Mexican politicians are demanding action to protect the tequila industry from Chinese competition.
Mexican tequila sells well in the US
The lower house of Congress voted to urge the government to stop Chinese firms patenting maguey - a type of agave cactus used in tequila.
MPs are also worried that Chinese and Japanese firms could target the market in another cactus species, nopal.
Nopal leaves are increasingly popular in the US, where there is already strong demand for tequila.
"Nopal and Maguey are Mexican plants and if we don't take the necessary measures in time, we run the risk of losing the denomination of origin", Cesar Duarte, the deputy who sponsored the move, told the Efe news agency.
Mr Duarte said the main Mexican farmers' union had been told that Chinese firms had begun legal moves to register the nopal plant with the European Commission as a Chinese product.
But the Mexican Agriculture Ministry said that so far Brussels had received no requests regarding either mopal or maguey.
The Mexican tequila industry has expanded rapidly since the early 1990s.
Marketing experts have tried to change its reputation from a cheap peasant drink to a sophisticated international spirit like whisky.
In 2005, Mexico produced a record 210m litres of tequila - almost half of which was exported. Sales to the US alone were worth more than $400m.
Mexican tequila producers have pushed for tequila products to have a denomination of origin system similar to the one used in the wine industry.
Mexico argues that the maguey is a uniquely Mexican product because 150 of the 200 varieties of the plant are found in its territory.