BGPT: Paper Review: Function and evolution of plant annexins in response to abiotic stresses

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Paper reviewed: Function and evolution of plant annexins in response to abiotic stresses (BMC Plant Biology, 2025; DOI: 10.1186/s12870-025-07450-5).

The review argues (i) evolutionary conservation + expansion of annexins across green-plant lineages and (ii) abiotic-stress–linked functional diversity mediated through calcium-dependent membrane interactions, ion transport, trafficking, and cytoskeletal coupling, supported by sequence/HMM phylogenetics and cross-lineage expression heatmaps compiled from public transcriptomes.

Long Explanation

Plant Annexins: Evolution + Abiotic Stress (Critical Review)

Paper: Deng et al., 2025 • 10.1186/s12870-025-07450-5

What the review claims (and what kind of evidence is used)

Protein family logic: annexins are Ca²⁺-dependent phospholipid-binding proteins with a variable N-terminus and conserved C-terminal core; the paper links this architecture to functional diversification in stress contexts.
Evolutionary claims: annexins are presented as evolutionarily conserved across green plants and expanded on land, with the review proposing early origins in green-plant evolutionary history and lineage-dependent gene number increases.
Stress-function synthesis: the review compiles literature connecting annexins to roles such as Ca²⁺ signaling, ion transport/efflux-influx regulation, membrane trafficking, cytoskeletal organization, and stress-tolerance phenotypes, with repeated emphasis that many mechanisms remain to be experimentally resolved.

Visual 1 — Annexin gene-family size across plant evolution (from the paper’s reported summary numbers)

Values correspond to the review’s stated counts/approximations (chlorophyte algae ~1; bryophytes and gymnosperms ~9; angiosperms ~20) and its specific example Chara braunii (17).

Visual 2 — Scope of the paper’s comparative analyses (numbers the review reports)

The review states: 521 annexin genes across 37 representative species; a HMM-based search yielding 309 putative ANN orthologs across 24 species; and a OneKP dataset of 1,322 terrestrial plants and algae used to assess orthology presence for AtANN1-like proteins.

Key mechanistic synthesis (and where certainty is limited)

1) Ca²⁺-dependent membrane interaction as a unifying theme

The review consistently treats annexin membrane binding—driven by Ca²⁺ and acidic phospholipids—as a plausible upstream step connecting diverse downstream phenotypes (trafficking, ion conductance claims, stress transcription programs). Supporting background for annexins as Ca²⁺/phospholipid-binding proteins is also consistent with earlier plant annexin reviews.

2) Ion transport / channel-like hypotheses: plausible but not universally settled

The review discusses annexins as potential Ca²⁺-permeable channel/transporters (e.g., recombinant annexins regulating Ca2+-permeable conductance, and annexin effects on Ca2+/K+ conductance in root cells). However, the same section explicitly states that the extent to which annexin-mediated Ca2+ transport via channel/transporters is the primary in vivo physiological function remains under debate.

3) Evolution: gene-family expansion and clade structure—what is robust vs. interpretive

The review reports (i) a phylogenetic classification of ANN proteins into seven clades (A–G) and (ii) an evolutionary trend of increasing annexin gene number across plant land-associated transitions, with Chara braunii as an example of early expansion. Skeptical note: phylogeny-based “origin” statements (e.g., “likely originating from Rhodophyta” in the abstract) are interpretive and depend on sampling and model choices; the paper itself relies on database-driven inference plus HMM-based identification, so orthology assignment and domain architecture prediction may shape the inferred evolutionary narrative.

4) Stress biology: cross-lineage expression patterns + mechanism calls for more direct tests

The review integrates multi-species tissue/stress transcriptome datasets and reports that annexin gene family members tend to show elevated expression under stresses such as cold, heat, salinity, and drought in several angiosperm lineages. Critical limitation: expression correlation does not prove causality; the review frequently aggregates results from diverse experiments (different species, tissues, stress protocols), so mechanistic unification should be treated as hypothesis-level unless direct functional assays are compared under standardized settings.

Methodological critique (skeptical checklist)

Component	What the review did	Skeptical risk / failure mode
ANN identification	HMM-based identification against Superfamily and local retrieval; phylogeny built using maximum-likelihood.	HMM/domain boundary errors can mis-assign repeats/orthology, influencing clade placement and copy-number narratives.
Phylogenetic interpretation	Seven clades (A–G) and ortholog/paralog patterns are discussed.	Gene-tree vs species-tree discordance, incomplete taxon sampling, and rate heterogeneity can bias clade-to-time narratives.
Expression heatmaps	Heatmaps generated from public transcriptomes; expression shown as log2(TPM+1), using Tbtools.	Cross-study normalization, tissue/stage mismatch, and missingness can create apparent consensus “stress responsiveness.”
Mechanism unification	Literature synthesis links annexins to Ca2+ signaling and stress phenotypes.	A review can overweight mechanistic stories that have published positive results, while underweighting contradictory or non-replicated findings.

Actionable takeaways for the reader (what to do with this review)

Use the evolutionary/cluster framing (clades A–G; expansion patterns) as a starting point for which annexin subfamilies to prioritize in functional experiments across lineages, rather than assuming one-to-one stress roles per annexin.
Treat stress-response co-expression as necessary-but-not-sufficient. The review explicitly highlights that several proposed mechanisms (e.g., structural basis for ion channel formation; in-plants physical interaction with SNARE proteins) remain experimentally unvalidated.
When interpreting calcium-linkage models, disambiguate whether annexins primarily act upstream (Ca2+ signature shaping), downstream (effectors), or in parallel (e.g., membrane repair/trafficking) — the review itself notes debate about primary physiological roles.

Author Review Links (bespoke)

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Updated: April 07, 2026