Cytomorphology, physiological and biochemical characteristics of male sterility plant in Parakmeria omeiensis

Parakmeria omeiensis an evergreen tree belonged to Parakmeria of Magnoliaceae, is listed as a critically endangered plant under the first-grade State protection. Aimed to clarify the abortion period of male sterility in bisexual flowers of P. omeiensis and its physiological and biochemical characteristics, sterile stamens of bisexual flower and fertile stamens of male flower were test materials, the anther development was observed by paraffin section, the contents of soluble sugar, soluble protein, proline were determined, and catalase (CAT) and peroxidase (POD) activities were analyzed. The results were as follows: (1) Significant difference were detected in meiosis stage in anther development between sterile stamens and fertile stamens, the tapetum layer of sterile stamens was dense and undeveloped, the microspore mother cells didn’t develop into the tetrad and subsequently disintegrated, so the pollen sac was empty. The tapetum layer and the microspore mother cells of fertile stamens developed normally, most pollen sac were broken and pollen grain were export. (2) The contents of soluble sugar, soluble protein, proline of sterile stamens were significantly lower than fertile stamens during the stages of meiosis, microspore monuclear and pollen mature. (3) POD activity of sterile stamens increased overall and was significantly higher than fertile stamens during the stages of meiosis, microspore monuclear and pollen mature. CAT activity of sterile stamens decreased as a whole and was significantly lower than fertile stamens in the same stage. We conclude that the microspore abortion occurs at the stage of meiosis, the decrease in metabolism of material and energy causes the abortion of male in bisexual flowers, the tapetum layer don’t develop further and it doesn’t provide nutrients to the microspore mother cells. CAT and POD activities are abnormal which results in the failure of timely scavenging free radicals in cells, and meiosis of microspore mother cells is blocked, so tetrads fail to be formed.