Morphological characteristics of flower organs and in vitro micropropagation of male sterile lines of Lilium hybrids

Lily pollen causes many problems affecting humans’ quality of life and health, such as clothing contamination and skin or nasal allergies. The manual removal of anthers is time-consuming and labour-intensive, and thus, not conducive to commercial production. It is of great importance to produce pollen-free lily varieties with beautiful shapes. In this study, we studied the morphological characteristics of flower organs and polyploids of six pollen-free filial generations of four lily species and their micropropagations. Lily ‘5-21’ is male sterile and produces uncrackable anthers with inactive pollens under natural conditions. Lily ‘3-12’ is unable to produce anthers, because the petals become stamens, thereby leading to infertility. Lilies ‘3-1’, ‘5-4’, ‘5-35’ and ‘0-0.2’ are unable to produce anthers, because they lack floral organs. Polyploids of six hybrid lilies were identified by flow cytometry and chromosome counting, and the results showed that lily ‘5-4’ was triploid and the rest were diploid. Morphological observation indicated that flowering periods were from early July to early August and lasted for about 11 days. Six male sterile lilies had low seed setting rates when they were used as female parents. Most of the seeds were flaky with developed embryos. Therefore, asexual reproduction is optimal for these six male sterile lilies. The male sterility of six lilies was associated with their parents’ pollen activity. Scales of ‘5-4’ and ‘5-35’ were used as explants for micropropagation. The findings of the present study lay a foundation for breeding of pollen-free lilies.