A team led by Dr. Guang-Yuh Jauh, an Associate Research Fellow of the Institute of Plant and Microbial Biology recently revealed the gene expression profile of pollen tubes growing within a flower using a novel scalpel-less strategy. The study, which advances understanding of the pollination process, highlights the advantage of using a microgenomics approach for studying cell-type-specific gene expression on a genome-wide scale. The research was published in the prestigious journal The Plant Cell on February 14, 2014 and was highlighted in a commentary article in the issue.

         In flowering plants, pollen deposited on the stigma of a flower germinates by producing a pollen tube that grows through the style and into the micropyle of an ovule to release its two sperm cells for double fertilization with the egg and central cell.

         Up until now scholars have used pollen tubes cultured in vitro (in test tubes) to study the genes involved in pollination (i.e., to conduct genome-wide gene expression prolife analysis). However, it is known that signals from maternal tissue are vital for the fertilization processes in the plant, but collection of pollen tubes growing within the floral solid material has proved difficult.

         Dr. Jauh’s team developed an innovative genomics technique (i.e., using transgenic Arabidopsis plants expressing a pollen-specific LAT52 promoter to generate epitope-tagged polysomal-RNA complexes that were affinity purified) to obtain the “translatome” (the complete set of mRNAs undergoing translation) of in vivo-grown pollen tubes. Over 500 transcripts specifically enriched in in vivo elongating pollen tubes were obtained. Functional analyses of several mutants of these pollination-enhanced transcripts exposed defective pollination, fertilization and seed formation. Cytological observation confirmed the involvement of these genes in specialized processes including micropylar guidance, pollen tube burst and repulsion of multiple pollen tubes in embryo sac during pollination.

         The research was funded by National Science Council of Taiwan and Academia Sinica and was conducted in collaboration with Dr. Julia Bailey-Serres at University of California, Riverside, in the USA.

         The complete list of authors is: Shih-Yun Lin, Pei-Wei Chen, Ming-Hsiang Chuang, Piyada Juntawong, Julia Bailey-Serres and Guang-Yuh Jauh.

         The complete article entitled “Profiling of translatomes of in vivo–grown pollen tubes reveals genes with roles in micropylar guidance during pollination in Arabidopsis” can be found at The Plant Cell journal website at: http://www.plantcell.org/content/early/2014/02/13/tpc.113.121335.abstract .