Led by Ralph Bock from the Max Planck Institute of Molecular Plant Physiology in Germany, researchers studied genetically modified tobacco in which the transgene was integrated in chloroplasts.[14] A transplastomic tobacco plant generated through chloroplast mediated transformation was bred with plants that were male sterile with an untouched chloroplast.[14] The transplastomic plants were engineered to have resistance to the antibiotic spectinomycin and engineered to produce a green fluorescent protein molecule (GFP).[14] Therefore, it was hypothesized that any offspring produced by from these two lines of tobacco plant should not be able to grow on spectinomycin or be fluorescent, as the genetic material in the chloroplast should not be able to transfer via pollen.[14] However, it was found that some of the seeds were resistant to the antibiotic and could germinate on spectinomycin agar plates.[14] Calculations showed that 1 out of every million pollen grains contained plastid genetic material, which would be significant in an agricultural farm setting.[14] Because tobacco has a strong tendency towards self-fertilisation, the reliability of transplastomic plants is assumed to be even higher under field conditions.