• The Plant Pathology Journal
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• 제16권5호
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• pp.257-263
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• 2000

Infection with rice blast fungus (Magnaporthe grisea) significantly reduced foliar net photosynthesis (A) of rice cultivars: Ilpoom, Hwasung, and Choochung in greenhouse experiments. By measuring the amount of diseased leaf area with a computer image analysis system, the relation between disease severity (DS) and net photosynthetic rate was curvilinearly correlated (r=0.679). Diseased leaves with 35% blast symptom can be predicted to have a 50% reduction of photosynthesis. The disease severity was linearly correlated (r=0.478) with total chlorophyll (chlorophyll a and chlorophyll b) per unit leaf area(TC). Light use efficiency was reduced by the fungal infection according to the light response curves. However, dark respiration (Rd) did not change after the fungal infection (p=0.526). Since the percent of reduction in photosynthesis greatly exceeded the percent of leaf area covered by blast lesions, loss of photosynthetic tissue on an area basis could not by itself account for the reduced photosynthesis. Quantitative photosynthetic reduction can be partially explained by decreasing TC, but cannot be explained by decreasing Rd. By photosynthesis (A)-internal CO$_2$ concentration (C$_i$ curve analysis, it was suggested that the fungal infection reduced ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity, ribulose-1,5-bisphosphate (RuBP) regeneration, and inorganic phosphate regeneration. Thus, the reduction of photosynthesis by blast infection was associated with decreased TC and biochemical capacity, which comprises all carbon metabolism after CO$_2$ enters through the stomata.

• Journal of Photoscience
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• 제9권2호
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• pp.332-334
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• 2002

We examined the effects of supplementary ultraviolet-B (UV-B) radiation on the changes in synthesis and degradation of ribulose-I, 5-biphosphate carboxylase /oxygenase (Rubisco) and light-harvesting chlorophyll a/b binding protein of PSII (LHCII), as well as mRNA levels for small and large subunits of Rubisco (rbcS and rbcL, respectively) and LHCII (cab) with leaf age in UV-sensitive rice (Norin I) and UV-resistant rice (Sasanishiki). Both Rubisco and LHCII were actively synthesized until the leaf had fully expanded, and then decreased with leaf age. Synthesis of Rubisco, but not LHCII, was significantly suppressed by UV-B in Norin 1. The degradation of Rubisco was enhanced by UV-B around the time of the leaf maturation in the two cultivars. The levels of rbcS and rbcL were reduced by UV-B at the early leaf stages after emergence in both cultivars. The level of cab was first present at the highest level in the two cultivars, but drastically decreased due to UV-B treatment immediately after leaf emergence in Norin 1. It was proved that synthesis and degradation of Rubisco and LHCII greatly changed with leaf age: Rubisco synthesis was significantly suppressed by supplementary UV-B radiation at the transcription step during the early leaf stages. It was also suggested that the difference between the two rice cultivars in sensitivity to UV-B in the synthesis of Rubisco might be due to the specific suppression not only after transcription but also at transcription.

• Journal of Ginseng Research
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• 제43권4호
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• pp.572-579
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• 2019

Background: Panax ginseng has been used in traditional medicine to strengthen the body and mental well-being of humans for thousands of years. Many elite ginseng cultivars have been developed, and ginseng cultivation has become well established during the last century. However, heat stress poses an important threat to the growth and sustainable production of ginseng. Efforts have been made to study the effects of high temperature on ginseng physiology, but knowledge of the molecular responses to heat stress is still limited. Methods: We sequenced the transcriptomes (RNA-Seq) of two ginseng cultivars, Chunpoong (CP) and Yunpoong (YP), which are sensitive and resistant to heat stress, respectively, after 1- and 3-week heat treatments. Differential gene expression and gene ontology enrichment along with profiled chlorophyll contents were performed. Results: CP is more sensitive to heat stress than YP and exhibited a lower chlorophyll content than YP. Moreover, heat stress reduced the chlorophyll content more rapidly in CP than in YP. A total of 329 heat-responsive genes were identified. Intriguingly, genes encoding chlorophyll a/b-binding proteins, WRKY transcription factors, and fatty acid desaturase were predominantly responsive during heat stress and appeared to regulate photosynthesis. In addition, a genome-wide scan of photosynthetic and sugar metabolic genes revealed reduced transcription levels for ribulose 1,5-bisphosphate carboxylase/oxygenase under heat stress, especially in CP, possibly attributable to elevated levels of soluble sugars. Conclusion: Our comprehensive genomic analysis reveals candidate loci/gene targets for breeding and functional studies related to developing high temperature-tolerant ginseng varieties.

• 한국식물학회:학술대회논문집
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• 한국식물학회 1987년도 식물생명공학 심포지움 논문집 Proceedings of Symposia on Plant Biotechnology
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• pp.63-79
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• 1987

Light regulates a variety of genes in higher plants. The expression of light-induced plant genes is regulated at the level of transcription via red- light photomorphogenic receptor, phytochrome, as well as unknown blue light photoreceptor(s). Ribulose-5-phosphate carboxylase/oxygenase (Rubisco) small subunit (SSB) and light harvesting chlorophyll a/b (Cab) protein are those of the best understood genes regulated by light. 5'-upstream flanking sequence (- -400) of Rubisco SSB and Cab genes sis known as a light responsive, enhance-like element. It responses to red and blue light in transgenic plant system as a tissue specific manner. Phytochrome gene is also regulated by light. In contrast to most of the light regulated plant genes, it is negatively controlled by red light. Search for the cis- and trans-acting factors responsible for the light signal is in progress to understant photomorphogenesis and development in higher plants.

• 한국농림기상학회지
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• 제2권4호
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• pp.167-174
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• 2000

광합성이 비교적 안정적인 자연광을 이용한 가스 노출 생장상을 사용하여 황금콩과 장엽콩 두 가지 콩 품종에 3일간 150 n1 1$^{-1}$의 농도로 오존을 처리한 후 잎에 나타나는 가시피해 뿐만 아니라 광합성, 기공 전도도, 엽록소 함량 등 생리적인 반응을 측정하였다. 잎에 나타난 가시피해는 기존의 보고와 마찬가지로 미세한 구릿빛 반점이었는데 장엽콩이 황금콩에 비해 빈번히 발생하였다. 하지만 오존 처리후 광합성은 황금콩에서 약 60%감소한 반면 장엽콩에서는 13%정도여서 황금콩의 오존 피해가 더 켰다. 오존으로 인한 콩잎의 광합성 감소 원인은 기공 전도도 감소에 따른 이산화탄소 공급량의 감소와 암반응의 동화효소인 rubisco의 활성저해로 설명이 가능하였다. 하지만 오존 처리로 인해 엽록소 함량 저해는 없었고, 가시피해의 면적도 전체 잎면적에 차지하는 비중이 미미하였으므로 이들은 광합성 감소 원인이 될 수 없었다. 한편, 오존 처리 완료 24시간 후에 광합성과 기공 전도도를 측정한 결과 24시간 전과 거의 비슷하므로 오존으로 인한 광합성 저해와 기공 닫힘의 변화가 하루만에 회복되지 않았다. 장엽콩은 무처리에서도 황금콩보다 광합성이 높았고, 오존 처리시 급격한 광합성 감소나 rubisco효소 활성도 크게 영향 받지 않았으며 다만 기공 전도도만 약간 낮아졌을 뿐이었다 이러한 생리적 결과로 미루어볼 때 장엽콩은 황금콩보다 오존에 저항성 품종이라 여겨진다. 비록 가시피해는 장엽콩에서 황금콩보다 빈번하게 발생되었지만 전반적인 생리적 피해는 황금콩에서 심각하므로 가시피해만으로 오존의 저항성, 감수성을 판단하는 것은 잘못된 것이다.

• The Plant Pathology Journal
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• 제16권3호
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• pp.151-155
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• 2000

A cDNA (Oslls1) encoding Lls1-homologue of maize was isolated from cDNA library of rice (Oryza sativa cv. Ilpum). The 2,138 bp of full length Oslls1 clone contains an open reading frame of 1,623 nucleotides encoding 575 amino acid residues. The deduced amino acid sequence of Oslls1 has a high level of homology with chlorophyll a oxygenases of Arabidopsis thaliana (67%) and Marchantia polymorpha (65%). Southern blot analysis of genomic DNA indicates the existence of a small gene family for Oslls1 in the rice genome. The expression of Oslls1 mRNA was induced in leaves and germinating seeds. Treatment of $H_2O$$_2$significantly down-regulated Oslls1 expression. The expression of Oslls1 mRNA was consititutively down-regulated in the blm, a rice mutant exhibiting spontaneous necrotic lesions. These results suggest that this Oslls1 gene may be involved incell death mechanisms in the blm mutant of rice.