Ji-Hong Cho

Expressing the sweet potato orange gene in transgenic potato improves drought tolerance and marketable tuber production

Potato (Solanum tuberosum L.) is generally considered to be sensitive to drought stress. Even short periods of water shortage can result in reduced tuber production and quality. We previously reported that transgenic potato plants expressing the sweet potato orange gene (IbOr) under the control of the stress-inducible SWPA2 promoter (referred to as SOR plants) showed increased tolerance to methyl viologen-mediated oxidative stress and high salinity, along with increased carotenoid contents. In this study, in an effort to improve the productivity and environmental stress tolerance of potato, we subjected transgenic potato plants expressing IbOr to water-deficient conditions in the greenhouse. The SOR plants exhibited increased tolerance to drought stress under greenhouse conditions. IbOr expression was associated with slightly negative phenotypes, including reduced tuber production. Controlling IbOr expression imparted the same degree of drought tolerance while ameliorating these negative phenotypic effects, leading to levels of tuber production similar to or better than those of wild-type plants under drought stress conditions. In particular, under drought stress, drought tolerance and the production of marketable tubers (over 80g) were improved in transgenic plants compared with non-transgenic plants. These results suggest that expressing the IbOr transgene can lead to significant gains in drought tolerance and tuber production in potato, thereby improving these agronomically important traits.

Vitamin C content of potato clones from Korean breeding lines and compositional changes during growth and after storage

Vitamin C is the main vitamin source in potato tubers, and its antioxidant activity is known to benefit human health. To improve the vitamin C content and understand its accumulation patterns, we selected 10 advanced clones with high vitamin C content from 268 clones. The levels of the selected clones ranged from 32.3 to 38.9 mg·100 g−1 fresh weight. Among them, four double-cropping clones with short dormancy were selected for further analysis. The vitamin C content of the potato tubers from six potato clones, including two control cultivars, ‘Dejima’ and ‘Chubaek’, was determined on specific days after planting (DAP) and during development. Developmental stages were categorized by weight: I (5–10 g), II (30–40 g), III (70–80 g), and IV (> 120 g). Vitamin C content was highest 90 DAP and dropped slowly by 100 and 110 DAP. Until 90 DAP, we found that developmental stages I and II showed higher contents of vitamin C; however, there were small differences by developmental stage (I to IV) by 100 and 110 DAP. In conclusion, vitamin C content was higher in younger tubers than in mature tubers, and its content was highest 90 DAP in the selected clones. During storage, vitamin C content significantly declined in all clones. The decrease was highest in H06035-4 and H06085-2 compared to ‘Chubaek’ and ‘Dejima’, and the differences between selected clones and control varieties narrowed after 4 months of storage. When we consider the agronomic characteristics and consistency of high vitamin C content, H06035-4 was selected as a high vitamin C content promising line.

Growth, quality, and yield characteristics of transgenic potato (Solanum tuberosum L.) overexpressing StMyb1R-1 under water deficit

Abstract This study was conducted to evaluate agronomic characteristics such as growth, quality, and yields of StMyb1R-1 transgenic potato and also to obtain the basic data for establishing assessment guidelines of transgenic potato. Three transgenic lines (Myb 1, Myb 2, and Myb 8) were cultivated under conventional irrigation, drought condition, and severe drought condition and were analyzed by com-paring with wild type, non-transgenic cv. Superior. Myb 2 showed a different flower color from wild type and Myb 1 had much bigger secondary leaflets than wild type. Myb 1 and Myb 2 showed higher P 2 O 5 content in both top and root zone and longer shaped tubers than wild type. In yield factors, transgenic lines had more tubers than wild type, however their yield decreases were severe because of the poor enlargement of tuber under water deficit condition. This tendency was noticeable in Myb 1 and Myb 2. In TR ratio, chlorophyll content, dry matter rate, and relative water content, there were no big differences between transgenic lines and wild type. Meanwhile, in phenotype, growth, quality, and yield factors, substantial equivalent was confirmed between Myb 8 and wild type. Then, Myb 8 showed the highest marketable tuber yield under conventional irrigation, while showed lower level than wild type under water deficit. Judged by this result, the enhancing drought-tolerance by

Mitochondrial genome sequence of tuber-bearing wild potato, Solanum commersonii Dunal

Abstract We report two complete mitochondrial genome sequences of a tuber-bearing wild potato species (Solanum commersonii). The genomes are circular DNA molecules with lengths of 213,676 bp and 338,427 bp containing 80 nonredundant genes totally, including 34 protein-coding genes, 25 hypothetical open reading frames, 18 tRNA genes, and 3 rRNA genes. Phylogenetic analysis using common protein-coding sequences confirmed that S. commersonii belongs to the Solanoideae subfamily in the Solanaceae family.

The complete chloroplast genome sequence of Solanum hougasii, one of the potato wild relative species

Abstract Solanum hougasii is a wild tuber-bearing species belonging to the family Solanaceae. The complete chloroplast genome of S. hougasii was constituted by de novo assembly, using a small amount of whole genome sequencing data. The chloroplast genome of S. hougasii was a circular DNA molecule with a length of 155,549 bp and consisted of 85,990 bp of large single copy, 18,373 bp of small single copy, and 25,593 bp of a pair of inverted repeat regions. A total of 158 genes were annotated, including 105 protein-coding genes, 45 tRNA genes, and eight rRNA genes. Maximum likelihood phylogenetic analysis with 25 Solanaceae species revealed that S. hougasii is most closely grouped with S. tuberosum.

Chloroplast genome of the wild tuber-bearing diploid potato relative Solanum chacoense

Abstract Solanum chacoense is a wild tuber-bearing species belonging to Solanaceae family. The chloroplast genome of the species was completed by de novo assembly using a small amount of whole genome sequencing data. The genome is the circular DNA molecule with a length of 155,532 bp containing 159 predicted genes totally, including 105 protein-coding, 45 tRNA and eight rRNA genes. Maximum-likelihood phylogenetic analysis with 26 species in Solanaceae revealed that S. chacoense is the most closely grouped with S. commersonii.

The complete mitochondrial genome sequences of potato (Solanum tuberosum L., Solanaceae)

Abstract Potato (Solanum tuberosum) from the Solanaceae is the fourth most important food crop worldwide. In this study, five complete mitochondrial genome sequences of S. tuberosum were characterized through de novo assembly of whole genome sequencing data. The resulting circular mitochondrial DNA molecules ranged from 49,171 bp to 297,014 bp in size and contained a total of 80 non-redundant genes, comprising 34 protein-coding genes, 24 hypothetical open reading frames, 19 tRNA genes, and 3 rRNA genes. Phylogenetic analysis using common protein-coding sequences confirmed that S. tuberosum belongs to the Solanoideae subfamily in the Solanaceae family.

Characterization of trichome morphology and aphid resistance in cultivated and wild species of potato

Trichomes are specialized epidermal structures that protect plants from abiotic and biotic stresses. Cultivated potato (Solanum tuberosum) is known to have both glandular and non-glandular trichomes. However, the criteria for trichome type classification have not been studied in detail. In addition, there is a poor understanding of the types of trichomes that exist in wild potato species. Here, the morphology and density of trichomes were compared between a representative cultivated potato variety and 17 wild potato species using Cryo Scanning Electron Microscopy (CryoSEM). Based on trichome morphology, the cultivated variety and each of the wild species were seen to have two glandular and two non-glandular trichome types. We classified the eighteen potato species into four groups using trichome type and density criteria. Groups I and II represented species with a higher density of glandular or non-glandular trichomes, respectively, on both abaxial and adaxial leaf surfaces. Group III represented species with a higher density of non-glandular trichomes on abaxial leaf surfaces alone. Group IV represented species with an overall lower trichome density on both abaxial and adaxial leaf surfaces, but which was formed of both glandular and non-glandular types. Honey dew spots were quantified following infestation with the aphid Macrosiphum euphorbiae to test whether trichome composition is associated with resistance to aphid feeding. Fewer honey dew spots were observed in the Group I representative species S. berthaultii and S. hougasii compared to that in species from other groups. Furthermore, correlation coefficient analysis showed that honey dew spot number was negatively associated with glandular trichome density. These results imply that glandular trichomes play an important role in aphid resistance and thus can be used for developing insect-resistant potato.

The complete chloroplast genome sequences of potato wild relative species, Solanum commersonii

Abstract Solanum commersonii Dunal is a well-known wild potato belonging to Solanaceae family and commonly used as materials for somatic hybridization due to various biotic and abiotic stress resistances. The complete chloroplast genome of S. commersonii was constituted by de novo assembly using a small amount of whole genome sequencing data. The chloroplast genome of S. commersonii was 155 525 bp in length, consisted of 86 013 bp of large single copy, 18 366 bp of small single copy region and 25 573 bp of a pair of inverted repeats. A total of 113 genes were annotated including 79 protein-coding genes, 30 tRNA genes and four rRNA genes. Maximum likelihood phylogenetic analysis with 14 Solanaceae species revealed that S. commersonii is much closely related to Solanum tuberosum and S. bulbocastanum.

The Correlation between Stem Characteristics and Its Resistance to Hail Damage in Potato Cultivars

BACKGROUND: Recently, weather disasters such as hail and typhoon occur frequently. These threaten the stable cultivation of potatoes. It is very important to cultivate potatoes with stable under unexpected weather disasters. This study was performed to investigate the correlation between mophological characteristics of potato stem and its resistance to hail damage in different potato cultivars. METHODS AND RESULTS: Hail fall occurred for 8 minutes on May 31, 2012 in the field of Highland Agriculture Research Center located in Jinbu-myeon Gangwon-do. Potato crop grown in the field was affected by hail due to which the stems of potato were broken. The percentage of broken stem of potato was investigated as the level of damage by hail. To determine the difference in the ratio of broken stem among the potato cultivars, physical characteristics of potato stem such as diameter and hardness were measured. To evaluate recovery phase after hail damage, ground coverage and yield were measured. The percentage of broken stem of cv. Goun and cv. Saebong were 30%, 26%, respectively, whereas it was 5% in the cv. Atlantic. Damage by hail was the lowest in cv. Atlantic. Diameter of the stem was 15 mm in cv. Atlantic, 13 mm in cv. Goun and 11 mm in cv. Saebong. The hardness of potato cultivars was measured which was 74 N in cv. Atlantic. 71 N in cv. Goun and 59 N in cv. Saebong. The ground coverage in cv. Atlantic was 79%, which was the highest followed by 73% in cv. Saebong and 56% in cv. Goun. The yield of cv. Atlantic was monitored at 90 days after planting which was 40 MT/ha and that of cv. Saebong was 36 MT/ha, whereas in cv. Goun, it was 30 MT/ha which was the lowest. CONCLUSION: The ratio of broken stem in cv. Atlantic was the lowest compared to cultivars. In the physical characteristics of stem, cv. Atlantic was the highest in value of diameter and hardness. Based on these results, it was considered that cv. Atlantic was resistant to hail damage compared to other cultivars.