://bmcplantbiol.biomedcentral.com/articles/10.1186/s12870-016-0914-1 DB - PRIME DP - Unbound Medicine ER -