Abstract
Pectins are commonly found in the primary wall and the middle lamella region of the wall where two adjacent cells abut. Homogalacturonans are the major components of pectic polysaccharides and play an important role in plant development and morphogenesis. We have specifically degraded homogalacturonans in poplar by expressing apple polygalacturonase. Cell walls of transgenic poplars showed a 15% reduction in galacturonic acid content as compared with the wild type. In comparison to the wild type, transgenic plants showed a reduced growth rate with stem height and diameter. Anatomical analysis of stem transverse sections revealed that the cells from transgenic poplars were smaller than those from the wild type. Moreover, length of xylem fibers from transgenic poplars were also shorter than those from the wild type. These observations indicate that the homogalacturonan is a critical factor in plant cell growth.
