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A new early maturing satsuma mandarin (Citrus unshiu Marc.) ‘Haryejosaeng’ was developed at the Citrus Research Institute, Korea. The present study investigated the variation in total phenolics (TP), flavonoid, and antioxidant activity of fruits of ‘Haryejosaeng’ according to the harvest from September 2018 to December 2018, in Jeju. Colorirmetric methods were employed for the quantitative TP analysis, and the antioxidant activity by in vitro assay methods for DPPH, ABTS, hydroxyl radical, superoxide anion radical, nitric oxide, and hydrogen peroxide. The flavonoid and carotenoid compositions of ‘Haryejosaeng’ were compared with HPLC method. The total phenolics contents, flavonoid, antioxidant activity in both peel and flesh of ‘Haryejosaeng’ decreased during ripening. However, the amounts of β-cryptoxanthin in flesh increased from 0.2 to 1.86 mg/100 g during ripening. The major flavonoids of ‘Haryejosaeng’ extract were narirutin, hesperidin, rutin, nobiletin, and tangeretin. The changes observed for the antioxidant activity of ‘Haryejosaeng’ was correlated with the content of flavonoid and phenolics which can indicate that these compounds may act by capturing free radicals. Therefore, these results suggest that fruits of ‘Haryejosaeng’ are a significant source of antioxidant compounds such as phenolics, flavonoid and β-cryptoxanthin. These finding will allow the determination of appropriate times for harvesting Haryejosaengs containing the highest amount of specific bioactive makers for achieving improved health benefits and functional properties.

Many citrus varieties are hybridized to improve their quality and to overcome the effects of climate change. However, there is limited information on the effect of the chemical profiles of hybrid varieties on their quality. In this study, we analyzed 10 citrus varieties and evaluated the correlation with their general characteristics and antioxidant activities. Chemical profiles, including the contents of sugars, organic acid compounds, flavonoids, limonoids, and carotenoids, which are related to taste, color, and health benefits, were significantly different depending on the citrus varieties, leading to different antioxidant capacities and general quality parameters. Based on these data, the correlations were investigated, and 10 citrus varieties were clustered into four groups—Changshou kumquat and Jeramon (cluster I), Setoka (cluster II-1), Natsumi, Satsuma mandarin, and Navel orange (cluster Ⅱ-2), Kanpei, Tamnaneunbong, Saybyeolbong, and Shiranui (cluster II-3). Moreover, a metabolomic pathway was proposed. Although citrus peels were not analyzed and the sensory and functional qualities of the citrus varieties were not investigated in this study, our results are useful to better understand the relationship between citrus quality and metabolite profiles, which can provide basic information for the development and improvement of new citrus varieties.

Anthocyanins, one of the major plant pigments, are responsible for the coloration of various plant tissues and organs, including fruits. They are known to have significant health benefits. Anthocyanin biosynthesis is influenced by environmental factors such as cold temperature and is transcriptionally regulated by MYB/bHLH/WD40 complexes composed of R2R3-MYB, basic helix-loop-helix (bHLH), and WD40-type transcription factors (TFs). The Ruby locus, which encodes a MYB TF, controls anthocyanin production in the fruit of blood orange varieties in a dominant manner. For the marker-assisted selection of citrus breeding lines with high anthocyanin production, we established PCR-based molecular markers for robust genotyping of Ruby locus alleles. Two dominant Ruby alleles, RD-1 and RD-2, were specifically detected in the blood orange varieties with high anthocyanin contents in their fruit flesh, but not in the varieties rich in lycopene. For functional analysis of Ruby alleles, we generated transgenic Arabidopsis expressing a functional wild-type R, a non-functional r-1, or a dominant RD-2 allele. Expression levels of flavonoid/anthocyanin biosynthetic genes and anthocyanin production were highly increased in the transgenic plants expressing the dominant Ruby allele by its retrotransposon-mediated native promoter under cold treatment, suggesting that the retrotransposon may contain cis-regulatory elements that respond to cold temperature. Our results also support that the MYB TF encoded by Ruby could be a key component of regulatory complexes that control flavonoid/anthocyanin biosynthesis in citrus.

Many citrus cultivars have the polyembryony trait that develops many nucellar embryos alongside a single zygotic embryo in an individual seed by sporophytic apomixis. This unique botanical trait hinders citrus breeding by genetic hybridization and affects breeding efficiency and cost. Techniques to efficiently identify nucellar and zygotic individuals in citrus are still very limited. For a systematic and targeted citrus breeding program, we collected 101 citrus genetic resources and determined their embryo types, which revealed 22 monoembryo, 54 polyembryo, and 25 mixed types. We also developed 17 simple sequence repeat (SSR) markers showing polymorphism among the genetic resources from the public resources and our own comparative genome analysis. Seventeen SSR markers detected a total of 181 alleles, ranging from 5 to 16 alleles per locus. The average polymorphism information content value was 0.67, ranging from 0.43 to 0.84. Genetic cluster analysis based on similarity matrices of alleles revealed that several genetic resources of the genus Citrus were fragmented and/or scattered throughout the entire dendrogram, not forming unique groups, due to frequent natural or intended genetic crossings. Application of these polymorphic SSR markers to F1 individuals derived from several genetic crosses using polyembryonic citrus cultivars as a female parent revealed that the polyembryony trait decreased the breeding efficiency due to the poor occurrence rate of zygotic individuals. Therefore, our results suggest that identification of nucellar and zygotic embryo-derived F1 individuals using SSR markers as a genotyping technology may be a powerful tool for establishing a systematic molecular breeding program in citrus.

세계적인 과수작물로서의 경제적 중요성에도 불구하고, 감귤 생산은 주로 자연교잡 실생이나 눈 돌연변이로부터의 선발 또는 단순 품종 도입 등을 통해 이루어지고 있는 실정이다. 긴 유년기, 다배성, 자가불화합성과 같은 감귤 고유의 식물학적 특성, 주요 형질들(병저항성, 수량성, 품질 등)의 QTL에 의한 조절 등은 전통...

*Citrus Research Station, NIHHS, RDA, Jeju 699-943, Korea.**Planning and Coordination Division, NIHHS, RDA, Suwon 440-706, Korea.ABSTRACT : The major objective of this study was to investigate the usability as cultivar for processing of new Citrushybrid ‘Hamilgam’. We investigated various antioxidant activities, such as DPPH radical, ABTS radical, Hydroxyl radicaland Superoxide anion radical effect, along with total polyphenol content and total flavonoid content of Citrus hybrid ‘Hamil-gam’, C. unshiu, C. natsudaidai. The total polyphenol content and total flavonoid content were the highest in the Hamilgam.The major flavonoids of Hamilgam and Natsudaidai were naringin and neohesperidin, and those of Unshu were narirutinand hesperidin, as determined by HPLC. Especially, the neohesperidin content of Hamilgam showed much higher (100times over) than that of Unshu. However, the aglycone form was not found. DPPH and ABTS radical scavenging activitieswere the highest in Hamilgam peels. Hydroxyl radical scavenging activity was high in the order of Unshu, Hamilgam andNatsudaidai. Superoxide anion radical scavenging of 3 cultivars peels displayed low activities compared to DPPH and ABTSradical scavenging. Based on these results, Hamilgam peel extracts possess antioxidant activities and may thus serve aspotential sources of functional food, cosmetic products, etc.Key Words : Citrus, Hamilgam, Polyphenol, Antioxidant Activities, Functional Food

The study was conducted to investigate the effect of fruit bearing type with leafy (LY) and leafless (LS) fruits on fruit growth, sugar, and acid characteristics in satsuma mandarin. Fruit growth including fruit length, diameter, shape index (diameter/length), weight, and size distribution was not different between LY and LS fruits at ripening time. Total soluble solids (TSS) concentration of the fruit juice increased and acidity decreased continuously and then TSS:acidity ratio increased with fruit development from 100 days after anthesis to ripening time. Soluble sugar was continuously increased, whereas organic acid decreased. Theses tendencies were related to the increase of sucrose and decline of citric acid, respectively. However, there was no effect of fruit bearing type on TSS, acidity, and TSS:acidity ratio, and soluble sugar and organic acid composition in fruit juice. Also, photosynthetic rate and chlorophyll index with SPAD value were not different between leaves adjacent to LY and LS fruits. The results indicated that fruit growth and sugar and acid characteristics were not affected by fruit bearing type with leafy and leafless fruits in satsuma mandarin.

Agrobacterium-mediated transformation in Satsuma mandarin (Citrus unshiu Marc.) cv. Miyagawa wase was achieved with reasonable transformation efficiency of about 22%, which was the percentage of transgenic plantlets confirmed by genomic PCR (37 plantlets/168 hygromycin-resistant calli). Embryogenic calli of Miyagawa wase were infected with Agrobacterium tumefaciens strain EHA105 harboring binary vector pCAMBIA1300 that contained miraculin gene (a taste-modifying protein) and hygromycin as a selection marker. After 5 days of co-culture in the medium containing 100 μM acetosyringone, calli were transferred to the liquid half embryogenic cell culture medium (half concentration of Murashige and Tucker’s (MT) medium modified with the addition of 500 mg·L− malt extract, 50 g·L− sucrose and 1.55 g·L− glutamine) with 15 mg·L− hygromycin and 250 mg·L− cefotaxime, and were cultured for two weeks. Then, the calli were grown on the solid selection medium with 20 mg·L− hygromycin for four weeks and 25 mg·L− hygromycin for another four weeks. The resistant embryos were selected and transferred to the embryo maturation medium. After 3 weeks of culture, the heart shaped embryos were transferred to the MT medium containing 1.0 mg ·L− GA3, 20.0 mL·L− coconut water, 0.02 mg·L− NAA and 0.0146 mg·L− coumarin for embryo germination. Finally the germinated embryos were cultured on MT medium containing 3.0% sucrose and 0.8% agar for growing to the normal plant. Stable integration of the transgene in the plant genome was confirmed by PCR and Southern blot analysis.

Li(Ni, Co, Mn)O2 has been known as one of the most promising cathode materials for lithium secondary batteries. However, it has some problems to overcome for commercialization such as inferior rate capability and unstable thermal stability. In order to address these problems, surface modification of cathode materials by coating has been investigated. In the coating techniques, selection of coating material is a key factor of obtaining enhanced properties of cathode materials. In this work, we introduced solid electrolyte (Li-La-Ti-O) as a coating material on the surface of Li[Ni0.3Co0.4Mn0.3]O2 cathode. Specially, we focused on a rate performance of Li-La-Ti-O coated Li[Ni0.3Co0.4Mn0.3]O2 cathode. Both bare and Li-La-Ti-O 2 wt.% coated sample showed similar discharge capacity at 0.5C rate. However, as the increase of charge-discharge rate to 3C, the coated samples displayed better discharge capacity and cyclic performance than those of bare sample.

The particle size of Li[Ni 0.2 Li 0.2 Mn 0 ]O 2 cathode powder was controlled effectively by dispersion using lauric acid as a surfactant. The samples treated by lauric acid showed smaller particles of approximately half the original size compared to the particles of a pristine sample. A structural change due to the dispersion of Li[Ni 0.2 Li 0.2 Mn 0.6 ]O 2 powder was not detected. The rate performance of the Li[Ni 0.2 Li 0.2 Mn 0.6 ]O 2 cathode was improved by dispersion using lauric acid, which was likely due to the decrease of the particle size. In particular, a sample dispersed pristine powder using lauric acid (L2) presented a greatly enhanced discharge capacity and capacity retention at a high C rate. The discharge capacity of a pristine sample was only 133 mAhg -1 (3C rate) and 96 mAhg -1 (12C rate) at the tenth cycle. In contrast, the L2 electrode delivered higher discharge capacities of 160 mAhg -1 (3C rate) and 129 mAhg -1 (12C rate) at the tenth cycle. The capacity retention at a rate of 12C/2C was also enhanced from ~ 45% (pristine sample) to 57% (L2) by treatment with lauric acid.

We investigated the correlation between the flavonoid content and NO production inhibitory activity of fruit peel extracts using 20 citrus plants. The contents of seven flavonoids (naringin, naringenin, hesperidin, hesperetin, rutin, nobiletin, and tangeretin) were determined by HPLC analysis. Each citrus peel extract varied in flavonoid content, but the contents of nobiletin and tangeretin, which were contained in all 20 fruit peels, showed a positive and significant correlation with each other (r=0.879, p