Characteristics of dynamic changes of the callose in male sterile anthers of Lycium barbarum L.

Abstract [Objective] Callose is a beta-1, 3-bonded glucan that forms a wall structure, which occurs only in certain tissues. When degrading prematurely or delayed, it may lead to pollen abortion. Examining the dynamics of callose deposition is important for understanding the mechanism of male sterility and its application. [Methods] The fertile line ‘Ningqi No.1’ and sterile line ‘Ningqi No.5’ of Lycium barbarum L. were studied using semi-thin section technique, and callose was labeled with aniline blue and periodic acid- Schiff stain (PAS). The dynamic characteristics of callose in fertile and sterile anthers of L. barbarum at different developmental stages were compared under optical microscope, and the influence of callose on anther abortion of sterile line was analyzed. [Results] In the microspore mother stage, the extracellular deposits of fertile and sterile anthers formed an uneven thick callose wall, and the fluorescence reaction showed that the callose wall gradually was thickened after meiosis forming a tetrad. With the further development of anthers, the extracellular callose wall in fertile anthers gradually disintegrated and disappeared, releasing 4 microspores. However, in sterile anthers, the callose wall outside the tetrad was thickened continuously, and there was no sign of degradation. Until flowering, the small spores in the anther chamber still existed in the state of tetrad, and the callose wall was still wrapped around the deformed and disintegrated tetrad. [Conclusion] Abnormal callose degradation was the structural cause of pollen abortion in Ningxia wolfberry. This study further analyzed the reason why the callose wall of the sterile line tetrad did not degrade, and provides a theoretical basis for analyzing the male sterility mechanism of L. barbarum L..