• Proceedings of the Korean Society of Crop Science Conference
• /
• 2017.06a
• /
• pp.161-161
• /
• 2017

Seed endophytes are very remarkable groups of bacteria for their unique abilities of being vertically transmitted and conserved. As plants attain hybrid vigor and heterosis in the process of crossbreeding, this might also lead to the changes in the community structure and diversity of plant endophytes in the hybrid plants ultimately affecting the endophytes of the seeds. It would be interesting to characterize how seed endophyte composition change over time. The objective of this study is to gain insights into the influence of natural crossbreeding and parental lineage in the seed bacterial endophytic communities of two pure inbred lines exploring contributions of the two most important sources of plant endophytes - colonization from external sources and vertical transmission via seeds. Total genomic DNA was isolated from rice seeds and bacterial DNA was selectively amplified by PCR. The diversity of endophytic bacteria was studied through Terminal-Restriction Fragment Length Polymorphism (T-RFLP) analysis. Diversity between the original parents and the pure inbred line may show significant differences in terms of richness, evenness and diversity indices. Heat maps reveal astonishing contributions of both or either parents (IR29 ${\times}$ Pokkali and AT401 ${\times}$ IR31868) in the shaping of the bacterial seed endophytes of the hybrid, FL478 and IC32, respectively. Most of the T-RFs of the subsequent pure inbred line could be traced to any or both of the parents. Comparison of common and genotype-specific T-RFs of parents and their offspring reveals that majority of the T-RFs are shared suggesting higher transmission of bacterial communities common to both parents. The parents influence the bacterial community of their offspring. Unique T-RFs of the offspring also suggest external sources of colonization particularly as the seeds are cultivated in different ecogeographical locations. This study showed that host parental lines contributed greatly in the shaping of bacterial seed endophytes of their offspring. It also revealed transmission and potential conservation of core seed bacterial endophytes that generally become the dominant microbiota in the succeeding generations of plant hosts.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.14
• /
• pp.123-131
• /
• 1973

1. In order to evaluate the performance of the $F_2$ and $F_3$ generations of $F_1$ varietal crosses which in past trials yielded better than or as high as the recommended double-cross hybrids, eleven yellow and five white-endosperm $F_1$ varietal crosses, their $F_2$ and $F_3$ generations, and the parental open-pollinated varieties together with the standard double-cross hybrids were tested in performance trials in the 1963 wet and 1963-64 dry seasons. The former trials, however, failed due to a strong typhoon that damaged the crop. 2. Net hybrid vigor was highly manifested in grain yield in the $F_1$ varietal crosses, which on the average was 39.9 per cent of the mid-parent yields. Reduction in heterosis was 27.2 per cent in the $F_2$and 30.3 per cent in the $F_3$ generation, respectively. 3. A fairly high degree of reduction in yield occurred in the $F_2$ and $F_3$ generation. On the average, the $F_2$ generation decreased by 17.6 per cent and the $F_3$ by 20.7 per cent. The losses in two generations were exhibited in two levels; four crosses decreased by 10.9 per cent and twelve combinations by 22.0 per cent. The advanced generations of one yellow cross, Cuban Yellow Flint ${\times}$ Hawaiian Flinty Dent, and three white flint crosses, Bicol White Flint ${\times}$ Eto Blanco, College White Flint ${\times}$ Eto Blanco and Bicol White Flint ${\times}$ Nariono 330b, yielded as high as Philippine Hybrid No.1 and Philippine Hybrid No.4, respectively. 4. No significant differences in yield were obtained between the $F_2$ and $F_3$ populations, showing that genetic equilibrium was reached in $F_2$, as may be expected in view of the Hardy-Weinberg law on panmixis. 5. As in past trials, Hawaiian Flinty Dent, a variety, yielded as high as Philippine Hybrid No. 1.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.49 no.5
• /
• pp.373-380
• /
• 2004

The production of sweet (su) and super sweet corns (sh2) has been economically feasible in Korea in recent years. Major factors limiting super sweet corn production are low germination and low seedling vigor. Since seed quality is closely related to seed maturity, the optimum harvest time for the seed production of sweet and super sweet corns was studied and the quality of seeds with varying maturities was investigated in 2001 and 2002 cropping seasons. The parents of the sweet corn seeds were Hybrid Early Sunglow and 'Golden Cross Bantam 70' and those of super sweet corn were Xtrasweet 82 and 'For­tune'. Seeds were harvested at 21, 28, 35, 42, 49, and 56 days after silking (DAS). As the seeds developed, seed weight of sweet corn increased and the seed moisture content decreased faster than that of super sweet corn. Germination rates of sweet corn seeds harvested 21 and 28 DAS at $25^{\circ}C$ and emergence rates in the cold soil test were significantly lower than those of seeds harvested after 42 DAS in both years. Although the germination rates of super sweet corn seeds with varying maturities showed similar patterns as sweet corn seeds at $25^{\circ}C$, the emergence rate of super sweet corn seeds in cold soil test continuously increased with seed maturity. This suggests that seed quality of super sweet corn should be tested in a cold soil test to estimate field emergence. As the seeds developed, leakage of total sugars and electrolytes from the both sweet and super sweet corn seeds decreased up to 42 or 49 DAS. The $\alpha-amylase$ activities of both sweet and super sweet corn seeds increased with seed maturity from 21 to 35 or 49 DAS depending on genotype and year. The optimum harvest time for the seed production of sweet corn was 42 DAS and 49 DAS for super sweet corn considering emergence rate and plumule dry weight in the cold soil test, leakage of sugars and electrolytes from the seeds, and $\alpha-amylase$ activity.

• Journal of Korean Society of Forest Science
• /
• v.69 no.1
• /
• pp.19-27
• /
• 1985

Introgressive hybridization of Pinus densiflora in Korea was investigated by examining the position of resin ducts in 4,992 trees from 67 populations. Judging that P. densiflora has only external resin ducts, P. thunbergii only medial resin ducts, and any tree which has even one needle with external and medial resin ducts is hybrid, hybrids are found at all populations investigated. As variation in position of resin ducts was found among needles on a tree, the number of needles investigated from a tree affects judgment of the tree's hybridity. Therefore, hybridity seems to be judged by many traits rather than by the single trait, position of resin ducts. Seed production by artificial pollination between P. densiflora and P. thunbergii was very poor, i.e. one full seed from five female flowers or from two mature cones. This poor seed production, in addition to the low hybrid vigor, if any, seems to make the artificial pollination between the two species for mass-production of seeds for planting impractical.

• Journal of Life Science
• /
• v.12 no.3
• /
• pp.256-263
• /
• 2002

This study was carried out to estimate the degree of heterosis and heterobeltiosis, and the heritability and genetic correlation in F$_1$hybrid produced by reciprocal crosses between two six-rowed hulled barley (Gangbori and Olbori) and three six-rowed naked barley (Saechalssalbori, Saessalbori, and Moodeongssalbori). Heterosis was observed positively in traits such as cults length, spike length, awn length, leaf length, leaf width, number of spikes per plant, number of grains per spike, and 1000 grain weight. Heterosis and heterobeltiosis from the crosses with hulled barley as a material parent showed higher performance in culm length, leaf length, leaf width, number of spike per plant, number of grains per spike. The hulled grain characteristics is dominant over the naked one. The highest heritability was confirmed in leaf width with a value of 94.5% and overall high heritability was observed in most traits with the range from 76.7% to 94.5%. In an analysis of correlation coefficient, higher genetic correlations were observed between leaf length and number of spikes per plant(0.970), between cults length and number of grains per spike(0.963), and between awn length and leaf length(0.862) in the forward crosses in which hulled barley was maternal. In the reverse crosses, higher genetic correlation was observed between culm length and spike length(0.926), between awn length and leaf length(0.922), and between number of spikes per plant and number of grains per spike(0.713).

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.60 no.2
• /
• pp.190-196
• /
• 2015

We evaluated the morphological characteristics in 100 super sweet corn inbred lines, which were developed to breeding super sweet corn variety at Gyeongsangbuk-do Agricultural Research and Extension Services, by examining six quantitative and two qualitative characteristics. On the result of evaluation of two qualitative traits, most of inbred lines showed yellow (91 inbred lines) at seed color (QL1) and weak (68 inbred lines) at seedling vigor (QL2). In the survey of six quantitative traits, the average value for each trait indicated as follows: days of tasseling (QN1, 41.0 to 55.0 days), days of silking (QN2, 44.0 to 59.0 days), anthesis-silking interval (QN3, 2.0 to 7.0 days), tillering (QN4, 0.0 to 2.0), plant height (QN5, 96.0 to 187.0 cm) and ear height (QN6, 30.0 to 86.0 cm). In PCAs (principal component analysis) for 8 morphological characteristics, seedling vigor (QL2) and tillering (QN4) greatly contributed in negative direction and the days of tasseling (QN1) and days of silking (QN2) greatly contributed in positive direction on the first principal component. While, ear height (QN6) and plant height (QN5) contributed in positive direction on the second principal component. Thus these morphological traits, which were greatly contributed in the first and second principal components, might be considered to be useful for discrimination in 100 super sweet corn inbred lines. In our study, the results of morphological variation and PCAs for 100 super sweet corn inbred lines will be helpful for super sweet corn breeding programs such activities as planning crosses for hybrid and line development.

• Horticultural Science & Technology
• /
• v.33 no.3
• /
• pp.443-447
• /
• 2015

Fragaria ${\times}$ ananassa (Duch.) cultivars, 'Wongyo 3 115' a nd 'Wongyo 3 116', we re bre d as a n inte rme diate parent l ine using heterosis of $F_1$ hybrids in octoploid strawberry. These two new cultivars were developed as inbred lines ($S_9$ generation) propagated from both seed and runners/stolons. 'Wongyo 3115', an inbred line derived from the 'Benihoppe' cultivar, has a semi-upright plant shape showing a vigorless growth habit, weaker than the original 'Benihoppe' cultivar; it has early flower bud differentiation and produces 10 flowers per cluster when grown from healthy seed. 'Wongyo 3115' has low yields of conical type fruit with pink colored skin; average fruit weight is approximately 11 g. The important characteristic of 'Wongyo 3115' is its excellent fruit firmness, firmer than the original variety. 'Wongyo 3116', an inbred line derived from the 'Doyonoka' cultivar, has an upright plant shape, vigorless growth habit, weaker than that of the original 'Doyonoka' cultivar; it has early flower bud differentiation and produces 8 flowers per cluster when grown from healthy seed. 'Wongyo 3 116' has oblate type fruits with red skin and an ave rage weight of approximately 12 g. The important characteristics of 'Wongyo 3116' are excellent fruit shape and higher yield than other inbred lines, although it produces small fruits compared to the original cultivar. Both cultivars have excellent taste, high sugar/acid ratio, and good texture. In regards to disease and pest resistance, 'Wongyo 3115' and 'Wongyo 3116' have a tendency to be sensitive to powdery mildew, anthracnose and the two-spotted spider mite.

• Korean Journal of Agricultural Science
• /
• v.34 no.2
• /
• pp.119-123
• /
• 2007

Germination ratio on the 300 collected genetic resources showed 80 to 100 percentage, but those of some accessions were very low as below 30 percentage. Early growth phase of most of these lines were very poor while some collected lines were very vigor. Range of stem height showed from 150 to 199cm, but that of some accessions showed below 100cm as five percentage and some of them was over 250cm as eight percentage. Number of tillers per plant appeared less one but some collected lines have two to three tillers per plant. In days to tasseling, some accessions showed more four per plant. Ear length of these accession showed above 60 percentage as 11 to 15cm, while that of some collected lines showed over 10 percentage as 16 to 20cm.

• Journal of Korean Society of Forest Science
• /
• v.51 no.1
• /
• pp.1-21
• /
• 1981

Populus glandulosa and Populus tomentiglandulosa, which were known to be natural hybrids, were examined for morphological, physiological and karyological traits to illucidate its hybridity and taxonomical importance. The results abtained were as follows; 1. Survival rate in rooting of cuttings and grafting was different between the hybrids and their rooting abilities showed incomplete dominance. 2. Their leaf openings showed incomplete dominance. The leaf longevities of P. alba ${\times}$ glandulosa and P. tomentiglandulosa were stronger than the other hybrids. 3. There were differences in resistance to toxicity of $KClO_3$ between the hybrids. 4. Many external leaf characters of the hybrids also showed incomplete dominance. P. tomentiglandulosa was similar in those characters to P. alba ${\times}$ glandulosa while P. glandulosa was similar to hybrids crossed, reciprocally crossed or back-crossed between P. davidiana and P. alba. 5. Their numbers of male flower showed incomplete dominance or hybrid vigor. The numbers of P. tomentiglandulosa were similar to thosa of P. alba ${\times}$ glandulosa while those of P. glandulosa to those of P. alba ${\times}$ davidiana or P. davidiana ${\times}$ alba. 6. Morphology and band color of male catkin bract showed incomplete dominance. Those of P. glandulosa were similar to those of P. alba ${\times}$ davidiana while those of P. tomentiglandulosa to those of. P. alba ${\times}$ glandulosa. 7. There were differences in vascular bundle number and arrangement of petiole between the hybrids. 8. Differences in the anatomical traits of stem did not exist between the hybrids but those in wood fiber size existed. 9. The chromosomes of artificial hybrids, P. glandulosa and P. tomentiglandulosa showed irregular behavior in metaphase I and II. 10. All hybrids including P. glandulosa and P. tomentiglandulosa showed small number of P.M.C. with 19 II but many univalent chromosomes were exhibited in metaphase I. 11. All hybrids including P. glandulosa and P. tomentiglandulosa showed a little abnormal nuclear plates as laggard chromosome and chromosome bridge in anaphase I and II. 12. The frequency of pollen tetrad and fertile pollen was low in most of the hybrids including P. glandulosa and P. tomentiglandulosa.

• Journal of Sericultural and Entomological Science
• /
• v.26 no.1
• /
• pp.25-29
• /
• 1984

Since 1966, practical use of active heavy analogs of the hormones has been also worked out as an insecticide and brought the features of it to the light as cocoon producer. On the other hand, it is expected to afford the increase of silk productivity resulted from control of the fifth larval period by delaying normal development. With these regards, some of analogs have been tried to apply practically to the silkworm for an increase of cocoon productivity. One of the synthesized juvenile hormone available is "Manina". And it is presently used for the increase of silk productivity in Korea. For the practical use, it is very essential the varietal differences in the increase of silk productivity by topical application was tested and the obtained results are summarized as follows. 1. It was evident that the fifty larval period was extended by topical application after 48 hrs. of the last ecdysis, ranging from 8 hrs. to one day, as compared to the control. 2. In pupal rates, there is no significance between control and treatments. It proved that there was no toxicity to silkworm by topical application in general, except jam 120. With regards to an increase of cocoon yield in Japanese, it was resulted from 17∼24% of cocoon yield from 10,000 larvae, as compared to that of control. In case of Chinese, the incrasing rates were varied from 15∼26% of cocoon yield, 17.8kg of it with 26% increase for Jam 122 and 16.7kg of it with 25% increase for Jam 118. In case of all hybrids, an increase of the cocoon yield took places from 20% to 31% and the weight of cocoon layer for the Japanese increased by 6 to 14%, those for the Chinese by 4 to 7% and those for the hybrids ranged from 21 to 29% increase. 3. It was recognized that the hybrid vigor rate took places with the hybrids between high responsing parents to juvenile hormones.