Intertwined signatures of desiccation and drought tolerance in grasses

Abstract

<jats:title>Abstract</jats:title><jats:p>Grasses are among the most resilient plants and some can survive prolonged desiccation in semi-arid regions with seasonal rainfall. This vegetative desiccation tolerance has arisen independently multiple times within the grass family, but the genetic elements that differentiate desiccation tolerant and sensitive grasses are largely unknown. Here we leveraged comparative genomic approaches with the resurrection grass <jats:italic>Eragrostis nindensis</jats:italic> and the closely related desiccation sensitive cereal <jats:italic>Eragrostis tef</jats:italic> to identify changes underlying desiccation tolerance. We extended the analyses to include the grasses maize, sorghum, rice, and the model desiccation tolerant grass <jats:italic>Oropetium thomaeum</jats:italic> to identify broader evolutionary conservation and divergence. We identified changes in chromatin architecture and expression dynamics related to desiccation in <jats:italic>E. nindensis</jats:italic>. It was previously hypothesized that transcriptional re-wiring of seed desiccation pathways confers vegetative desiccation tolerance. We demonstrate that the majority of seed dehydration related genes show similar expression patterns in leaves of desiccation tolerant and sensitive species during dehydration. However, we discovered a small set of orthologs with expression specific to leaves of desiccation tolerant species, and seeds of sensitive species. This supports a nuanced role of seed-related genes where many overlap with typical drought responses but some crucial genes are desiccation specific in resurrection plants.</jats:p>

Comparative transcriptome analysis suggests convergent evolution of desiccation tolerance in Selaginella species

“…Previous studies using comparative approaches to dissect DT traits have included physiological [27,28], metabolic [13,29], gene expression [30,31], and genome analysis [32,33]. The present study compares the transcriptional responses during dehydration and rehydration of two tolerant species with highly different morphologies (S. sellowii and S. lepidophylla) with the response in a sensitive species (S. denticulata).…”

Silicon Enhances Biomass and Grain Yield in an Ancient Crop Tef [Eragrostis tef (Zucc.) Trotter]

“…The beneficial role of Si in enhancing abiotic stress tolerance and productivity has been studied for crops such as rice and sugar cane (Liang et al, 2015b;de Oliveira et al, 2016;Agostinho et al, 2017;Pardo et al, 2019). In rice, Si treatment has been reported to strengthen the stem by increasing silica deposition in the shoot, increasing the thickness of the culm wall and vascular bundle, enhancing stem stability (Fallah, 2012), forming a physical barrier, and delaying pathogen colonization (Cai et al, 2008;de Oliveira et al, 2016;Wang et al, 2017).…”

“…In rice, Si treatment has been reported to strengthen the stem by increasing silica deposition in the shoot, increasing the thickness of the culm wall and vascular bundle, enhancing stem stability (Fallah, 2012), forming a physical barrier, and delaying pathogen colonization (Cai et al, 2008;de Oliveira et al, 2016;Wang et al, 2017). Rice and sugarcane are significant Si accumulators among Poaceae and have been reported to remove 470 and 700 kg of Si per ha on Si-rich soils, respectively (Pardo et al, 2019), which increased the yield of these crops by up to 50% (Alvarez et al, 2004;Liang et al, 2015b). However, the effect of Si application in low-yielding and lodging-susceptible crops such as tef has never been studied.…”

Editorial: Unifying Insights into the Desiccation Tolerance Mechanisms of Resurrection Plants and Seeds

“…Their contribution underscores the view that resurrection species share “core” mechanisms for withstanding extreme water loss, but also employ species-specific features, even among closely related species. In light of the universality of DT among plant taxa, and indeed variation among seeds in precise mechanisms of DT, the view that DT in angiosperms evolved through rewiring of their seed genes is being questioned ( Lyall et al, 2019 ; Pardo et al, 2020 ). Rather, seeds should be considered as a subset of desiccation tolerant entities, each being equipped with similar core mechanisms but with their specific variation on the DT theme.…”