A REASSESSMENT OF THE PATTERN OF ENDOSPERM HYDROLYSIS (MODIFICATION) IN GERMINATED BARLEY

Microscopic and enzymic studies of germinated barley have confirmed that excised barley embryos can produce α‐amylase because the peripheral areas of the scutellar tissue contain aleurone cells. In contrast, the aleurone‐free tissue of the scutellum is incapable of producing significant quantities of α‐amylase. The potential of excised embryos to develop α‐amylase is not correlated with the in vivo elongation of the scutellar epithelial cells in the grain because these cells do not elongate in excised embryos. Detailed anatomical studies revealed that the highly insoluble Intermediate layer of cell wall material, which is located between the embryo and the starchy endosperm, is broken‐down asymmetrically, thus confirming that enzymic modification of the endosperm is under aleurone rather than scutellar control, in germinated barley. Other studies which have sited the scutellum of barley as inducing symmetric break‐down of the endosperm have not linked structural changes, in vivo , with fluorescent or non‐fluorescent staining patterns. Some of these studies have failed to recognise the possibility that grains such as sorghum and rice may have a different pattern of endosperm break‐down from that of barley.