Characterization of expression dynamics of WOX homeodomain transcription factors during somatic embryogenesis in Vitis vinifera

Abstract

Different cultivars of Vitis vinifera vary in their potential to form embryogenic tissues. The WUSCHEL (WUS)-related homeobox (WOX) genes have been shown to play an important role in coordinating the gene transcription involved in the early phases of embryogenesis. The expression dynamics of 12 VvWOX genes present in the V. vinifera genome in embryogenic and other tissues of 'Chardonnay' were analysed. In order to understand the influence of WOX genes on the somatic embryogenic process, their expression profiles were compared in two cultivars of V. vinifera ('Chardonnay' and 'Cabernet Sauvignon') that show different aptitudes for embryogenesis. The expression of all VvWOX genes was influenced by culture conditions. VvWOX2 and VvWOX9 were the principal WOX genes expressed during the somatic embryogenesis process, and the low aptitude for embryogenesis of 'Cabernet Sauvignon' was generally correlated with the low expression levels of these VvWOX genes. VvWOX3 and VvWOX11 were strongly activated in correspondence to torpedo and cotyledonary stages of somatic embryos, with low expression in the earlier developmental stages (pre-embryogenic masses and globular embryos) and during embryo germination. VvWOX genes appeared to be key regulators of somatic embryogenesis in grapevine, and the regulation of these genes during early phases of somatic embryogenesis differed between the two cultivars of the same species.

Polyamines and WOX genes in the recalcitrance to plant conversion of somatic embryos of Habanero pepper (Capsicum chinense Jacq.)

“…Our results differ from reports on the behavior of WOX3 transcript accumulation for other species, in which the transcripts have been observed to accumulate in advanced stages of embryonic development and to diminish significantly in the phases prior to germination (Haecker et al, 2004;Gambino et al, 2011). There is evidence to support the argument that WOX3 malfunction can be related to malformations of the aerial part, as this gene is associated with early leaf formation (Nakata et al, 2012;Lin et al, 2013;Shimizu et al, 2009;Vandenbussche et al, 2009).…”

“…patterns show greater presence of transcripts in the more advanced stages of embryonic development (Gambino et al, 2011;Haecker et al, 2004;Lin et al, 2013). Previous reports have demonstrated that over-expression and under-expression of WOX1 can cause alterations in plant phenotype due to the fact that this gene is associated with the organization of cellular division in leaves, organs and carpels (Lin et al, 2013;Vandenbussche et al, 2009;Zhang et al, 2011).…”

“…This behavior differed when compared to ZEs and untreated SEs, where the WUS transcript levels were significantly lower in GH+Spm compared to GH with a significant increase in TC+Spm when compared to TC. The presence of WUS has been detected in the early stages of embryogenesis, and is seen to diminish as the embryo develops (Gambino et al, 2011;Su et al, 2009), this behavior was observed in the ZEs and SEs of C. chinense. When the SEs were treated with Spm the WUS transcript levels showed an opposite behavior to previous reports.…”

“…Extensive effort has been focused on the identification of "master" genes required for this, although it is now apparent that the induction of the embryogenic pathway is not governed by a single gene, but is under the control of an intrincated genetic network. Recent studies have revealed that the transcript accumulation of WUSCHELHomeobox (WOX) genes determines apical and basal dominions in different species (Gambino et al, 2011;Haecker et al, 2004;Lin et al, 2013;Palovaara et al, 2010 a,b;Vandenbussche et al, 2009;Van der Graaff et al, 2009;Zhang et al, 2011). One of the early expressed genes is WUSCHEL (WUS) which maintains a reservoir of undifferentiated cells in the SAM and its abnormal expression produces plants with discontinual growth and a compromised SAM identity (Gambino et al, 2011;Haecker et al, 2004;Ji et al, 2010;Stuurman et al, 2002;Su et al, 2009).…”

“…Recent studies have revealed that the transcript accumulation of WUSCHELHomeobox (WOX) genes determines apical and basal dominions in different species (Gambino et al, 2011;Haecker et al, 2004;Lin et al, 2013;Palovaara et al, 2010 a,b;Vandenbussche et al, 2009;Van der Graaff et al, 2009;Zhang et al, 2011). One of the early expressed genes is WUSCHEL (WUS) which maintains a reservoir of undifferentiated cells in the SAM and its abnormal expression produces plants with discontinual growth and a compromised SAM identity (Gambino et al, 2011;Haecker et al, 2004;Ji et al, 2010;Stuurman et al, 2002;Su et al, 2009). Other genes of this family such as WOX1 and WOX3 are involved in the cotyledon determination; WOX1 is expressed in the central part of the cotyledon primordia meanwhile WOX3 is expressed earlier in the peripheral area of the cotyledon (Hacker et al, 2004;Vandenbussche et al, 2009 (Lin et al, 2013;Nakata et al, 2012;Vandenbussche et al, 2009;Zhang et al, 2011) The aim of this study was to evaluate the effect of polyamines on the efficiency and morphology of the somatic embryogenesis in Capsicum chinense, and characterize the most frequent deformations in the somatic embryos of this species.…”