A kiwifruit bHLH149 transcription factor modulates carotenoid biosynthesis by directly activating <i>LCYB</i> during postharvest ripening

Zengyu Gan; Yupei Zhang; Caining Yang; Qing Cao; Liqin Zhu; Wenbin Kai; Chuying Chen; Zhenyu Huang; Jinyin Chen; Zengyu Gan; Yupei Zhang; Caining Yang; Qing Cao; Liqin Zhu; Wenbin Kai; Chuying Chen; Zhenyu Huang; Jinyin Chen

doi:10.48130/frures-0024-0036

Figure 1.

Color change during postharvest ripening of Actinidia valvata. (a) Appearance of mesocarp during postharvest ripening of Actinidia valvata. Changes in (b) firmness, (c) a*, and (d) b* of mesocarp during postharvest ripening of Actinidia valvata. Bars with different letters indicate significant difference (p < 0.05).

Figure 2.

Changes in (a) total carotenoid, (b) lutein, (c) β-carotene, (d) β-cryptoxanthin, (e) neoxanthin, and (f) zeaxanthin during postharvest ripening of Actinidia valvata. Bars with different letters indicate significant difference (p < 0.05).

Figure 3.

Changes of relative expression levels of (a) carotenoid biosynthesis, and (b) degradation genes during postharvest ripening of Actinidia valvata. Bars with different letters indicate significant difference (p < 0.05).

Figure 4.

bHLH149 transcription factor was obtained by Y1H screening of LCYB promoter as bait. (a) LCYB promoter activation activity was inhibited on SD/-His/-Leu/-Trp + 5 mM 3AT medium. (b) Y1H verifies the interaction between bHLH149 transcription factor and the LCYB promoter.

Figure 5.

Phylogenetic tree of bHLH149 and analysis of bHLH protein sequences with other species. (a) Phylogenetic analysis of bHLH149 with bHLH members from other species. (b) Multiple sequence comparison analysis of bHLH149 with bHLH members from other species. The bHLH domain is overlined. Cl, Camellia lanceoleosa (KAI8024841.1); Cf, Cornus florida (XP_059652277.1); In, Ipomoea nil (XP_059652277.1); Lb, Lycium barbarum (XP_060167312.1); Lf, Lycium ferocissimum (XP_059313316.1); Vv, Vitis vinifera (XP_059313316.1); Zj, Ziziphus jujuba (XP_015874890.3); Dz, Durio zibethinus (XP_015874890.3); At, Arabidopsis thaliana (AT1G09250).

Figure 6.

Molecular characterization of bHLH149. (a) Changes of relative expression level of bHLH149 during postharvest ripening of Actinidia valvata. Bars with different letters indicate significant difference (p < 0.05). (b) Subcellular localization of bHLH149 in Arabidopsis protoplasts. Bar = 10 μm. (c) Detection of self-activation of bHLH149 in yeast cells.

Figure 7.

bHLH149 activates LCYB promoter activity. (a) Schematic diagram of the double reporter. (b) bHLH149 activated the activity of LCYB promoter. Asterisks indicate significant difference (p < 0.01).