Read: Reinhardt, D, Frenz, M, Mandel, T, Kuhlemeier, C (2003) Microsurgical and laser ablation analysis of interactions between the zones and layers of the tomato shoot apical meristem. Development 130:4073-4083


Answer the following questions.


1. Classical experiments mentioned in the introduction, where meristems were variously dissected or pricked with needles, led to the conclusion that shoot meristems were “regulative”. That is, the cell population is able to self organize into a new functional meristem. What insights into the molecular basis of this phenomenon does this study provide?



2. Ablation of the whole central zone led to the ectopic induction of WUS expression. However, ablation of only the outer 4-5 cell thicknesses of the CZ did not result in the induction of WUS expression. Explain why this latter result is surprising, given our current understanding of SAM regulation.



3. On what basis do the authors conclude that the gene they are monitoring expression of is the WUS gene of tomato? Do their criteria constitute a rigorous proof? Explain why or why not.