A simple method for mitochondrial respiration and calcium uptake assessment in pollen tubes.

Key mitochondrial processes are known to be widely conserved throughout the eukaryotic domain. However, the scarce availability of working materials may restrict the assessment of such mitochondrial activities in several working models. Pollen tube mitochondrial studies represent one example of this, where tests have been often restricted due the physical impossibility of performing experiments with isolated mitochondria in enough quantities. Here we detail a method to measure in situ mitochondrial respiratory chain activity and calcium transport in tobacco pollen tubes. •Digitonin-mediated plasmalemma permeabilization allows efficient assessment of mitochondrial respiration and calcium uptake.•This method allows quick, reliable and portable measurements from low to high cellular densities, versus methods requiring intracellular calcium reporters.

In situ assessment of mitochondrial calcium transport in tobacco pollen tubes.

Pollen tubes require functional mitochondria in order to achieve fast and sustained growth. In addition, cell wall expansion requires a calcium gradient in the tube apex formed by a dedicated array of calcium pumps and channels. Most studies have traditionally focused on the molecular aspects of calcium interactions and transport across the pollen tube plasmalemma. However, calcium transients across mitochondrial membranes from pollen tubes are beginning to be studied. Here, we report the presence of a ruthenium red-sensitive mitochondrial calcium uniporter-like activity in tobacco pollen tubes with functional oxidative phosphorylation. The present study provides a framework to measure in situ specifics of mitochondrial transport and respiration in pollen tubes from different plants. The relevance of a mitochondrial calcium uniporter for pollen tube growth is discussed.