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Alternative splicing of pre-mRNAs is crucial for plant growth and development. Serine/arginine-rich (SR) proteins are a conserved family of RNA-binding proteins that are critical for both constitutive and alternative splicing. However, how phosphorylation of SR proteins regulates gene transcription and alternative splicing during plant development is poorly understood. We found that the Arabidopsis thaliana L. SR protein-specific kinase II family proteins (SRPKIIs) play an important role in plant development, including flowering. SRPKIIs regulate the phosphorylation status of a subset of specific SR proteins, including SR45 and SC35, which subsequently mediates their subcellular localization. A phospho-dead SR45 mutant inhibits the assembly of the apoptosis-and splicing-associated protein complex and thereby upregulates the expression of FLOWERING LOCUS C (FLC) via epigenetic modification. The splicing efficiency of FLC introns was significantly increased in the shoot apex of the srpkii mutant. Transcriptomic analysis revealed that SRPKIIs regulate the alternative splicing of c. 400 genes, which largely overlap with those regulated by SR45 and SC35-SCL family proteins. In summary, we found that Arabidopsis SRPKIIs specifically affect the phosphorylation status of a subset SR proteins and regulate the expression and alternative splicing of FLC to control flowering time., (© 2023 The Authors New Phytologist © 2023 New Phytologist Foundation.)

Very-long-chain fatty acids (VLCFAs) are precursors for the synthesis of various lipids, such as triacylglycerols, sphingolipids, cuticular waxes, and suberin monomers, which play important roles in plant growth and stress responses. However, the underlying molecular mechanism regulating VLCFAs' biosynthesis in quinoa ( Chenopodium quinoa Willd.) remains unclear. In this study, we identified and functionally characterized putative 3-ketoacyl-CoA synthases (KCSs) from quinoa. Among these KCS genes, CqKCS2B.1 showed high transcript levels in the root tissues and these were rapidly induced by salt stress. CqKCS2B.1 was localized to the endoplasmic reticulum. Overexpression of CqKCS2B.1 in Arabidopsis resulted in significantly longer primary roots and more lateral roots. Ectopic expression of CqKCS2B.1 in Arabidopsis promoted the accumulation of suberin monomers. The occurrence of VLCFAs with C22-C24 chain lengths in the overexpression lines suggested that CqKCS2B.1 plays an important role in the elongation of VLCFAs from C20 to C24. The transgenic lines of overexpressed CqKCS2B.1 showed increased salt tolerance, as indicated by an increased germination rate and improved plant growth and survival under salt stress. These findings highlight the significant role of CqKCS2B.1 in VLCFAs' production, thereby regulating suberin biosynthesis and responses to salt stress. CqKCS2B.1 could be utilized as a candidate gene locus to breed superior, stress-tolerant quinoa cultivars.

Background: Organ shape and size covariation (allometry) factors are essential concepts for the study of evolution and development. Although ample research has been conducted on organ shape and size, little research has considered the correlated variation of these two traits and quantitatively measured the variation in a common framework. The genetic basis of allometry variation in a single organ or among different organs is also relatively unknown., Results: A principal component analysis (PCA) of organ landmarks and outlines was conducted and used to quantitatively capture shape and size variation in leaves and petals of multiparent advanced generation intercross (MAGIC) populations of Arabidopsis thaliana. The PCA indicated that size variation was a major component of allometry variation and revealed negatively correlated changes in leaf and petal size. After quantitative trait loci (QTL) mapping, five QTLs for the fourth leaf, 11 QTLs for the seventh leaf, and 12 QTLs for petal size and shape were identified. These QTLs were not identical to those previously identified, with the exception of the ER locus. The allometry model was also used to measure the leaf and petal allometry covariation to investigate the evolution and genetic coordination between homologous organs. In total, 12 QTLs were identified in association with the fourth leaf and petal allometry covariation, and eight QTLs were identified to be associated with the seventh leaf and petal allometry covariation. In these QTL confidence regions, there were important genes associated with cell proliferation and expansion with alleles unique to the maximal effects accession. In addition, the QTLs associated with life-history traits, such as days to bolting, stem length, and rosette leaf number, which were highly coordinated with climate change and local adaption, were QTL mapped and showed an overlap with leaf and petal allometry, which explained the genetic basis for their correlation., Conclusions: This study explored the genetic basis for leaf and petal allometry and their interaction, which may provide important information for investigating the correlated variation and evolution of organ shape and size in Arabidopsis.

Hydrogen peroxide (H 2 O 2 ) is generated in many metabolic processes. As a signaling molecule, H 2 O 2 plays important roles in plant growth and development, as well as environmental stress response. In Arabidopsis, there are three catalase genes, CAT1, CAT2, and CAT3. The encoded catalases are predominately peroxisomal proteins and are critical for scavenging H 2 O 2 . Since CAT1 and CAT3 are linked on chromosome 1, it has been almost impossible to generate cat1/3 and cat1/2/3 mutants by traditional genetic tools. In this study, we constructed cat1/3 double mutants and cat1/2/3 triple mutants by CRISPR/Cas9 to investigate the role of catalases. The cat1/2/3 triple mutants displayed severe redox disturbance and growth defects under physiological conditions compared with wild-type and the cat2/3 double mutants. Transcriptome analysis showed a more profound transcriptional response in the cat1/2/3 triple mutants compared to the cat2/3 mutants. These differentially expressed genes are involved in plant growth regulation as well as abiotic and biotic stress responses. In addition, expression of OXI1 (OXIDATIVE SIGNAL INDUCIBLE 1) and several MAPK cascade genes were changed dramatically in the catalase triple mutant, suggesting that H 2 O 2 produced in peroxisomes could serve as a peroxisomal retrograde signal., (© 2018 Institute of Botany, Chinese Academy of Sciences.)

Summary: Alternative splicing of pre‐mRNAs is crucial for plant growth and development. Serine/arginine‐rich (SR) proteins are a conserved family of RNA‐binding proteins that are critical for both constitutive and alternative splicing. However, how phosphorylation of SR proteins regulates gene transcription and alternative splicing during plant development is poorly understood.We found that the Arabidopsis thaliana L. SR protein‐specific kinase II family proteins (SRPKIIs) play an important role in plant development, including flowering. SRPKIIs regulate the phosphorylation status of a subset of specific SR proteins, including SR45 and SC35, which subsequently mediates their subcellular localization.A phospho‐dead SR45 mutant inhibits the assembly of the apoptosis‐and splicing‐associated protein complex and thereby upregulates the expression of FLOWERING LOCUS C (FLC) via epigenetic modification. The splicing efficiency of FLC introns was significantly increased in the shoot apex of the srpkii mutant. Transcriptomic analysis revealed that SRPKIIs regulate the alternative splicing of c. 400 genes, which largely overlap with those regulated by SR45 and SC35‐SCL family proteins.In summary, we found that Arabidopsis SRPKIIs specifically affect the phosphorylation status of a subset SR proteins and regulate the expression and alternative splicing of FLC to control flowering time. [ABSTRACT FROM AUTHOR]

A cDNA ( SsCAX1) encoding a tonoplast-localised Ca/H exchanger was isolated from a C halophyte Suaeda salsa (L.). To clarify the role of SsCAX1 in plant salt tolerance, Arabidopsis plants expressing SsCAX1 were treated with NaCl. Transgenic Arabidopsis plants displayed decreased salt tolerance. Although Na content was close to wild-type plants, transgenic plants accumulated more Ca and retained less K in leaves than the wild-type plants in salinity. Furthermore, transgenic lines held higher leaf membrane leakage than wild-type lines under NaCl treatment. In addition, transgenic plants showed a 23% increase in vacuolar H-ATPase activity compared with wild-type plants in normal condition. But the leaf V-H-ATPase activity had subtle changes in transgenic plants, while significantly increased in wild-type plants under saline condition. These results suggested that regulated expression of Ca/H antiport was critical for maintenance of cation homeostasis and activity of V-H-ATPase under saline condition. [ABSTRACT FROM AUTHOR]