Evolutionary, genetic, environmental and hormonal-induced plasticity in the fate of organs arising from axillary meristems in Passiflora spp.

Abstract

Tendrils can be found in different plant species. In legumes such as pea, tendrils are modified leaves produced by the vegetative meristem but in the grape vine, a same meristem is used to either form a tendril or an inflorescence. Passiflora species originated in ecosystems in which there is dense vegetation and competition for light. Thus climbing on other plants in order to reach regions with higher light using tendrils is an adaptive advantage. In Passiflora species, after a juvenile phase, every leaf has a subtending vegetative meristem, and a separate meristem that forms both flowers and a tendril. Thus, flowers are formed once a tendril is formed yet whether or not this flower will reach bloom depends on the environment. For example, in Passiflora edulis flowers do not develop under shaded conditions, so that tendrils are needed to bring the plant to positions were flowers can develop. This separate meristem generally forms a single tendril in different Passiflora species yet the number and position of flowers formed from the same meristem diverges among species. Here we display the variation among species as well as variation within a single species, P. edulis. We also show that the number of flowers within a specific genotype can be modulated by applying Cytokinins. Finally, this separate meristem is capable of transforming into a leaf-producing meristem under specific environmental conditions. Thus, behind what appears to be a species-specific rigid program regarding the fate of this meristem, our study helps to reveal a plasticity normally restrained by genetic, hormonal and environmental constraints.

The molecular control of tendril development in angiosperms

“…As summarized by Gangstad (), early works dating from the 19 th century hypothesized different origins for the Passiflora tendril, while emphasizing an origin from reproductive structures (although at least one hypothesis was based on the modification of a vegetative axis). More recently, ontogenetic studies suggest that tendrils in Passifloraceae may represent modified reproductive shoots (Cutri et al ., ) or a modification of the central flower pedicel in a dichasial cyme (Krosnick & Freudenstein, ; Feuillet & Macdougal, ). Specifically in Passiflora , tendril and flower primordia originate from a common bud complex (Shah & Dave, ; Scorza et al ., ).…”

Vegetative Phase Change and Shoot Maturation in Plants

“…These changes sometimes resemble those that occur early in the growth of the shoot (Critchfield, 1960), but differ in that they occur regularly, rather than only once. Changes in vegetative morphology may also arise from environmental heterogeneity, such as variation in light quality, temperature, growth substrate, and humidity (Bruni et al, 1995; Cutri et al, 2013; Deschamp and Cooke, 1985; Fisher et al, 2002; Goliber and Feldman, 1990; Jones, 1995; Lee and Richards, 1991; Ray, 1987), and may also be induced by damage from herbivory or disease (Boege and Marquis, 2005). Changes produced by these environmental conditions can resemble the changes that occur during phase change, but it is unclear if they are mediated by the same regulatory mechanism.…”

Identifying developmental phases in the Arabidopsis thaliana rosette using integrative segmentation models

“…This term was first used to differentiate plant species in which substantial differences were observable between earlier and later formed phytomers, from species with gradual changes along the shootthe 'homoblastic' species. Observable changes along the shoot can be due to ontogeny, developmental phase changes, physiological aging, increase in shoot size (Day et al, 2002;Poethig, 2003;Mencuccini et al, 2007), or environmental heterogeneity such as soil humidity, light quality, temperature or nutrient availability (Ray, 1987;Jones, 1995;Bruni et al, 1996;Fisher et al, 2002;Cutri et al, 2013). They can be related to individual leaf size and shape, internode size and branching patterns but also leaf and/or internode growth (Gu edon et al, 2001;Andrieu et al, 2006;Cookson et al, 2007;Willmann & Poethig, 2011).…”