Abstract
Global warming leads to a progressive rise in environmental temperature. Plants, as sessile organisms, are threatened by these changes; the male gametophyte is extremely sensitive to high temperature and its ability to preserve its physiological status under heat stress is known as acquired thermotolerance. This latter can be achieved by exposing plant to a sub-lethal temperature (priming) or to a progressive increase in temperature. The present research aims to investigate the effects of heat priming on the functioning of tobacco pollen grains. In addition to evaluating basic physiological parameters (e.g., pollen viability, germination and pollen tube length), several aspects related to a correct pollen functioning were considered. Calcium (Ca2+) level, reactive oxygen species (ROS) and related antioxidant systems were investigated, also to the organization of actin filaments and cytoskeletal protein such as tubulin (including tyrosinated and acetylated isoforms) and actin. We also focused on sucrose synthase (Sus), a key metabolic enzyme and on the content of main soluble sugars, including UDP-glucose. Results here obtained showed that a pre-exposure to sub-lethal temperatures can positively enhance pollen performance by altering its metabolism. This can have a considerable impact, especially from the point of view of breeding strategies aimed at improving crop species.
Highlights
Pollen and pollen tubes are the male gametophyte of seed plants and are a key evolutionary step in the success of land plants [1]
Analysis were conducted in 5 different groups: Control Group (C) maintained at room temperature (25 ◦C—RT) for the whole duration of the experiment; Primed Group (P) subjected to sub-lethal condition (1 h at 30 ◦C); Stressed Group (S) subjected to acute heat stress (2 h at 35 ◦C); Primed and Recovered Group (PR) subjected to priming and later to recovery (1 h at 30 ◦C and 3 h at RT) and the Primed, Recovered and Stresses Group (PRS) subjected to priming, recovery and stress (1 h at 30 ◦C, 3 h at RT and 2 h at 35 ◦C)
We investigated how tobacco pollen can memorize a mild heat treatment and effectively respond to more drastic conditions
Summary
Pollen and pollen tubes are the male gametophyte of seed plants and are a key evolutionary step in the success of land plants [1]. Pollen activation and cytoplasmic polarization are fundamental for efficient pollen tube emergence and elongation, a prerequisite for fertilization [2]. Despite these processes involve countless proteins and ions, calcium is one the key players and its differential accumulation is fundamental to initiate cytoplasmic polarization and promote pollen tube growth [3]. Interactions between ion flux, such as Ca2+, ROS production, protein phosphorylation (and others not mentioned here) contribute to the polarization of pollen tubes and promote the secretion and deposition of new cell wall components in a finely- and timely-regulated manner [5,6]. Metabolism is fundamental in cell wall deposition because it provides the activated monosaccharides for polysaccharide elongation (both pectin and cellulose) [7]. Among the many sugar-metabolizing enzymes, sucrose synthase (Sus) provides UDP-glucose, an energetic reservoir as well as the substrate for cellulose and callose synthesis [8]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
