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Tseng M.-N.,National Taiwan University | Tseng M.-N.,Kaohsiung District Agricultural Research and Extension Station | Chung C.-L.,National Taiwan University | Tzean S.-S.,National Taiwan University
PLoS ONE | Year: 2014

The entomopathogenic fungus Metarhizium anisopliae MA05-169 is a transformant strain that has been metabolically engineered to express dihydroxynaphthalene-melanin biosynthesis genes. In contrast to the wild type strain, the transformant displays a greater resistance to environmental stress and a higher virulence toward target insect host. However, the underlying mechanisms for these characteristics remain unclear; hence experiments were initiated to explore the possible mechanism(s) through physiological and molecular approaches. Although both transformant and wild type strains could infect and share the same insect host range, the former germinated faster and produced more appressoria than the latter, both in vivo and in vitro. The transformant showed a significantly shorter median lethal time (LT50) when infecting the diamondback moth (Plutella xylostella) and the striped flea beetle (Phyllotreta striolata ), than the wild type. Additionally, the transformant was more tolerant to reactive oxygen species (ROS), produced 40-fold more orthosporin and notably overexpressed the transcripts of the pathogenicity-relevant hydrolytic enzymes (chitinase, protease, and phospholipase) genes in vivo. In contrast, appressorium turgor pressure and destruxin A content were slightly decreased compared to the wild type. The transformant's high anti-stress tolerance, its high virulence against five important insect pests (cowpea aphid Aphis craccivora, diamondback moth Pl. xylostella, striped flea beetle Ph. striolata, and silverleaf whitefly Bemisia argentifolii) and its capacity to colonize the root system are key properties for its potential bio-control field application. © 2014 Tseng et al.

Lin Y.,Kaohsiung District Agricultural Research and Extension Station
Clean - Soil, Air, Water | Year: 2010

The application of potassium fertilizer by farmers is often not appropriate and causing environmental pollution. By understanding the adsorptive characteristics of potassium (K) on different soils, we can prevent excessive application of K-fertilizer that can cause environmental impact. The Gapon exchange coefficient (K G), for exchange between K and Ca, was considered as an important factor influencing the adsorption of K. This study was conducted to compare the constant K G of five important farm soils in Taiwan. The K G and CEC were then used to predict K buffering capacity (PBC). Finally, the relationship between exchangeable K ratio (E P) and K adsorption ratio (PAR) was examined. The results show that five soils have same trends, indicating that K G decreases with increase in K saturation. The CEC and K G of Liuying (Ly) soil are both high, so that their K buffering capacity is high. The K G and CEC of Chanjing (Cj) and Sanhua (Sh) soil show moderate values. The CEC of Erling (El) soil is high, but its K G is low, so that its K buffering capacity is moderate. On the other hand, the K G of Newniaokang (Nnk) soil is high but its CEC is low, so its K buffering capacity is also moderate. The correlations between E P and PAR of five soil show linear relationship at three treatments of CaCl 2 concentration. This study may provide an important clue to the fertilization management of K-fertilizer on the different soil properties in Taiwan.This paper describes on the basis of simple equations exchange behaviors between potassium and other cations in soil. Thus, it may provide a clue to the application method of K-fertilizers. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tseng M.N.,National Taiwan University | Tseng M.N.,Kaohsiung District Agricultural Research and Extension Station | Chung P.C.,National Taiwan University | Chung P.C.,Miaoli District Agricultural Research and Extension Station | Tzean S.S.,National Taiwan University
Applied and Environmental Microbiology | Year: 2011

Entomopathogenic fungi have been used for biocontrol of insect pests for many decades. However, the efficacy of such fungi in field trials is often inconsistent, mainly due to environmental stresses, such as UV radiation, temperature extremes, and desiccation. To circumvent these hurdles, metabolic engineering of dihydroxynaphthalene (DHN) melanin biosynthetic genes (polyketide synthase, scytalone dehydratase, and 1,3,8-trihydroxynaphthalene reductase genes) cloned from Alternaria alternata were transformed into the amelanotic entomopathogenic fungus Metarhizium anisopliae via Agrobacterium-mediated transformation. Melanin expression in the transformant of M. anisopliae was verified by spectrophotometric methods, liquid chromatography/mass spectrometry (LC/MS), and confocal microscopy. The transformant, especially under stresses, showed notably enhanced antistress capacity and virulence, in terms of germination and survival rate, infectivity, and reduced median time to death (LT 50) in killing diamondback moth (Plutella xylostella) larvae compared with the wild type. The possible mechanisms in enhancing the stress tolerance and virulence, and the significance and potential for engineering melanin biosynthesis genes in other biocontrol agents and crops to improve antistress fitness are discussed. © 2011, American Society for Microbiology.

Tsai C.C.,Kaohsiung District Agricultural Research and Extension Station
Acta Horticulturae | Year: 2014

Phalaenopsis is one of the important economic orchids in the world. To date, thousands of Phalaenopsis cultivars have been bred and commercialized. In order to introduce unique characteristics of the spur structure from the flower of Amesiella into Phalaenopsis germplasm, intergeneric hybridization between Phalaenopsis 'Sogo Yukidian' and Amesiella philippinensis were conducted by artificial pollination. Four months later, the capsules were harvested. The immature embryos with placenta were manipulated and placed into germination medium. Approximately 300 intergeneric embryos of each capsule were rescued. After subculturing for one year in the culture medium and two-week hardiness, intergeneric hybrids were cultivated in greenhouse. After one and half years of cultivation, the first flower of the hybrid bloomed. The new hybrid was named as Amenopsis 'Kaohsiung Magic' and registered at the Royal Horticulture Society. Leaf morphology of the hybrid is lanceolate, coriaceus and dark green. The hybrid bears greenish-white flower with black markings on the lip and a short spur at the back of the lip.

Tsai C.-C.,Kaohsiung District Agricultural Research and Extension Station
Acta Horticulturae | Year: 2014

Sixteen polymorphic microsatellite loci were developed for mango (Mangifera indica L.), to evaluate genetic diversity and identify cultivars of this important commercial fruit tree in East Asia. The 16 polymorphic microsatellite markers were developed using a magnetic bead-enrichment method and polymorphisms were identified when DNA samples from 22 mango cultivars were screened. The number of alleles ranged from 2 to 8, with an expected heterozygosity ranging from 0.304 to 0.826. The polymorphism information content (PIC) ranged from 0.253 to 0.756 (average = 0.543). These polymorphic loci should be useful and convenient for further studies of the genetic diversity and identification of cultivars in mango.

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