Ovule development, a new model for lateral organ formation

Abstract

In spermatophytes the ovules upon fertilization give rise to the seeds. It is essential to understand the mechanisms that control ovule number and development as they ultimately determine the final number of seeds and, thereby, the yield in crop plants. In Arabidopsis thaliana, ovules arise laterally from a meristematic tissue within the carpel referred to as placenta. For a correct determination of the number of ovules, a precise establishment of the positions where ovule primordia emerge is needed, and a tight definition of the boundaries between ovules is therefore also required. In the last decades, few factors have been identified to be involved in the determination of ovule number. Recently, plant hormones have also been revealed as fundamental players in the control of the initiation of ovule formation. In this review we summarize the current knowledge about both the molecular and hormonal mechanisms that control ovule formation in Arabidopsis thaliana.

microRNA159‐targetedSlGAMYBtranscription factors are required for fruit set in tomato

“…The miR159 family is highly conserved in land plants (Cuperus et al, 2011). Arabidopsis thaliana has three miR159 precursors, each of which generates a distinct mature sequence (miR159a, -b and -c; Jones-Rhoades et al, 2006).…”

A conserved role for CUP‐SHAPED COTYLEDON genes during ovule development

“…While the different tissues constituting the ovule and the genes involved in their development are well described, the first step of ovule primordia initiation and how these primordia arise from the placenta in a such regularly spaced pattern remains more elusive (reviewed in Cucinotta et al, 2014). So far, few genes have been involved in ovule initiation and differentiation.…”

Molecular basis of fruit development

“…The interactions between the primordial and boundary regions, as well as cytokinin regulation are required for the proper expression and localization of the PIN-FORMED1 (PIN1) auxin transporter and thus for proper auxin fluxes. Brassinosteroid signaling is proposed to support ovule initiation through the stimulation of ANT activity in ovule primordia (Huang et al, 2013;Cucinotta et al, 2014).…”

“…Their work suggested that proper termination of the floral meristem may be required for the complete development of the CMM and ovules. Cucinotta et al (2014) reviewed the early ovule development with a focus on the formation of the CMM and the initiation of ovule primordia in Arabidopsis. They presented a model of ovule initiation that relates the functions of CUC and ANT genes as well as the action of auxin, cytokinin, and brassinosteroid hormones (Galbiati et al, 2013;Cucinotta et al, 2014).…”

“…Cucinotta et al (2014) reviewed the early ovule development with a focus on the formation of the CMM and the initiation of ovule primordia in Arabidopsis. They presented a model of ovule initiation that relates the functions of CUC and ANT genes as well as the action of auxin, cytokinin, and brassinosteroid hormones (Galbiati et al, 2013;Cucinotta et al, 2014). Their model posits a role for ANT in the growth of the organ primordia, and CUC genes in the specification of the boundary zones between ovules.…”