• Journal of Plant Biotechnology
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• v.44 no.2
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• pp.142-148
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• 2017

Drought stress is one of the important factors that restrict the expansion of Hevea brasiliensis cultivation to non-traditional regions experiencing extreme weather conditions. Plants respond to drought stress by triggering expression of several drought responsive genes including transcription factors which in turn trigger expression of various downstream signalling pathways and adaptive networks. Expression of such drought responsive genes may revert back to their original level upon re-watering. However, no reports are available on such phenomenon in Hevea and hence, this study was initiated. For this purpose, NAC transcription factor (NAC tf) was chosen as candidate gene. Its expression levels were monitored under intermittent drought as well as irrigated conditions in two clones (RRII 105 and RRIM 600) of H. brasiliensis with contrasting tolerance level. Copy number of NAC tf was found similar in both the clones. Expression of NAC tf was found highly up-regulated in RRIM 600 (a relatively drought tolerant clone) than in RRII 105 (a relatively drought susceptible clone) throughout the drought incidences which upon re-watering, reached back to its original levels in both the clones. The study indicated the existence of an association between expression of NAC tf and drought tolerance trait exhibited by the tolerant clone RRIM 600. The study also proves the influence of drought and re-watering on the leaf photosynthesis and expression of NAC tf in H. brasiliensis.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.111-111
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• 2017

The development and productivity of maize (Zea mays L.) is frequently impacted by water scarcity, and consequently to increased drought tolerance in a priority target in maize breeding programs. To elucidate the molecular mechanisms of resistance to drought stress in maize, RNA-seq of the public database was used for transcriptome profiling of the seedling stage exposed to drought stress of three levels, such as moderate, severe drought stress and re-watering. In silico analysis of differentially expressed genes (DEGs), 176 up-regulated and 166 down-regulated DEGs was detected at moderated stress in tolerance type. These DEGs was increasing degradation of amino acid metabolism in biological pathways. Six modules based on a total of 4,771 DEGs responses to drought stress by the analysis of co-expression network between tolerance and susceptible type was constructed and showed to similar module types. These modules were discriminated yellow, greenyellow, turquoise, royalblue, brown4 and plum1 with 318, 2433, 375, 183, 1405 and 56 DEGs, respectively. This study was selected 30 DEGs to predicted drought stress response gene and was evaluated expression levels using drought stress treated sample and re-watering sample by quantitative Real-Time Polymerase Chain Reaction (qRT-PCR). 23 genes was shown increasing with drought stress and decreasing with re-watering. This study contribute to a better understanding of the molecular mechanisms of maize seedling stage responses to drought stress and could be useful for developing maize cultivar resistant to drought stress.

• Journal of Life Science
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• v.8 no.5
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• pp.557-562
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• 1998

This study was conducted to investigate the influence of soil moisture on the photosynthetic rate, transpiration rate, stomatal conductance, leaf water content and its any correlation in soybean. Followings were achieved as a conclusion. At the soil moisture was moved from drought condition to saturation condition, the photosynthetic rate, transpiration rate, stomatal conductance and leaf water content were gradually increased on the period of re-watering treatment. The recovery of photosynthetic rate was faster than others. There were positive correlation with the photosynthetic rate and leaf water content, the stomatal conductance and leaf water content, the photosynthetic rate and stomatal conductance respectively, but the correlation coefficient of photosynthetic rate and leaf water content was high.

• The Korean Journal of Mycology
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• v.3 no.1
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• pp.1-19
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• 1975

Since the importance of casing in fruit body formation of Agaricus bisporus has been emphasized, physico-chemical characteristics of casing materials were discussed by many workers and a mixture of peat and mineral soil as proper casing material has been adopted in many of mushroom growing countries. Because of limited resources of peat in Korea, it is necessary to find practical performance and substitutional materials for casing. The effect of casing on mycelial growth and mushroom yield of A. bisporus varied with materials, its combination and practices etc. The experiments to be discussed in this paper are concerned with pH and Ca of casing material which influence A bisporus, and changes of physico-chemical characteristics with mixing ratio of casing materials and its effect on A. bisporus. The optimum range of moisture content of each material, management of watering and application of physico-chemical characteristics casing materials was also investigated and re-use of weathered spent compost for casing material was described. 1. The effect of calcium on mycelial growth of A. bisporus at various pH in Halbschalentest showed different results with calcium sources. Best results were obtained around neutrality and fresh weight of fruit bodies grown in the range of pH 7 to 8 was highest among the tested levels. 2. Available moisture, pore space, organic matter, cation exchangeable capacity and exchangeable cation was increased by an increase of mixing ratio of peat in casing materials, while an adverse effect was obtained by addition of sand. 3. Mycelial growth on clay loam was more rapid at a lower bulk density of 0.75g/cc and at 20% moisture content on a dry weight basis at the same bulk density. 4. Mixing ratio of casing materials, 60 to 80 per cent by volume of peat mixed with 20 to 40 per cent of clay loam produced the highest yield of fresh fruit bodies and sand the lowest. However, per cent of open cap was highest in peat and lowest in sand. 5. Days required for fruit body initiation was shortened in mixtures of peat and clay loam by one to three days compared with other materials and the formation of flushes was clear. 6. The effect of some physico-chemical characteristics of casing materials on the fresh weight of fruit bodies were estimated by a multiple regression equation; Y=-923.86+$8.18X_1+8.04X_2+7.90X_3+0.12X_4+2.03X_5-0.82X_6-0.54X_7$ where $X_1,X_2,X_3,X_4,X_5,X_6,X_7$ are sand, silt, clay, available moistuer, porosity, organic matter and exchangeable cation respectively. The productivity of certain casing material could be predicted from this equation. 7. Fresh weight of fruit bodies was positively correlated with porosity exchangeable cation, organic matter, available moisture, silt and clay of materials; while sand was negatively correlated. On the contrary, sand was the unique factor reducing per cent of open cap. 8. Distribution of three phases of high productive casing material was concentrated in the range of 10 to 30 per cent solids, 15 to 30 per cent liquids, and 50 to 60 per cent in air volume. 9. Fresh weight of fruit bodies from peat was not affected with heavy watering but in clay loam and sandy loam severe crop losses occurred. Fresh weight of individual fruit was increased and open caps were decreased with heavy watering but light watering resulted in adverse effects: its effect was especially great in peat. 10. Optimum range of moisture content by weight on a dry basis was different with each casing material. To maintain optimum moisture content concerned with yield of fruit bodies and open cap, sandy loam and peat mixtures required daily watering of 0.6, 0.6 to 1. 2 and 1.2 to 2.4 liters per $3.3m^2$ of bed area, respectively. 11. Maximum yield of fruit body was recorded in the range of pF 2. 0 to 2. 5 of casing materials if organic matter content was below 4.2 per cent and in pF 1. 3 to 1.8 if above 7.1%. 12. pF curve of a certain casing material could be draws from moisture content at various pF values by multiple regression equations provided texture, organic matter and calcium of the casing material are given. Optimum moisture range of the casing materials also could be estimated by the equation. 13. It was possible to improve the phyico-chemical characteristics of clay loam and sandy loam by addition of weathered spent compost although the effect was less than in the case of peat. Fresh weight of fruit bodies wsa increased by addition of weathered spent compost but its effect was not as remarkable as peat. Accordingly, further studies will be required.

• Journal of Bio-Environment Control
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• v.18 no.2
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• pp.132-136
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• 2009

To investigate the effect of mycorrhiza on drought resistance and plant growth, Ardisia pusilla were colonized with arbuscular mycorrhiza (AM), Glomus spp. Host plants were cultured in a growth chamber for 30 days after colonization with AM. Water stress treatment was carried out by repeating five days off-watering and re-watering for 60 days. The growth of A. pusilla was enhanced by AM colonization compared to that of control, while the proline contents was significantly reduced in AM colonized plants compared to that of non-mycorrhizal plants. The inorganic nutrient contents i.e. Fe, Mn, Zn, and Cu in arbuscular mycorrhizal plants were higher than those of control.

• Korean Journal of Medicinal Crop Science
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• v.28 no.6
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• pp.412-420
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• 2020

Background: Measurement of chlorophyll fluorescence (CF) is useful for detection the ability of plants to tolerate environmental stresses such as drought, and excessive sunlight. Cnidium officinale Makino is highly sensitive to water stress and excessive sunlight. In this study, we evaluated the effect of soil water and shade treatment on the photosynthesis and leaf temperature change of C. officinale. Methods and Results: C. officinale was cultivated under uniform irrigation for 1 week drought stress (no watering) for 6 days. A significant decrease in CF was observed on the 5th day of withholding water (approximately 6% of soil water content) regardless of shading. Notably, the Rfd_lss parameter (CF decrease rates) with and without shade treatment was reduced by 73.1% and 56.5% respectively, at 6 days compared with those at the initial stage (0 day). The patterns of the degree of CF parameters corresponded to those of the soil water content and difference between leaf temperature (Ts) and air temperature (Ta). Meanwhile, CF parameters recovered to the 3 - 4 days levels after re-watering, while the soil water potential was completely restored. The suitable soil water content for C. officinale optimal growth was between -5 kPa and -10 kPa in this experiment. Conclusions: Lack of soil water in the cultivation of C. officinale, even with shading, decreased latent heat cooling through transpiration. As a result, heat dissipation declined, and the plant was subjected to drought stress. Soil water content plays a major role in photosynthesis and leaf temperature in C. officinale.

• BMB Reports
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• v.46 no.1
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• pp.31-36
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• 2013

Heat shock proteins play an important role in plant stress tolerance and are mainly regulated by heat shock transcription factors (Hsfs). In this study, we generated transgenic rice over-expressing OsHsfA7 and carried out morphological observation and stress tolerance assays. Transgenic plants exhibited less, shorter lateral roots and root hair. Under salt treatment, over-expressing OsHsfA7 rice showed alleviative appearance of damage symptoms and higher survival rate, leaf electrical conductivity and malondialdehyde content of transgenic plants were lower than those of wild type plants. Meanwhile, transgenic rice seedlings restored normal growth but wild type plants could not be rescued after drought and re-watering treatment. These findings indicate that over-expression of OsHsfA7 gene can increase tolerance to salt and drought stresses in rice seedlings.

• Korean Journal of Environmental Biology
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• v.39 no.4
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• pp.536-541
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• 2021

Pantala flavescens is a dominant Odonata species in the rice fields in Korea. To determine the effects of different temperatures on its larval growth and emergence, field and laboratory experiments were conducted. Larval growth was also monitored in mono-cropping and double-cropping rice fields. The growth of larvae was monitored every week by measuring the head width. In the field experiment, no difference was found in larval growth and emergence between the control temperature and +1.9℃ of the control temperature. The larval growth was greater at 23℃ than at 20℃ laboratory temperatures, and no emergence was recorded at either temperature after eight weeks of monitoring. There was a quadratic relationship between larval growth and temperature in an incubator at five temperature regimes of 15, 20, 25, 30, and 35℃. Midseason water drainage caused the extinction of the existing individuals and newly hatched larvae dominated after re-watering in the rice fields. Larval size was greater in double-cropping fields than in mono-cropping fields in late July but the tendency was reversed in early August. The results of this study suggest that temperature warming will directly promote the larval growth of P. flavescens and indirectly influence seasonal growth via changes in water management in rice fields.

• Journal of Plant Biotechnology
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• v.43 no.3
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• pp.376-382
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• 2016

DNA methylation regulations gene expression, thus having pivotal roles in a myriad of physiological and pathological processes. In this study, the morphology and stress tolerance of transgenic rice overexpressing NtROS2a were determined. Transgenic plants exhibited less and shorter lateral shoots. Under various treatments, rice overexpressing NtROS2a showed alleviation of damage symptoms with higher survival rate. After drought and re-watering treatment, transgenic rice seedlings restored their normal growth. However, wild type plants could not be rescued. These findings indicate that overexpression of NtROS2a gene in rice seedlings can increase their tolerance to drought stresses.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.4
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• pp.432-440
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• 2019

Global climate change exerts adverse effects on maize production. Among abiotic stresses, drought stress during the tasseling stage (VT) can increase anthesis-silking intervals (ASI) and decrease yield. We performed an evaluation of ASI and yield using a drought-sensitive line (Ki3) and a drought-tolerant line (Ki11) to analyze the correlation with ASI and yield. Moreover, the de novo data of Ki11 were analyzed to find putative novel transcripts related todrought stress in tropical maize. A total of 182 transcripts, with a log2 ratio >1.5, were found by comparing drought conditions to a control. The top 40 transcripts of high expression levels in the de novo analysis were selected and analyzed with PCR. Of the 40 transcripts, six novel transcripts were detected by quantitative real-time PCR (qRT-PCR) using seedling and VT stage samples. Five transcripts (transcripts_1, 12, 34, 35, and 40) were up-regulated in the Ki11 shoot at seedling stage, and transcripts_1, 12, and 40 were up-regulated at the re-watering stage after 12 h of drought stress. The transcripts_32 and 34 were up-regulated at the VT stage. Hence, transcript_34 possibly plays a significant role in drought tolerance during the seedling and VT stages. The transcript_32 was identified as chloramphenicol acetyltransferase (CAT) by Pfam domain analysis. The function of the other transcripts remained unknown. Further characterization of these novel transcripts in genetic regulation will be of great value for the improvement of maize production.