Abstract
In flowering plants, auxin produced in seeds after fertilization promotes fruit initiation. The application of auxin to unpollinated ovaries can also induce parthenocarpy (seedless fruit production). Previous studies have shown that auxin signalling components SlIAA9 and SlARF7 (a class A AUXIN RESPONSE FACTOR (ARF)) are key repressors of fruit initiation in tomato (Solanum lycopersicum). A similar repressive role of class A ARFs in fruit set has also been observed in other plant species. However, evidence is lacking for a role of any class A ARF in promoting fruit development as predicted in the current auxin signalling model. Here we generated higher-order tomato mutants of four class A SlARFs (SlARF5, SlARF7, SlARF8A and SlARF8B) and uncovered their precise combinatorial roles that lead to suppressing and promoting fruit development. All four class A SlARFs together with SlIAA9 inhibited fruit initiation but promoted subsequent fruit growth. Transgenic tomato lines expressing truncated SlARF8A/8B lacking the IAA9-interacting PB1 domain displayed strong parthenocarpy, further confirming the promoting role of SlARF8A/8B in fruit growth. Altering the doses of these four SlARFs led to biphasic fruit growth responses, showing their versatile dual roles as both negative and positive regulators. RNA-seq and chromatin immunoprecipitation–quantitative PCR analyses further identified SlARF8A/8B target genes, including those encoding MADS-BOX transcription factors (AG1, MADS2 and AGL6) that are key repressors of fruit set. These results support the idea that SlIAA9/SlARFs directly regulate the transcription of these MADS-BOX genes to inhibit fruit set. Our study reveals the previously unknown dual function of four class A SlARFs in tomato fruit development and illuminates the complex combinatorial effects of multiple ARFs in controlling auxin-mediated fruit set and fruit growth.
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Data availability
The RNA-seq data have been deposited in the NCBI Sequence Read Archive under BioProject PRJNA929538. Source data are provided with this paper.
References
Gillaspy, G., Ben-David, H. & Gruissem, W. Fruits: a developmental perspective. Plant Cell 5, 1439–1451 (1993).
Seymour, G. B., Ostergaard, L., Chapman, N. H., Knapp, S. & Martin, C. Fruit development and ripening. Annu. Rev. Plant Biol. 64, 219–241 (2013).
Fenn, M. A. & Giovannoni, J. J. Phytohormones in fruit development and maturation. Plant J. 105, 446–458 (2021).
Srivastava, A. & Handa, A. K. Hormonal regulation of tomato fruit development: a molecular perspective. J. Plant Growth Regul. 24, 67–82 (2005).
Dorcey, E., Urbez, C., Blazquez, M. A., Carbonell, J. & Perez-Amador, M. A. Fertilization-dependent auxin response in ovules triggers fruit development through the modulation of gibberellin metabolism in Arabidopsis. Plant J. 58, 318–332 (2009).
Serrani, J. C., Fos, M., Atares, A. & Garcia-Martinez, J. L. Effect of gibberellin and auxin on parthenocarpic fruit growth induction in the cv Micro-Tom of tomato. J. Plant Growth Regul. 26, 211–221 (2007).
Gorguet, B., van Heusden, A. W. & Lindhout, P. Parthenocarpic fruit development in tomato. Plant Biol. (Stuttg.) 7, 131–139 (2005).
Mutte, S. K. et al. Origin and evolution of the nuclear auxin response system. eLife 7, e33399 (2018).
Israeli, A., Reed, J. W. & Ori, N. Genetic dissection of the auxin response network. Nat. Plants 6, 1082–1090 (2020).
Kato, H. et al. Design principles of a minimal auxin response system. Nat. Plants 6, 473–482 (2020).
Lavy, M. & Estelle, M. Mechanisms of auxin signaling. Development 143, 3226–3229 (2016).
Morffy, N. & Strader, L. C. Structural aspects of auxin signaling. Cold Spring Harb. Perspect. Biol. 14, a039883 (2022).
Leyser, O. Auxin signaling. Plant Physiol. 176, 465–479 (2018).
Weijers, D. & Wagner, D. Transcriptional responses to the auxin hormone. Annu. Rev. Plant Biol. 67, 539–574 (2016).
Leydon, A. R. et al. Repression by the Arabidopsis TOPLESS corepressor requires association with the core mediator complex. eLife 10, e66739 (2021).
Guilfoyle, T. J. & Hagen, G. Auxin response factors. Curr. Opin. Plant Biol. 10, 453–460 (2007).
Audran-Delalande, C. et al. Genome-wide identification, functional analysis and expression profiling of the Aux/IAA gene family in tomato. Plant Cell Physiol. 53, 659–672 (2012).
Zhang, J. et al. A single-base deletion mutation in SlIAA9 gene causes tomato (Solanum lycopersicum) entire mutant. J. Plant Res. 120, 671–678 (2007).
Hu, J., Israeli, A., Ori, N. & Sun, T. P. The interaction between DELLA and ARF/IAA mediates crosstalk between gibberellin and auxin signaling to control fruit initiation in tomato. Plant Cell 30, 1710–1728 (2018).
Wang, H. et al. The tomato Aux/IAA transcription factor IAA9 is involved in fruit development and leaf morphogenesis. Plant Cell 17, 2676–2692 (2005).
Ueta, R. et al. Rapid breeding of parthenocarpic tomato plants using CRISPR/Cas9. Sci. Rep. 7, 507 (2017).
Liu, S. et al. Tomato AUXIN RESPONSE FACTOR 5 regulates fruit set and development via the mediation of auxin and gibberellin signaling. Sci. Rep. 8, 2971 (2018).
de Jong, M., Wolters-Arts, M., Feron, R., Mariani, C. & Vriezen, W. H. The Solanum lycopersicum auxin response factor 7 (SlARF7) regulates auxin signaling during tomato fruit set and development. Plant J. 57, 160–170 (2009).
Goetz, M., Vivian-Smith, A., Johnson, S. D. & Koltunow, A. M. AUXIN RESPONSE FACTOR8 is a negative regulator of fruit initiation in Arabidopsis. Plant Cell 18, 1873–1886 (2006).
Du, L. et al. SmARF8, a transcription factor involved in parthenocarpy in eggplant. Mol. Genet. Genomics 291, 93–105 (2016).
Zhou, J. et al. Gibberellin and auxin signaling genes RGA1 and ARF8 repress accessory fruit initiation in diploid strawberry. Plant Physiol. 185, 1059–1075 (2021).
Kumar, R., Khurana, A. & Sharma, A. K. Role of plant hormones and their interplay in development and ripening of fleshy fruits. J. Exp. Bot. 65, 4561–4575 (2014).
Zouine, M. et al. Characterization of the tomato ARF gene family uncovers a multi-levels post-transcriptional regulation including alternative splicing. PLoS ONE 9, e84203 (2014).
Liu, N. et al. Down-regulation of AUXIN RESPONSE FACTORS 6 and 8 by microRNA 167 leads to floral development defects and female sterility in tomato. J. Exp. Bot. 65, 2507–2520 (2014).
Israeli, A. et al. Multiple auxin-response regulators enable stability and variability in leaf development. Curr. Biol. 29, 1746–1759 e1745 (2019).
Pierre-Jerome, E., Jang, S. S., Havens, K. A., Nemhauser, J. L. & Klavins, E. Recapitulation of the forward nuclear auxin response pathway in yeast. Proc. Natl Acad. Sci. USA 111, 9407–9412 (2014).
Pierre-Jerome, E., Moss, B. L., Lanctot, A., Hageman, A. & Nemhauser, J. L. Functional analysis of molecular interactions in synthetic auxin response circuits. Proc. Natl Acad. Sci. USA 113, 11354–11359 (2016).
Wu, M. F., Tian, Q. & Reed, J. W. Arabidopsis microRNA167 controls patterns of ARF6 and ARF8 expression, and regulates both female and male reproduction. Development 133, 4211–4218 (2006).
Pnueli, L., Hareven, D., Rounsley, S. D., Yanofsky, M. F. & Lifschitz, E. Isolation of the tomato AGAMOUS gene TAG1 and analysis of its homeotic role in transgenic plants. Plant Cell 6, 163–173 (1994).
Scharf, K. D., Berberich, T., Ebersberger, I. & Nover, L. The plant heat stress transcription factor (Hsf) family: structure, function and evolution. Biochim. Biophys. Acta 1819, 104–119 (2012).
Nakatsuka, A. et al. Differential expression and internal feedback regulation of 1-aminocyclopropane-1-carboxylate synthase, 1-aminocyclopropane-1-carboxylate oxidase, and ethylene receptor genes in tomato fruit during development and ripening. Plant Physiol. 118, 1295–1305 (1998).
Nitsch, L. M. et al. Abscisic acid levels in tomato ovaries are regulated by LeNCED1 and SlCYP707A1. Planta 229, 1335–1346 (2009).
Tournier, B. et al. New members of the tomato ERF family show specific expression pattern and diverse DNA-binding capacity to the GCC box element. FEBS Lett. 550, 149–154 (2003).
Olimpieri, I. et al. Tomato fruit set driven by pollination or by the parthenocarpic fruit allele are mediated by transcriptionally regulated gibberellin biosynthesis. Planta 226, 877–888 (2007).
Munoz-Bertomeu, J., Miedes, E. & Lorences, E. P. Expression of xyloglucan endotransglucosylase/hydrolase (XTH) genes and XET activity in ethylene treated apple and tomato fruits. J. Plant Physiol. 170, 1194–1201 (2013).
Quiroga, M. et al. A tomato peroxidase involved in the synthesis of lignin and suberin. Plant Physiol. 122, 1119–1127 (2000).
Allegre, A., Silvestre, J., Morard, P., Kallerhoff, J. & Pinelli, E. Nitrate reductase regulation in tomato roots by exogenous nitrate: a possible role in tolerance to long-term root anoxia. J. Exp. Bot. 55, 2625–2634 (2004).
Yang, Z., Tian, L., Latoszek-Green, M., Brown, D. & Wu, K. Arabidopsis ERF4 is a transcriptional repressor capable of modulating ethylene and abscisic acid responses. Plant Mol. Biol. 58, 585–596 (2005).
Shinozaki, Y. et al. Ethylene suppresses tomato (Solanum lycopersicum) fruit set through modification of gibberellin metabolism. Plant J. 83, 237–251 (2015).
Wang, H. et al. Regulatory features underlying pollination-dependent and -independent tomato fruit set revealed by transcript and primary metabolite profiling. Plant Cell 21, 1428–1452 (2009).
Tang, N., Deng, W., Hu, G., Hu, N. & Li, Z. Transcriptome profiling reveals the regulatory mechanism underlying pollination dependent and parthenocarpic fruit set mainly mediated by auxin and gibberellin. PLoS ONE 10, e0125355 (2015).
Klap, C. et al. Tomato facultative parthenocarpy results from SlAGAMOUS-LIKE 6 loss of function. Plant Biotechnol. J. 15, 634–647 (2017).
Molesini, B., Dusi, V., Pennisi, F. & Pandolfini, T. How hormones and MADS-box transcription factors are involved in controlling fruit set and parthenocarpy in tomato. Genes (Basel) 11, 1441 (2020).
Hu, G. et al. Histone posttranslational modifications rather than DNA methylation underlie gene reprogramming in pollination-dependent and pollination-independent fruit set in tomato. N. Phytol. 229, 902–919 (2021).
Lavy, M. et al. Constitutive auxin response in Physcomitrella reveals complex interactions between Aux/IAA and ARF proteins. eLife 5, e13325 (2016).
Tao, S. & Estelle, M. Mutational studies of the Aux/IAA proteins in Physcomitrella reveal novel insights into their function. N. Phytol. 218, 1534–1542 (2018).
Peterson, B. A. et al. Genome-wide assessment of efficiency and specificity in CRISPR/Cas9 mediated multiple site targeting in Arabidopsis. PLoS ONE 11, e0162169 (2016).
Bajwa, V. S. et al. Identification and functional analysis of tomato BRI1 and BAK1 receptor kinase phosphorylation sites. Plant Physiol. 163, 30–42 (2013).
Heberle, H., Meirelles, G. V., da Silva, F. R., Telles, G. P. & Minghim, R. InteractiVenn: a web-based tool for the analysis of sets through Venn diagrams. BMC Bioinf. 16, 169 (2015).
Tian, T. et al. agriGO v2.0: a GO analysis toolkit for the agricultural community, 2017 update. Nucleic Acids Res. 45, W122–W129 (2017).
Acknowledgements
We thank T. Nolan and L. Wang for helpful advice on QuantSeq analysis; Z. Nimchuk for providing the CRISPR–Cas9 vectors; J. Nemhauser and E. Pierre-Jerome for providing the ARC constructs, yeast strains and detailed protocols; and N. Ori and A. Israeli for sharing their unpublished results. We also thank A. Israeli, N. Ori, Z.-M. Pei, J. Reed and L. Strader for helpful comments on the manuscript and the China Scholarship Council (CSC) for scholarship support (CSC fellowship no. 201803250091 to X.L.). This work was supported by the US Department of Agriculture (grant no. 2018-67013-27395 to T.-P.S.) and the National Institutes of Health (grant no. R01 GM100051 to T.-P.S.).
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J.H. and T.-P.S. conceived and designed the research project. J.H. and X.L. performed the experiments. J.H., X.L. and T.-P.S. analysed the data. J.H. and T.-P.S. wrote the manuscript.
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Hu, J., Li, X. & Sun, Tp. Four class A AUXIN RESPONSE FACTORs promote tomato fruit growth despite suppressing fruit set. Nat. Plants 9, 706–719 (2023). https://doi.org/10.1038/s41477-023-01396-y
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DOI: https://doi.org/10.1038/s41477-023-01396-y