Microgravity effects on thylakoid, single leaf, and whole canopy photosynthesis of dwarf wheat

Abstract

The concept of using higher plants to maintain a sustainable life support system for humans during long-duration space missions is dependent upon photosynthesis. The effects of extended exposure to microgravity on the development and functioning of photosynthesis at the leaf and stand levels were examined onboard the International Space Station (ISS). The PESTO (Photosynthesis Experiment Systems Testing and Operations) experiment was the first long-term replicated test to obtain direct measurements of canopy photosynthesis from space under well-controlled conditions. The PESTO experiment consisted of a series of 21-24 day growth cycles of Triticum aestivum L. cv. USU Apogee onboard ISS. Single leaf measurements showed no differences in photosynthetic activity at the moderate (up to 600 micromol m(-2) s(-1)) light levels, but reductions in whole chain electron transport, PSII, and PSI activities were measured under saturating light (>2,000 micromol m(-2) s(-1)) and CO(2) (4000 micromol mol(-1)) conditions in the microgravity-grown plants. Canopy level photosynthetic rates of plants developing in microgravity at approximately 280 micromol m(-2) s(-1) were not different from ground controls. The wheat canopy had apparently adapted to the microgravity environment since the CO(2) compensation (121 vs. 118 micromol mol(-1)) and PPF compensation (85 vs. 81 micromol m(-2) s(-1)) of the flight and ground treatments were similar. The reduction in whole chain electron transport (13%), PSII (13%), and PSI (16%) activities observed under saturating light conditions suggests that microgravity-induced responses at the canopy level may occur at higher PPF intensity.

Microgravity effects on leaf morphology, cell structure, carbon metabolism and mRNA expression of dwarf wheat

“…These measurements suggest that the spaceXight environment (hereafter referred to as g) does not adversely aVect the development of the photosynthetic apparatus or the eYciency of photosynthesis of developing tissue or canopy photosynthesis during vegetative growth Stutte et al 2005). These observations are consistent with reports of Aliyev et al (1987) who reported no signiWcant changes in the nuclei, mitochondria, rhizomes or chloroplasts of Pisum sativum leaves grown in space for 29 day on Salyut 7.…”

Photosynthetic and water use characteristics in three natural secondary shrubs on Shell Islands, Shandong, China

“…The plant photosynthesis is closely related to its existent ecological environment, and the research on plant photosynthetic characteristics is one of the effective ways to reveal the ecological adaptability of different plants to its existent environment. In recent years, research on crop photosynthesis and its impact factors of microenvironment achieved some results (Stutte et al 2005;Hegedü šová & Senko 2011;Manolaki & Papastergiadou 2012;Pippo et al 2012). However, the research on the connection between photosynthesis and soil moisture of shrub species in different fragile ecological regions is still in the beginning stage, which limits the exploitation and utilization of shrub resources to a certain degree.…”

Agriculture for Space: People and Places Paving the Way

“…In addition, extensive testing on crop responses to temperature, humidity, mineral nutrition, PAR, photoperiod, even light spectral quality were conducted as part of the CELSS and subsequent Advanced Life Support programs (Bonsi et al, 1994;Bugbee and Monje, 1992;Tibbitts, 1991, 1994;Dougher and Bugbee, 2001;Frantz et al, 2000;Grotenhuis and Bugbee, 1997;Knight and Mitchell, 1988;Mortley et al, 1993;Wheeler et al, 1986a;1991b). NASA Stutte et al, 2005). Expanded discussions of the Veggie plant unit for food production and crop research on the ISS are reviewed by Massa et al (2017) in this issue.…”