Hello Ozcan

As far as I know, there should be only two types of gene transfers, vertical and horizontal. Endosymbiotic gene transfer is regarded as a type of horizontal gene transfers. I do not know about zygotic induction.

Best,

Kyungtaek

Kyungtaek is correct that there are only two types of gene transfer: vertical and horizontal (covering anything not vertical). The types of horizontal are varied though: conjugation, transformation and transduction are the classic versions, endosymbiotic transfer is another although it probably occurred as a result of one of the first three. Gene Transfer Agents (GTAs) are arguably another method of exchange, although similar to transduction (first reported: http://www.pnas.org/content/71/3/971). "Mating" is a form of cell fusion in the Haloarchaea with colossal stretches of DNA exchanged (first reported: http://jb.asm.org/content/162/1/461.short). Additionally, one could argue that transformation should be subdivided into several categories based on levels of natural and induced competence and levels of selectivity for the DNA being taken up (DNA uptake sequences) and deliberately or accidentally transformed (some organisms appear to take the DNA up as nutrient with recombination happening by accident, while others, such as those with DUS', may be taking up related DNA for use in chromosome repair).

I know little about zygotic induction, but I do not think it is involved in HGT other than how any lysogenic phage may be involved in transduction.

You also have the potential of horizontal gene transfer by outer membrane vesicles in addition to the classic ones. This publication have some more details http://aem.asm.org/content/early/2014/03/18/AEM.04248-13

And finally, there is both theoretical ground and empirical evidence that lightning strokes, by inducing electroporation of microorganisms in the environment into which they strike, render these microorganisms temporarily permeable to exogenous DNA, as well as leaking their own DNA that can then electrotransform another microorganism nearby. The article with many more details can be downloaded here:

https://www.researchgate.net/publication/240308811_Lightning-triggered_electroporation_and_electrofusion_as_possible_contributors_to_natural_horizontal_gene_transfer

Article Lightning-triggered electroporation and electrofusion as pos...