A phloem-localized Arabidopsis metacaspase (AtMC3) improves drought tolerance

Abstract

Increasing drought phenomena pose a serious threat to agricultural productivity. Although plants have multiple ways to respond to the complexity of drought stress, the underlying mechanisms of stress sensing and signalling remain unclear. The role of the vasculature, in particular the phloem, in facilitating inter-organ communication is critical. Here, we investigated the role of AtMC3, a phloem-specific member of the metacaspase family, in osmotic stress responses in Arabidopsis thaliana. Overexpression of AtMC3 conferred drought tolerance by enhancing the differentiation of the metaphloem sieve elements and maintaining higher levels of vascular-mediated transportation, whilst plants lacking the protein showed an impaired response to drought and inability to respond effectively to the hormone abscisic acid. Analyses of the proteome in plants with altered AtMC3 levels revealed differential abundance of proteins related to osmotic stress. Overall, our data highlight the importance of AtMC3 and vascular plasticity in fine-tuning early drought responses at the whole plant level without affecting growth or yield.

An annual gene expression profile of markers for programmed cell death and polyphenols biosynthesis across heartwood forming stems inRobinia pseudoacacia

“…This makes an intriguing comparison to the previous report, where only type-I MCs were identified in similar contexts. In A. thaliana , AtMC3 had been shown to confer drought tolerance in the phloem by enhancing the differentiation of the metaphloem sieve elements and maintaining higher levels of vascular-mediated transportation 73 . In the gene expression analysis on the MC family during the season of active xylogenesis in Populus, including both type I and II, distinct upregulation in the phloem was shown with MC-I ( PttMC7, 8, 10 ) 48 ; the role of type-II MCs in the phloem await future investigation.…”

Roadmap for the next decade of plant programmed cell death research

“…Techniques based on positive enrichment or negative enrichment of N‐termini that have been used to study plant proteases include Combined Fractional Diagonal Chromatography (COFRADIC) (Gevaert et al ., 2003), terminal amine isotopic labelling of substrates (TAILS) (Huesgen & Overall, 2012), and high‐efficiency undecanal‐based N‐termini enrichment (HUNTER) (Weng et al ., 2019). COFRADIC (Tsiatsiani et al ., 2013; Willems et al ., 2017), TAILS (H. Zhang et al ., 2018) and HUNTER (Pitsili et al ., 2023), but more research is needed specifically in the context of PCD. Such degradomics techniques have limitations linked to detection threshold and protein cleavage redundancy.…”

“…Likewise, research on metacaspases may lead to increased potential to develop new plant varieties that are more resilient to the increasingly volatile weather conditions linked to climate change. For example, the metacaspase AtMC3 is involved in modulating vascular plasticity in response to drought (Pitsili et al ., 2023) and overexpressing this protease results in plants that are more tolerant to drought with no apparent negative effects on growth or yield. As different stresses elicit both common and distinct pathways for the regulation of PCD (Burke et al ., 2023), the coordination of cell death pathways in response to combinations of stresses, and to adverse conditions outside the laboratory, will be an exciting area for future studies and an excellent way to validate the impact of findings on how plant PCD is controlled in real‐world scenarios.…”

Seed Longevity is Controlled by Metacaspases

“…1a). MCA-Is modulate pathogen-induced programmed cell death, vasculature development, and protein aggregate clearing (6)(7)(8), while the plant-specific MCA-IIs are involved in stress responses, wound-induced damage-associated molecular pattern signalling and developmental cell death events such as clearance of cell corpses (9)(10)(11)(12).…”