Linking stem cells to germ cells

In response to their sessile nature and a need for flexibility in adapting to the environment, plants can often propagate through organ regeneration, develop functional gametes without a need to eliminate half of their chromosomes, generate embryos from somatic cells in almost any tissue, or produce viable seeds in the absence of fertilization. In many cases, this intriguing flexibility relies on developmental alternatives to classic sexual reproduction. Like many multicellular organisms, most plant species harbor gametes poised to give rise to progeny after fusion of a sperm and egg. However, plants generate gamete precursors from adult somatic tissue, rather than during embryogenesis. On page [396][1] of this issue, Zhao et al. ( 1 ) report the role of a signaling circuit that, by controlling cell proliferation and differentiation in young reproductive organs, is essential for initiating meiosis and generating gametes in the sexual model species Arabidopsis thaliana. The finding opens new opportunities for establishing an integrative view of how reiterative developmental mechanisms contribute to the acquisition and maintenance of reproductive versatility in plants. [1]: http://www.sciencemag.org/content/356/6336/aaf6532