The Fate of Inflorescence Meristems Is Controlled by Developing Fruits in Arabidopsis

Abstract

~~~The relationship between fruit development and the proliferative capacities of inflorescence meristems has been examined in Arabidopsis fhaliana. In the wild-type Landsberg erecta (Ler) line, flower production ceases coordinately on all inflorescence branches by a process we have designated global proliferative arrest (CPA). Morphological studies indicate that CPA involves a cessation of proliferative activity at the meristems, but a retention of the structural characteristics of the proliferating meristems. CPA does not occur in the male-sterile (msl-7) line, nor in wild-type Ler when fruits are surgically removed. In these cases, inflorescence meristems continue to proliferate, ultimately terminating by a different process, designated terminal differentiation, in which disruptions in patterning at the apex are followed by the loss of the inflorescence meristem. We present an argument that CPA is mediated by a specific communication system between inflorescence meristems and developing fruits. Analysis of reduced-fertility mutants provided evidence that CPA is dependent on seed development specifically. Mutations conferring hormone deficiency or insensitivity did not disrupt the correlative interactions leading to CPA.

Seed Production Affects Maternal Growth and Senescence in Arabidopsis

“…The sequential production of flowers in Arabidopsis eventually stops once a certain number of fruits (under given growth conditions) have been produced (Hensel et al, 1994;Noodén and Penney, 2001). We found that sterile plants produced many more ovaries and axillary branches than fertile ones over their lifetimes ( Fig.…”

“…We found that sterile plants produced many more ovaries and axillary branches than fertile ones over their lifetimes ( Fig. 1; see also Hensel et al [1994] and Noodén and Penney [2001]). Under given growth conditions, fruit production leads to a characteristic arrest of growing inflorescences visible through the production of terminal clusters of nonmaturing flower buds (Fig.…”

“…In the monocarpic species Arabidopsis (Arabidopsis thaliana), correlative control of developing fruits over maternal growth and longevity has also been reported (Hensel et al, 1994;Noodén and Penney, 2001). Under constant growth conditions, an Arabidopsis plant produces a certain number of flowers before its reproductive meristems arrest.…”

“…Under constant growth conditions, an Arabidopsis plant produces a certain number of flowers before its reproductive meristems arrest. This process is termed global proliferative arrest (GPA) as correlative inhibition through offspring affects all maternal aboveground meristematic activity (Hensel et al, 1994). At the same time, the senescence of Arabidopsis rosette leaves has been reported to be uncoupled from reproduction (Hensel et al, 1993;Noodén and Penney, 2001), but some results from experimental removal of reproductive bolts have suggested a negative feedback from shoots to leaves affecting chlorophyll levels (Ye et al, 2000).…”

Genetic Characterization and Functional Analysis of the GID1 Gibberellin Receptors inArabidopsis

“…This increase in final height is unexpected considering that the Arabidopsis GID1 genes act as positive regulators of stem elongation. It is conceivable that this increase in stem elongation in gid1a-1 gid1b-1 is an indirect consequence of the reduced fertility (Hensel et al, 1994) observed in this mutant (see below; Table 1). …”