The Retinoblastoma-related gene RBL901 can trigger drought response actions in potato.

KEY MESSAGE: This study provided new insights into response of potato to drought stress.

Glycoalkaloid Composition and Flavonoid Content as Driving Forces of Phytotoxicity in Diploid Potato.

Despite their advantages, biotechnological and omic techniques have not been applied often to characterize phytotoxicity in depth. Here, we show the distribution of phytotoxicity and glycoalkaloid content in a diploid potato population and try to clarify the source of variability of phytotoxicity among plants whose leaf extracts have a high glycoalkaloid content against the test plant species, mustard. Six glycoalkaloids were recognized in the potato leaf extracts: solasonine, solamargine, α-solanine, α-chaconine, leptinine I, and leptine II. The glycoalkaloid profiles of the progeny of the group with high phytotoxicity differed from those of the progeny of the group with low phytotoxicity, which stimulated mustard growth. RNA sequencing analysis revealed that the upregulated flavonol synthase/flavonone 3-hydroxylase-like gene was expressed in the progeny of the low phytotoxicity group, stimulating plant growth. We concluded that the metabolic shift among potato progeny may be a source of different physiological responses in mustard. The composition of glycoalkaloids, rather than the total glycoalkaloid content itself, in potato leaf extracts, may be a driving force of phytotoxicity. We suggest that, in addition to glycoalkaloids, other metabolites may shape phytotoxicity, and we assume that these metabolites may be flavonoids.

Transcriptomic and proteomic data provide new insights into cold-treated potato tubers with T- and D-type cytoplasm.

MAIN CONCLUSION: Tuber-omics in potato with the T- and D-types of cytoplasm showed different sets of differentially expressed genes and proteins in response to cold storage. For the first time, we report differences in gene and protein expression in potato (Solanum tuberosum L.) tubers possessing the T- or D-type cytoplasm. Two F1 diploid reciprocal populations, referred to as T and D, were used. The pooling strategy was applied for detection of differentially expressed genes (DEGs) and differentially expressed proteins (DEPs) in tubers consisting of extreme chip colour after cold storage. RNA and protein bulks were constructed from contrasting phenotypes. We recognized 48 and 15 DEGs for the T and D progenies, respectively. DEPs were identified in the amyloplast and mitochondrial fractions. In the T-type cytoplasm, only 2 amyloplast-associated and 5 mitochondria-associated DEPs were detected. Of 37 mitochondria-associated DEPs in the D-type cytoplasm, there were 36 downregulated DEPs in the dark chip colour bulks. These findings suggest that T- and D-type of cytoplasm might influence sugar accumulation in cold-stored potato tubers in different ways. We showed that the mt/nucDNA ratio was higher in D-possessing tubers after cold storage than in T progeny. For the D-type cytoplasm, the pt/nucDNA ratio was higher for tubers characterized by dark chip colour than for those with light chip colour. Our findings suggest that T- and D-type cytoplasm might influence sugar accumulation in cold-stored potato tubers in different ways.

eQTL mapping of the 12S globulin cruciferin gene PGCRURSE5 as a novel candidate associated with starch content in potato tubers.

Tuber starch content (TSC) is a very important trait in potato (Solanum tuberosum L.). This study is the first to use expression quantitative trait loci (eQTL) mapping of transcript-derived markers for TSC in potato. Thirty-four differentially expressed genes were selected by comparing the RNA-seq data of contrasting bulked segregants. For the 11 candidate genes, we determined their relative expression levels across the segregating diploid potato population using RT-qPCR. We detected 36 eQTL as candidate genes distributed on all twelve potato chromosomes, and nine of them overlapped with QTL for TSC. Peaks for two eQTL, eAGPaseS-a and ePGRCRURSE5, were close to the corresponding loci of the large subunit of ADP-glucose pyrophosphorylase (AGPaseS-a) and the 12S globulin cruciferin gene (PGCRURSE5), respectively. The eQTL peaks for AGPaseS-a and PGRCRURSE5 explained 41.0 and 28.3% of the phenotypic variation at the transcript level. We showed the association of the DNA markers for AGPaseS-a and PGRCRURSE5 with QTL for TSC, and significant correlation between the expression level of PGRCRURSE5 and TSC. We did not observe a significant correlation between the expression level of AGPaseS-a and TSC. We concluded that the cruciferin gene PGRCRURSE5 is a novel candidate involved in the regulation of starch content in potato tubers.

Cytoplasmic diversity of potato relatives preserved at Plant Breeding and Acclimatization Institute in Poland.

Among different types of potato cytoplasmic genomes, some are associated with male sterility or affect agronomic traits. The goal of this study was to analyze types of chloroplast and mitochondrial genomes of selected potato relatives originating from collection of the Institute of Plant Industry, Saint Petersburg, Russia, and preserved in Poland. Using chloroplast and mitochondrial markers the cytoplasm types were determined for 401 genotypes belonging to 43 seed accessions of 28 Solanum species. Among characterized genotypes, 201 (50.1%), 156 (38.9%) and 44 (11%) had cytoplasm types W, D, M, respectively. No accessions with the T, P or A cytoplasm were found. Within cytoplasm W, genotypes with the subtypes: W/α and W/ß were identified, but not with W/γ. In S. famatinae, we detected unusual product of the T marker with 65 bp insertion earlier seen exclusively in S. vernei. Among the genotypes of S. leptophyes, two profiles of the ALM_4/ALM_5 marker were observed. S. famatinae and S. vernei come from Argentina, provinces Catamarca and Tucumán. Possibly the insertion in marker T occurred independently in two species, or the accessions were misidentified. Segregation of the ALM_4/ALM_5 marker within S. leptophyes indicates that potato seed accessions are heterogeneous not only due to nuclear DNA polymorphisms but have diversified cytoplasm, too. Our findings are important for exploitation of the tested material in potato breeding. Male-fertile cytoplasm types give a chance of avoiding fertility problems and widening the range of crosses in future generations of breeding materials.

Genetic composition of interspecific potato somatic hybrids and autofused 4x plants evaluated by DArT and cytoplasmic DNA markers.

KEY MESSAGE: Using DArT analysis, we demonstrated that all Solanum × michoacanum (+) S. tuberosum somatic hybrids contained all parental chromosomes. However, from 13.9 to 29.6 % of the markers from both parents were lost in the hybrids. Somatic hybrids are an interesting material for research of nucleus-cytoplasm interaction and sources of new nuclear and cytoplasmic combinations. Analyses of genomes of somatic hybrids are essential for studies on genome compatibility between species, its evolution and are important for their efficient exploitation. Diversity array technology (DArT) permits analysis of the composition of nuclear DNA of somatic hybrids. The nuclear genome compositions of 97 Solanum × michoacanum (+) S. tuberosum [mch (+) tbr] somatic hybrids from five fusion combinations and 11 autofused 4x mch were analyzed for the first time based on DArT markers. Out of 5358 DArT markers generated in a single assay, greater than 2000 markers were polymorphic between parents, of which more than 1500 have a known chromosomal location on potato genetic or physical map. DArT markers were distributed along the entire length of 12 chromosomes. We noticed elimination of markers of wild and tbr fusion components. The nuclear genome of individual somatic hybrids was diversified. Mch is a source of resistance to Phytophthora infestans. From 97 mch (+) tbr somatic hybrids, two hybrids and all 11 autofused 4x mch were resistant to P. infestans. The analysis of the structure of particular hybrids' chromosomes indicated the presence of markers from both parental genomes as well as missing markers spread along the full length of the chromosome. Markers specific to chloroplast DNA and mitochondrial DNA were used for analysis of changes within the organellar genomes of somatic hybrids. Random and non-random segregations of organellar DNA were noted.