Pectin methyltransferases from suspension-cultured cells and seedlings of flax (Linum usitatissimum L.)

Charge and molecular weight differences for fourteen guaiacol peroxidase isozymes in flax indicate that most are encoded by different structural genes

“…2c). (ii) The presence of these stress-inducible anionic isozymes in cell cultures supports the general idea that tissue culture is stressful. It also suggests that other stress-induced isoforms might also occur in these cultures, which is in line with the suggestion by Bruyant et al [16] that there may be ªa putative role for the neutral forms in a stress phenomenonº (page 421 in [16]). The slow migrating diffuse region of induced cationic activity, seen between the origin and C.Prx b in stressed seedlings (Fig.…”

“…In summary, most of the 16 IEF isoforms seen in the cell cultures [16] can be attributed to the isozymes seen in normal and/or stress-induced seedlings. Conversely, the highly acidic, stem/hypocotyl-specific isozymes A.Prx 3, 4a, 4 1 and 4 2 (and any other bands in this complex), as well as the root-specific isozyme A.Prx r, and probably also C.Prx r, were not seen in the tissue culture extracts examined by IEF.…”

“…The correlation between y-intercepts for the five isozymes (Table 1) and pI values for IEF bands A2±A6 (calculated from Fig. 3 in [16]) was r 3 = +0.979, p < 0.01 (Fig. 2c). (ii) The presence of these stress-inducible anionic isozymes in cell cultures supports the general idea that tissue culture is stressful.…”

“…Since that time, there have been several other reports of IEF applied to flax isozymes. The first demonstrated isoforms which were not tissue-specific at pI 9.4, 4.2, and 3.2, and two which were tissue-specific, at pI 8.2 in roots and pI 4.8 The relationship between the y-intercepts for isozymes A.Prx 0 to A.Prx 2 in stressed seedlings and the pI values for Group-A isoforms [16] in cultured tissues, indicates that the minor isoforms in tissue cultures correspond to the stress-induced isozymes in seedlings.…”

“…The more recent of these studies [16] examined extracts from flax cell cultures, and provides a useful description of the IEF pattern as consisting of three distinct groups encompassing pI from 4.0 to 5.1 (six acidic isoforms, A-group), 6.5±8.0 (four neutral isoforms, N-group), and 8.4±9.3 (six basic isoforms, Bgroup), respectively. The two main isoforms seen in Agroup, at 4.6 and 4.0, are almost certainly A.Prx 1 and A.Prx 2.…”