XVI International Botanical Congess

Heat stress induces male sterility in several plants. We studied about development of anther of snap bean in optimal and high temperature conditions. In optimal condition pollen developed normally, tapetum broke down at about binucleate two-celled pollen stage. Development of anther tissue was normal till pollen tetrad in high temperatures. But after callose digestion and pollen grains release, the structure inside pollen was collapsed, and tapetum were damaged. Abnormal pollen grains and degenerated tapetum were observed at binucleate two-celled pollen stage. Vascular bundle of anther was degenerated finally. Pollen fertility was closely related to the temperature about 10 days before flowering from heat treatment examination. The stage after pollen grains release from pollen tetrad which occurred about 10 days before flowering was most sensitive stage by heat stress in snap bean.