Tomato’s ABA receptors reveal hidden roles in growth, aging, and fruit Color

Overexpressing these receptors caused ABA hypersensitivity, dwarfism, delayed senescence, reproductive anomalies, and enhanced fruit pigmentation. The findings reveal how ABA signaling integrates hormonal crosstalk to fine-tune tomato growth, aging, and reproduction, offering valuable insights for crop improvement under stress-prone environments.

Abscisic acid (ABA) is a vital hormone orchestrating plant development and stress adaptation. While its role in stress responses and fruit ripening has been extensively studied, how ABA influences vegetative growth and flower development remains poorly understood. ABA signaling relies on the PYR/PYL/RCAR receptor family, which functions as molecular switches that activate downstream kinases to trigger physiological responses. In model plants like Arabidopsis, these receptors are known to regulate drought tolerance, seed dormancy, and fruit ripening. However, the redundant and diverse roles of receptor subfamilies have hindered full understanding of how ABA controls developmental plasticity. Tomato, a model for fruit development and hormone interaction studies, provides an ideal system to bridge these gaps. Given the evolutionary diversification of ABA receptor families, clarifying their functions in both vegetative and reproductive phases is essential to better understand plant resilience and yield formation under environmental challenges.

A study (DOI: 10.48130/ph-0025-0013) published in Plant Hormones on 08 July 2025 by  Ning Tang’s & Zexiong Chen’s team, Chongqing University of Arts and Sciences, establishs a molecular framework for optimizing growth-defense trade-offs in horticultural crops through hormone engineering.

Researchers mined tomato genome databases and transcriptomic datasets to identify members of the PYR/PYL/RCAR receptor family. Fifteen SlPYR/PYL genes were discovered and phylogenetically classified into three subfamilies corresponding to their Arabidopsis homologs: subfamily I (SlPYL4.1–4.3, SlPYL6.2–6.4), subfamily II (SlPYR1.1, SlPYR1.2, SlPYL2.1, SlPYL2.2), and subfamily III (SlPYL8.1, SlPYL8.2, SlPYL9.1, SlPYL9.2, SlPYL6.1). Expression profiling under various hormonal and environmental treatments revealed that SlPYR1.1 and SlPYL8.1 were markedly responsive to ABA, salt, and ethylene, with predominant expression in roots and leaves but strong suppression during fruit ripening. Subcellular localization of GFP-tagged proteins in Nicotiana benthamiana confirmed their presence in both the nucleus and cytoplasm, suggesting a dual regulatory role in ABA-mediated transcriptional control. Functional validation using overexpression (OX) lines demonstrated that SlPYR1.1-OX plants exhibited hypersensitivity to ABA, reduced germination, shorter roots, and a pronounced dwarf phenotype caused by the downregulation of SlGID1, a key gibberellin receptor, implying antagonism between ABA and GA pathways. In contrast, SlPYL8.1-OX plants displayed delayed leaf senescence characterized by dark-green, thickened leaves with higher chlorophyll and carotenoid contents due to enhanced mesophyll cell proliferation. However, SlPYL8.1 overexpression also led to reproductive anomalies, including floral bud abortion and altered inflorescence orientation, reflecting developmental trade-offs. Remarkably, SlPYL8.1-OX fruits accumulated elevated lycopene levels and exhibited deeper red pigmentation, indicating that this gene not only mediates stress and growth regulation but also fine-tunes fruit coloration and ripening in tomato.

This study highlights SlPYR1.1 and SlPYL8.1 as central nodes linking ABA signaling to developmental and stress-related responses. By tuning their expression, it may be possible to achieve desirable agricultural traits—such as enhanced stress resilience, delayed leaf aging, or improved fruit color—without compromising overall plant vitality. The ability of SlPYL8.1 to enhance lycopene accumulation provides a promising strategy for improving tomato nutritional quality and shelf life. At the same time, understanding receptor-mediated reproductive inhibition can guide breeding strategies to prevent yield loss. 

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References

DOI

10.48130/ph-0025-0013

Original Source URL

https://doi.org/10.48130/ph-0025-0013

Funding Information

This work was financially supported by Chongqing talent program (cstc2024ycjh-bgzxm0105), the Chongqing Natural Science Foundation Innovation and Development Joint Fund Project (CSTB2023NSCQ-LZX0146).

About Plant Hormones

Plant Hormones (e-ISSN 3067-221X) is an open access, online-only, academic journal publishing rigorously peer-reviewed original articles, reviews, break-through methods, editorials, and perspectives on broad aspects of plant hormone biosynthesis, signal transduction, and crosstalk. The journal primarily publishes fundamental research that represents significant advances or new insight into specialized areas of plant hormones, and review articles that provide comprehensive and critical review of current research areas and offer directions or perspectives for future research. The journal publishes applied research that has significant implications for the development of agriculture, horticulture, and forestry. Plant Hormones also provides a community forum by publishing editorials and perspective papers for expressing opinions on specific issues or new perspectives about existing research on particular topics. Plant Hormones is hosted by Chongqing University, and published by Maximum Academic Press.