Pollen development stages relevant for successful anther culture in two indica rice varieties

Abstract

Pollen maturity stages were examined in two local indica rice varieties, kurulu thuda and Bg 250, to identify the appropriate stage for anther culture. Haematoxylin stain was used to differentiate between uni- and bi-nucleate pollen. A morphological marker, the distance between the flag leaf and penultimate leaf auricle of the plant, proved to be an effective guide to estimate panicle maturity. In each variety, anthers of panicles harvested when this distance was 3 and 4 cm contained uni-nucleate pollen only. Panicles at 5 and 6 cm distance had both uni- and bi-nucleate microspores and only bi-nucleate pollen was found at 7 and 8 cm distances. In var. kurulu thuda, only anthers from panicles corresponding to the marker distance 7 and 8 cm produced callus, while in var. Bg 250 callus induction was observed only from anthers collected from panicles when this distance was 6 and 7 cm, indicating that for both varieties anthers with bi-nucleate pollen are suitable for culture. Highest callus induction frequency was in var. Kurulu thuda (17.2%) from anthers that were the most mature examined (from 8 cm distance). In contrast, anther response in var. Bg 250 was relatively poor and the best callus induction frequency was 1.4% from panicles corresponding to the 6 cm distance.