DNA shuffling to produce herbicide selective crops

A method of obtaining a recombinant herbicide tolerance nucleic acid which can confer tolerance to an herbicide upon a plant in which the recombinant herbicide tolerance nucleic acid is present, the method comprising:

• (i) recombining a plurality of variant forms of one or more parental nucleic acid, wherein the plurality of variant forms comprises segments derived from the parental nucleic acid, wherein the parental nucleic acid encodes an herbicide tolerance activity, or can be shuffled to encode an herbicide tolerance activity, and wherein the plurality of variant forms differ from each other in at least one nucleotide, to produce a library of recombinant nucleic acids;
• (ii) screening the library to identify at least one recombinant herbicide tolerance nucleic acid, wherein the recombinant herbicide tolerance nucleic acid encodes an activity which confers herbicide tolerance to a cell.