Light significantly inhibits hypocotyl cell elongation, and dark-grown seedlings exhibit elongated, etiolated hypocotyls. Microtubule regulatory proteins function as positive or negative regulators that mediate hypocotyl cell elongation by altering microtubule organization. However, it remains unclear how plants coordinate these regulators to promote hypocotyl growth in darkness and inhibit growth in the light. Here, we demonstrate that WAVE-DAMPENED 2–LIKE3 (WDL3), a microtubule regulatory protein of the WVD2/WDL family from Arabidopsis thaliana, functions in hypocotyl cell elongation and is regulated by a ubiquitin-26S proteasome–dependent pathway in response to light. WDL3 RNA interference Arabidopsis seedlings grown in the light had much longer hypocotyls than controls. Moreover, WDL3 overexpression resulted in overall shortening of hypocotyl cells and stabilization of cortical microtubules in the light. Cortical microtubule reorganization occurred slowly in cells from WDL3 RNA interference transgenic lines but was accelerated in cells from WDL3-overexpressing seedlings subjected to light treatment. More importantly, WDL3 protein was abundant in the light but was degraded through the 26S proteasome pathway in the dark. Overexpression of WDL3 inhibited etiolated hypocotyl growth in regulatory particle non-ATPase subunit-1a mutant (rpn1a-4) plants but not in wild-type seedlings. Therefore, a ubiquitin-26S proteasome–dependent mechanism regulates the levels of WDL3 in response to light to modulate hypocotyl cell elongation.

Pseudogenes (Ψs), nonfunctional relatives of functional genes, form by duplication or retrotransposition, and loss of gene function by disabling mutations. Evolutionary analysis provides clues to Ψ origins and effects on gene regulation. However, few systematic studies of plant Ψs have been conducted, hampering comparative analyses. Here, we examined the origin, evolution, and expression patterns of Ψs and their relationships with noncoding sequences in seven angiosperm plants. We identified ∼250,000 Ψs, most of which are more lineage specific than protein-coding genes. The distribution of Ψs on the chromosome indicates that genome recombination may contribute to Ψ elimination. Most Ψs evolve rapidly in terms of sequence and expression levels, showing tissue- or stage-specific expression patterns. We found that a surprisingly large fraction of nontransposable element regulatory noncoding RNAs (microRNAs and long noncoding RNAs) originate from transcription of Ψ proximal upstream regions. We also found that transcription factor binding sites preferentially occur in putative Ψ proximal upstream regions compared with random intergenic regions, suggesting that Ψs have conditioned genome evolution by providing transcription factor binding sites that serve as promoters and enhancers. We therefore propose that rapid rewiring of Ψ transcriptional regulatory regions is a major mechanism driving the origin of novel regulatory modules.

Drought is one of the most severe abiotic stresses limiting agricultural productivity and threatening global food security. As the central organelle responsible for photosynthesis and stress perception, the chloroplast is highly sensitive to drought, and its structural and functional stability directly determines plant adaptability. Recent studies have revealed that chloroplasts undergo pronounced ultrastructural alterations under drought stress, including thylakoid membrane shrinkage, disorganization of grana stacks, and accumulation of reactive oxygen species (ROS). Excessive ROS production causes oxidative damage to lipids, proteins, and nucleic acids, whereas moderate ROS levels act as retrograde signals to regulate nuclear gene expression. In parallel, calcium (Ca²⁺) oscillations and retrograde signaling pathways—such as those mediated by GENOMES UNCOUPLED PROTEIN1 (GUN), 3′-phosphoadenosine-5′-phosphate (PAP), and Methylerythritol cyclodiphosphate (MecPP)—integrate chloroplast-derived stress cues with nuclear responses. To counteract drought-induced damage, plants activate a series of antioxidant systems—both enzymatic (Superoxide Dismutase (SOD), Ascorbate Peroxidase (APX), Catalase (CAT)) and non-enzymatic (Ascorbic Acid (ASA), (Glutathione) GSH, tocopherols, carotenoids)—along with protective proteins such as fibrillins (FBNs) and WHIRLYs that stabilize thylakoid and membrane structures. In addition, autophagy and plastid degradation pathways selectively remove severely damaged chloroplasts to maintain cellular homeostasis. Exogenous substances, including melatonin, 5-aminolevulinic acid (ALA), and Zinc oxide (ZnO) nanoparticles, have also been shown to enhance chloroplast stability and antioxidant capacity under drought stress. In this review, we discuss the structural and functional changes in chloroplasts, signaling networks, and protective repair mechanisms under drought stress. Furthermore, we highlight future research prospects for enhancing plant stress resilience through multi-omics integration, application of functional regulators, and molecular design breeding.

In bacteria and chloroplasts, the GTPase filamentous temperature-sensitive Z (FtsZ) is essential for division and polymerizes to form rings that mark the division site. Plants contain two FtsZ subfamilies (FtsZ1 and FtsZ2) with different assembly dynamics. FtsZ1 lacks the C-terminal domain of a typical FtsZ protein. Here, we show that the conserved short motif FtsZ1 Carboxyl-terminus (Z1C) (consisting of the amino acids RRLFF) with weak membrane-binding activity is present at the C-terminus of FtsZ1 in angiosperms. For a polymer-forming protein such as FtsZ, this activity is strong enough for membrane tethering. Arabidopsis thaliana plants with mutated Z1C motifs contained heterogeneously sized chloroplasts and parallel FtsZ rings or long FtsZ filaments, suggesting that the Z1C motif plays an important role in regulating FtsZ ring dynamics. Our findings uncover a type of amphiphilic beta-strand motif with weak membrane-binding activity and point to the importance of this motif for the dynamic regulation of protein complex formation.