The transcriptional response of apple alcohol acyltransferase (MdAAT2) to salicylic acid and ethylene is mediated through two apple MYB TFs in transgenic tobacco

Abstract

Volatile esters are major factors affecting the aroma of apple fruits, and alcohol acyltransferases (AATs) are key enzymes involved in the last steps of ester biosynthesis. The expression of apple AAT (MdAAT2) is known to be induced by salicylic acid (SA) or ethylene in apple fruits, although the mechanism of its transcriptional regulation remains elusive. In this study, we reveal that two apple transcription factors (TFs), MdMYB1 and MdMYB6, are involved in MdAAT2 promoter response to SA and ethylene in transgenic tobacco. According to electrophoretic mobility shift assays, MdMYB1 or MdMYB6 can directly bind in vitro to MYB binding sites in the MdAAT2 promoter. In vivo, overexpression of the two MYB TFs can greatly enhance MdAAT2 promoter activity, as demonstrated by dual luciferase reporter assays in transgenic tobacco. In contrast to the promoter of MdMYB1 or MdMYB6, the MdAAT2 promoter cannot be induced by SA or ethephon (ETH) in transgenic tobacco, even in stigmas in which the MdAAT2 promoter can be highly induced under normal conditions. However, the induced MYB TFs can dramatically enhance MdAAT2 promoter activity under SA or ETH treatment. We conclude that MdMYB1 and MdMYB6 function in MdAAT2 responses to SA and ethylene in transgenic tobacco, suggesting that a similar regulation mechanism may exist in apple.

Genome-Wide Identification and Expression Analysis of MIKC-Type MADS-Box Gene Family in Punica granatum L.

“…This result is consistent with that by research reports on grape and Phyllostachys edulis [66,67], indicating that the promoter regulatory element of the MADS-box gene has a certain conservatism among different species. Previous studies have found that ABRE is associated with drought, ABA induction, and high salt stress in plants [68,69]. There were many ABRE elements in PgMADS13, PgMADS03, PgMADS16, PgMADS30, and PgMADS25, which were speculated to be related to pomegranate response to drought, ABA induction or high salt stress.…”

Transcriptional and epigenetic analysis reveals that NAC transcription factors regulate fruit flavor ester biosynthesis

“…However, (i) the relatively high expression of PpAAT1 in fruit, (ii) the in vitro enzyme activity and in planta overexpression results, and (iii) the correlation with ester contents across different cultivars all indicate that peach PpAAT1 is a major component of peach fruit volatile ester biosynthesis. Recently, TFs that regulate AAT expression have been identified in plants (Guo et al, 2018;Li et al, 2014). However, direct effects of these TFs on volatile ester synthesis remain undetermined.…”

Genome-wide Identification and Expression Analysis of TALE Gene Family in Pomegranate (Punica granatum L.)

“…It indicated that the promoter of the TALE gene has a certain conservative. Previous studies have found that ABRE is associated with plant drought, ABA induction, and high salt stress in plants [31,65]. In addition, there are a series of elements related to stress, such as ARE, MBS and LTR.…”

“…The dimer formed by the A. thaliana homeobox 1 (ATH1) protein and the shoot meristemless (STM) protein participates in the development of plant meristems [29], while the dimer formed by the ATH1 protein and the KNOTTED-like from A. thaliana 2 (KNAT2) protein regulates the development of plant inflorescence tissue [30]. The interaction of BLH6 and KNAT7 affects the development of secondary cell walls [31]. The KNOX gene family contains KNOX1, KNOX2, ELK and homeodomain, except for a novel gene KNATM without the homeodomain [32,33].…”