Extensive transcriptome changes underlying the fruit skin colour intensity variation in purple eggplant

Xiaohui Zhou,Jun Liu,Yaping Liu,Yong Zhuang,Songyu Liu,Dan Wang,Yan Yang

doi:10.15835/nbha49312434

Abstract

Fruit skin colour intensity is one of the most important economic traits of purple eggplant. A wide diversity for fruit skin colour intensity exists in purple eggplant and the accumulation of anthocyanins and chlorophylls of fruit skin mainly affected colour intensity. However, limited information is available contributing to the molecular mechanisms underlying fruit skin colour intensity variation in purple eggplant. In the present study, variation of two purple eggplant advanced lines EP26 and EP28, with different fruit skin colour intensity was investigated. Higher anthocyanin contents and lower chlorophyll contents were observed in EP26 with deeper fruit skin colour intensity at two developmental stages. Comparative transcriptome analysis of EP26 and EP28 identified a total of 2218 differential expressed genes (DEGs) at two developmental stages. Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathway enrichment analysis showed that these DEGs were mainly involved in flavonoid biosynthesis and photosynthesis. In addition, a total of 131 transcription factors including MYB, bHLH, WRKY, and NAC exhibited dynamic changes, which might be responsible for the variation of fruit pigments accumulation between EP26 and EP28. Taken together, these results expand our knowledge of molecular mechanisms underlying fruit skin colour intensity variation in eggplant, which allowing for improvement of fruit coloration in eggplant breeding.

Highlights

Eggplant (Solanum melongena L.) belongs to the Solanaceae family, is an important vegetable crop and is of substantial economic importance in Asia, Africa, and the subtropics (Toppino et al, 2020)
A broad spectrum of colour intensity exists within the group of dark purple-coloured cultivars, but intensive, uniform and lasting fruit colour types are most preferred by consumers than the paler types, especially in China (He et al, 2019)
In our preliminary study, the fruit peel colour intensity and anthocyanin contents, as well as chlorophyll contents of a set of purple advanced lines were measured, and we found that there is a significant positive correlation between colour intensity and anthocyanin content in eggplant fruit peel. These results suggest that the anthocyanin content variation rather than the chlorophyll content variation contributes to fruit peel colour intensity variation at the physiological level

Summary

Introduction

Eggplant (Solanum melongena L.) belongs to the Solanaceae family, is an important vegetable crop and is of substantial economic importance in Asia, Africa, and the subtropics (Toppino et al, 2020). The fruit skin colour of eggplant ranges from white to dark purple, and is one of the primary exterior quality and economic characteristics. There is a big diversity of eggplant varieties varying in shape and colour, the dark purple type receives more attention for high levels of anthocyanin accumulation (Li et al, 2018). A broad spectrum of colour intensity exists within the group of dark purple-coloured cultivars, but intensive, uniform and lasting fruit colour types are most preferred by consumers than the paler types, especially in China (He et al, 2019). Received in revised form: 21 Sep 2021. From Volume 49, Issue 1, 2021, Notulae Botanicae Horti Agrobotanici Cluj-Napoca journal uses article numbers in place of the traditional method of continuous pagination through the volume. The journal will continue to appear quarterly, as before, with four annual numbers

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