Despite major advances in understanding cold signaling, cold acclimation, and freezing protection in model and crop species, and extensive studies of natural variation in freezing tolerance in Arabidopsis accessions, the question of which genes and mechanisms underlie freezing tolerance of wild species has remained largely unanswered. Because freezing tolerance generally exhibits continuous variation, it is amenable to quantitative trait locus (QTL) mapping to identify relevant chromosomal regions. Arisz et al. (10.1104/pp.18.00503) have performed a quantitative trait locus (QTL) study of acclimated freezing tolerance in seedlings of Boechera stricta, a relative of Arabidopsis that is native to the Rocky Mountains. A single QTL was identified that contained the gene encoding ACYL-COA:-DIACYLGLYCEROL ACYLTRANSFERASE1 (BstDGAT1), whose expression is highly cold responsive. DGAT1 catalyzes the final step in assembly of triacylglycerol (TAG) by acyl transfer from acyl-CoA to diacylglycerol. Freezing tolerant plants showed higher DGAT1 expression during cold acclimation than more sensitive plants, and this resulted in increased accumulation of TAG in response to subsequent freezing. The levels of oligogalactolipids that are produced by SFR2 (SENSITIVE TO FREEZING2), an indispensable element of freezing tolerance in Arabidopsis, were also higher in freezing-tolerant plants. SFR2 transfers galactosyl groups from monogalactosyldiacylglycerol to other galactolipids to generate oligogalactolipids, including tri- and tetragalactosyldiacylglycerol, which are thought to stabilize chloroplast membranes, and diacylglycerol. Overexpression of AtDGAT1 in Arabidopsis also resulted in a substantial increase in freezing tolerance. Together, the data suggest a mechanism by which DGAT1-mediated TAG assembly confers tolerance to freezing stress.
You might also like
Buffering effects of soil seed banks on plant community composition in response to land use and climate (Glob. Ecol. Biogeogr.)
A prion-like protein regulator of seed germination undergoes hydration-dependent phase separation ($) (Cell)
Endosidin20 targets the cellulose synthase catalytic domain to inhibit cellulose biosynthesis (Plant Cell)
A chloroplast-localized mitochondrial calcium uniporter transduces osmotic stress in Arabidopsis (Nature Plants)