Abstract: The immunohistochemical localization of IAA and the comparison of their relative levels were carried out for the first time in the anthers of Nongken 58S and its wild type Nongken 58 (Oryza sativa subsp. japonica) after long-day and short-day treatments. The distribution of free-IAA in anthers and its dynamic variation could be reflected by this method. The results showed that the IAA level in the anthers of Nongken 58S after long-day treatment was much lower than that in short-day-treated Nongken 58S and those in wild type Nongken 58 in five stages from pistil and stamen primordia formation to late uninucleate stage. The possible reasons for IAA deficiency in Nongken 58S-LD anthers and its relationship with fertility alteration were also discussed.

Key words: rice anther, auxin, photoperiod, male sterility, immunohistochemical localization