Comparative studies of live tapetum cells in sterile garlic (Allium sativum) and fertile leek (Allium ampeloprasum) using the fluorescence lifetime imaging analytical method

Commercially cultivated Allium sativum has lost the ability to reproduce sexually due to various developmental abnormalities mainly in the male line associated with a phenomenon called male sterility. Numerous studies focused on discovering the cause of garlic male sterility at the tissue and cellular level have not yet fully resolved this issue. Here, we have focused our attention on the tapetum, i.e. a nutritive tissue regarded in plants as a critical factor for formation of viable pollen. We have applied a novel method, Fluorescence Lifetime Imaging (FLIM), which represents one of the most sensitive biophysical tools for assessment of changes in fluorophore lifetime, depending on its metabolic state in a live cell. Contrary to traditional methods based on cell fixation, FLIM analysis provides live tapetal cell imaging, which facilitates monitoring metabolic changes in the cell. We have shown qualitative metabolic discrepancies in live cells of the tapetum in sterile garlic and fertile leek and proposed a correlative metabolic model of microspore and tapetum development in garlic cultivars, indicating that the disturbances in the temporal coordination of programmed cell death within the anther might be regarded as the main cause of male sterility in the analysed A. sativum cultivars.