Validation of Aintegumenta as a gene to modify floral size in ornamental plants

Abstract

Summary The gene AINTEGUMENTA (AtANT) is an APETALA2 transcription factor in Arabidopsis activating growth downstream of auxin signalling. Lateral organ size is positively correlated with ANT expression in Arabidopsis. We tested the use of AtANT as a tool to modify floral size in two different plants used as model organisms and ornamental crops, Petunia × hybrida and Antirrhinum majus. Petunia plants expressing PhANT RNAi showed a decrease in PhANT expression correlated with smaller petal limbs. In contrast Petunia plants overexpressing AtANT had larger petal limbs. Petal tube length was less affected in down‐regulation of PhANT or overexpression of AtANT. Overexpression of AtANT in Antirrhinum caused increased flower size via increased petal limb width and tube length. Down‐regulation of PhANT showed an effect on cell size while overexpression of AtANT in Petunia and Antirrhinum caused significant increases in cell expansion that could explain the differences in floral organ size. The endogenous expression levels of PhANT and AmANT tended to be higher in the limb than in the tube in both Antirrhinum and Petunia. AtANT overexpression caused significant AmANT up‐regulation in Antirrhinum limbs but not of PhANT in Petunia, indicating differences in the regulatory network. The differential effect of AtANT on limb and tube in Petunia and Antirrhinum correspond to phenotypic differences observed in natural variation in the corresponding genus indicating a relation between the phenotypic space of a genus and the effect of modified ANT levels, validating ANT as a gene to modify floral size.

The clock gene Gigantea 1 from Petunia hybrida coordinates vegetative growth and inflorescence architecture

“…The W115 Mitchell double haploid was transformed as described before 81 using Agrobacterium tumefaciens strain EHA105. Shoots, developed under selective conditions, were confirmed as transformed through PCR detection of the selection marker gene nptII (T0, T1) and DNA blot analysis (T0) with a nptII DIG-labeled DNA probe (Fig.…”

Molecular and transcriptional structure of the petal and leaf circadian clock inPetunia hybrida

“…Once organ identity is established and right after anthesis, there is a transcriptional reprogramming (Manchado-Rojo et al , 2012). Furthermore, in sympetalous flowers with petals forming a tube and a limb, both parts of the flower appear to have different functions and transcriptional control (Delgado-Benarroch et al , 2009; Manchado-Rojo et al , 2014). The petal function after anthesis includes concealing the sexual organs and attracting pollinators.…”

Meristem maintenance, auxin, jasmonic and abscisic acid pathways as a mechanism for phenotypic plasticity in Antirrhinum majus

“…4 ). As auxin signalling maybe localized in primordia, we tested the expression of AmAINTEGUMENTA , an AP2 transcription factor involved in auxin signaling and lateral organ formation 10 13 29 . As found for AmTAR2 expression.…”

“…The AP2 transcription factor AINTEGUMENTA has a dual function in activation of the polarity genes and the establishment of floral organ identity 9 . It also plays a role in lateral organ size via control of cell division and expansion in Arabidopsis, Petunia and Antirrhinum 10 11 12 , and is downstream of the auxin signalling pathway 13 . As lateral organs initiate, organ polarity genes take over and a combination of transcription factors and siRNAs establish the growth planes of lateral organs 14 .…”