Anther Culture of Potato: Method and Applications.

Anther culture provides a tool to produce haploid lines from cultivated potato (Solanum tuberosum L.), which has a tetraploid (2n = 4x = 48) genome constitution. Shoot regeneration via direct embryogenesis in anther culture procedure is preferred to produce dihaploid (2n = 2x = 24) potato lines, which can be applied in breeding of potato varieties. The anther culture protocol described in the present chapter can be conducted not only in cultivated potato (S. tuberosum) but also in other genetically related potato species.

Profiling beneficial phytochemicals in a potato somatic hybrid for tuber peels processing: phenolic acids and anthocyanins composition.

The purpose of this study was to characterize the peels of a CN1 somatic hybrid obtained from two dihaploid potato lines (Cardinal H14 and Nicola H1) in terms of the health-promoting phenolic compounds (phenolic acids and anthocyanins). The CN1 hybrid is defined by a pink tuber skin color making it different from the light-yellow-skinned "Spunta," which is the most commonly grown potato cultivar in Tunisia. Oven-dried peel samples derived from CN1 hybrid and cv. Spunta were ground, and phenolic compounds were extracted with water or methanol for quantification. Lyophilized peels were used for the phenolic acid and anthocyanin analyses. Higher total quantities of phenolic compounds were recovered in methanol extracts compared with water extracts. A slightly higher concentration of phenolic acids (100 mg/100 g DW) was obtained in the lyophilized peels extract of CN1 hybrid than in the cv. Spunta corresponding sample (83 mg/100 g DW). The profiles of the chlorogenic acid isomers were almost identical in both of CN1 hybrid and cv. Spunta. Caffeic acid (CA) and three caffeoylquinic acids (CQAs): 3-CQA, 4-CQA, and 5-CQA, were identified from both genotypes, 5-CQA being the dominant form in both potatoes. Since the CN1 hybrid has a pink skin color, its anthocyanin profile was also determined. The anthocyanin quantity in the CN1 peels was 5.07 mg/100 g DW, involving six different anthocyanins that were identified within the extract, namely, Pelargonidin-3-rutinoside-5-glucoside, peonidin-3-rutinoside-5-glucoside, coumaroyl ester of pelargonidin-3-rutinoside-5-glucoside, coumaroyl ester of peonidin-3-rutinoside-5-glucoside, feruloyl ester of pelargonidin-3-rutinoside-5-glucoside, and feruloyl ester of peonidin-3-rutinoside-5-glucoside. These results suggest that the peel waste of CN1 somatic hybrid can be considered as a promising source of high-value compounds for food industry.

Assessment of physiological age and antioxidant status of new somatic hybrid potato seeds during extended cold storage.

Yield components of potato are largely affected by the physiology age of the tuber seeds at planting. The current study focuses on monitoring seed tuber aging in two CN1 and CN2 somatic hybrid lines and Spunta (Sp) variety during 270 days of storage at 4 °C. Aging rate was monitored based on sprouting, emergence and tissue oxidation rates. Investigation of sprouting parameters such as physiological age index (PAI) considering physiological and chronological age and the incubation period (IP) indicated lower physiological age in hybrids than in Sp during the storage. Moreover, these analyses showed that off-seasonal growing conditions increased the aging, more clearly, in Sp tubers than in hybrid ones. However, dormancy periods (endodormancy and after storage dormancy) were equivalent in the different tuber lots. PAI and IP data when combined with those from emergence parameters (duration until emergence and stem number) seem more efficient for the characterization of the different potato lines. However, emergence indicators, when considered separately, were not able to distinguish clearly between seasonal and off-seasonal tubers. Data suggest that hybrid seeds exhibited high performances since they produced higher stem number per plant than Sp. The high aging rate in Sp tubers seems to be associated with the few developed stems. Biochemical analyses supported in part morphophysiological differences between hybrids and Sp seeds although these indicators seem more sensitive to aging. Indeed data showed that the dormancy break, and then, the development were associated with some level of tissue oxidation. Antioxidants such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX) and carotenoids seem more enhanced after the release of dormancy. However, induction of these activities started earlier in off-seasonal tubers than in seasonal ones, this was consistent with their advanced aging level revealed by PAI and IP data. Activation of these antioxidants appears to respond effectively to the increase of ROS suggesting a better control of postharvest development and tissue deterioration especially in CN2 off-seasonal tubers. This study suggests that CN2 followed by CN1 exhibited the best performance compared to Sp variety.

Genetic diversity and structure in the northern populations of European hazelnut (Corylus avellana L.).

European hazelnut (Corylus avellana L.) is a strictly cross-pollinated diploid tree species, which has its northernmost populations in Fennoscandia, and it was one of the first species to recolonize northern Europe after the last ice age. Hazelnut produces edible nuts in Finland but nowadays they are underutilized as food, and currently no breeding programmes exist. In the present study, 300 hazelnut specimens were collected from 20 different locations (= populations) in Finland, and they were genetically analyzed using nine simple sequence repeat (SSR) markers. Most of the genetic diversity existed within populations (83%). According to different genetic analyses (STRUCTURE, principal coordinates analysis, and clustering), a general lack of structure was observed, suggesting extensive gene flow among hazelnuts between 17 investigated populations. However, genetic structuring was clearly observed in three populations: Hakavuori, Mustiala, and Pähkinämäki, which might have become isolated due to geographical barriers that kept them separate, diminishing gene flow from other populations. Studying the diversity of European hazelnut is of great interest for understanding population genetics of a species distributed in its marginal areas in the north, and the results are also valuable for further uses in plant conservation, selection, and possible future breeding actions in Finland.

Size and location of radish chromosome regions carrying the fertility restorer Rfk1 gene in spring turnip rape.

In spring turnip rape (Brassica rapa L. spp. oleifera), the most promising F1 hybrid system would be the Ogu-INRA CMS/Rf system. A Kosena fertility restorer gene Rfk1, homolog of the Ogura restorer gene Rfo, was successfully transferred from oilseed rape into turnip rape and that restored the fertility in female lines carrying Ogura cms. The trait was, however, unstable in subsequent generations. The physical localization of the radish chromosomal region carrying the Rfk1 gene was investigated using genomic in situ hybridization (GISH) and bacterial artificial chromosome-fluorescence in situ hybridization (BAC-FISH) methods. The metaphase chromosomes were hybridized using radish DNA as the genomic probe and BAC64 probe, which is linked with Rfo gene. Both probes showed a signal in the chromosome spreads of the restorer line 4021-2 Rfk of turnip rape but not in the negative control line 4021B. The GISH analyses clearly showed that the turnip rape restorer plants were either monosomic (2n=2x=20+1R) or disomic (2n=2x=20+2R) addition lines with one or two copies of a single alien chromosome region originating from radish. In the BAC-FISH analysis, double dot signals were detected in subterminal parts of the radish chromosome arms showing that the fertility restorer gene Rfk1 was located in this additional radish chromosome. Detected disomic addition lines were found to be unstable for turnip rape hybrid production. Using the BAC-FISH analysis, weak signals were sometimes visible in two chromosomes of turnip rape and a homologous region of Rfk1 in chromosome 9 of the B. rapa A genome was verified with BLAST analysis. In the future, this homologous area in A genome could be substituted with radish chromosome area carrying the Rfk1 gene.

Influence of incorporated wild Solanum genomes on potato properties in terms of starch nanostructure and glycoalkaloid content.

Interspecific somatic hybrids produced by protoplast fusion between two wild Solanum species (S. acaule, acl; S. brevidens, brd) and cultivated potato Solanum tuberosum (tbr) were analyzed in terms of the starch nanometer-range structure and glycoalkaloid (GA) contents. The crystallinity of starch granules, the average size of starch crystallites, and the lamellar distances were obtained from tuber samples using wide-angle and small-angle X-ray scattering methods. These measurements showed that incorporation of wild genomes from either nontuberous (brd) or tuberous (acl) Solanum species caused no significant modifications of the nanostructure of potato starch. In contrast, the GA profiles of the hybrids, which were analyzed by LC-ESI-MS in both tuber and foliage samples, differed considerably from those of cultivated potato. Regardless of the low total tuber GA concentrations (approximately 9 mg/100 g of fresh weight), the somatic hybrids contained GAs not detected in the parental species. A high proportion of spirotype GAs consisting of 5,6-dihydrogenated aglycons, for example, alpha-tomatine and tomatidine bound with solatriose, and chacotriose were found in the hybrids. In conclusion, the foliage of interspecific hybrids contained a higher variation in the structures of GAs than did the tubers.

Potato oxysterol binding protein and cathepsin B are rapidly up-regulated in independent defence pathways that distinguish R gene-mediated and field resistances to Phytophthora infestans.

SUMMARY Suppression subtractive hybridization was used to isolate the genes which are specifically up-regulated in the biotrophic phase of the incompatible interaction between a potato genotype, 1512 c(16), containing the resistance gene R2, and a Phytophthora infestans isolate containing the avirulence gene Avr2. Eight cDNAs were up-regulated in the biotrophic phase of the incompatible interaction. Seven of these were also up-regulated in the compatible interaction, but not until late in the necrotrophic phase. Amongst the sequences to be isolated were genes encoding the cysteine protease cathepsin B, StCathB, and an oxysterol binding protein, StOBP1; equivalent genes are involved in programmed cell death (PCD) processes in animals, but have yet to be implicated in such processes in plants. Whereas StOBP1 was up-regulated early in potato plants containing either R gene-mediated or moderate to high levels of field resistance, the highest levels of up-regulation of StCathB were observed early in R gene-mediated resistance but gradually increased from the early to late stages of field resistance, revealing these genes to be components of independent defence pathways and providing a means of distinguishing between these forms of resistance. StOBP1 was up-regulated by oligogalacturonides (plant cell wall breakdown products generated by pectinase activities), indicating that it is also a component of a general, non-specific defence pathway and is unlikely to play a role in PCD. In contrast, the expression of StCathB was unaffected by oligogalacturonide treatment, further associating its up-regulation specifically with the gene-for-gene interaction.