Possible Role of Crystal-Bearing Cells in Tomato Fertility and Formation of Seedless Fruits.

Ekaterina N Baranova,Ludmila N Konovalova,Alexander A Gulevich,Inna A Chaban,Ludmila V Kurenina,Natalia V Varlamova,Marat R Khaliluev

doi:10.3390/ijms21249480

Abstract

Crystal-bearing cells or idioblasts, which deposit calcium oxalate, are located in various tissues and organs of many plant species. The functional significance of their formation is currently unclear. Idioblasts in the leaf parenchyma and the development of crystal-bearing cells in the anther tissues of transgenic tomato plants (Solanum lycopersicon L.), expressing the heterologous FeSOD gene and which showed a decrease in fertility, were studied by transmission and scanning electron microscopy. The amount of calcium oxalate crystals was found to increase significantly in the transgenic plants compared to the wild type (WT) ones in idioblasts and crystal-bearing cells of the upper part of the anther. At the same time, changes in the size and shape of the crystals and their location in anther organs were noted. It seems that the interruption in the break of the anther stomium in transgenic plants was associated with the formation and cell death regulation of a specialized group of crystal-bearing cells. This disturbance caused an increase in the pool of these cells and their localization in the upper part of the anther, where rupture is initiated. Perturbations were also noted in the lower part of the anther in transgenic plants, where the amount of calcium oxalate crystals in crystal-bearing cells was reduced that was accompanied by disturbances in the morphology of pollen grains. Thus, the induction of the formation of crystal-bearing cells and calcium oxalate crystals can have multidirectional effects, contributing to the regulation of oxalate metabolism in the generative and vegetative organs and preventing fertility when the ROS balance changes, in particular, during oxidative stresses accompanying most abiotic and biotic environmental factors.

Highlights

In plants, the formation of calcium oxalate crystals is a regulated process that accompanies specific transformations in tissue cells, which are characterized by the presence of these crystals [1,2]
Changes in the size and shape of the crystals and their location in anther organs were noted. It seems that the interruption in the break of the anther stomium in transgenic plants was associated with the formation and cell death regulation of a specialized group of crystal-bearing cells
Perturbations were noted in the lower part of the anther in transgenic plants, where the amount of calcium oxalate crystals in crystal-bearing cells was reduced that was accompanied by disturbances in the morphology of pollen grains

Summary

Introduction

The formation of calcium oxalate crystals is a regulated process that accompanies specific transformations in tissue cells, which are characterized by the presence of these crystals [1,2]. In various families of higher plants, calcium oxalate occurs quite frequently and is observed in most plant tissues and organs in the form of intracellular and extracellular deposits [3]. Plants produce and deposit oxalate up of 3–80% of the total dry weight [4]. In this case, up to 90% of the total content of plant calcium can be in the form of oxalate crystals [5]. Intracellular crystals are fairly common in specialized mesophyll cells called idioblasts [6]. These cells have an altered organelle ultrastructure [7], and despite being located in actively photosynthetic tissue, have underdeveloped systems of thylakoids and granae

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