Some of the world's largest biotechnology companies have filed hundreds of patents on "climate ready" gene-altered crops, hoping to dominate a market expected to emerge as farmers respond to environmental stresses caused by global warming, an advocacy group for subsistence farmers said in a report today. BASF, Monsanto, Bayer, Syngenta, Dupont and biotech partners have filed 532 patent documents around the world for crops genetically altered to adapt to rising temperatures, the ETC Group's report says.