Expression of stress-related genes in zebrawood (Astronium fraxinifolium, Anacardiaceae) seedlings following germination in microgravity

Abstract

Seeds of a tropical tree species from Brazil, Astronium fraxinifolium, or zebrawood, were germinated, for the first time in microgravity, aboard the International Space Station for nine days. Following three days of subsequent growth under normal terrestrial gravitational conditions, greater root length and numbers of secondary roots was observed in the microgravity-treated seedlings compared to terrestrially germinated controls. Suppression subtractive hybridization of cDNA and EST analysis were used to detect differential gene expression in the microgravity-treated seedlings in comparison to those initially grown in normal gravity (forward subtraction). Despite their return to, and growth in normal gravity, the subtracted library derived from microgravity-treated seedlings was enriched in known microgravity stress-related ESTs, corresponding to large and small heat shock proteins, 14-3-3-like protein, polyubiquitin, and proteins involved in glutathione metabolism. In contrast, the reverse-subtracted library contained a comparatively greater variety of general metabolism-related ESTs, but was also enriched for peroxidase, possibly indicating the suppression of this protein in the microgravity-treated seedlings. Following continued growth for 30 days, higher concentrations of total chlorophyll were detected in the microgravity-exposed seedlings.

Epigenomic Regulators Elongator Complex Subunit 2 and Methyltransferase 1 Differentially Condition the Spaceflight Response in Arabidopsis

“…DNA methylation plays a crucial role in regulating stress responses and physiological adaptation in plants ( Boyko and Kovalchuk, 2010 ; Dowen et al, 2012 ; Zhang, 2012 ; Wang et al, 2013 ; Yu et al, 2013 ; Garg et al, 2015 ; Tameshige et al, 2015 ; Yong-Villalobos et al, 2015 ; Zhou et al, 2019 ). Physiological adaptation to spaceflight engages gene expression changes that at least mimic several terrestrial stress responses ( Hoson et al, 2002 ; Gao et al, 2008 ; Salmi and Roux, 2008 ; Blancaflor, 2013 ; Correll et al, 2013 ; Paul et al, 2013 ; Zupanska et al, 2013 ; Ferl et al, 2014 ; Inglis et al, 2014 ; Nakashima et al, 2014 ; Sugimoto et al, 2014 ; Kwon et al, 2015 ; Schüler et al, 2015 ; Zhang et al, 2015 ; Barker et al, 2017 ; Choi et al, 2019 ; Kruse et al, 2020 ; Supplementary Table 2 ). In addition, the first whole-genome survey of DNA methylation in wild-type WS Arabidopsis plants grown entirely in the spaceflight environment showed correlated changes in DNA methylation accompanying regulation of DEGs in spaceflight, especially in stress response genes such as those associated with defense responses and ROS signaling ( Zhou et al, 2019 ).…”

“…The genes differentially expressed in response to spaceflight share similarities with many documented terrestrial responses. Hallmarks of spaceflight responses include differential expression of genes involved in pathways associated with cell wall remodeling, reactive oxygen species (ROS), pathogen attacks, wounding, salt stress, drought stress, and hormone signaling ( Hoson et al, 2002 ; Gao et al, 2008 ; Salmi and Roux, 2008 ; Blancaflor, 2013 ; Correll et al, 2013 ; Paul et al, 2013 ; Zupanska et al, 2013 ; Ferl et al, 2014 ; Inglis et al, 2014 ; Nakashima et al, 2014 ; Sugimoto et al, 2014 ; Kwon et al, 2015 ; Schüler et al, 2015 ; Zhang et al, 2015 ; Ferl and Paul, 2016 ; Herranz et al, 2019 ; Vandenbrink et al, 2019 ; Barker et al, 2020 ; Califar et al, 2020 ; Kruse et al, 2020 ; Angelos et al, 2021 ; Manian et al, 2021b ). Plants further respond to spaceflight with changes in DNA methylation, again similarly to the epigenetic effects that occur during terrestrial stresses.…”

Comparative Seeds Storage Transcriptome Analysis of Astronium fraxinifolium Schott, a Threatened Tree Species from Brazil

“…Thus, due to overexploitation, its current distribution is limited to small forest fragments and the margins of highways, and as a result the species is considered to be threatened with extinction [28,29]. Astronium fraxinifolium was also studied in the International Space Station (ISS) by the Brazilian astronaut Coronel Marcos César Pontes in an experiment with seed germination in micro gravity [30].…”

3D-clinorotation induces specific alterations in metabolite profiles of germinating Brassica napus L. seeds

“…During the recent decade, these aspects were comprehensively addressed by the methods of functional genomics. The profiles of gene expression (Aubry-Hivet et al, 2014;Inglis et al, 2014) and protein dynamics (Zupanska et al, 2013;Mazars et al, 2014) were comprehensively characterized in plant seedlings, organs and tissues. Thereby the genes involved in oxidative stress, calcium signaling and response to abiotic and biotic stressors were shown to be affected by microgravity (Paul et al, 2012;Correll et al, 2013;Krishnamurthy et al, 2018).…”