Excess sterols disrupt plant cellular activity by inducing stress-responsive gene expression

• Published in: Journal of plant research Vol. 133; no. 3; pp. 383 - 392
• Main Authors: Shimada, Takashi L., Yamaguchi, Katsushi, Shigenobu, Shuji, Takahashi, Hiro, Murase, Masataka, Fukuyoshi, Shuichi, Hara-Nishimura, Ikuko
• Format: Journal Article
• Language: English
• Published: Singapore Springer Singapore 01-05-2020; Springer Nature B.V
• Subjects: Accumulation; Biomedical and Life Sciences; Cell membranes; Defects; Desiccation; Elongation; Esters; Gene expression; Genes; Homeostasis; Leaves; Life Sciences; Lipids; Low temperature; Mutants; Organs; Phenotypes; Phospholipids; Plant Biochemistry; Plant Ecology; Plant growth; Plant Physiology; Plant Sciences; Regular Paper – Physiology/Biochemistry/Molecular and Cellular Biology; Seedlings; Senescence; Sterols; Sucrose; Sugar; RNA sequencing; HIGH STEROL ESTER 1; PHOSPHOLIPID STEROL ACYL TRANSFERASE 1; Sterols; Arabidopsis thaliana
• ISSN: 0918-9440; 1618-0860
• DOI: 10.1007/s10265-020-01181-4

Sterols are important lipid constituents of cellular membranes in plants and other organisms. Sterol homeostasis is under strict regulation in plants because excess sterols negatively impact plant growth. HIGH STEROL ESTER 1 (HISE1) functions as a negative regulator of sterol accumulation. If sterol production exceeds a certain threshold, excess sterols are detoxified via conversion to sterol esters by PHOSPHOLIPID STEROL ACYL TRANSFERASE 1 (PSAT1). We previously reported that the
Arabidopsis thaliana
double mutant
hise1-3 psat1-2
shows 1.5-fold higher sterol content than the wild type and consequently a severe growth defect. However, the specific defects caused by excess sterol accumulation in plants remain unknown. In this study, we investigated the effects of excess sterols on plants by analyzing the phenotypes and transcriptomes of the
hise1-3 psat1-2
double mutant. Transcriptomic analysis revealed that 435 genes were up-regulated in
hise1-3 psat1-2
leaves compared with wild-type leaves. Gene ontology (GO) enrichment analysis revealed that abiotic and biotic stress-responsive genes including
RESPONSIVE TO DESICCATION 29B/LOW-TEMPERATURE-INDUCED 65
(
RD29B/LTI65
) and
COLD-REGULATED 15A
(
COR15A
) were up-regulated in
hise1-3 psat1-2
leaves compared with wild-type leaves. Expression levels of senescence-related genes were also much higher in
hise1-3 psat1-2
leaves than in wild-type leaves.
hise1-3 psat1-2
leaves showed early senescence, suggesting that excess sterols induce senescence of leaves. In the absence of sucrose,
hise1-3 psat1-2
exhibited defects in seedling growth and root elongation. Together, our data suggest that excess sterol accumulation disrupts cellular activities of vegetative organs including leaves and roots, resulting in multiple damages to plants.