BcXTH1, a Brassica campestris homologue of Arabidopsis XTH9, is associated with cell expansion.
Xyloglucan endotransglucosylase/hydrolases (XTHs) are a group of the enzymes that are responsible for reorganization of the cellulose-xyloglucan framework by catalyzing cleavage and religation of the xyloglucan chains in the plant cell wall. In this study, we report the isolation and characterization of a XTH gene from a pistil cDNA library of Brassica campestris. Sequence analysis of the gene, designated BcXTH1, revealed that it is homologous to the XTH9 gene of Arabidopsis. The highly conserved domain (DEIDFEFLG) found among all XTHs was also present in BcXTH1 but with the two amino acid substitutions (NEFDFEFLG) also found in Arabidopsis XTH9. These results suggest that BcXTH1 is the B. campestris homologue of XTH9. Expression analysis of BcXTH1 revealed that it was expressed in most of the plant organs. In situ hybridization showed that the gene is highly expressed in the floral primodia, especially in the epidermal cell layer. Southern blot analysis indicated that the BcXTH1 gene exists as a multi-copy gene in the B. campestris genome. The function of the BcXTH1 gene was deduced from using an overexpression strategy in Arabidopsis. Interestingly, the transgenic plants showed a pronounced cell expansion phenotype. Immunoelectron microscopy shows that BcXTH1 is localized almost exclusively to the cell wall, supporting our conclusion that it participates in the regulation of cell expansion in B. campestris.
Shin
Yoon-Kyung
YK
School of Life Sciences and Biotechnology, Korea University, 136-701 Seoul, Anam-Dong, Korea.
Yum
Hyunsik
H
Kim
Eun-Sook
ES
Cho
Hongju
H
Gothandam
Kodiveri M
KM
Hyun
Jiyoung
J
Chung
Yong-Yoon
YY
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics*; D001937:Brassica / Q000166:cytology / Q000201:enzymology* / Q000235:genetics; D049108:Cell Enlargement; D016695:Glycosyltransferases / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D030821:Plants, Genetically Modified / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein
D010940:Plant Proteins; D016695:Glycosyltransferases; C473049:xyloglucan - xyloglucosyltransferase