[Differential expression on cell wall formative genes in cell suspension cultures of Populus tomentosa Carr]

With fine and granular suspension cultures established from P. tomentosa, differential expression of 12 genes related to cell wall formation including cell expansion, cellulose synthesis, lignin synthesis, etc, were investigated by reverse transcript PCR (RT-PCR) technique. Fine suspension cells showed high expression on 3 alpha-Exp genes with the highest alpha-Exp2 followed by alpha-Exp3 and alpha-Exp1 suggesting their strong cell expansion, while granular suspension cells only exist high expression on alpha-Exp3 indicating their later period of cell expansion or initial stage of secondary cell wall formation. Among the 6 genes relating to cellulose synthesis, both fine and granular cultures have high expression on CesA4 and CaSy1 and some expression on CesA1, CesA3-1 and CesA3-2, indicating their primary cell wall formation initiated, however a little higher expression on CesA3-1 and CesA3-2 in granular cells may reflect its more cellulose synthesis and more primary cell wall formation. The occurrence of Lac1 and Unk1 could not been detected in the 2 cell suspension cultures, showing no significant lignin biosynthesis and matural secondary cell wall formation.