Source: MICHIGAN STATE UNIV submitted to
MINING THE WILD SPECIES SOLANUM MICRODONTUM FOR IMPROVEMENT OF CULTIVATED POTATO
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
1025273
Grant No.
2021-67013-33946
Project No.
MICL08606
Proposal No.
2020-03719
Multistate No.
(N/A)
Program Code
A1141
Project Start Date
Jan 15, 2021
Project End Date
Apr 14, 2021
Grant Year
2021
Project Director
Buell, C.
Recipient Organization
MICHIGAN STATE UNIV
(N/A)
EAST LANSING,MI 48824
Performing Department
PLANT BIOLOGY
Non Technical Summary
Potato relatives offer a more diverse and accessible germplasm resource than is found in any other crop. Potato and wild species relatives grow from sea level to 4300 m and are found in a tremendously wide array of environments. Most of these wild relatives cross readily with cultivated potato, producing offspring with acceptable tuber yield and type that can provide the genetic diversity to needed for potato production in stressful environments, including those with heat stress and disease pressure. One diploid species that was central in the domestication and improvement of potato was Solanum microdontum with clear association of adaptive traits present in modern cultivars that can be traced to introgressions during the movement of cultivated potatoes from Peru/Bolivia to southern Argentina. To build on germplasm resources for a diploid potato breeding approach, in this project, we will phenotypically characterize available S. microdontum germplasm for key agronomic traits that can be readily incorporated into breeding material. We will also generate a chromosome-scale reference genome and catalogue genetic diversity in this species to understand the underlying genetic diversity that contributes to phenotypic diversity. Through the identification of loci and alleles linked to late blight resistance and heat tolerance, we will address not only the major disease pressure in potato production but also position potato breeding such that it can address concerns associated with climate change.
Animal Health Component
0%
Research Effort Categories
Basic
100%
Applied
(N/A)
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
20113101080100%
Knowledge Area
201 - Plant Genome, Genetics, and Genetic Mechanisms;

Subject Of Investigation
1310 - Potato;

Field Of Science
1080 - Genetics;
Goals / Objectives
Wild species relatives of potato provide a more diverse and accessible germplasm resource compared to any other crop as they grow from sea level to 4300 m and are found in a wide array of environments including cold high grasslands, hot semi-deserts, seasonally dry habitats, humid subtropical to temperate mountain rainforests, and coastal beaches. Most wild relatives cross readily with cultivated potato, producing offspring with acceptable tuber yield and type that can provide the genetic diversity required to adapt potato production to stressful environments, including those with low water availability, seasonal frost, heat stress, and disease/pest pressure. One diploid species that was central in the domestication and improvement of potato was Solanum microdontum in which a clear association of adaptive traits in modern North American cultivars can be traced to introgressions from S. microdontum during the movement of cultivated potatoes from Peru/Bolivia to southern Argentina. To build towards genomic and germplasm resources for a diploid potato breeding approach, in this project, we will interrogate the diversity of S. microdontum at the sequence and phenotype level to provide germplasm, sequence, and molecular resources that will enable efficient breeding of potato varieties with resistance to late blight, the major pathogen of potato, as well as tolerance to heat associated with global warming.Our specific objectives are:Objective 1. Phenotype a S. microdontum diversity panel for late blight resistance, heat tolerance, and resistance to late blight under elevated temperature to address challenges in potato production due to climate change.Objective 2. Generate a chromosome-scale long read-generated S. microdontum reference genome sequence, characterize allelic diversity within the species S. microdontum, and provide single genotyped and phenotyped clones to the USDA Potato Genebank.
Project Methods
Objective 1. Phenotype a S. microdontum diversity panel for late blight resistance, heat tolerance, and resistance to late blight under elevated temperature to address challenges in potato production due to climate change.All independent S. microdontum PIs will be ordered from the USDA GRIN Genebank and maintained in tissue culture on Murashigi and Skoog media. Cuttings from each tissue culture plant will be planted into SureMix Perlite Mix along with four control clones known to be resistant or susceptible to late blight; plants will be grown in a controlled growth chamber with a 22 ?C day/18 ?C night with 12 hr day length. Five isolates of P. infestans which represent a large portion of the clonal diversity in the US and Canada will be used to score late blight resistance using a detached leaflet inoculation as described by previously. The severity of late blight on foliar tissue will expressed as the Relative Area Under the Disease Progress Curve.We will perform a replicated experiment to determine extent of the impact of heat stress on vegetative fitness, reproductive fitness, and late blight resistance. Cuttings from tissue culture plants will be planted into SureMix Perlite Mix and grown under permissive temperatures and allowed to establish for 3 weeks. Plants will then be transitioned to the two selected heat stress conditions or control conditions and grown till maturity; three phenotypes will be scored. Vegetative Fitness: Plant vigor at harvest [a 1-5 scale where 1 represents the weakest plants based on above-ground biomass and 5 represents the most vigorous plants], total above-ground biomass at harvest, and below-ground biomass (tuber number, tuber yield) at harvest will be determined. Reproductive fitness: We will determine the impact of heat stress on inflorescence number and pollen viability. Late blight resistance under heat stress will be tested under heat stress.Objective 2. Generate a chromosome-scale long read-generated S. microdontum reference genome sequence and characterize allelic diversity within the species S. microdontum.We will use the Oxford Nanopore Technology to generate a chromosome-scale assembly of theS. microdontum clone that has exhibited the highest level of disease resistance and heat tolerance to be the reference genotype. The genome will be annotated using robust transcriptome evidence generated through RNA-sequencing. Whole genome shotgun libraries from the S. microdontum diversity panel will be constructed and sequenced; allelic diversity will be determined from single nucleotide polymorphisms and small insertions/deletions.The S. microdontum reference genome sequence, annotation, gene atlas expression data and allelic diversity data will be made available via deposit in the National Center for Biotechnology, publication, and through SpudDB, an on-line resource for potato genome, sequence, and diversity data (http://solanaceae.plantbiology.msu.edu/).

Progress 01/15/21 to 04/14/21

Outputs
Target Audience:Potato breeders and geneticists are the target audience although research scientists in the broader field will have interest in this project's findings. Plant pathologists also will be interested in the results due to the cataloguing of resistance to late blight under control and elevated temperatures. Changes/Problems:PD Buell has accepted a position at the University of Georgia effective August 1, 2021. A grant transfer request to USDA will be submitted in April 2021. The objectives and goals of the project remain unchanged and a subaward will be made to coPD Douches at Michigan State University to perform late blight screening of the S. microdontum diversity panel. What opportunities for training and professional development has the project provided?To date, this project has provided a training opportunity for 2 undergraduate students to learn plant tissue culture. How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals?While this is a final report for the award to Michigan State University, once the grant is transferred to University of Georgia in the next reporting period, we will complete Aim 1 of the project, screening all S. microdontum accessions for resistance to multiple isolates/races of P. infestans. We will also pilot growth conditions for heat tolerance for S. microdontum to identify conditions (day and night-time temperatures) that represent heat stress for this wild potato species.

Impacts
What was accomplished under these goals? We have germinated seed of all S. microdontum accessions from the USDA-GRIN repository and selected a single individual for further analyses. We have obtained additional isolates of Phytophthora infestans for late blight screening.

Publications