• Plant Breeding and Biotechnology
• /
• v.5 no.3
• /
• pp.204-212
• /
• 2017

There is a growing preference for using doubled haploids (DHs) in maize breeding programs because they reduce the time required to generate and evaluate new lines to 2 years or less. However, there is an urgent need for efficient techniques that accurately discriminate between haploid and diploid maize kernels. Here, we investigate the effects of several hormones and chemicals on the germination of haploid and diploid maize kernels, including auxin, cytokinin, ethylene, abscisic acid (ABA) biosynthesis inhibitor (fluridone), ABA catabolism inhibitor (diniconazole), methyl jasmonate (MeJA), and NaCl. Ethylene effectively stimulated the germination of both haploid and diploid maize kernels. The ABA biosynthesis inhibitor fluridone, the ABA catabolism inhibitor diniconazole, and MeJA selectively stimulated the germination of haploid maize kernels. By contrast, gibberellin, 1-naphthaleneacetic acid (NAA), kinetin, and NaCl inhibited the germination of both haploid and diploid maize kernels. These results indicate that the germination of haploid maize kernels is selectively stimulated by fluridone and diniconazole, and suggest that ABA-mediated germination of haploid maize kernels differs from that of diploid maize kernels and other plant seeds.

• Korean Journal of Breeding Science
• /
• v.40 no.3
• /
• pp.250-257
• /
• 2008

Knowledge of genetic diversity and of the genetic relationships among elite breeding materials has had a significant impact on the improvement of crops. In maize, this information is particularly useful in i) planning crosses for hybrid and line development, ii) in assigning lines to heterotic groups and iii) in plant variety protection. We have used the SSR technique to study the genetic diversity and genetic relationships among 76 Korean waxy corn accessions, representing a diverse collection from throughout Korea. Assessment of genetic diversity among members of this group was conducted using 30 microsatellite markers. Among these 30 microsatellite markers, we identified a total of 127 alleles (with an average of 4.2 and a range of between 2 and 9 alleles per locus). Gene diversity at these 30 microsatellite loci varied from 0.125 to 0.795 with an average of 0.507. The cluster tree generated with the described microsatellite markers recognized two major groups with 36.5% genetic similarity. Group I includes 63 inbred lines, with similarity coefficients of between 0.365 and 0.99. Group II includes 13 inbred lines, with similarity coefficients of between 0.45 and 0.85. The present study indicates that the 30 microsatellite loci chosen for this analysis are effective molecular markers for the assessment of genetic diversity and genetic relationships between Korean waxy corn accessions. Specifically, this study's assessment of genetic diversity and relationships between a set of 76 Korean waxy corn inbred lines will be helpful for such activities as planning crosses for hybrid and line development and association mapping analyses of maize breeding programs in Korea.

• Genomics & Informatics
• /
• v.18 no.3
• /
• pp.29.1-29.11
• /
• 2020

Maize seed pigmentation is one of the important issue to develop maize seed breeding. The differently gene expression was characterized and compared for three inbred lines, such as the pigment accumulated seed (CM22) and non-pigmented seed (CM5 and CM19) at 10 days after pollination. We obtained a total of 63,870, 82,496, and 54,555 contigs by de novo assembly to identify gene expression in the CM22, CM5, and CM19, respectably. In differentially expressed gene analysis, it was revealed that 7,044 genes were differentially expressed by at least two-fold, with 4,067 upregulated in colored maize inbred lines and 2,977 upregulated in colorless maize inbred lines. Of them,18 genes were included to the anthocyanin biosynthesis pathways, while 15 genes were upregulated in both CM22/5 and CM22/19. Additionally, 37 genes were detected in the metabolic pathway concern to the seed pigmentation by BINs analysis using MAPMAN software. Finally, these differently expressed genes may aid in the research on seed pigmentation in maize breeding programs.

• Plant Breeding and Biotechnology
• /
• v.7 no.3
• /
• pp.186-199
• /
• 2019

We selected 68 Chinese maize inbred lines to understand the genetic diversity, population structure, and marker-trait associations for eight agronomic traits and 50 simple sequence repeats (SSRs) markers. In this study, effective traits, such as days of anthesis (DA), days of silking (DS), ear height (EH), plant to ear height ratio (ER), plant height (PH), and leaf width (LW) were divided into PC1 and PC2 by PCA analysis for maize inbred lines. Genetic diversity analysis revealed a total of 506 alleles at 50 SSR loci. The mean number of alleles per locus was 10.12. The averages of genetic diversity (GD) and polymorphic information content (PIC) values were 0.771 and 0.743, respectively. Based on a membership probability threshold of 0.80, the population structure revealed that the total inbred lines were divided into three major groups with one admixed group. A marker-trait association using Q + K MLM showed that nine SSR markers (bnlg1017, umc2041, umc2400, bnlg105, umc1229, umc1250, umc1066, umc2092, and umc1426) were related with seven agronomic traits. Among these SSR markers, eight SSR markers were associated with only one agronomic trait (DA, DS, ER, LL, LW, PH, and ST), whereas one SSR marker (umc1229) was associated with two agronomic traits (DA and ST). These results will help in optimizing the choice of inbred lines for cross combinations, as well as in selecting markers for further maize breeding programs.

• Korean Journal of Breeding Science
• /
• v.43 no.5
• /
• pp.430-441
• /
• 2011

Maize is divided into two types based on the starch composition of the endosperm in the seed, normal maize(or non-waxy maize) and waxy maize. In this study, genetic diversity and population structure were investigated among 80 waxy maize and normal inbred lines(40 waxy maize inbred lines and 40 normal maize inbred lines) using 50 SSR markers. A total of 242 alleles were identified at all the loci with an average of 4.84 and a range between 2 and 9 alleles per locus. The gene diversity values varied from 0.420 to 0.854 with an average of 0.654. The PIC values varied from 0.332 to 0.838 with an average of 0.602. To evaluate the population structure, STRUCTURE 2.2 program was employed to confirm genetic structure. The 80 waxy and normal maize inbred lines were separated with based on the membership probability threshold 0.8, and divided into groups I, II and admixed group. The 13 waxy maize inbred lines were assigned to group I. The 45 maize inbred lines including 7 waxy maize inbred lines and 38 normal maize inbred lines were assigned to group II. The 22 maize inbred lines with 20 waxy maize inbred lines and 2 normal maize inbred lines were contained in the admixed group. The cluster tree generated using the described SSR markers recognized three major groups at 31.7% genetic similarity. Group I included 40 waxy maize inbred lines and 11 normal maize inbred lines, and Group II included 27 normal maize inbred lines. Group III consist of only 2 normal maize inbred lines. The present study has demonstrated the utility of SSR analysis for the study of genetic diversity and the population structure among waxy and normal maize inbred lines. The information obtained from the present studies would be very useful for designing efficient maize breeding programs in Maize Experiment Station, Kangwon Agricultural Research and Extension Services.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.59 no.3
• /
• pp.312-318
• /
• 2014

We evaluated the morphological characteristics of 156 maize inbred lines, which were developed to breeding normal maize variety at Maize Experiment Station, Gangwon Agricultural Research and Extension Services, by examining 11 quantitative and three qualitative characteristics. On the evaluation of three qualitative traits for 156 maize inbred lines, most inbred lines showed yellow (85 and 84 inbred lines) at tassel color (QL1) and silk color (QL2), and showed semi erect (105 inbred lines) at plant type (QL3). While, the evaluation of 11 quantitative traits for 156 maize inbred lines, they showed the morphological variation in days of tasseling (QN1, 56.5 to 76.0 days), days of silking (QN2, 59.0 to 85.5 days), stem thickness (QN3, 12.7 to 42.9 mm), plant height (QN4, 111.8 to 239.8 cm), ear height (QN5, 48.2 to 126.5 cm), 100 kernel weight (QN6, 14.9 to 36.4 g), ear length (QN7, 10.0 to 79.0 cm), setted kernel length (QN8, 8.0 to 70.5 cm), ear thickness (QN9, 4.0 to 22.0 cm), total kernel weight (QN10, 22.0 to 490.0 kg) and water content (QN11, 9.3 to 11.9%), respectively. As a result, 11 inbred lines (00hf3, 00hf19, 00hf30, 00hf36, 02S8069, 02S8072, 02S8090, 02S8099, 05S10011, 06S8085-6, 07S8011) in the 156 normal maize inbred lines have showed comparatively high values. While, the results of PCA (principal component analysis) indicated that the ear length (QN7), setted kernel length (QN8), ear thickness (QN9) and total kernel weight (QN10) greatly contributed in positive direction on the first principal components. And also, days of tasseling (QN1), days of silking (QN2), plant height (QN4) and ear height (QN5) contributed in negative direction on the second principal component. Thus these morphological characters, which were greatly contributed in the first and second principal components, might be considered to be useful for discrimination among 156 normal inbred lines. Specifically, this study's assessment of morphological characteristics of 156 normal inbred lines will be helpful useful for normal maize breeding programs such activities as planning crosses for hybrid and line development at Maize Experiment Station, Gangwon Agricultural Research and Extension Services.

• Korean Journal of Plant Resources
• /
• v.17 no.3
• /
• pp.304-313
• /
• 2004

This study was conducted to find out the scientific maize breeding protocol for developing high performing single cross hybrid using introduced U.S. elite inbred lines; the pattern of inheritance, heterosis and heritabilities of six agronomic traits were studied in the progenies derived from five crosses (Mo17/B14A, Va85/B73, C103/ND203, FR35/Oh43, Wf9/A632). Among the five cross combinations, the cross combination of Mo17/B14A showed the highest heterosis for the most agronomic traits. Among 6 agronomic traits, the grain yield showed the highest heterosis effect in most cross combinations. Most of the agronomic traits in this study showed more than 50% heritability for six cross combinations, with an exception of the ear length trait. In conclusion, since Mo17/B14A showed excellent performance for most of the agronomic traits, these inbred lines were desirable combination and regarded as superior germ plasm sources for F1 hybrid development. The results of current studies will be utilized for developing high performing single cross hybrid from maize inbred lines, and will be used for the further genetic analysis of agronomic traits and maize breeding programs.

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

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.48 no.4
• /
• pp.316-321
• /
• 2003

Analysis of breeding gains in grain yield has been intensively conducted in wheat, barley, oat, maize, and soybean. Such information is limited in rice. The objective of this study was to compare the breeding gains and cultural gains contributed to yield gains of Korean rice varieties since early 1900s. Two sets of yield data were used for analysis; the historical yield data of 1908 for old japonica cultivars, and present yield data in the years from 1996 to 1998 for the six cultivars, consisting of previous two old cultivars and four contemporary cultivars. The old cultivars were two native cultivars, Jodongi and Damageum, while contemporary cultivars were two premium quality japonica cultivars, Hwaseongbyeo and Dongjinbyeo, and two Tongil-type cultivars, high yielding cultivars developed from indica/japonica hybridization, Milyang23 and Dasanbyeo. The yield differences of old cultivars between the experiments in 1908 and the experiments from 1996 to 1998 were estimated as cultural gains (1.84 tons $\textrm{ha}^{-1}$) due to the improvement of cultivation technology. Yield differences between the old cultivars and contemporary cultivars were considered total yield gains during the periods. These were 2.51 tons $\textrm{ha}^{-1}$ for japonica cultivars and 3.81 tons $\textrm{ha}^{-1}$ for Tongil-type cultivars. From these data, the genetic gain of 0.67 tons $\textrm{ha}^{-1}$ and 1.97 tons $\textrm{ha}^{-1}$ were estimated for japonica cultivars and Tongil-type cultivars respectively. The ratio between cultural gain and genetic gain appeared to be 2.7:1 for japonica cultivars and 1:1 for Tongil-type cultivars. This analysis clearly showed the higher genetic contribution in Tongil-type cultivars than in japonica cultivars, suggesting a guideline to be used when planning new yield improvement programs. Additional implication has emerged when a better yield response to modem cultivation technology was found in one of the old cultivars, suggesting the combined improvement between breeding and cultural improvement is necessary for attaining the maximum yield capacity of a crop.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.58 no.3
• /
• pp.267-273
• /
• 2013

We evaluated the morphological characteristics of 79 popcorn inbred lines, which were developed to breeding popcorn variety at Maize Experiment Station, Gangwon Agricultural Research and Extension Services, by examining ten quantitative and three qualitative characteristics. In the survey of 3 qualitative traits for 79 popcorn inbred lines, most inbred lines respectively showed purple (46 inbred lines) at tassel color (QL1), green (55inbred lines) at silk color (QL2) and green (75 inbred lines) at stem color (QL3). While, on the survey of 10 quantitative traits among 79 popcorn inbred lines, they showed the morphological variation in plant height (QN1, $174.2{\pm}34.9$ cm), ear height (QN2, $103.4{\pm}24.7$ cm), ear length (QN3, $9.4{\pm}3.0$ cm), kernel setting length (QN4, $8.4{\pm}2.6$ cm), ear thickness (QN5, $24.9{\pm}7.7$ mm), ear row number (QN6, $14.0{\pm}2.3$ number), ear weight (QN7, $36.5{\pm}26.0$ g), kernel weight (QN8, $30.9{\pm}19.3$ g), 100 kernel weight (QN9, $10.4{\pm}3.8$ g) and germination rate (QN10, $95.3{\pm}8.1%$), respectively. As a result, 5 inbred lines (PS0-001, PS0-003, PS1-002, PS1-003, PS2-009) in the 79 popcorn inbred lines have showed comparatively high values for the five quantitative traits. On the principal component analysis, silk color (QL2), ear length (QN3), kernel setting length (QN4), ear thickness (QN5), ear weight (QN7), kernel weight (QN8) and 100 kernel weight (QN9) greatly contributed in positive direction on the first principal components, whereas tassel color (QL1), stem color (QL3), ear height (QN2) and ear row number (QN6) contributed in negative direction on the first principal component. In addition, plant height (QN1), ear height (QN2), and kernel weight (QN8) contributed in positive direction on the second principal component, and also tassel color (QL1), silk color (QL2), ear length (QN3), ear row number (QN6) and 100 kernel weight (QN9) contributed in negative direction on the second principal component.