Ethylene Differentially Modulates Hypoxia Responses and Tolerance across Solanum Species

Abstract

The increasing occurrence of floods hinders agricultural crop production and threatens global food security. The majority of vegetable crops are highly sensitive to flooding and it is unclear how these plants use flooding signals to acclimate to impending oxygen deprivation (hypoxia). Previous research has shown that the early flooding signal ethylene augments hypoxia responses and improves survival in Arabidopsis. To unravel how cultivated and wild Solanum species integrate ethylene signaling to control subsequent hypoxia acclimation, we studied the transcript levels of a selection of marker genes, whose upregulation is indicative of ethylene-mediated hypoxia acclimation in Arabidopsis. Our results suggest that ethylene-mediated hypoxia acclimation is conserved in both shoots and roots of the wild Solanum species bittersweet (Solanum dulcamara) and a waterlogging-tolerant potato (Solanum tuberosum) cultivar. However, ethylene did not enhance the transcriptional hypoxia response in roots of a waterlogging-sensitive potato cultivar, suggesting that waterlogging tolerance in potato could depend on ethylene-controlled hypoxia responses in the roots. Finally, we show that ethylene rarely enhances hypoxia-adaptive genes and does not improve hypoxia survival in tomato (Solanum lycopersicum). We conclude that analyzing genes indicative of ethylene-mediated hypoxia acclimation is a promising approach to identifying key signaling cascades that confer flooding tolerance in crops.

Identification of ABA-Mediated Genetic and Metabolic Responses to Soil Flooding in Tomato (Solanum lycopersicum L. Mill)

“…Genes encoding plant cysteine oxidases (Solyc02g087740, Solyc03g113130, and Solyc10g007990) showed a significant transcriptional activation with no differences between genotypes, suggesting the activation of the N-degron pathway (Figure 6). It has been recently suggested that tomato ERFVIIs might be uncoupled from hypoxia-responsive gene induction (Hartman et al, 2020); nevertheless, our data indicate a clear correlation between the RAP2.2 ortholog and the expression of hypoxia-related transcripts. Interestingly, genes encoding known NO synthesis genes in plants, Solyc11g013810, encoding a nitrate reductase, and genes encoding for phytoglobins (Solyc08g068070 and Solyc07g008240), known for their ability to scavenge NO (Gupta et al, 2019), showed an upregulation in flooded tissues, with a larger fold change value in WT than in not.…”

A digital sensor to measure real-time leaf movements and detect abiotic stress in plants

“…Both of these nastic movements have been attributed to an altered ethylene metabolism, either by accumulation of ethylene gas due to diffusion barriers in water ( Sasidharan et al, 2017 ), or by upregulation of its biosynthesis pathway ( Bradford and Yang, 1980 ). Within the Solanaceae family, differentiation of epinasty in response to ethylene has been previously observed ( Edelman and Jones, 2014 ), as well as of their plasticity to waterlogging ( Hartman et al, 2020 ). Our results show that there indeed exists a differential responsiveness of species such as tomato, potato, and bell pepper to waterlogging, but also that leaf age plays a substantial role in this epinastic response ( Figures 4 and 6 ).…”

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.…”