Glycoalkaloids as Biomarkers for Recognition of Cultivated, Wild, and Somatic Hybrids of Potato

Abstract

Cultivated and wild potato species synthesize a wide variety of steroidal glycoalkaloids (GAs). During breeding programs, species genomes are often put together through either sexual or somatic hybridization. Therefore, the determination of the GA composition of hybrids is very important in that it may affect either human consumption, or resistance to pathogen and pests. Here, we report the results of GA analysis performed on wild Solanum bulbocastanum, haploids of cultivated potato S. tuberosum and their interspecific somatic hybrids. GAs were extracted from tubers and analyzed by HPLC. HPLC Profile of S. tuberosum haploids showed, as expected, the presence of a-solanine and a-chaconine. The profile of S. bulbocastanum extract showed lack of a-solanine and a-chaconine, and the presence of four GAs. The GA pattern of the somatic hybrids was the sum of their parents profile. This represents a noteworthy tool for their unequivocal recognition. Interestingly, two hybrids produced not only GAs of both parents but also new compounds to be further investigated. This provided evidence that somatic hybridization induced the synthesis of new metabolites. The nature of the probable unidentified GAs associated to S. bulbocastanum and its somatic hybrids was ascertained by chemical degradation and spectroscopic analysis of their aglycones and sugar moieties. Our results suggest their close relation with GAs of both wild and cultivated potato species.

Starch granule evidence for the earliest potato use in North America

“…Tissues of S. jamesii are reported to contain the glycoalkaloids solanine, tomatine, and chaconine, which produce the bitterness. These compounds are steroid-based with various sugar moieties attached to hydroxyl groups on the genin portion (28). One report on the glycoalkaloid content of S. jamesii found ∼100 mg tomatine/g of dried tuber from samples collected at Zuni Pueblo (29)…”

Glycoalkaloid Profile in Potato Haploids Derived from Solanum tuberosum–S. bulbocastanum Somatic Hybrids

“…BuOH. The combined extracts were evaporated under reduced pressure by the azeotrope formed by addition of Milli-Q H 2 O as reported in [11]. The residue was detected by TLC (SiO 2 ; AcOEt/MeOH/1% NH 3 5 : 3 : 2) and re-dissolved in 1 ml of MeOH for direct analysis by HPLC.…”

“…As expected, the analysis of the chromatographic profile of Spunta showed only asolanine (S) and a-chaconine (C) peaks (not shown). The HPLC profile of the organic extract of five anther-derived haploids of somatic hybrid HF6A is shown in the Figure. In describing the GA profile, we used the same codes reported in [11]. Compared to their parent, three haploids (AS6A1, AS6A2, and AS6A4) lost the peak labelled 5 (t R 10.39 min).…”

“…This method was previously used to determine the GA profile of the parental hybrids of our haploids [11] and was derived from [1]. It should be also pointed out that the GA nature of the unidentified molecules associated to peaks present in the HPLC chromatographic profile was ascertained by chemical degradation and spectroscopic analysis.…”

“…In the frame of a breeding program aimed at efficiently exploit this wild species, we have produced tetraploid (2n ¼ 4x ¼ 48) S. bulbocastanum (þ) S. tuberosum somatic hybrids. They have been characterized for phenotypic traits of interest and also for their GA patterns [11] [12]. Determination of GAs in genotypes containing the S. bulbocastanum genome is considered very important, since several GAs have been identified in tubers and leaves of this species.…”