Germline Transformation for Crop Improvement

Abstract

In present times, when genetically modified (GM) crops are creating a niche for themselves in the agricultural arena, germline transformation is likely to reduce the time and effort to produce transgenics. In the last three decades of transgenic research, phenomenal success has been achieved but has remained limited to species that lent themselves easily to genetic modification. More than 15 dicot and 11 monocot taxa have been tested for male germline transformation. On the other hand at least 23 three dicot and four monocot taxa have been tested for genetic modification through female germline. Amongst the male germ cells, cel- lular systems ranging from microspore, immature and mature pollen, pollinaria, pollen protoplasts, pollen tubes, exine detached pollen (EDP) and pollen derived embryos have been tested for transient or stable integration of foreign genes. A variety of methods and variants and combinations of methods such as agrolistics that combines Agrobacterium mediated transformation and biolistics, are available for the introduction of genes into the male germline, as it is accessible to treatments under a variety of conditions. Amongst the methods tested in male germline transformation, particle bombardment remains the most preferred method. The female germline, being largely inaccessible has lent itself to modification mostly via Agrobacterium-mediated methods. The success of in planta vacuum infiltration and floral dip exercise seems to be confined to Crucifers with ovule as the prime target. Applicability of germline transformation methods is being tested on a wider range of crop plants. ?