Find in Library

As a major component of the plant primary cell wall, structure changes in pectin may affect the formation of the secondary cell wall and lead to serious consequences on plant growth and development. Pectin-modifying enzymes including pectate lyase-like proteins (PLLs) participate in the remodeling of pectin during organogenesis, especially during fruit ripening. In this study, we used <i>Arabidopsis</i> as a model system to identify critical <i>PLL</i> genes that are of particular importance for vascular development. Four <i>PLL</i> genes, named <i>AtPLL15</i>, <i>AtPLL16</i>, <i>AtPLL19,</i> and <i>AtPLL26,</i> were identified for xylem-specific expression. A knock-out T-DNA mutant of <i>AtPLL16</i> displayed an increased amount of pectin, soluble sugar, and acid-soluble lignin (ASL). Interestingly, the <i>atpll16</i> mutant exhibited an irregular xylem phenotype, accompanied by disordered xylem ray cells and an absence of interfascicular phloem fibers. The xylem fiber cell walls in the <i>atpll16</i> mutant were thicker than those of the wild type. On the contrary, <i>AtPLL16</i> overexpression resulted in expansion of the phloem and a dramatic change in the xylem-to-phloem ratios. Altogether, our data suggest that <i>AtPLL16</i> as a pectate lyase plays an important role during vascular development in <i>Arabidopsis</i>.