Cell-type specific heat-induced proteomics changes provide new insights in tomato pollen production under elevated temperature

Authors: THAPA, PRYIA - Tennessee State University; PRANDHAN, KAGO - Tennessee State University; GUO, JUN - Tennessee State University; THAPA, DIBYA - Tennessee State University; MADHAVARAPU, SUDHAKAR - Tennessee State University; ZOU, JING - Tennessee State University; POTTS, JESSE - Tennessee State University; LI, HIU - Tennessee State University; O'HAIR, JOSHUA - Tennessee State University; WANG, CHEN - Tennessee State University; ZHOU, SUPING - Tennessee State University; Yang, Yong; Fish, Tara; Thannhauser, Theodore

Submitted to: Proteomes
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/21/2025
Publication Date: 3/25/2025
Citation: Thapa, P., Prandhan, K., Guo, J., Thapa, D., Madhavarapu, S., Zou, J., Potts, J., Li, H., O'Hair, J., Wang, C., Zhou, S., Yang, Y., Fish, T., Thannhauser, T.W. 2025. Cell-type specific heat-induced proteomics changes provide new insights in tomato pollen production under elevated temperature. Proteomes. 13(2). https://doi.org/10.3390/proteomes13020013.
DOI: https://doi.org/10.3390/proteomes13020013

Interpretive Summary: Researchers from the USDA-ARS at Ithaca, New York and Tennessee State University conducted a study to investigate the impact of heat stress on pollen productivity in two tomato varieties, 'Black Vernissage' and 'Micro-Tom'. The rationale for this study stems from the heatwaves that occur during the growing season, which pose significant challenges to tomato production by affecting pollen viability and fruit set. The study compared pollen productivity under optimal (26°C/21°C) and heat-treated (37°C/26°C) conditions. Techniques utilized included laser capture micro-dissection (LCM) and single-cell type tandem mass tag (TMT) quantitative proteomics analysis to identify heat-induced proteomes in meiotic pollen mother cells and free microspores. Results indicated that both varieties experienced significant reductions in pollen count per flower under heat stress. However, 'Black Vernissage' demonstrated greater heat tolerance, with a lower rate of decline in pollen productivity compared to 'Micro-Tom'. Specifically, 'Black Vernissage' showed a 52% reduction in pollen count, while 'Micro-Tom' exhibited a 64% reduction. Proteomic analysis revealed that heat stress induced differential expression of proteins involved in meiosis and pollen wall formation. 'Black Vernissage' was enriched with heat shock proteins (HSPs) and proteins affecting meiosis fidelity, contributing to its higher thermotolerance. Additionally, the study identified significant changes in proteins associated with pollen wall formation, which are crucial for protecting the male gametophyte and ensuring successful reproduction. The most important finding of this study is the identification of specific proteins and mechanisms that confer heat tolerance in 'Black Vernissage'. These insights provide a foundation for developing heat-tolerant tomato varieties.

Technical Abstract: Tomatoes are self-pollinating plants, and successful fruit set depends on the production of functional pollen within the same flower. Our previous studies have shown that the ‘Black Vernis-sage’ tomato variety exhibits greater resilience to heat stress in terms of pollen productivity compared to the ‘Micro-Tom’ variety. Pollen productivity is determined by meiotic activity during microsporogenesis and the development of free microspores during gametogenesis. This study focused on identifying heat stress-induced proteomes in pollen mother cells (PMCs) and microspores. Tomato plants were grown under two temperature conditions: 26°C (non-heat-treated control) and 37°C (heat-treated). Homogeneous cell samples of meiotic PMC (prior to the tetrad stage) and free microspores were collected using laser capture microdissection (LCM). Tandem Mass Tag (TMT)-quantitative proteomics analysis identified proteins enriched in the meiotic cell cycle in PMCs and the pre-mitotic process in free microspores, con-firming a correlation between proteome expression and developmental stage. Under heat stress, PMCs in both tomato varieties were enriched with heat shock proteins (HSPs). However, the ‘Black Vernissage’ variety exhibited a greater diversity of HSP species and a higher level of enrichment compared to the ‘Micro-Tom’ variety. Additionally, several proteins involved in gene expression and protein translation were down regulated in PMCs and microspores of both varieties. In the PMC proteomes, the relative abundance of proteins showed no significant differences between the two varieties under normal conditions, with very few exceptions. However, heat stress induced significant differential expression both within and between the varieties. In microspores, most heat stress-induced protein changes were consistently observed across both varieties, with only a few proteins showing significant differences between them under heat stress. Results suggest that heat stress-induced proteins in meiotic PMCs may have a more pronounced effect on pollen productivity, as observed in the two varieties. Heat stress-induced proteins specific to each variety and cell type were identified. This research highlights the importance of a single-cell type proteomics approach in identifying stress responses. It provides valuable in-sights into the molecular mechanisms underlying heat stress tolerance in tomato pollen development, offering potential targets for breeding heat-resilient tomato varieties.