A SmelAAT Acyltransferase Variant Causes a Major Difference in Eggplant (Solanum melongena L.) Peel Anthocyanin Composition

Abstract

Eggplant berries are rich in anthocyanins like delphinidin-3-rutinoside (D3R) and nasunin (NAS), which are accumulated at high amounts in the peel. NAS is derived by D3R through acylation and glycosylation steps. The presence of D3R or NAS is usually associated with black-purple or lilac fruit coloration of the most cultivated varieties, respectively. Building on QTL mapping position, a candidate gene approach was used to investigate the involvement of a BAHD anthocyanin acyltransferase (SmelAAT) in determining anthocyanin type. The cDNA sequence comparison revealed the presence of a single-base deletion in D3R-type line ‘305E40’ (305E40_aat) with respect to the NAS-type reference line ‘67/3’. This is predicted to cause a frame shift mutation, leading to a loss of SmelAAT function and, thus, D3R retention. RT-qPCR analyses confirmed SmelAAT and 305E40_aat expression during berry maturation. In D3R-type lines, ‘305E40’ and ‘DR2’ overexpressing the functional SmelAAT allele from ‘67/3’, the transcript levels of the transgene, correlated with the accumulation of NAS in fruit peel. Furthermore, it was also found a higher expression of the transcript for glucosyltransferase Smel5GT1, putatively involved with SmelAAT in the last steps of anthocyanin decoration. Finally, an indel marker matching with anthocyanin type in the ‘305E40’ × ’67/3’ segregating population was developed and validated in a wide number of accessions, proving its usefulness for breeding purposes.

Discovery of a DFR gene that controls anthocyanin accumulation in the spiny Solanum group: roles of a natural promoter variant and alternative splicing

“…In addition, several studies evaluated the effect of genetic and physiological factors on anthocyanin accumulation in eggplant. This led to the identification of several quantitative trait loci and selective sweeps related to anthocyanin content (Barchi et al, 2012(Barchi et al, , 2021Cericola et al, 2014;Florio et al, 2021;Toppino et al, 2016), and revealed that both light and temperature treatments affect anthocyanin content in eggplant (Jiang et al, 2016;Zhang et al, 2019). Except for the recent discovery that a single-base deletion in SmelAAT, encoding an anthocyanin acyltransferase, causes a major difference in the anthocyanin composition, and thereby color, in several eggplant cultivars (Florio et al, 2021), it is still largely unknown whether and how variation in structural genes of the anthocyanin biosynthetic pathway affect anthocyanin accumulation patterns in eggplant.…”

Modifying Anthocyanins Biosynthesis in Tomato Hairy Roots: A Test Bed for Plant Resistance to Ionizing Radiation and Antioxidant Properties in Space

“…Solyc05g010180.3.1 (Log 2 Fc = −2.22; tomato carotenoid isomerase CRTISO ) is involved in carotenoids biosynthesis. In MicroTom fruits, the downregulation of carotenoid isomerase has been demonstrated to induce an accumulation of zeta-carotene and cis -prolycopene ( dos Santos et al, 2017 ; Florio et al, 2021 ), both elevating and modifying carotenoid profiles toward more bioavailable forms compared to wild-type ( Pelletier et al, 1997 ).…”

Integrating Transcriptomic and Metabolomic Analyses to Explore the Effect of Color Under Fruit Calyx on That of Fruit Apex in Eggplant (Solanum melongena L.)

“…In previous research, the delphinidins were reported as the main anthocyanins in purple plants’ peels ( Liang et al, 2022 ; Wang et al, 2021 ). In purple eggplant peels, delphinidin 3-O-glucoside ( Yang et al, 2022 ), delphinidin-3-rutinoside (D3R) ( Florio et al, 2021 ), delphinidin-3-(p-coumaroylrutinoside)-5-glucoside ( Azuma et al, 2008 ) and delphinidin 3-O-rutinoside ( Condurache et al, 2021 ) were enriched. They all belonged to the delphinidin though their structure were different.…”