The Banana Transcriptional Repressor MaDEAR1 Negatively Regulates Cell Wall-Modifying Genes Involved in Fruit Ripening

Abstract

Ethylene plays an essential role in many biological processes including fruit ripening via modulation of ethylene signaling pathway. Ethylene Response Factors (ERFs) are key transcription factors (TFs) involved in ethylene perception and are divided into AP2, RAV, ERF, and DREB sub-families. Although a number of studies have implicated the involvement of DREB sub-family genes in stress responses, little is known about their roles in fruit ripening. In this study, we identified a DREB TF with a EAR motif, designated as MaDEAR1, which is a nucleus-localized transcriptional repressor. Expression analysis indicated that MaDEAR1 expression was repressed by ethylene, with reduced levels of histone H3 and H4 acetylation at its regulatory regions during fruit ripening. In addition, MaDEAR1 promoter activity was also suppressed in response to ethylene treatment. More importantly, MaDEAR1 directly binds to the DRE/CRT motifs in promoters of several cell wall-modifying genes including MaEXP1/3, MaPG1, MaXTH10, MaPL3, and MaPME3 associated with fruit softening during ripening and represses their activities. These data suggest that MaDEAR1 acts as a transcriptional repressor of cell wall-modifying genes, and may be negatively involved in ethylene-mediated ripening of banana fruit. Our findings provide new insights into the involvement of DREB TFs in the regulation of fruit ripening.

MaBZR1/2 act as transcriptional repressors of ethylene biosynthetic genes in banana fruit

“…B), also confirming their negative roles in fruit ripening. The inhibitory effect of MaBZRs in fruit ripening is possibly due to the presence of EAR domain, consistent with the cases of several EAR‐containing proteins in fruit ripening including MaERF11 and MaDEAR1 from banana (Fan et al , Han et al ) and CpERF9 from papaya (Fu et al ). Moreover, MaBZR1/2 transcripts were markedly reduced in the ripening stage particularly in BR treatment (Fig.…”

“…Thus, unraveling the molecular mechanism(s) underpinning banana ripening can help us to explore effective practices to prolong the storage life and to maintain postharvest quality of the fruit. Previous studies have found that transcriptional regulation of ripening‐associated genes mediated by TFs were involved in banana ripening, as in the cases of MaERFs (Xiao et al , Han et al ), MaLBDs (Ba et al ), MaDofs (Feng et al ), MaDREBs (Fan et al , Kuang et al ) and MabHLH6 (Xiao et al ). However, there are at least 3155 TFs present in the banana genome (D'Hont et al ) and the limited number isolated so far can not account for elucidating the transcriptional regulatory networks of banana fruit ripening.…”

A banana R2R3‐MYB transcription factor MaMYB3 is involved in fruit ripening through modulation of starch degradation by repressing starch degradation‐related genes and MabHLH6

“…The promoter activity was assayed according to Fan et al . (). The construct CaMV35S‐REN/ MaMYB3 pro‐LUC (~20 μg) was transformed into tobacco BY‐2 protoplasts ( c .…”

The Banana Fruit SINA Ubiquitin Ligase MaSINA1 Regulates the Stability of MaICE1 to be Negatively Involved in Cold Stress Response

“…The resulting constructs were then introduced into the Agrobacterium tumefaciens strain GV3101, and co-infiltrated into the abaxial side of 4- to 6-week-old tobacco ( N. benthamiana ) leaves using a 1-mL needleless syringe as described previously (Fan et al, 2016). Infected tissues were analyzed at 48 h after infiltration.…”