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4. Cell Wall Invertases from Maternal Tissues Modulate Sucrose Flux in Apoplastic Pathways During Rice Anther and Seed Development.

Author

Lee, Sang-Kyu, Shim, Su-Hyeon, Eom, Joon-Seob, Cho, Jung-Il, Kwak, Jae-Ung, Eom, Seong-Cheol, and Jeon, Jong-Seong

Subjects
RICE seeds, SEED development, MALE sterility in plants, PLANT development, CROP yields
Abstract

Efficient sucrose transport and metabolism are vital for seed and pollen development in plants. Cell wall invertases (CINs) hydrolyze sucrose into glucose and fructose, maintaining a sucrose gradient in the apoplast of sink tissues. In rice, two CIN isoforms, OsCIN1 and OsCIN2, were identified as being specifically expressed in the anthers but not in pollen. Functional analyses through genetic crosses and mutant characterization showed that oscin1/2 double mutants exhibit a sporophytic male-sterile phenotype and produce shrunken seeds. This suggests that CIN activity is essential for proper pollen development and seed formation in rice. Observation of the progeny genotypes and phenotypes from various genetic crosses revealed that the phenotype of oscin1/2 seeds is determined by the genotype of the maternal tissue, indicating the critical role of CIN function in the apoplast between maternal and filial tissues for sucrose transport and metabolism. The CIN activity in the anthers and seeds of wild-type rice was found to be significantly higher—over 500-fold in the anthers and 5-fold in the seeds—than in the leaves, highlighting the importance of CIN in facilitating the efficient unloading of sucrose. These findings suggest that the fine-tuning of CIN activity in the apoplast, achieved through tissue-specific expression and CIN isoform regulation, plays a key role in determining the carbohydrate distribution across different tissues. Understanding this regulatory mechanism could provide opportunities to manipulate carbohydrate allocation to sink organs, potentially enhancing crop yields. [ABSTRACT FROM AUTHOR]

Published
2024
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15. Changes in High School Teachers' Constructivist Philosophies.

Author

Cho, Jung-Il, Yager, Robert E., Park, Do-Yong, and Seo, Hae-Ae

Abstract

Reports on the evaluation of the effect of the University of Iowa's program on the development of teachers' constructivist philosophies by participating Korean inservice high school science teachers (n= 70). Concludes that the effect of the workshop was significant and that learning was retained. Contains 11 references. (Author/ASK)

Published
1997

17. Physiological Aspects of Germination and Early Seedling Establishment of Pleurotus sajor-caju Glyceraldehyde-3-Phosphate Dehydrogenase Expressing Transgenic Rice in Saline Environment

Author

Siddiqui, Zamin Shaheed, primary, Lee, Gang-Seob, additional, Cho, Woosuk, additional, Jeong, Mi-Jeong, additional, Park, Soo-Chul, additional, Kwon, Taek-Ryoun, additional, Zulfiqar, Faisal, additional, Umar, Muhammad, additional, Abideen, Zainul, additional, Uddin, Zaheer, additional, Ansari, Hafiza Hamna, additional, Wajid, Danish, additional, and Cho, Jung-Il, additional

Published
2022
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23. Role of the rice hexokinases OsHXK5 and OsHXK6 as glucose sensors

Author

Cho, Jung-Il, Ryoo, Nayeon, Eom, Joon-Seob, Lee, Dae-Woo, Kim, Hyun-Bi, Jeong, Seok-Won, Lee, Youn-Hyung, Kwon, Yong-Kook, Cho, Man-Ho, Bhoo, Seong Hee, Hahn, Tae-Ryong, Park, Youn-Il, Hwang, Ildoo, Sheen, Jen, and Jeon, Jong-Seong

Subjects
Rice -- Physiological aspects, Rice -- Genetic aspects, Mitochondria -- Chemical properties, Hexokinases -- Properties, Glucose metabolism -- Research, Biological sciences, Science and technology
Published
2009

32. Deficiency of rice hexokinase HXK5 impairs synthesis and utilization of starch in pollen grains and causes male sterility

Author

Lee, Sang-Kyu, Kim, Hyunbi, Cho, Jung-Il, Nguyen, Cong Danh, Moon, Sunok, Park, Jeong Eun, Park, Hye Rang, Huh, Jin Hoe, Jung, Ki-Hong, Guiderdoni, Emmanuel, Jeon, Jong-Seong, Lee, Sang-Kyu, Kim, Hyunbi, Cho, Jung-Il, Nguyen, Cong Danh, Moon, Sunok, Park, Jeong Eun, Park, Hye Rang, Huh, Jin Hoe, Jung, Ki-Hong, Guiderdoni, Emmanuel, and Jeon, Jong-Seong

Abstract

There is little known about the function of rice hexokinases (HXKs) in planta. We characterized hxk5-1, a Tos17 mutant of OsHXK5 that is up-regulated in maturing pollen, a stage when starch accumulates. Progeny analysis of self-pollinated heterozygotes of hxk5-1 and reciprocal crosses between the wild-type and heterozygotes revealed that loss of HXK5 causes male sterility. Homozygous hxk5-1, produced via anther culture, and additional homozygous hxk5-2, hxk5-3 and hxk5-4 lines created by CRISPR/Cas9 confirmed the male-sterile phenotype. In vitro pollen germination ability and in vivo pollen tube growth rate were significantly reduced in the hxk5 mutant pollen. Biochemical analysis of anthers with the mutant pollen revealed significantly reduced hexokinase activity and starch content, although they were sufficient to produce some viable seed. However, the mutant pollen was unable to compete successfully against wild-type pollen. Expression of the catalytically inactive OsHXK5-G113D did not rescue the hxk5 male-sterile phenotype, indicating that its catalytic function was responsible for pollen fertility, rather than its role in sugar sensing and signaling. Our results demonstrate that OsHXK5 contributes to a large portion of the hexokinase activity necessary for the starch utilization pathway during pollen germination and tube growth, as well as for starch biosynthesis during pollen maturation.

Published
2020

36. The effect of concurrent elevation in CO2 and temperature on the growth, photosynthesis, and yield of potato crops.

Author

Lee, Yun-Ho, Sang, Wan-Gyu, Baek, Jae-Kyeong, Kim, Jun-Hwan, Shin, Pyeong, Seo, Myung-Chul, and Cho, Jung-Il

Subjects
POTATO yields, CROP yields, TEMPERATURE control, ATMOSPHERIC carbon dioxide, PHOTOSYNTHESIS, HIGH temperatures, POTATOES
Abstract

Global climate change accompanied by continuous increases in atmospheric carbon dioxide (CO2) concentration and temperature affects the growth and yield of important crops. The present study investigated the effect of elevated temperature and CO2 concentrations on the growth, yield, and photosynthesis of potato (Solanum tuberosum L. cv. Superior) crops using Korean Soil-Plant-Atmosphere-Research chambers that allow the regulation of temperature and CO2 concentration under daylight conditions. Based on the average temperature from 1991 to 2010 in the Jeonju area, South Korea, potato plants were exposed to four different conditions: ambient weather (400 μmol mol-1, aCaT), elevated temperature (+4°C, aCeT), elevated CO2 concentration (800 μmol mol-1, eCaT), and concurrently elevated CO2 concentration and temperature (eCeT). Under aCeT conditions, the temperature exceeded the optimal growth temperature range towards the late growth phase that decreased stomatal conductance and canopy net photosynthetic rate and subsequently reduced biomass and tuber yield. Stomatal conductance and chlorophyll concentration were lower under eCaT conditions than under aCaT conditions, whereas late-growth phase biomass and tuber yield were greater. Compared to other conditions, eCeT yielded a distinct increase in growth and development and canopy net photosynthetic rate during tuber initiation and bulking. Consequently, biomass and canopy net photosynthesis increased, and tuber yield increased by 20.3%, which could be attributed to the increased tuber size, rather than increased tuber number. Elevated CO2 reduced chlorophyll, magnesium, and phosphorus concentrations; reducing nitrogen concentration (by approximately 39.7%) increased the C:N ratio. The data indicate that future climate conditions will likely change nutrient concentration and quality of crops. The present study shows that while elevated temperature may negatively influence the growth and yield of potato crops, especially towards the late-growth phase, the concurrent and appropriate elevation of CO2 and temperature could promote balanced development of source and sink organs and positively effect potato productivity and quality. [ABSTRACT FROM AUTHOR]

Published
2020
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37. An Investigation of Fifth and Eighth Grade Korean Students' Misconceptions of Photosynthesis.

Author

Cho, Jung-il

Abstract

Many researchers believe that prior knowledge is the single most important variable influencing learning. Learning in the classroom is determined or affected positively or negatively, to some degree, by the knowledge people bring to the classroom. This study was designed to: (1) assess fifth- and eighth-grade Korean students' misconceptions of concepts related to photosynthesis; and (2) investigate change in students' concept understanding as it related to logical reasoning ability, textbook emphasis and background variables. Results showed that students in both groups had misconceptions of concepts related to photosynthesis--the meaning of making food, the use of light by plants, the functions of plant roots and leaves, photosynthetic products, and requirements of elements. Reductions in misconceptions between grade 5 and grade 8 was on items regarding the use of light by plants, exchange of materials between organisms in a system, knowledge of glucose, protein, fat, and nitrogen, and the skill of reading a graph. Appendices include a concept map of photosynthesis, tests, the questionnaire used, variable labels, correlation matrices, and a comparative achievement analysis. (RT)

Published
1988

44. Evidence for a role of hexokinases as conserved glucose sensors in both monocot and dicot plant species

Author

Cho, Jung-Il, Ryoo, Nayeon, Eom, Joon-Seob, Lee, Dae-Woo, Kim, Hyun-Bi, Jeong, Seok-Won, Lee, Youn-Hyung, Kwon, Yong-Kook, Cho, Man-Ho, Bhoo, Seong Hee, Hahn, Tae-Ryong, Park, Youn-Il, Hwang, Ildoo, Sheen, Jen, and Jeon, Jong-Seong

Subjects
Mutant, Green Fluorescent Proteins, Molecular Sequence Data, Arabidopsis, Plant Science, Biosensing Techniques, Biology, Mitochondrion, Caulimovirus, Genes, Reporter, Hexokinase, Arabidopsis thaliana, Amino Acid Sequence, Psychological repression, Plant Proteins, Oryza sativa, Arabidopsis Proteins, fungi, food and beverages, Oryza, biology.organism_classification, Genetically modified rice, Article Addendum, Repressor Proteins, Glucose, Biochemistry, Nuclear localization sequence, Research Article
Abstract

The Arabidopsis (Arabidopsis thaliana) hexokinase 1 (AtHXK1) is recognized as an important glucose (Glc) sensor. However, the function of hexokinases as Glc sensors has not been clearly demonstrated in other plant species, including rice (Oryza sativa). To investigate the functions of rice hexokinase isoforms, we characterized OsHXK5 and OsHXK6, which are evolutionarily related to AtHXK1. Transient expression analyses using GFP fusion constructs revealed that OsHXK5 and OsHXK6 are associated with mitochondria. Interestingly, the OsHXK5DeltamTP-GFP and OsHXK6DeltamTP-GFP fusion proteins, which lack N-terminal mitochondrial targeting peptides, were present mainly in the nucleus with a small amount of the proteins seen in the cytosol. In addition, the OsHXK5NLS-GFP and OsHXK6NLS-GFP fusion proteins harboring nuclear localization signals were targeted predominantly in the nucleus, suggesting that these OsHXKs retain a dual-targeting ability to mitochondria and nuclei. In transient expression assays using promoterluciferase fusion constructs, these two OsHXKs and their catalytically inactive alleles dramatically enhanced the Glc-dependent repression of the maize (Zea mays) Rubisco small subunit (RbcS) and rice alpha-amylase genes in mesophyll protoplasts of maize and rice. Notably, the expression of OsHXK5, OsHXK6, or their mutant alleles complemented the Arabidopsis glucose insensitive2-1 mutant, thereby resulting in wild-type characteristics in seedling development, Glc-dependent gene expression, and plant growth. Furthermore, transgenic rice plants overexpressing OsHXK5 or OsHXK6 exhibited hypersensitive plant growth retardation and enhanced repression of the photosynthetic gene RbcS in response to Glc treatment. These results provide evidence that rice OsHXK5 and OsHXK6 can function as Glc sensors.

Published
2009

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