Arabidopsis thaliana FAR‐RED ELONGATED HYPOCOTYLS3 (FHY3) and FAR‐RED‐IMPAIRED RESPONSE1 (FAR1) modulate starch synthesis in response to light and sugar

Abstract

In living organisms, daily light/dark cycles profoundly affect cellular processes. In plants, optimal growth and development, and adaptation to daily light-dark cycles, require starch synthesis and turnover. However, the underlying molecular mechanisms coordinating daily starch metabolism remain poorly understood. To explore the roles of Arabidopsis thaliana light signal transduction proteins FAR-RED ELONGATED HYPOCOTYLS3 (FHY3) and FAR-RED-IMPAIRED RESPONSE1 (FAR1) in starch metabolism, the contents of starch and water-soluble polysaccharides, and the structure of starch granules were investigated in fhy3, far1 and fhy3 far1 mutant plants. Disruption of FHY3 or FAR1 reduced starch accumulation and altered starch granule structure in the fhy3-4, far1-2, and fhy3-4 far1-2 mutant plants. Furthermore, molecular and genetic evidence revealed that the gene encoding the starch-debranching enzyme ISOAMYLASE2 (ISA2) is a direct target of FHY3 and FAR1, and functions in light-induced starch synthesis. Our data establish the first molecular link between light signal transduction and starch synthesis, suggesting that the light-signaling proteins FHY3 and FAR1 influence starch synthesis and starch granule formation through transcriptional activation of ISA2.

Whirly1 enhances tolerance to chilling stress in tomato via protection of photosystem II and regulation of starch degradation

“…() and Ma et al . (), respectively. The obtained DNA product was detected by quantitative PCR (qPCR) using the specific primers listed in Table S1.…”

“…Two isoamylases ISA1 and ISA2 are involved in starch synthesis. While ISA1 acts as an active enzyme, ISA2 functions as a regulatory subunit (Hussain et al ., ; Ma et al ., ). For starch degradation, α‐amylase, β‐amylase, and debranching enzymes are required (Asatsuma et al ., ).…”

FHY3 and FAR1 Integrate Light Signals with the miR156-SPL Module-Mediated Aging Pathway to Regulate Arabidopsis Flowering

“…Quantitative reverse transcription-PCR (qRT-PCR) analysis showed that transcript levels of FHY3 and FAR1 decreased significantly upon EOD-FR treatment compared with those under WL conditions ( Figure 1C). Moreover, western blotting analysis using pFHY3::FHY3-YFP and p35S::FLAG-FAR1-HA transgenic plants (Lin et al, 2008;Ma et al, 2017) showed that accumulation of both the FHY3 and FAR1 proteins significantly declined after EOD-FR treatment ( Figure 1D). To corroborate this finding, a line overexpressing FHY3 fused with the b-glucuronidase (GUS) reporter gene (p35S::GUS-FHY3) (Wang and Deng, 2002) was subjected to EOD-FR treatment.…”

“…The p35S::GUS-FHY3 transgenic line has been described in Wang and Deng (2002). The pFHY3::FHY3-YFP and p35S::FLAG-FAR1-HA transgenic lines have been described in Lin et al (2008) and Ma et al (2017), respectively. Seeds were surface sterilized, sown on Murashige and Skoog agar medium supplemented with 1% sucrose, and stratified in darkness for 3 days at 4 C. The plates were then transferred to a growth chamber at 23 C (16 h light/8 h dark) with white fluorescent light (~80 mmol m À2 s À1 ) for germination and growth.…”

Molecular Mechanisms Governing Shade Responses in Maize

“…To generate transgenic ZmHB53-OE lines in the Arabidopsis Col-0 background, the coding region of ZmHB53 was PCR-amplified from cDNA of inbred line B73 using the primers pair ZmHB53-F and ZmHB53-R (Table S3). Then, ZmHB53 fragment was inserted into the BamH I and Xba I digested pPZP211-35Spro∷3FLAG binary vector (Ma et al, 2017) to produce 35Spro∷ZmHB53-3FLAG . More than 20 independent transgenic lines were selected and verified by RT-qPCR, followed by immunoblot analysis as described previously (Ma et al, 2016).…”