Plants growth from single cells

Growth of Plants and Animals from Single Cells. 329... 

Genes in all cellular organisms are made of DNA. The same is true for some viruses, but for others the genetic material is RNA. Viruses are genetic elements enclosed in protein coats that can move from one cell to another but are not capable of independent growth. One well-studied example of an RNA virus is the tobacco mosaic virus, which infects the leaves of tobacco plants. This virus consists of a single strand of RNA (6930 nucleotides) surrounded by a protein coat of 2130 identical subunits. An RNA-directed RNA polymerase catalyzes the replication of this viral RNA. 

The first definition, cracial for a better understanding of the subject, is that of vegetable liber. This term denotes a single cell having contributed to the growth of the plant from which it had been extracted and which has now ceased its vital functions (Fig. 1.6). 

The multicellular system of a higher plant grows by sexual propagation from a single cell, the zygote. This growth denotes only one aspect of development, however. We will remember that the individual cells of a plant can be very different from each other. This development of dissimilarity, this differentiation, is the second aspect of development. 

---