• Journal of Plant Biotechnology
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• v.47 no.1
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• pp.26-39
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• 2020

In maize, immature embryos (IEs) are highly regenerative explants most suitable for producing high frequencies of plantlet regeneration in vitro. Apart from media, explants, and hormones, genotypic variation also influences in vitro characters to a great extent. In the present study, IEs were used to study the distinctive effect of variation of size/stage and hormones in different genotypes on five in vitro characters viz., frequency of callus induction, growth rate of total callus, frequency of E. callus induction, and volume and number of regenerated plantlets. LS medium with different concentrations of 2,4-D (0.5, 1.5, 2.5, 4.0 and 5.0 mg/L) were used to study the former four in vitro characters, and medium with 6-benzylaminopurine and kinetin (0.5 mg/L, each) was used for plantlet regeneration. IEs of 1.0, 1.5, 2.0, 2.5 and 3.0 mm in size were isolated from four inbred lines viz., NM74C, NM81A, NM5883 and NM5884. Two-way ANOVA revealed that explant size and genotypes, as well as hormonal concentrations showed significant effects on in vitro characters. Two millimeter IEs were found to be suitable for in vitro cultures. LS medium with 1.5 mg/L 2,4-D and LS with BAP and Kn (0.5 mg/L, each) were found to be the best hormonal concentrations for callus induction, maintenance, and regeneration, respectively. Among the four genotypes, NM81A and NM5883 yielded more non-embryogenic and Type I E. calli. In contrast, NM74C and NM5884 yielded more highly regenerative Type II calli. Inbred line NM5884 was found to be the best among these four genotypes.

• Korean Journal of Agricultural Science
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• v.44 no.2
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• pp.196-210
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• 2017

The synergistic effect on phosphate solubilization of single- and co-inoculation of two phosphate solubilizing bacteria, Burkholderia cepacia (C1) and Alcaligenes aquatilis (H6), was assessed in liquid medium and maize plants. Co-inoculation of two strains was found to release the highest content of soluble phosphorus (309.66 ?g/mL) into the medium, followed by single inoculation of B. cepacia (305.49 ?g/mL) and A. aquatilis strain (282.38 ?g/mL). Based on a plant growth promotion bioassay, co-inoculated maize seedlings showed significant increases in shoot height (75%), shoot fresh weight (93.10%), shoot dry weight (84.99%), root maximum length (55.95%), root fresh weight (66.66%), root dry weight (275%), and maximum leaf length (81.53%), compared to the uninoculated control. In a field experiment, co-inoculated maize seedlings showed significant increases in cob length (136.92%), number of grain/cob (46.68%), and grain weight (67.46%) over control. In addition, single inoculation of maize seedlings also showed improved result over control. However, there was no significant difference between single inoculation of either bacterial strains and co-inoculation of these two bacterial strains in terms of phosphate solubilization index, phosphorous release, pH of the media, and plant growth parameters. Thus, single inoculation and co-inoculation of these bacteria could be used as biofertilizer for improving maize growth and yield.

• Journal of Life Science
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• v.16 no.4
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• pp.699-703
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• 2006

Maize (Zea mays L.) is a monoecious plant, which separates male (tassel) and female (ear) floret that evolved into increasing heterogeneity. In each floret, male or female, bears both one pistil and three stamens primodia before diverged to unisexual state. When diverged to tassel, pistil cell death occurs in the pistil primodium, which is mediated by TASSELSEED genes. In contrast, cell protection occurs in the ear pistil from TASSELSEED-mediated cell death, which is mediated by SILKLESS1 gene. On the other hand, cell cycle arrest occurred for a long time in the ear stamens and then the stamens eventually dye. The cell cycle regulating genes such as CYCLIN B and WEE1 are involved in this process. Furthermore, the temporal and spatial regulation of gibberellin biosynthesis may cause cell cycle block in arresting stamen cells. This review describes the cell death, cell protection, and cell cycle arrest mechanism during maize sex determination process at the molecular, cellular and developmental biology, and genetic levels.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.2
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• pp.85-91
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• 2000

Antioxidant activity and related components including tocopherols, phenolic compounds and carotenoids in the corn(Zea mays L.) kernels were measured to understand effects of fertilizer application. Hybrids used were Chalok 2, a waxy corn, and Suwon 19, a dent corn. The standard fertilizer level of N-P-K was 14.5-3-6 for Chalok 2 and 17.4-3-6.9 for Suwon 19. The treatments of the fertilizer levels were the standard level, half and two fold amounts of N, P, and K, and no fertilizer. The antioxidant activity was determined by measuring electron donating ability. The antioxidant activity of Chalok 2 was higher than Suwon 19. The antioxidant activity was the highest at the standard fertilizer treatment for Chalok 2, but was statistically not significant. The antioxidant activity and the related compounds content in Suwon 19, however, were the highest in the two fold nitrogen treatment, and the differences were significant. The contents of tocopherols, phenolic compounds and carotenoids were 30.0~38.1, 104.7~118.8, $0.1{\mu}gml^{-1}$, respectively for Chalok 2 and 16.7~20.1, 59.9~72.7, $35.5{\sim}50.0{\mu}gml^{-1}$, respectively for Suwon 19. The antioxidant activity was positively correlated with the grain yield in both cultivars. The shorter the ASI the higher the yield of the plant. The difference in genetic factors would affect greater influence than fertilizer effect on the antioxidant activity of corn.

• Proceedings of the Korean Society of Life Science Conference
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• 2001.09a
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• pp.103-103
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• 2001

• Proceedings of the Korean Society of Crop Science Conference
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• 2001.05a
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• pp.240-241
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• 2001

• Proceedings of the Korean Society of Life Science Conference
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• 2000.09a
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• pp.24-24
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• 2000

• Proceedings of the Korean Society of Crop Science Conference
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• 2020.11a
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• pp.135-135
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• 2020

• Journal of Environmental Science International
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• v.19 no.12
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• pp.1323-1334
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• 2010

The effect of nitric oxide (NO) on antioxidant system and protective mechanism against oxidative stress under UV-B radiation was investigated in leaves of maize (Zea mays L.) seedlings during 3 days growth period. UV-B irradiation caused a decrease of leaf biomass including leaf length, width and weight during growth. Application of NO donor, sodium nitroprusside (SNP), significantly alleviated UV-B stress induced growth suppression. NO donor permitted the survival of more green leaf tissue preventing chlorophyll content reduction and of higher quantum yield for photosystem II than in non-treated controls under UV-B stress, suggesting that NO has protective effect on chloroplast membrane in maize leaves. Flavonoids and anthocyanin, UV-B absorbing compounds, were significantly accumulated in the maize leaves upon UV-B exposure. Moreover, the increase of these compounds was intensified in the NO treated seedlings. UV-B treatment resulted in lipid peroxidation and induced accumulation of hydrogen peroxide ($H_2O_2$) in maize leaves, while NO donor prevented UV-B induced increase in the contents of malondialdehyde (MDA) and $H_2O_2$. These results demonstrate that NO serves as antioxidant agent able to scavenge $H_2O_2$ to protect plant cells from oxidative damage. The activities of two antioxidant enzymes that scavenge reactive oxygen species, catalase (CAT) and ascorbate peroxidase (APX) in maize leaves in the presence of NO donor under UV-B stress were higher than those under UV-B stress alone. Application of 2-(4-carboxyphenyl)-4, 4, 5, 5-tetramethylimidazoline-1-oxyl-3- oxide (PTIO), a specific NO scavenger, to the maize leaves arrested NO donor mediated protective effect on leaf growth, photosynthetic pigment and free radical scavenging activity. However, PTIO had little effect on maize leaves under UV-B stress compared with that of UV-B stress alone. $N^{\omega}$-nitro-L-arginine (LNNA), an inhibitor of nitric oxide synthase (NOS), significantly increased $H_2O_2$ and MDA accumulation and decreased antioxidant enzyme activities in maize leaves under UV-B stress. This demonstrates that NOS inhibitor LNNA has opposite effects on oxidative resistance. From these results it is suggested that NO might act as a signal in activating active oxygen scavenging system that protects plants from oxidative stress induced by UV-B radiation and thus confer UV-B tolerance.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.5
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• pp.392-396
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• 2003

Maysin, a C-glycosylflavone, was isolated from the silks of maize, Zea mays L. The ESI mass spectrum indicates that molecular weight of maysin is $577\textrm{M}^+$m/z, and the ether-linked sugar is rhamnose, $431\textrm{M}^+$m/z (MW$^{+}$-146). The DPPH (1,1-Diphenyl-2-picrylhydrazyl) radical scavenging activity of maysin was higher than that of rutin. However, as compared with its aglycon luteolin, maysin showed the relatively moderate DPPH scavenging activity mainly due to the glycosylation of two sugars moieties, keto-fucose and rhamnose. In the in vitro cytotoxicity test against the five human tumor cell lines such as lung (A549), ovarian (SK-OV-3), melanoma (SK-MEL-2), central nerve system (XF-489), and colon (HCT-15), maysin exhibited the relatively weaker activities than cisplatin. The $\textrm{ED}_{50}$ values of maysin were 62.24, 43.18, 16.83, 37.22, and 32.09/$m\ell$, respectively. Result suggests that maysin is a potential cytotoxicity compound, particularly for human colon, central nerve system, and melanoma tumors.s.