Physiological and biochemical responses of Eucalyptus seedlings to hypoxia

Abstract

& Key message Hypoxia promoted distinct changes in the levels of hormones, amino acids and organic acids in the roots and shoots of a seedling from 2 Eucalyptus clones. These results indicate that modulation of hormone production, as well as specific chemical constituents associated with primary metabolism, contributes to the regulation of growth of Eucalyptus seedlings under hypoxic conditions. & Context Although floods in areas under Eucalyptus cultivation in Brazil negatively affect plant growth, chemical markers and/ or indicators of hypoxia contributes to the regulation.s & Aims This study aimed to evaluate the hormonal and metabolic alterations induced by hypoxia on seedling growth. & Methods Seedlings of Eucalyptus urograndis clones VCC 975 and 1004 were grown in liquid solution and submitted to bubbling with air or with nitrogen. Levels of indol-3-acetic acid (IAA), abscisic acid (ABA), ethylene, 1-aminocyclopropane-1-carboxylic acid (ACC), primary metabolite profile and photosynthetic parameters were evaluated after fourteen days. & Results Hypoxia did not affect shoot dry mass of the seedlings. However, it decreased stomatal conductance and photosynthetic CO 2 assimilation rate, and increased levels of ABA in the shoot. Hypoxia greatly reduced the dry mass and volume of roots, concomitantly with higher ACC and ethylene production. Moreover, hypoxia promoted distinct changes in IAA levels, and in amino acid and organic acid metabolism in roots and shoots. & Conclusion The biosynthesis of ABA, ethylene and IAA and its quantity in root tissues indicates the regulation of metabolism in response to hypoxia in Eucalyptus clones. Handling Editor: Erwin DreyerContribution of the co-authors: EFM designed, executed the study, and was the main contributor to the writing of the manuscript. Gustavo CV MAYRINK and Cleide R DIAS contributed to maintaining and completing the experiment. Camilo E VITAL performed the LC-MS analysis. Dimas M RIBEIRO, Ivo R SILVA, and Andrew MERCHANT assisted in the design of the experiment, analysis of the results and composition of the paper.Electronic supplementary material The online version of this article (https://doi.

Hypoxia and Anoxia Stress: Plant responses and tolerance mechanisms

“…Hér.) (Medina et al., 2019) many folds. However, the level of ABA remains stable in hypoxia‐sensitive plants such as garden sorrel ( Rumex acetosa L.) (Benschop et al., 2005).…”

Comprehensive In Silico Analysis and Transcriptional Profiles Highlight the Importance of Mitochondrial Dicarboxylate Carriers (DICs) on Hypoxia Response in Both Arabidopsis thaliana and Eucalyptus grandis

“…On the other hand, the expression of both genes returned to basal levels after 72 h of waterlogging. Interestingly, hypoxia has been shown to negatively affect the levels of 2-oxoglutarate, a pivotal metabolite of the TCA cycle, in the roots of a Eucalyptus urograndis clone tolerant to oxygen depletion, whereas a significant decrease in citrate levels was observed in the roots of a sensitive clone [14]. In addition, an increase in gamma-aminobutyric acid (GABA) and succinate (2.5-fold) levels were observed in the roots of both clones under hypoxic conditions [14].…”

“…Interestingly, hypoxia has been shown to negatively affect the levels of 2-oxoglutarate, a pivotal metabolite of the TCA cycle, in the roots of a Eucalyptus urograndis clone tolerant to oxygen depletion, whereas a significant decrease in citrate levels was observed in the roots of a sensitive clone [14]. In addition, an increase in gamma-aminobutyric acid (GABA) and succinate (2.5-fold) levels were observed in the roots of both clones under hypoxic conditions [14]. These data suggest that modulation of the TCA cycle intermediates is part of the Eucalyptus metabolic adjustments during exposure to short-term hypoxia, a feature that probably requires DIC activity.…”

“…Here, by combining in silico and in vivo analysis, we provide evidence that DICs are partially redundant, important in plant adaptation to environmental stresses and part of a low-oxygen response in both A. thaliana and Eucalyptus grandis, an economically important forestry species. It should be emphasized that eucalyptus plantations in South America have been facing problems associated with short-term hypoxia mainly due to soil compaction [14] and a better understanding of the underlying molecular mechanisms implicated in adaptation to hypoxia in woody plants is of special interest.…”

Irrigation frequency and vermiculite proportion in substrate for Eucalyptus grandis seedling

“…In general, irrigation is carried out with a high frequency and in an amount higher than the water required by plants, causing waste of water (Freitag, Morais, & Nishijima, 2012). In addition, excess water can cause seedling losses due to hypoxia (Medina et al, 2019) or diseases, leading to shriveling and chlorosis of leaves and negative root geotropism (Silva et al, 2015). Another important factor to be considered is that excess water can cause the leaching of nutrients in the substrate, negatively influencing seedling development, besides providing a microclimate favorable to disease development (Freitag et al, 2012, Queiroz, Pereira, Silva, Fonsenca, Martins, 2017.…”