Receptor-like protein kinases (RLKs) are a large group of transmembrane proteins playing critical roles in cell-cell and cell-environment communications. Based on extracellular domain structures, RLKs were classified into more than 21 subfamilies, among which leucine-rich repeat RLKs (LRR-RLKs) belong to the largest subfamily in plants such as Arabidopsis and rice. In Arabidopsis, there are approximately 223 LRR-RLKs, but only about 60 of which have been functionally described to date. To systematically investigate the roles of LRR-RLKs in regulating plant growth, development, and stress adaptations, we generated promoter::GUS transgenic plants for all 223 LRR-RLK genes in Arabidopsis and analyzed their detailed expression patterns at various developmental stages. The results provide valuable resources for functionally elucidating this large and essential signaling protein subfamily.
SummaryCotton (Gossypium hirsutum) is the major source of natural textile fibers. Brassinosteroids (BRs) play crucial roles in regulating fiber development. The molecular mechanisms of BRs in regulating fiber elongation, however, are poorly understood.pagoda1 (pag1) was identified via an activation tagging genetic screen and characterized by genome walking and brassinolide (BL) supplementation. RNA-Seq analysis was employed to elucidate the mechanisms of PAG1 in regulating fiber development.pag1 exhibited dwarfism and reduced fiber length due to significant inhibition of cell elongation and expansion. BL treatment rescued its growth and fiber elongation. PAG1 encodes a homolog of Arabidopsis CYP734A1 that inactivates BRs via C-26 hydroxylation. RNA-Seq analyses showed that the constitutive expression of PAG1 downregulated the expression of genes involved in very-long-chain fatty acids (VLCFA) biosynthesis, ethylene-mediated signaling, response to cadmium, cell wall development, cytoskeleton organization and cell growth.Our results demonstrate that PAG1 plays crucial roles in regulating fiber development via controlling the level of endogenous bioactive BRs, which may affect ethylene signaling cascade by mediating VLCFA. Therefore, BR may be a critical regulator of fiber elongation, a role which may in turn be linked to effects on VLCFA biosynthesis, ethylene and cadmium signaling, cell wall-and cytoskeleton-related gene expression.
Summary
Temperature, one of the most critical environmental cues, greatly affects plant growth, development, and reproduction. PHYTOCHROME-INTERACTING FACTOR 4 (PIF4), a key transcription factor in light signaling pathway, plays a central role in temperature-mediated growth responses. How higher temperature regulates the function of PIF4, however, is not well understood. Here we demonstrate that three phylogenetically related TEOSINTE BRANCHED 1/CYCLOIDEA/PCF (TCP) transcription factors, TCP5, TCP13, and TCP17, play fundamental roles in promoting thermoresponsive hypocotyl growth by positively regulating the activity of PIF4. TCP17 was found to interact with a blue light receptor, CRYPTOCHROME 1 (CRY1), at lower temperature, leading to reduced activity of TCP17. Higher temperature can increase the stability of TCP17, and release TCP17 from the CRY1-TCP17 complex, allowing it to upregulate the expression of
PIF4
and enhance the transcriptional activity of PIF4. This study revealed the important roles of TCPs in regulating the activity of PIF4 in thermomorphogenesis.
Receptor-like protein kinases (RLKs) play key roles in regulating plant growth, development and stress adaptations. There are at least 610 RLKs (including receptor-like cytoplasmic kinases) in Arabidopsis. The functions of the majority of RLKs have not yet been determined. We previously generated promoter::GUS transgenic plants for all leucine-rich repeat (LRR)-RLKs in Arabidopsis and analyzed their expression patterns during various developmental stages. We found the expression of two LRR-RLKs, MUSTACHES (MUS) and MUSTACHES-LIKE (MUL), are overlapped in lateral root primordia. Independent mutants, mus-3 mul-1 and mus-4 mul-2, show a significantly decreased emerged lateral root phenotype. Our analyses indicate that the defects of the double mutant occur mainly at stage I of lateral root development. Exogenous application of auxin can dramatically enhance the transcription of MUS, which is largely dependent on AUXIN RESPONSE FACTOR 7 (ARF7) and ARF19. MUS and MUL are inactive kinases in vitro but are phosphorylated in planta, possibly by an unknown kinase. The kinase activity of MUS is dispensable for its function in lateral root development. Many cell wall related genes are down regulated in mus-3 mul-1. In conclusion, we identified MUS and MUL, two kinase-inactive RLKs, in controlling the early development of lateral root primordia likely via regulating cell wall synthesis and remodeling.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.