Gladiolus hybridus ABSCISIC ACID INSENSITIVE 5 (GhABI5) is an important transcription factor in ABA signaling that can enhance Gladiolus corm dormancy and Arabidopsis seed dormancy

Abstract

The phytohormone abscisic acid (ABA) regulates plant development and is crucial for abiotic stress response. In this study, cold storage contributes to reducing endogenous ABA content, resulting in dormancy breaking of Gladiolus. The ABA inhibitor fluridone also promotes germination, suggesting that ABA is an important hormone that regulates corm dormancy. Here, we report the identification and functional characterization of the Gladiolus ABI5 homolog (GhABI5), which is a basic leucine zipper motif transcriptional factor (TF). GhABI5 is expressed in dormant vegetative organs (corm, cormel, and stolon) as well as in reproductive organs (stamen), and it is up-regulated by ABA or drought. Complementation analysis reveals that GhABI5 rescues the ABA insensitivity of abi5-3 during seed germination and induces the expression of downstream ABA response genes in Arabidopsis thaliana (EM1, EM6, and RD29B). Down-regulation of GhABI5 in dormant cormels via virus induced gene silence promotes sprouting and reduces the expression of downstream genes (GhLEA and GhRD29B). The results of this study reveal that GhABI5 regulates bud dormancy (vegetative organ) in Gladiolus in addition to its well-studied function in Arabidopsis seeds (reproductive organ).

Signalling regulators of abscisic and gibberellic acid pathways are involved in dormancy breaking of Norway maple (Acer platanoides L.) seeds

“…This protein has shown nuclear localisation in epidermal cells (of onion and Nicotiana benthamiana), stamen and corn (of gladiolus) (Wu et al 2015). In dry Norway maple seeds, ABI5 was noticeable in cell nuclei in each part of the embryo axes.…”

Endosperm sugar accumulation caused by mutation of PHS8/ISA1 leads to pre‐harvest sprouting in rice

“…The activated SnRK2s phosphorylate downstream transcription factors and promote ABA responses. Among these transcription factors, ABA-INSENSITIVE 3 (ABI3) and ABI5 are crucial positive regulators in the control of seed germination (Hoecker et al, 1995;Merlot et al, 2001;Lopez-Molina et al, 2002;McCourt et al, 2002;Shu et al, 2013;Wu et al, 2015). In rice, OsABI3, the ortholog of VP1 (Viviparous 1) in maize, encodes a B3 domain-containing transcription factor necessary for the response of seeds to ABA (Hattori et al, 1994;Hobo et al, 1999).…”

Mechanisms of vegetative propagation in bulbs : a molecular approach

“…However, the buds that are initiated when the shoot apical meristem (SAM) of their mother has transitioned into the reproductive state ('A and B' buds in tulip), are able to skip this kind of dormancy (Chapter 4 and (Rees 1968)). This particular dormancy is known as paradormancy and imposed by apical dominance (Lang et al 1987 (Yao and Finlayson 2015;González-Grandío et al 2017;GomezRoldan et al 2008;Liang et al 2010;Pasare et al 2013;González-Grandío and Cubas 2014;Wu et al 2015;Hartmann et al 2011). …”

“…This functional analysis could be achieved using virusinduced gene silencing (VIGS) by vacuum infiltrating small bulb scale explants. This methodology has recently proven to work in the geophyte species Gladiolus hybridus, when used to silence ABSCISIC ACID INSENSITIVE 5 (GhABI5) in cormels (Wu et al 2015), which are underground storage organs, representing structures homologous to daughter bulbs in tulip, or to bulblets in lily. Furthermore, VIGS was recently successfully applied in lily vegetative tissues and flowers (Tasaki et al 2016), highlighting the potential of this methodology.…”