Keep Calm and Survive: Adaptation Strategies to Energy Crisis in Fruit Trees under Root Hypoxia

Abstract

Plants are permanently facing challenges imposed by the environment which, in the context of the current scenario of global climate change, implies a constant process of adaptation to survive and even, in the case of crops, at least maintain yield. O2 deficiency at the rhizosphere level, i.e., root hypoxia, is one of the factors with the greatest impact at whole-plant level. At cellular level, this O2 deficiency provokes a disturbance in the energy metabolism which has notable consequences on the yield of plant crops. In this sense, although several physiological studies describe processes involved in plant adaptation to root hypoxia in woody fruit trees, with emphasis on the negative impacts on photosynthetic rate, there are very few studies that include -omics strategies for specifically understanding these processes in the roots of such species. Through a de novo assembly approach, a comparative transcriptome study of waterlogged Prunus spp. genotypes contrasting in their tolerance to root hypoxia was revisited in order to gain a deeper insight into the reconfiguration of pivotal pathways involved in energy metabolism. This re-analysis describes the classically altered pathways seen in the roots of woody fruit trees under hypoxia, but also routes that link them to pathways involved with nitrogen assimilation and the maintenance of cytoplasmic pH and glycolytic flow. In addition, the effects of root hypoxia on the transcription of genes related to the mitochondrial oxidative phosphorylation system, responsible for providing adenosine triphosphate (ATP) to the cell, are discussed in terms of their roles in the energy balance, reactive oxygen species (ROS) metabolism and aerenchyma formation. This review compiles key findings that help to explain the trait of tolerance to root hypoxia in woody fruit species, giving special attention to their strategies for managing the energy crisis. Finally, research challenges addressing less-explored topics in recovery and stress memory in woody fruit trees are pointed out.

Hydrogen Sulfide Enhances Plant Tolerance to Waterlogging Stress

“…The occurrence of adventitious roots is one of the ways for plants to adapt to low oxygen stress in waterlogging [ 77 , 78 , 79 ]. H 2 S produced by microorganisms in soil is little absorbed by roots for its poor water solubility, and the main pathway of H 2 S accumulation is endogenous production in root cells.…”

Genetic Variation Based on RAPD Profiling and Production Loss of Cayenne Pepper due to Periodic Flooding

“…Then, when followed by drainage, plants were immediately exposed to high oxygen concentrations and plants suffered from dehydration, high risk of pests, diseases, etc. In this condition, the plants suffered from a post-flood injury due to oxidative stress [13], [28]- [30]. To survive these conditions, the plant tries to deal with oxidative stress by the limited energy and finally results in a delay in plant height growth.…”

“…Non-photosynthetic tissue becomes the primary source of H2O2 due to the activation of NAD(P)H oxidation and disruption in the electron transfer chain. In hypoxic conditions, interference with the electron transfer chain in the mitochondria increases H2O2, causing cells to undergo oxidative stress [12], [13]. Hydrogen peroxide is known to cause large changes in gene expression levels in plants [14], [15].…”

Comparative transcriptomic analysis reveals potential mechanisms for high tolerance to submergence in arbor willows

“…The molecular mechanism of flooding tolerance was uncovered by studies primarily on herbaceous plants, particularly rice and Arabidopsis . With regards to the mechanisms for flooding tolerance in trees, studies using transcriptome, physiological, and metabolome analyses have identified few key regulator genes, despite the enormous economic, ecological, and social importance of forest ecosystems ( Juntawong et al, 2014 ; Kreuzwieser & Rennenberg, 2014 ; Qi et al, 2014 ; Zhang et al, 2017 ; Salvatierra et al, 2020 ). In general, trees have been found to survive O 2 deficiency stress by slowing down the anabolic processes and maintaining a steady supply ( Kreuzwieser & Rennenberg, 2014 ; Salvatierra et al, 2020 ).…”