Uridylation and the SKI complex orchestrate the Calvin cycle of photosynthesis through RNA surveillance of TKL1 in Arabidopsis.

RNA uridylation, catalyzed by terminal uridylyl transferases (TUTases), represents a conserved and widespread posttranscriptional RNA modification in eukaryotes that affects RNA metabolism. In plants, several TUTases, including HEN1 SUPPRESSOR 1 (HESO1) and UTP: RNA URIDYLYLTRANSFERASE (URT1), have been characterized through genetic and biochemical approaches. However, little is known about their physiological significance during plant development. Here, we show that HESO1 and URT1 act cooperatively with the cytoplasmic 3'-5' exoribonucleolytic machinery component SUPERKILLER 2 (SKI2) to regulate photosynthesis through RNA surveillance of the Calvin cycle gene TRANSKETOLASE 1 (TKL1) in Arabidopsis. Simultaneous dysfunction of HESO1, URT1, and SKI2 resulted in leaf etiolation and reduced photosynthetic efficiency. In addition, we detected massive illegitimate short interfering RNAs (siRNAs) from the TKL1 locus in heso1 urt1 ski2, accompanied by reduced TKL1/2 expression and attenuated TKL activities. Consequently, the metabolic analysis revealed that the abundance of many Calvin cycle intermediates is dramatically disturbed in heso1 urt1 ski2. Importantly, all these molecular and physiological defects were largely rescued by the loss-of-function mutation in RNA-DEPENDENT RNA POLYMERASE 6 (RDR6), demonstrating illegitimate siRNA-mediated TKL silencing. Taken together, our results suggest that HESO1- and URT1-mediated RNA uridylation connects to the cytoplasmic RNA degradation pathway for RNA surveillance, which is crucial for TKL expression and photosynthesis in Arabidopsis.

Establishment of an efficient early flowering-assisted CRISPR/Cas9 gene-editing system in Arabidopsis.

KEY MESSAGE: Ectopic expression of the florigen FT gene along with the Cas9 cassette promotes fast reproduction of the T1 transgenic plants, and the late-flowering phenotype serves as a convenient marker for transgene-free plants screening in T2 segregation population.

Enhanced phosphate removal from aqueous environments using three-dimensional La-doped carboxylic carbon nanotubes/alginate: Performance and mechanisms.

The excessive amounts of phosphorus (P) discharged and usage have caused eutrophication and algal blooms, which seriously jeopardize the environment even the human health. In this study, carbon nanotubes (CNTs) served as carriers to develop a lanthanum-based sodium alginate hydrogel (La-CNT-COOH/SA) aimed at efficiently removing phosphate from wastewater. Characterization results confirmed successful deposition of La(OH)3 nanoparticles onto CNT-COOH. The optimal adsorption efficiency of La-CNT-COOH/SA hydrogels occurred at pH 4, with a maximum adsorption capacity of 54.4 mg/g under an initial phosphate concentration of 60 mg/L. Batch experiments demonstrated that La-CNT-COOH/SA performed well across a favorable pH range and exhibited high tolerance to common coexisting ions during phosphate adsorption. Adsorption isotherms indicated a dominance of both physical and chemical mechanisms in phosphate removal by La-CNT-COOH/SA. At elevated phosphate concentrations, the adsorption process followed quasi-second-order kinetics, primarily driven by chemical adsorption. Multi-instrument characterization emphasized that the substantial loading of La(OH)3 on CNT-COOH significantly contributed to adsorption, alongside crosslinked lanthanum ions on sodium alginate and abundant hydroxyl groups. Mechanisms of adsorption by La-CNT-COOH/SA encompassed electrostatic interactions, surface precipitation, and in-sphere complexation (La-O-P). These findings on fabrication, properties, and adsorption mechanisms of the phosphate-removal hydrogel lay a theoretical foundation for applying biomass-based materials in large-scale remediation practices.