• The Plant Pathology Journal
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• 제32권4호
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• pp.300-310
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• 2016

Pathogen infection in plants induces complex responses ranging from gene expression to metabolic processes in infected plants. In spite of many studies on biotic stress-related changes in host plants, little is known about the metabolic and phenotypic responses of the host plants to Pseudomonas cichorii infection based on image-based analysis. To investigate alterations in tomato plants according to disease severity, we inoculated plants with different cell densities of P. cichorii using dipping and syringe infiltration methods. High-dose inocula (${\geq}10^6cfu/ml$) induced evident necrotic lesions within one day that corresponded to bacterial growth in the infected tissues. Among the chlorophyll fluorescence parameters analyzed, changes in quantum yield of PSII (${\Phi}PSII$) and non-photochemical quenching (NPQ) preceded the appearance of visible symptoms, but maximum quantum efficiency of PSII ($F_v/F_m$) was altered well after symptom development. Visible/near infrared and chlorophyll fluorescence hyperspectral images detected changes before symptom appearance at low-density inoculation. The results of this study indicate that the P. cichorii infection severity can be detected by chlorophyll fluorescence assay and hyperspectral images prior to the onset of visible symptoms, indicating the feasibility of early detection of diseases. However, to detect disease development by hyperspectral imaging, more detailed protocols and analyses are necessary. Taken together, change in chlorophyll fluorescence is a good parameter for early detection of P. cichorii infection in tomato plants. In addition, image-based visualization of infection severity before visual damage appearance will contribute to effective management of plant diseases.

• ALGAE
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• 제39권1호
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• pp.17-30
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• 2024

Red macroalga Pyropia yezoensis is a high valuable cultivated marine crop. Its acclimation to cold stress is especially important for long cultivation period across winter in coasts of warm temperate zone in East Asia. In this study, the response of P. yezoensis thalli to low temperature was analyzed on physiology and transcriptome level, to explore its acclimation mechanism to cold stress. The results showed that the practical photosynthesis activity (indicated by Φ_PSII and qP) was depressed and pigment allophycocyanin content was decreased during the cold stress of 48 h. However, the F_v/F_m and non-photochemical quenching increased significantly after 24 h, and the average growth rate of thalli also rebounded from 24 to 48 h, indicating a certain extent of acclimation to cold stress. On transcriptionally, the low temperature promoted the expression of differentially expressed genes (DEGs) related to carbohydrate metabolism and energy metabolism, while genes related to photosynthetic system were depressed. The increased expression of DEGs involved in ribosomal biogenesis and lipid metabolism which could accelerate protein synthesis and enhance the degree of fatty acid unsaturation, might help P. yezoensis thallus cells to cope with cold stress. Further co-expression network analysis revealed differential expression trends along with stress time, and corresponding hub genes play important roles in the systemic acquired acclimation to cold stress. This study provides basic mechanisms of P. yezoensis acclimation to cold temperature and may aid in exploration of functional genes for genetic breeding of economic macroalgae.

• ALGAE
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• 제38권2호
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• pp.141-150
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• 2023

Light quality is a common environmental factor which influences the metabolism of biochemical substances in algae and leads to the response of algal growth and development. Pyropia yezoensis is a kind of economic macroalgae that naturally grows in the intertidal zone where the light environment changes dramatically. In the present study, P. yezoensis thalli were treated under white light (control) and monochromatic lights with primary colors (blue, green, and red) for 14 days to explore their physiological response to light quality. During the first 3 days of treatment, P. yezoensis grew faster under blue light than other light qualities. In the next 11 days, it showed better adaptation to green light, with higher growth rate and photosynthetic capacity (reflected by a higher rETR_max = 61.58 and E_k = 237.78). A higher non-photochemical quenching was observed in the treatment of red light than others for 14 days. Furthermore, the response of P. yezoensis to light quality also results in the difference of photosynthetic pigment contents. The monochromatic light could reduce the synthesis of all pigments, but the reduction degree was different, which may relate to the spectral absorption characteristics of pigments. It was speculated that P. yezoensis adapted to a specific or changing light environments by regulating the synthesis of pigments to achieve the best use of light energy in photosynthesis and premium growth and metabolism.

• 한국산림과학회지
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• 제99권6호
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• pp.922-928
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• 2010

겨울철 제설제로 사용되고 있는 염화칼슘($CaCl_2$)이 산벚나무(P. sargentii) 가로수에 미치는 영향을 조사하기 위해서, 염화칼슘 농도가 다른 수용액을 2회 처리 후 엽록소형광이미지와 광반응-광합성속도와 같은 광합성기구의 반응, 엽과 근원경 생장을 조사하였다. 3년생 산벚나무를 대상으로 개엽 전에 염화칼슘 0.5%(9 mM), 1.0%(18 mM), 3.0%(54 mM)를 2(1 L)회 뿌리둘레 부위에 처리하였다. 염화칼슘의 처리결과, 염화칼슘의 농도가 짙어짐에 따라 대조구에 비해 염화칼슘처리구의 총엽록소함량과 엽록소 a/b, 광합성속도, 양자수율, 암호흡이 감소하였다. 반면 광보상점은 염화칼슘의 농도가 높아짐에 따라 증가였다. 광합성과 양자수율, 암호흡, 광보상점과의 상관관계에서 양자수율과 광보상점에서 유의성이 나타났다(p<0.05). 한편, 최대형광($F_M$)과 최소형광($F_0$)의 차이인 Fv값의 형광이미지를 통해 빛을 이용하는 능력의 차이가 처리구와 대조구간에 확실하게 나타나는 것을 알 수 있었으며, 광계의 활성(Fv/$F_M$과 비광화학적 소멸(NPQ)의 처리 80일째 값이 모든 처리구에서 대조구에 비해 급격히 감소하였다. 이와 같은 결과로 염화칼슘 수용액에 의해서 산벚나무의 광합성, 동화기관 및 비대생장이 장애를 받고 있음을 알 수 있었다.