DNA in Storage Tissues

In peanut cotyledons DNA levels may double up to the 7th-10th day after imbibition even though no cell division seems to occur they decrease thereafter over several days [30, 77]. Part of this increase in DNA could be due to synthesis of mitochondrial DNA (Table 5.4), although it appears that this cannot account for more than 1-2% of the new synthesis [19]. Thus, most DNA synthesis is probably nuclear in origin. The reasons for such synthesis in the absence of cell division are obscure—amplification of genes for enzymes involved in reserve degradation is an attractive, but wholly unsubstantiated suggestion. 

In the megagametophyte of gymnosperms DNA content varies but slightly during embryo germination, e.g. Pseudotsuga menziesii [32], Pinus resinosa [107] and P. nigricans [12]. 

In this chapter we have considered those events essential for the establishment of the metabolism of germinating and growing tissue. In the following chapter we will turn our attention to the post-germination mobilization of stored reserves and the provision of catabolites for continued embryo (seedling) growth. 

---