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A Populus BAHD/HXXXD acyltransferase was identified as hydroxyacid/fatty alcohol hydroxycinnamoyltransferase. When ectopically expressed in Arabidopsis, it increased the incorporation of ferulate in both suberin and cutin polyesters, which consequently enhanced the tolerance of transgenic plants to salt stress.Cutinized and suberized cell walls in plants constitute physiologically important environment interfaces. They act as barriers limiting the loss of water and nutrients and protecting against radiation and invasion of pathogens. The roles of cutin- and suberin polyesters are often attributed to their dominant aliphatic components, but the contribution of aromatic composition to their physiological function remains unclear. By functionally screening a subset of Populus trichocarpa BAHD/HXXXD acyltransferases, we identified a hydroxycinnamoyltransferase that shows specific transacylation activity on ω-hydroxyacids using both feruloyl- and p-coumaroyl- CoA as the acyl donors. We named this enzyme P. trichocarpa hydroxyacid/fatty alcohol hydroxycinnamoyltransferase 1 (PtFHT1). The ectopic expression of the PtFHT1 gene in Arabidopsis increased the incorporation of ferulate in root and seed suberins and in leaf cutin, but not that of p-coumarate, while the aliphatic load in both suberin and cutin polyesters essentially remained unaffected. The overaccumulation of ferulate in lipophilic polyester significantly increased the tolerance of transgenic plants to salt stress treatment; under sub-lethal conditions of salt stress, the ratios of their seed germination and seedling establishment were 50% higher than those of wild-type plants. Our study suggests that, although aromatics are the minor component of polyesters, they play important role in the sealing function of lipidic polymers in planta. [ABSTRACT FROM AUTHOR]

Plant growth requires cell wall extension. The cotton AtRD22-Like 1 gene GhRDL1, predominately expressed in elongating fiber cells, encodes a BURP domain-containing protein. Here, we show that GhRDL1 is localized in cell wall and interacts with GhEXPA1, an α-expansin functioning in wall loosening. Transgenic cotton overexpressing GhRDL1 showed an increase in fiber length and seed mass, and an enlargement of endopleura cells of ovules. Expression of either GhRDL1 or GhEXPA1 alone in Arabidopsis led to a substantial increase in seed size; interestingly, their co-expression resulted in the increased number of siliques, the nearly doubled seed mass, and the enhanced biomass production. Cotton plants overexpressing GhRDL1 and GhEXPA1 proteins produced strikingly more fruits (bolls), leading to up to 40% higher fiber yield per plant without adverse effects on fiber quality and vegetative growth. We demonstrate that engineering cell wall protein partners has a great potential in promoting plant growth and crop yield. [ABSTRACT FROM PUBLISHER]