ABSTRACT
Plants tightly control growth of their lateral organs, which led to the concept of apical dominance. However, outgrowth of the dormant lateral primordia is sensitive to the plant's nutritional status, resulting in an immense plasticity in plant architecture. While the impact of hormonal regulation on apical dominance is well characterized, the prime importance of sugar signaling to unleash lateral organ formation has just recently emerged. Here, we aimed to identify transcriptional regulators, which control the trade-off between growth of apical versus lateral organs. Making use of locally inducible gain-of-function as well as single and higher-order loss-of-function approaches of the sugar-responsive S1-basic-leucine-zipper (S1-bZIP) transcription factors, we disclosed their largely redundant function in establishing apical growth dominance. Consistently, comprehensive phenotypical and analytical studies of S1-bZIP mutants show a clear shift of sugar and organic nitrogen (N) allocation from apical to lateral organs, coinciding with strong lateral organ outgrowth. Tissue-specific transcriptomics reveal specific clade III SWEET sugar transporters, crucial for long-distance sugar transport to apical sinks and the glutaminase GLUTAMINE AMIDO-TRANSFERASE 1_2.1, involved in N homeostasis, as direct S1-bZIP targets, linking the architectural and metabolic mutant phenotypes to downstream gene regulation. Based on these results, we propose that S1-bZIPs control carbohydrate (C) partitioning from source leaves to apical organs and tune systemic N supply to restrict lateral organ formation by C/N depletion. Knowledge of the underlying mechanisms controlling plant C/N partitioning is of pivotal importance for breeding strategies to generate plants with desired architectural and nutritional characteristics.
Subject(s)
Basic-Leucine Zipper Transcription Factors , Plant Breeding , Basic-Leucine Zipper Transcription Factors/genetics , Basic-Leucine Zipper Transcription Factors/metabolism , Plants/metabolism , Signal Transduction/genetics , Sugars , Gene Expression Regulation, Plant , Plant Proteins/genetics , Plant Proteins/metabolismABSTRACT
Nucleotide sequences are the fundamental basis for work on molecular mechanisms and for phylogenetic analysis. Recently, we identified sequence errors in all of the LTR sequences of the prototypic foamy virus stored in the GenBank database. Here, we report the resequencing of the proviral plasmids pHSRV13 and pHSRV2. Sequence comparisons revealed an error rate for the foamy virus sequences stored in the database of up to 10 errors per 1000 bp. Even the newest sequences of the codon-optimized foamy virus synthetic Gag, Pol, and Env amino acid sequences showed exchanges compared to the new proviral pHSRV13n sequence. Our results provide evidence that some prototypic foamy virus sequences contain errors and should be revised.
