Skotomorphogenesis exploits threonine to promote hypocotyl elongation

Abstract

Mobilisation of seed storage reserves is important for seedling establishment in Arabidopsis. In this process, sucrose is synthesised from triacylglycerol via core metabolic processes. Mutants with defects in triacylglycerol-to-sucrose conversion display short etiolated seedlings. We found that whereas sucrose content in the indole-3-butyric acid response 10 (ibr10) mutant was significantly reduced, hypocotyl elongation in the dark was unaffected, questioning the role of IBR10 in this process. To dissect the metabolic complexity behind cell elongation, a quantitative-based phenotypic analysis combined with a multi-platform metabolomics approach was applied. We revealed that triacylglycerol and diacylglycerol breakdown were disrupted in ibr10, resulting in low sugar content and poor photosynthetic ability. Importantly, batch-learning self-organised map clustering revealed that threonine level was correlated with hypocotyl length. Consistently, exogenous threonine supply stimulated hypocotyl elongation, indicating that sucrose levels are not always correlated with etiolated seedling length, suggesting the contribution of amino acids in this process.

Leaf-size control beyond transcription factors: Compensatory mechanisms

“…Genetic studies of the TAG-to-Suc pathway identified several key enzymes whose loss-of-function affected seedling establishment with varying levels of penetrance ( Hayashi et al., 1998 ; Hooks et al., 1999 ; Froman et al., 2000 ; Eastmond et al., 2000 ; Germain et al., 2001 ; Footitt et al., 2002 ; Rylott et al., 2003 ; Fulda et al., 2004 ). To evaluate the link between TAG-to-Suc conversion and CCE, we phenotypically characterized icl-2 , mls-2 , pck1-2 ( Takahashi et al., 2017 ), and ibr10 mutants ( Tabeta et al., 2021 ; Tabeta et al., 2022 ), all of which displayed class II CCE ( Katano et al., 2016 ; Takahashi et al., 2017 ; Tabeta et al., 2021 ). Hence, producing Suc from TAG during seed germination is crucial for proper cotyledon development.…”

Roles of type II H+-PPases and PPsPase1/PECP2 in early developmental stages and PPi homeostasis of Arabidopsis thaliana

“…Peak areas were normalized using a quality control sample and the LOWESS/Spline normalization tool (Tsugawa et al, 2014a). Detailed GC-QqQ-MS parameters and MRM transitions for wide-target analysis were previously described (Tabeta et al, 2021;Tabeta et al, 2022).…”

Functions of serine from the phosphorylated pathway on growth, male gametogenesis, and metabolism in Marchantia polymorpha

“…The residue was dissolved in 250 μL of ethanol and centrifuged at 10,000 × g for 15 min. The supernatant was subjected to LC-MS/MS analysis 75 . The dataset was analyzed using MS-DIAL version 4.80.…”

“…Calculation and normalization of peak area values were conducted using MRMPROBS and LOWESS/Spline normalization tools as described previously 73 . Detailed GC-MS/MS parameters 74 and MRM transitions 75 for widely targeted analysis have been previously described.…”