Allelic variation for alpha-Glucan Water Dikinase is associated with starch phosphate content in tetraploid potato

Key message Association analysis resulted in the identification of specific StGWD alleles causing either an increase or decrease in starch phosphate content which was verified in diploid and tetraploid potato mapping populations. Abstract Potatoes are grown for various purposes like French fries, table potatoes, crisps and for their starch. One of the most important aspects of potato starch is that it contains a high amount of phosphate ester groups which are considered to be important for providing improved functionalization after derivatization processes. Little is known about the variation in phosphate content as such in different potato varieties and thus we studied the genetic diversity for this trait. From other studies it was clear that the phosphate content is controlled by a quantitative trait locus (QTL) underlying the candidate gene α-Glucan Water Dikinase (StGWD) on chromosome 5. We performed direct amplicon sequencing of this gene by Sanger sequencing. Sequences of two StGWD amplicons from a global collection of 398 commercial cultivars and progenitor lines were used to identify 16 different haplotypes. By assigning tag SNPs to these haplotypes, each of the four alleles present in a cultivar could be deduced and linked to a phosphate content. A high value for intra-individual heterozygosity was observed (Ho = 0.765). The average number of different haplotypes per individual (Ai) was 3.1. Pedigree analysis confirmed that the haplotypes are identical-by-descent (IBD) and offered insight in the breeding history of elite potato germplasm. Haplotypes originating from introgression of wild potato accessions carrying resistance genes could be traced. Furthermore, association analysis resulted in the identification of specific StGWD alleles causing either an increase or decrease in starch phosphate content varying from 12 nmol PO4/mg starch to 38 nmol PO4/mg starch. These allele effects were verified in diploid and tetraploid mapping populations and offer possibilities to breed and select for this trait.

Identification of the genetic diversity of sweet potato germplasm based on quantitative morphological characters

Sweet potato is one of the prospective food crops to be used as an export commodity. Information on genetic diversity of sweet potato is needed as a consideration for the improvement of superior sweet potato varieties that have export quality. The research was conducted in Wringin Songo village, Tumpang, Malang Regency. The materials used were 150 sweetpotato accessions in total that consisting of: 19 superior varieties, 38 local clones, 1 introduced variety and 92 promising clones. This experiment was arranged in randomized block design (RBD) with two replications. The qquantitative morphological variables such as: potential yield, tuber weight, dry matter, stover weight, harvest index and number of tubers plot−1 were observed. The results showed that the genetic diversity was quite high in the sweet potato germplasm, there were 41 clones that had yield potential (≥ 30 t ha−1). Some of these clones were prospective to be used as parents for crossing due to their ability to flower. Two sweet potato clones (MSU 10001-18 and MSU 07030-64) with dark purple flesh colour, Kidal variety with yelow flesh color and above 30% tuber dry matter have the criteria required for export market.

Neofunctionalisation of the Sli gene leads to self-compatibility and facilitates precision breeding in potato

Genetic gain in potato is hampered by the heterozygous tetraploid genome of cultivated potato. Converting potato into a diploid inbred-line based F1-hybrid crop provides a promising route towards increased genetic gain. The introduction of a dominant S-locus inhibitor (Sli) gene into diploid potato germplasm allows efficient generation of self-fertilized seeds and thus the development of potato inbred lines. Little is known about the structure and function of the Sli locus. Here we describe the mapping of Sli to a 12.6 kb interval on chromosome 12 using a recombinant screen approach. One of two candidate genes present in this interval shows a unique sequence that is exclusively present in self-compatible lines. We describe an expression vector that converts self-incompatible genotypes into self-compatible and a CRISPR-Cas9 vector that converts SC genotypes into SI. The Sli gene encodes an F-box protein that is specifically expressed in pollen from self-compatible plants. A 533 bp insertion in the promotor of that gene leads to a gain of function mutation, which overcomes self-pollen rejection.

Identifying Resistance to the Colorado Potato Beetle (Leptinotarsa decemlineata Say) in Potato Germplasm: Review Update

Developing plant germplasm that contains genetic resistance to insect pests is a valuable component of integrated pest management programs. In the last several decades, numerous attempts have been made to identify genetic sources of resistance to Colorado potato beetle Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae). This review focuses on compiling information regarding general L. decemlineata biology, ecology, and management focusing on discussing biochemical and morphological potato (Solanum tuberosum L.) plant traits that might be responsible for providing resistance; the review ends discussing past efforts to identify genetic material and highlights promising new strategies that may improve the efficiency of evaluation and selection of resistant material. Measurement strategies, that begin with field screening of segregating populations or wild germplasm to narrow research focus can be useful. Identifying particularly resistant or susceptible germplasm, will help researchers focus on studying the mechanisms of resistance in much greater detail which will help the development of long-term sustainable management program.

Genetic Diversity and Population Structure of Potato Germplasm in RDA-Genebank: Utilization for Breeding and Conservation

Potato (Solanum tuberosum L.) is an important staple food and economic crop in many countries. It is of critical importance to understand the genetic diversity and population structure for effective collection, conservation, and utilization of potato germplasm. Thus, the objective of the present study was to investigate the genetic diversity and population structure of potato germplasm conserved in the National Agrobiodiversity Center (NAC) of South Korea to provide basic data for future preservation and breeding of potato genetic resources. A total of 24 simple sequence repeat (SSR) markers were used to assess the genetic diversity and population structure of 482 potato accessions. A total of 257 alleles were detected, with an average of 10.71 alleles per locus. Analysis of molecular variance showed that 97% of allelic diversity was attributed to individual accessions within the population, while only 3% was distributed among populations. Results of genetic structure analysis based on STRUCTURE and discriminant analysis of principal components revealed that 482 potato accessions could be divided into two main subpopulations. Accessions of subpopulation 1 mainly belonged to cultivars and breeding lines. Accessions of subpopulations 2 basically corresponded to wild relatives of potatoes. Results of this study provide useful information for potato improvement and conservation programs, although further studies are needed for a more accurate evaluation of genetic diversity and phenotypic traits of potatoes.