* Climate change could bring lower yields, food crisis
* Crossing plant varieties to fight drought, heat
By Mica Rosenberg
EL BATAN, Mexico, Sept 17 (Reuters) - More than 500 years after Spanish priests brought wheat seeds to Mexico to make wafers for the Catholic Mass, those seeds may bring a new kind of salvation to farmers hit by global warming.
Scientists working in the farming hills outside Mexico City found the ancient wheat varieties have particular drought- and heat-resistant traits, like longer roots that suck up water and a capacity to store more nutrients in their stalks.
They are crossing the plants with other strains developed at the International Maize and Wheat Improvement Center (CIMMYT) in El Batan to grow types of wheat that can fight off the ill effects of rising temperatures around the world.
"It's like putting money in the bank to use, in this case, for a not rainy day," scientist Matthew Reynolds said of the resilient Mexican wheats his team collected.
Seed breeders say they are the first line of defense protecting farmers from climate change, widely expected to heat the planet between 1 and 3 degrees over the next 50 years.
Intensified drought, together with more intense and unpredictable rainfall, could hit crop yields and bring food shortages and spikes in commodity prices.
In Mexico, small farmers are grappling with the effects of unfavorable weather scientists say is exacerbated by climate change. Last year the country saw the lowest rainfall in 68 years and this year an active hurricane season battered corn-growing areas near the U.S. border.
Corn farmer Cesar Longoria, 56, said his family's harvest dropped by 30 percent in the 2009 drought, and then more than half of his fields in Reynosa were destroyed by floods in July when Hurricane Alex hammered northern Mexico.
"For the people that depend on corn this is a tragedy," said Carlos Salazar, head of the national corn growers association. "They have to buy more expensive corn to feed themselves and their animals."
The number of hungry people in the world had been rising for more than a decade, reaching a record spike in 2009 triggered by the economic crisis and high domestic food prices in several developing countries.
Nearly 1 billion people were considered undernourished this year, said the United Nations Food and Agriculture Organization in a report this week, and jumps in food prices have led to riots and social unrest.
Protests over a 30 percent rise in the price of bread in Mozambique killed 13 people this month after Russia's worst drought in more than a century led to a rally in international wheat prices that reverberated around the world.
In India, the world's second-largest wheat producer, rising temperatures could cut crop output by up to 25 percent in the next half century as the population booms.
India was one of the first nations to receive the benefits of innovative techniques of Nobel Peace Prize-winning plant scientist Norman Bourlag, the architect of the Green Revolution that helped pull the country from the brink of famine.
Bourlag started his pioneering research in the 1940s in Mexico, considered a birthplace for corn where native races of the grain dating to long before the Spanish conquest survive.
While CIMMYT, funded by governments, development banks and foundations, sends improved wheat and corn seeds around the world, even the lines best-adapted in the laboratory to climate extremes will fail unless farmers adopt methods of conserving water and recovering depleted soil.
Thousands of seeds are stored in CIMMYT's seed bank, where containers filled with red, blue and yellow and white corn are preserved in a refrigerated vault. The genes of some are being mapped to isolate useful traits to produce improved lines.
"Many of these land races have been around for tens of thousands, if not millions, of years and have lived through wide variations in the climate," Thomas Payne at the seed bank said. "They hold valuable information that can be used to confront the uncertainties of the future." (Editing by Missy Ryan and Jerry Norton)