Pleiotropic phenotype of transgenic <i>Arabidopsis</i> plants that produce the LOV domain of LOV KELCH PROTEIN2 (LKP2)

Abstract

LOV KELCH PROTEIN2 (LKP2) is a blue-light receptor protein composed of three functional domains: a light, oxygen, or voltage (LOV) domain, an F-box motif (F), and Kelch repeats. LKP2 is postulated to be a component of an SCF complex and function in ubiquitination of proteins that control the circadian clock and photoperiodic flowering. Transgenic Arabidopsis plants that produce LOV, F, or a combination of LOV and F fused to green fluorescent protein (named GL, GF, and GLF, respectively) were produced using constructs containing the Cauliflower mosaic virus 35S promoter. Under continuous white light, the circadian rhythms of control and GF plants were similar, whereas those of GL and GLF plants were shorter. Under continuous red light, the hypocotyl lengths of control and GF seedlings were similar, whereas that of GL seedlings was longer. Late flowering and down-regulation of CONSTANS and FLOWERING LOCUS T were observed in GL and GLF plants compared to GF and control plants under long-day conditions. These results suggest that the previously reported pleiotropic phenotype of LKP2-overproducing plants, which show altered circadian rhythm, hypocotyl elongation, and photoperiodic flowering, is not only due to the promotion of ubiquitination and subsequent degradation of substrate proteins of the SCF LKP2 complex but may also be due to the functional disruption of regulatory proteins that interact with LKP2 LOV.

Suppression of cuticular wax biosynthesis mediated by rice LOV KELCH REPEAT PROTEIN 2 supports a negative role in drought stress tolerance

“…As the bait vector encoding full‐length OsGI and OsLKP2 self‐activated, we used partial OsGI and OsLKP2 cDNA fragments for analysis (Figure 5a). OsLKP2 interacted with the N terminus of OsGI, and OsGI interacted with the LOV domain of OsLKP2 (Figure 5a); these interactions are similar to the previously reported interaction between LKP2 and GI in Arabidopsis (Takase et al, 2015).…”

“…In Arabidopsis, the LOV domains of ZTL family proteins physically interact with GI (Hwang et al, 2019; W. J. Kim et al, 2007; J. Kim, Geng, et al, 2013; Krahmer et al, 2019; Sawa et al, 2007; Song et al, 2014). In particular, LKP2 interacted with GI in vitro and in yeast (W. Y. Kim et al, 2007; Takase et al, 2015). In rice, OsFKF1, a homolog of OsLKP2, interacts with OsGI in the nucleus (Han et al, 2015), as FKF1 does in Arabidopsis.…”

“…In particular, LKP2 interacted with GI in vitro and in yeast (W. Y. Kim et al, 2007;Takase et al, 2015). In rice, OsFKF1, a homolog of OsLKP2, interacts with OsGI in the nucleus (Han et al, 2015), as FKF1 does in Arabidopsis.…”