Identification of QTLs and Candidate Genes Related to Flower Traits and Bolting Time in Radish (Raphanus sativus L.)

Yong Pyo Lim,Yinbo Ma,Sushil Satish Chhapekar,Tae Hyoung Gan,Su Ryun Choi,Seungho Kim,Jana Jeevan Rameneni

doi:10.3390/agronomy11081623

Abstract

Radish flower color, bolting time, and flowering time are important traits for attracting certain pollinators and affect fleshy root quality. In this study, an analysis of the anthocyanidins in radish flowers by high-performance liquid chromatography revealed that differences in the cyanidin content are likely to be associated with the variability in radish flower colors (i.e., purple and white petals). A quantitative trait loci (QTL) analysis identified nine QTLs on three Raphanus sativus linkage groups. Three QTLs—qRFC1, qRBT1, and qRFT1—which were consistently detected and explained a high proportion of the observed variation (10.30% to 34.57%), were considered as the major QTLs responsible for flower color, bolting time, and flowering time, respectively. A total of 16 and 11 candidate genes within the major QTL regions for flower color and bolting/flowering times, respectively, were preliminarily annotated. Six genes (Rs018140, Rs018950, Rs019220, Rs020080, Rs020590, and Rs021450) related to flower color were differentially expressed in the parental lines. On the basis of nucleotide and amino acid sequence diversity between the parental lines, Rs314940, Rs315000, Rs315310, and Rs315960 were identified as candidate genes mediating the radish bolting and flowering times. This study revealed the genetic complexity of the radish flower color, bolting time, and flowering time traits. The identified candidate genes in the QTL regions may be useful for radish breeding programs and also for functional characterization in radish.

Highlights

Radish (Raphanus sativus, 2n = 18), which belongs to the family Brassicaceae, is one of the most popular vegetable crops worldwide, but especially in eastern Asia
In this study, using the F2:3 population derived from ‘YR4’ and ‘YR18’ inbred lines, we investigated the inheritance of flower coloration, bolting time, and flowering time in radish
The results indicated that the purple petals (‘YR18’) contained more anthocyanidins than the white petals (‘YR4’)

Summary

Introduction

Radish (Raphanus sativus, 2n = 18), which belongs to the family Brassicaceae, is one of the most popular vegetable crops worldwide, but especially in eastern Asia. Flower-related traits—such as color, bolting time, and flowering time—are important radish characteristics. Certain flower colors can attract suitable pollinators, while repelling herbivorous insects and animals [1,2,3,4]. Bolting and flowering occur in a critical period in which plants transition from the vegetative phase to the reproductive phase of the life cycle [5]. There are relatively few reports describing research on the mechanism underlying the inheritance of flower-related traits, especially flower color, in radish. Clarifying the genetic basis of flower coloration, bolting time, and flowering time will provide plant breeding programs with useful information

Results

Discussion

Conclusion