OAKLAND, Calif. — Less than a dozen companies have filed 532 patents for plant genes designed to tolerate extreme weather and environmental conditions. While the biotech crops are designed to better survive conditions brought on by climate change, a report looking at the patents warns of how a gene patent monopoly could harm farmers.

"Patenting the 'Climate Genes' and Capturing the Climate Agenda" was complied by the ETC Group, a Canadian-based non-governmental organization focused on socially responsible development related to culture, ecological diversity and human rights.

In the past years, 532 so-called "climate-ready" gene patents within 55 patent families have been filed by companies including Monsanto, BASF, DuPont, Bayer and Dow. They cover plant genes that are designed to make crops more resistant to climate fluctuations and environmental stressors like drought, heat, cold, floods and soil containing salt that interferes with plant growth. Most patents are pending approval.

ETC Group notes that in some cases the companies are working with organizations, research groups and philanthropists. The Bill & Melinda Gates Foundation is providing a $47 million grant for Monsanto and BASF to develop drought-tolerant corn for use in the southern African countries of Kenya, Uganda, Tanzania and South Africa.

"We aim to be at once generous and also cognizant of our obligation to shareholders who have paid for our research," Ranjana Smetacek, a spokeswoman for Monsanto, told the Washington Post.

However, all that work on patenting crop genes, ETC Group says, stands to create a monopoly of power over crops and could hurt smaller, poorer farmers around the world. A widespread changeover to crops with patented genes would increase costs for farmers, stifle independent research and push out traditional farming methods or other practices for dealing with climate change, according to ETC Group. Farmers in areas such as southern Asia and southern Africa stand to suffer the most from climate change as well as a wholesale switch to "climate-ready" crops, according to the ETC Group.

Each patent family is a single patent submitted to apply to more than one country. BASF has filed 21 of the 55 patent families; Syngenta, 7; Monsanto, 6; Bayer, 5; Ceres, 4; Mendel Biotechnology, 3; Dow, 2; Evogene, 2; and DuPont, 1. The report lists out all 55 families, what company or group filed them, what they cover and when they were filed.