Cytological and biophysical comparative analysis of cell structures at the microsporogenesis stage in sterile and fertile Allium species

Abstract

Main conclusion Using a live-cell-imaging approach and autofluorescence-spectral imaging, we showed quantitative/qualitative fluctuations of chemical compounds within the meiocyte callose wall, providing insight into the molecular basis of male sterility in plants from the genus Allium.Allium sativum (garlic) is one of the plant species exhibiting male sterility, and the molecular background of this phenomenon has never been thoroughly described. This study presents comparative analyses of meiotically dividing cells, which revealed inhibition at the different microsporogenesis stages in male-sterile A. sativum plants (cultivars Harnas and Arkus) and sterile A. ampeloprasum var. ampeloprasum (GHG-L), which is phylogenetically related to garlic. Fertile species A. ampeloprasum (leek) was used as the control material, because leek is closely related to both garlic and GHG-L. To shed more light on the molecular basis of these disturbances, autofluorescence-spectral imaging of live cells was used for the assessment of the biophysical/biochemical differences in the callose wall, pollen grain sporoderm, and the tapetum in the sterile species, in comparison with the fertile leek. The use of techniques for live-cell imaging (autofluorescence-spectral imaging) allowed the observation of quantitative/qualitative fluctuations of autofluorescent chemical compounds within the meiocyte callose wall. The biophysical characterisation of the metabolic disturbances in the callose wall provides insight into the molecular basis of male sterility in A. sativum. In addition, using this method, it was possible for the first time, to determine precisely (on the basis of fluctuations of autofluorescence compounds) the meiosis stage in which normal microsporogenesis is disturbed, which was not visible using light microscopy.

Long distance RNA movement

“…Differentiated phloem remains symplasmic connected to neighbouring cells, but symplasmic connectivity is lost during xylem formation, guard cell differentiation, meiocyte (gamete) formation and embryogenesis. In these cell types PD connections are permanently closed via callose deposition, as seen in meiocytes (De Storme et al ., ; Tchorzewska et al ., ), or degraded (Kragler et al ., ). PD are transiently closed/opened via PD‐associated callose synthases/beta‐glucanases that increase or reduce the callose present at the PD pore neck region, respectively (Iglesias & Meins, ; Levy et al ., ; Vaten et al ., ).…”

Morphological Features of the Anther Development in Tomato Plants with Non-Specific Male Sterility

“…The tomato plant was from the Solanum lycopersicum L. line YaLF (control) and transgenic tomato plants expressing the ac gene, encoding chitin-binding protein were from Amaranthus caudatus L. with normal and abnormal phenotype, which was characterized by impaired development of generative organs. Putative transgenic tomato plants were produced by Agrobacterium-mediated transformation using pBI121ac binary vector [11]. The transgenic tomato lines with abnormalities were propagated by grafting lateral shoots formed on adult plants.…”

“…As is known, the process of pollen formation involves several stages and is regulated by a vast number of genes [1][2][3][4][5]. Numerous genes and proteins associated with the abortion of microspores and pollen [6,7] and the molecular mechanisms underlying various male sterile phenotypes have been characterized [6,[8][9][10][11][12]. However, the morphological and cytological aspects of pollen sterility have not been investigated The disturbances in the androecium development in the flowers of transgenic tomatoes with phenotypic abnormalities most often occurred after normally passing meiosis when the microspores converted into pollen grains.…”