Xyloglucan structure and post‐germinative metabolism in seeds of Copaifera langsdorfii from savanna and forest populations

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Abstract
The cotyledons of Copaifera langsdorfii Desf, have been shown to contain a water‐soluble xyloglucan (amyloid), which represents about 40% of the seed's dry weight. On acid hydrolysis its composition (Glc:Xyl:Gal = 4.0:2.8–2.9:1.5–1.7) was similar to that of the well‐characterized xyloglucan of Tamarindus indica L. (Glc:Xyl:Gal = 4.0:3.0–3.1:1.4). On hydrolysis with pure Trichoderma viride cellulase, both C. langsdorfii and T. indica xyloglucan gave the same xyloglucan oligosaccharides: image but in significantly different proportions A:B1:B2:C = 1:0.4–0.5:2.1–2.2:3.1–3.4 in T. indica, and 1:1.1:1.8:7.4 and 1:1.3:2.6:12 for C. langsdorfii, savanna and forest populations respectively. This demonstrated a difference in fine molecular structure, notably in the distribution of the terminal non‐reducing galactose substituents, between the xyloglucans of the two species and indicated differences in the specificities of their biosynthetic mechanisms. The xyloglucans obtained from C. langsdorfii seeds harvested from savanna and forest environments were slightly different, one from the other, in their sugar‐residue composition (Glc:Xyl:Gal = 4.0:2.9:1.5 and 4.0:2.8:1.7, respectively), and were significantly different in the relative proportions of the xyloglucan oligosaccharides released on cellulase hydrolysis (above). Using light microscopy and biochemical methods, no difference in the pattern or rate of postgerminative xyloglucan metabolism was detected in seeds of savanna and forest origin. This is the first clear experimental evidence for differences in a storage xyloglucan structure between populations of the same species. It may indicate environmental influences on xyloglucan biosynthesis.