EjAP2‐1, an AP2/ERF gene, is a novel regulator of fruit lignification induced by chilling injury, via interaction with EjMYB transcription factors

Abstract

SummaryLignin biosynthesis is regulated by many transcription factors, such as those of the MYB and NAC families. However, the roles of AP2/ERF transcription factors in lignin biosynthesis have been rarely investigated. Eighteen EjAP2/ERF genes were isolated from loquat fruit (Eriobotrya japonica), which undergoes postharvest lignification during low temperature storage. Among these, expression of EjAP2-1, a transcriptional repressor, was negatively correlated with fruit lignification. The dual-luciferase assay indicated that EjAP2-1 could trans-repress activities of promoters of lignin biosynthesis genes from both Arabidopsis and loquat. However, EjAP2-1 did not interact with the target promoters (Ej4CL1). Yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays indicated protein-protein interactions between EjAP2-1 and lignin biosynthesis-related EjMYB1 and EjMYB2. Furthermore, repression effects on the Ej4CL1 promoter were observed with the combination of EjAP2-1 and EjMYB1 or EjMYB2, while EjAP2-1 with the EAR motif mutated (mEjAP2-1) lost such repression, although mEjAP2-1 still interacted with EjMYB protein. Based on these results, it is proposed that EjAP2-1 is an indirect transcriptional repressor on lignin biosynthesis, and the repression effects were manifested by EAR motifs and were conducted via protein-protein interaction with EjMYBs.

Comparative Transcriptional Analysis of Loquat Fruit Identifies Major Signal Networks Involved in Fruit Development and Ripening Process

“…Moreover, MYB1 and MYB2 can bind directly the promoters of PAL1 or CL1/5 to modulate lignin biosynthesis [14]. A suppression complex between MYB and AP2/ERF showed a negative correlation with lignifications [16]. Some biochemical data also supported that MYB in complexes with bHLH and WD40 proteins could regulate anthocyanin and flavonoid accumulation in the fleshy fruit [52,53].…”

“…Very little research based on genetic and molecular levels has been carried out on the species due to its complex genetic background, large genome size, poor transgenic system, and long life cycle. To date, several genes involved in ethylene biosynthesis and lignin metabolism have been identified [13,14,15,16], suggesting a potential function during fruit development and softening. However, an integrity transcriptome of loquat fruit remains unavailable.…”

PpGST1, an anthocyanin‐related glutathione S‐transferase gene, is essential for fruit coloration in peach

“…Dual‐luciferase assays were conducted in Nicotiana benthamiana leaves according to a previous protocol (Zeng et al , ). Agrobacterium cultures (strain GV3101) containing the pGreen II 0029 62‐SK vector (SK) with the full‐length coding sequence of PpMYB10.1 / 2 / 3 , PpbHLH3 and the pGreen II 0800‐LUC ( PpGST1 ‐LUC) vector with the promoter of PpGST1 were transiently expressed in N. benthamiana leaves.…”

Hypoxia‐responsive ERFs involved in postdeastringency softening of persimmon fruit

“…Dual-luciferase assay was used as an efficient and rapid method to detect in vivo trans-activation or trans-repression effects of transcription factors (Yin et al, 2010;Zeng et al, 2015). Fulllength DkERF genes were fused to pGreen II 0029 62-SK vector (SK) by Min et al (2012Min et al ( , 2014.…”