Protocol for Enrichment of the Membrane Proteome of Mature Tomato Pollen

Proteomics of Reproductive Development, Fruit Ripening, and Stress Responses in Tomato

The fruits of the tomato crop (Solanum lycopersicum L.) are increasingly consumed by humans worldwide. Due to their rich nutritional quality, pharmaceutical properties, and flavor, tomato crops have gained a salient role as standout crops among other plants. Traditional breeding and applied functional research have made progress in varying tomato germplasms to subdue biotic and abiotic stresses. Proteomic investigations within a span of few decades have assisted in consolidating the functional genomics and transcriptomic research. However, due to the volatility and dynamicity of proteins in the regulation of various biosynthetic pathways, there is a need for continuing research in the field of proteomics to establish a network that could enable a more comprehensive understanding of tomato growth and development. With this view, we provide a comprehensive review of proteomic studies conducted on the tomato plant in past years, which will be useful for future breeders and researchers working to improve the tomato crop.

The coupling of transcriptome and proteome adaptation during development and heat stress response of tomato pollen

BACKGROUND

Pollen development is central for plant reproduction and is assisted by changes of the transcriptome and proteome. At the same time, pollen development and viability is largely sensitive to stress, particularly to elevated temperatures. The transcriptomic and proteomic changes during pollen development and of different stages in response to elevated temperature was targeted to define the underlying molecular principles.

RESULTS

The analysis of the transcriptome and proteome of Solanum lycopersicum pollen at tetrad, post-meiotic and mature stage before and after heat stress yielded a decline of the transcriptome but an increase of the proteome size throughout pollen development. Comparison of the transcriptome and proteome led to the discovery of two modes defined as direct and delayed translation. Here, genes of distinct functional processes are under the control of direct and delayed translation. The response of pollen to elevated temperature occurs rather at proteome, but not as drastic at the transcriptome level. Heat shock proteins, proteasome subunits, ribosomal proteins and eukaryotic initiation factors are most affected. On the example of heat shock proteins we demonstrate a decoupling of transcript and protein levels as well as a distinct regulation between the developmental stages.

CONCLUSIONS

The transcriptome and proteome of developing pollen undergo drastic changes in composition and quantity. Changes at the proteome level are a result of two modes assigned as direct and delayed translation. The response of pollen to elevated temperature is mainly regulated at the proteome level, whereby proteins related to synthesis and degradation of proteins are most responsive and might play a central role in the heat stress response of pollen.