XAL2, a MADS-box gene, studied by Pérez-Ruiz et al. (2015), is preferentially expressed in the roots, with less expression in the rosette leaf, stem, and cauline leaf. It is not present during the vegetative meristem stage; as XAL2 expression appears initially in the inflorescence. Following the inflorescence meristem stage into floral meristem stage, XAL2 expression increases significantly in order to regulate floral transition. Although XAL2 was found to have higher expression in the roots, it is still key in floral transitioning (Searle et al., 2006). The identification of XAL2 by Pérez-Ruiz et al. (2015) revealed that it promotes floral transitions, as well as gain or loss of function that is similar to the SOC1 clade. The SOC1 clade,
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Given its similarity to SOC1 as an activator of floral transitions, it led the researchers to hypothesize XAL2 is involving in flowering through a loop with other genes as well. Pérez-Ruiz et al. (2015) tested this hypothesis by fusing XAL2 to a 35SCaMV promoter for over-expression of XAL2 in comparison to the control XAL2. The 35S::XAL2 A. thaliana was planted along with a control and the xal2-2 mutant. The 35S::XAL2 line flowered the earliest and thus was largest, compared to the wild type which flowered second and the xal2-2 mutant flowered last and was the smallest (Figure 1). However, while XAL2 over-expression does quicken the floral transition time; it terminates the vegetative phase prematurely as a result. This caused the floral meristem to show inflorescence-like traits such as swollen carpels, instead of rosette-like leaves compared to the wild type. Thus, XAL2 was able to induce early flowering, however, it had detrimental effect on floral meristem maintenance. This confirms XAL2 works in conjugation with other genes in a regulatory …show more content…
Therefore, over expressing XAL2 will speed up floral transitions. However, problems maintaining proper flower determinacy was found with an over expressed XAL2. This is because there is a fixed amount of XAL2 needed in specific spatio-temporal locations for normal FM cell differentiation. Secondly, WUSCHEL (WUS), a gene involved in stem cell identity, becomes expressed during a specific stage in floral meristem development when it is normally repressed. This was identified by performing a RT-PCR analysis on the carpels of the wild type and 35S::XAL2 carpels. The up-regulated WUS then causes the stem cells to transform into inflorescence instead of exhibiting proper floral properties. Lastly, TFL1, a gene involved in floral repression and regulating the identity of the inflorescent meristem (Hanano and Goto, 2011), becomes over-expressed which interferes with the AP1 gene flowering ability. This was identified by crossing 35S::AP1, an overregulated AP1 line, with the 35S::XAL2 line to see if AP1 could outcompete TFL1. Since AP1 and TFL1 complement each other, the results were varied towards both AP1 and TFL1. The 35S::AP1 produced A. thaliana with smaller cauline leaves and flowers with reduced sepals in contrast to the large cauline leaves and no flowers in the 35S::XAL2 line (Figure 2). AP1 in this case, was able to out-compete the TFL1 gene. However, the
Given its similarity to SOC1 as an activator of floral transitions, it led the researchers to hypothesize XAL2 is involving in flowering through a loop with other genes as well. Pérez-Ruiz et al. (2015) tested this hypothesis by fusing XAL2 to a 35SCaMV promoter for over-expression of XAL2 in comparison to the control XAL2. The 35S::XAL2 A. thaliana was planted along with a control and the xal2-2 mutant. The 35S::XAL2 line flowered the earliest and thus was largest, compared to the wild type which flowered second and the xal2-2 mutant flowered last and was the smallest (Figure 1). However, while XAL2 over-expression does quicken the floral transition time; it terminates the vegetative phase prematurely as a result. This caused the floral meristem to show inflorescence-like traits such as swollen carpels, instead of rosette-like leaves compared to the wild type. Thus, XAL2 was able to induce early flowering, however, it had detrimental effect on floral meristem maintenance. This confirms XAL2 works in conjugation with other genes in a regulatory …show more content…
Therefore, over expressing XAL2 will speed up floral transitions. However, problems maintaining proper flower determinacy was found with an over expressed XAL2. This is because there is a fixed amount of XAL2 needed in specific spatio-temporal locations for normal FM cell differentiation. Secondly, WUSCHEL (WUS), a gene involved in stem cell identity, becomes expressed during a specific stage in floral meristem development when it is normally repressed. This was identified by performing a RT-PCR analysis on the carpels of the wild type and 35S::XAL2 carpels. The up-regulated WUS then causes the stem cells to transform into inflorescence instead of exhibiting proper floral properties. Lastly, TFL1, a gene involved in floral repression and regulating the identity of the inflorescent meristem (Hanano and Goto, 2011), becomes over-expressed which interferes with the AP1 gene flowering ability. This was identified by crossing 35S::AP1, an overregulated AP1 line, with the 35S::XAL2 line to see if AP1 could outcompete TFL1. Since AP1 and TFL1 complement each other, the results were varied towards both AP1 and TFL1. The 35S::AP1 produced A. thaliana with smaller cauline leaves and flowers with reduced sepals in contrast to the large cauline leaves and no flowers in the 35S::XAL2 line (Figure 2). AP1 in this case, was able to out-compete the TFL1 gene. However, the