Finding a few transgenic pollen grains in a large pool is usually like searching for a needle in a haystack. To study of gene flow and assessing the effectiveness of transgene containment mostly microscopic screening methods or progeny analyses are used, which are time-consuming and laborious.

A fast, simple and high-throughput method in which flow cytometry is employed, is able to count 5,000 pollen grains per minute. The technique, described by researchers around C. Neal Stewart Jr, University of Tennessee, Knoxville, TN, USA, is not less laborious than other methods, but it is very accurate for high green fluorescent protein (GFP)-expressing pollen grains. A suspension of non-transgenic tobacco pollen was spiked with a known amount of verified transgenic tobacco pollen synthesizing low or high amounts of GFP.

• An efficient and rapid transgenic pollen screening and detection method using flow cytometry
  H. S. Moon, S. Eda, A. M. Saxton, D. W. Ow, C. N. Stewart,
  Biotechnol. J. 2011, 6.
  DOI: 10.1002/biot.201000258