Medial pith cells per meter in twigs as a proxy for mitotic growth rate (Φ/m) in the apical meristem

摘要: The Φ model for plant mating system evolution proposes a causal link between Φ, the number of mitoses that occur within plant's lifetime from zygote to gamete production, and constraints on inbreeding depression thereby systems. Through its use stature, emphasizes important role morphology in creating developmental genetic evolution. However, estimation itself is likely be extraordinarily complex. Here I describe protocol estimating per meter linear growth by an apical meristem (Φ/m) using medial pith cells mature internodes twigs. While such are produced meristem, during internode elongation, these also undergo further mitoses, thus their measurement can only approximate "true" Φ/m via application multiplier (the adjustment ratio) partially corrects occurrence cell divisions beyond meristem. applied this method Delonix regia (Caesalpiniaceae) derived several ratios literature. Because variation have profound evolutionary implications, examined interspecific intraspecific as well within-individual Φ/m. Conifers apparently lower than do angiosperms, while 20% total variance D. was found among individual trees, with remainder trees. Given large differences stature "high-Φ" plants trees "low-Φ" herbs, results support idea per-generation mutation rate high-Φ many times higher low-Φ plants.