Lehrstuhl für Pflanzenzüchtung

Genetic analysis of storage root formation in sugar beet

 

storage root

Figure: Morphological differences of root development in sugar beet (top) and leaf beet (bottom) during 10 weeks after emergence. Bar, 10cm

 

Background

Roots are indispensable to plants by providing water, nutrient, anchorage, storage space and production of secondary metabolites (Saini et al. 2013). The plant kingdom shows a significant variation in root architectures resulting in different root types. Many crops like beets, carrots, radish, and turnips have storage roots as harvesting organs. An understanding of storage root formation is of greatest interest in terms of world’s food and feed supply in future.

Sugar beet is the most important sucrose-storing crop in the temperate regions. Despite decades of sugar beet research, the genetic control of sugar beet storage root development has not been analyzed in detail and no genes have been identified that may regulate storage root formation. Variation in root morphologies among Beta varieties and species can be exploited to study the genetics of taproot evolution and the effect of artificial selection due to breeding activities. Therefore, QTL studies in sugar beet could lead to the identification of genes that are controlling storage root formation. An identification of major regulators of storage root development could provide the opportunity to study homologous genes related to root thickening also in other crops.

Objectives

This study is focused on understanding the genetics behind the sugar beet storage root formation. As long terms objective identified genes can be exploited in breeding to monitor the belowground root growth without destructing the plant growth. Moreover, the comparative studies of other storage root crops can be facilitated from the knowledge supply by this study.

Results

A segregating sugar beet RIL5 population for storage root formation has been established from two independent crosses between two sugar beet parents and a leaf beet parent. The RIL5 population was phenotyped for storage root characters in three different years. For the construction of a genetic map, the genomes of the parents and F1 plants were re-sequenced. SNPs for KASP marker analyses have been identified by using different filtering methods after mapping the paired reads to the sugar beet reference genome. A genetic linkage map of the population was established. QTL mapping revealed major QTLs for sugar beet storage root formation. This study presents the first QTLs identified for beet storage formation based on sugar beet leaf beet derived RIL population. Therefore, the initial discoveries provide strategies to explore storage root development in sugar beet in more detail in the future. Moreover, both populations segregate for many traits such as leaf size, leaf shape, and flowering time, etc. Moreover, a large F2 population phenotyping experiment in the field was performed to phenotype root fresh and root circumference. DNA was isolated from smallest 100 and largest 100 plants for initial genotyping by AFLP and InDel markers. QTL mapping will be performed and coinciding QTL with the RIL5 populations will be used for fine mapping using a bulked sample sequencing approach.   The QTL regions will be narrowed down by BSA to identify candidate genes for storage root formation in sugar beets. Functional analysis of candidate genes will be revealed the key regulators of taproot thickening. Therefore, the present study will provide a great advantage to breeders to make more efficient breeding programs to select the best breeding materials before harvesting.

Project Team

M.Sc. Dilan Sarange
Dr. Siegbert Melzer

Prof. Dr. Christian Jung

Publications

Patiranage et al., 2017. Unraveling quantitative trait loci for storage root formation in sugar beet (Beta vulgaris) [poster], In: The International Plant Science Conference, the Botanikertagung; 2017 September 17-21; Kiel, Germany.

Sarange et al., 2018. Unraveling quantitative trait loci for storage root formation in sugar beet (Beta vulgaris) [poster], In: German Plant Breeding Conference, 2018 Feb 28 to March 02; Wernigerode, Germany.

 

Updated: 17.08.2018             Responsible for this webpage: Dilan Sarange