Abnormalities in pistil development result in low seed set in Leymus chinensis (Poaceae)

Megasporogenesis and megagametogenesis in Leymus chinensis and the callose deposition during these developmental processes were investigated. In addition, morphological and histochemical studies of pistils at anthesis and pollen behavior on the stigmas after pollination were examined. The results indicate that embryo sac development and callose deposition pattern of this grass follow the archetypal Polygonum type. Nearly half of the pistils developed abnormally in megagametogenesis, while only 8.6% of abnormalities occurred in megasporogenesis. Over 47% of pistils at anthesis were abnormal in appearance. By 24 h after anthesis, many pollen grains had germinated on the stigmas of normal pistils. The high percentage of abnormal pistils and their low capacity to capture pollen grains may be the main factor in the low seed set of L. chinensis.