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Identification of Heat-Induced Proteomes in Tomato Microspores Using LCM- Proteomics Analysis

Li H, Zhu Y, Rangu M, Wu X, Bhatti S, Zhou S, Yang Y, Fish T and Thannhauser TW

Pollen development is highly susceptible to heat stress (HS) and the production of inviable pollen causes reduction in seed- and fruit-set in plants. This study was carried out to identify HS-induced pollen proteins and the associated biological processes in tomato (Solanum lycopersicum). Tomato ‘Micro-Tom’ plants were incubated under 32°C//22°C (day/night, 12/12 h) for two weeks for heat treatment, and the non-treated control plants were incubated for the same time period at 25°C /22°C. Flower buds of 5 mm in length were confirmed to contain the heat sensitive uninucleate microspores. Pollen cells were harvested using laser capture microdissection (LCM) and protein was extracted using a one-step method under high pressure and vacuum. Approximately 60,000 LCMharvested microspore cells yielded about 18-20 μg proteins. The tandem mass tags (TMT) proteomics analysis identified a total of 6018 proteins, 4784 proteins were quantified, 37 proteins were identified as HS up-regulated significantly changed proteins (SCPs), and 83 proteins as HS down (dn)-regulated SCPs. Further analysis using the plant MetGenMap system showed that the HS up-regulated SCPs were enriched in the heat acclimation, pollen wall formation, protein folding/refolding gene ontology (GO) biological processes, and the HS dn-regulated SCPs were placed in the carbohydrate catabolism and de-novo protein biosynthesis GO terms. Biological processes such as mitosis, resistance to oxidative stresses, and carbohydrate and lipid metabolic processes contain both the HS up-, and dn-regulated SCPs. These results indicate that the LCM-TMT proteomics workflow is highly efficient in the identification of HS-induced pollen proteomes. These HS induced SCPs will be used for exploring heat tolerance of tomato pollens. The proteomics data are available via ProteomeXchange with identifier PXD010218.