Ja-Hwan Ku

Sequence Information on Simple Sequence Repeats and Single Nucleotide Polymorphisms through Transcriptome Analysis of Mungbean

Mungbean (Vigna radiata (L.) Wilczek) is a unique species in its ability to fix atmospheric nitrogen, with early maturity, and relatively good drought resistance. We used 454 sequencing technology for transcriptome sequencing. A total of 150 159 and 142 993 reads produced 5 254 and 6 374 large contigs (≥ 500 bp) with an average length of 833 and 853 for Sunhwa and Jangan, respectively. Functional annotation to known sequences yielded 41.34% and 41.74% unigenes for Jangan and Sunhwa. A higher number of simple sequence repeat (SSR) motifs was identified in Jangan (1 630) compared with that of Sunhwa (1 334). A similar SSR distribution pattern was observed in both varieties. A total of 8 249 single nucleotide polymorphisms (SNPs) and indels with 2 098 high-confidence candidates were identified in the two mungbean varieties. The average distance between individual SNPs was approximately 860 bp. Our report demonstrates the utility of transcriptomic data for implementing a functional annotation and development of genetic markers. We also provide large resource sequence data for mungbean improvement programs.

Inheritance and Quantitative Trait Loci Analysis of Resistance Genes to Bruchid and Bean Bug in Mungbean ( Vigna radiata L. Wilczek)

Bruchid (Callosobruchus chinenesis L.) and pod sucking bug (Riptortus clavatus Thunberg) are serious insect pests during the reproduction stage and seed storage period of legume crops worldwide. However, few sources of resistance to each of these insects have been identified and characterized, and no genetic studies have been carried out with simultaneous tests of these two insects. In this study, the inheritance of seed resistance to Callosobruchus chinenesis L. and Riptortus clavatus Thunberg was examined in a mungbean cultivar, Jangan mungbean, which was developed by backcrossing with the V2709 resistant donor. The F1, F2, and F3 seed generations were developed from the cross between susceptible and resistant parents, and evaluated for resistance to the two insects. It was found that resistance to bruchid and bean bug was controlled by a single dominant gene in the F1 and F2 seeds. However, the segregation pattern of reciprocal reaction to each insect in F2 seeds showed seeds were susceptible to each insect. These results suggest that the resistance genes in Jangan mungbean to bug and weevil are either different or closely linked with each other. A genetic linkage map 13.7 cM in length with 6 markers was successfully constructed. Two QTLs were identified for bruchid resistance, and a QTL for bean bug resistance was detected. One of the QTLs for resistance to bruchid was shared with the QTL for bean bug. These newly developed closely linked markers will be used for cloning of the resistance genes to bruchid and bean bug in the future.

Effects of Water-soaking and Mechanical and Chemical Scarifications on Seed germination of Hairy Vetch (Vicia villosa Roth)

Seed coat of hairy vetch is very thick and hard, and difficult to absorb water during germination. It requires much time that cotyledon comes out from seed coat. Therefore this experiment was carried out to increase the germination rate by enhancing water absorption through water-soaking of seed, chemical scarification by sulfuric acid, and mechanical scarification on seed coat. Water-soaking for 5 hours seemed to be highly effective in enhancing germination rate. Although not significant, water-soaking resulted in increase of germination rate by 9%. Effect of soaking temperature was not significant, but early germination rate was increased to be 5.0%, 31.7% and 48.3% at , and , respectively. Mechanical scarification of seed coat led to a germination rate of 97% whereas intact seed showed that of 65%. Chemical scarification by sulfuric acid for 10min, 20min and 30min resulted in a germination rate of 76.7%, 74.7% and 96.0% respectively. It is clear that scarification increased germination rate.

Change of Seed Yield, Germination Rate and Hard Seed Rate with Harvest Time in Hairy Vetch (Vicia villosa Roth)

This experiment was conducted to investigate an optimum harvest time for hairy vetch (HV) seed production. The seeds were harvested at 5 times, 35, 42, 48, 54, and 58 days after flowering (DAF) in 2009 and 2010. In 2011, 3 times of harvest, 39, 49, and 53 DAF were done at Suwon, middle part of Korea. HV plants were harvested and threshed by manually at each time. Seed yield, yield components, germination rate, hard seed rate, and viviparous germination rate were investigated. The highest seed yield represented 54 DAF in 2009, 42 DAF in 2010, and 49 DAF in 2011. When the triticale, HV support plant, comes to early lodging, the time of highest yield was delayed. 1,000-seed weight linearly increased from 35 DAF to 54 DAF. The later harvested seed showed a trend of increasing germination and hard seed ratio. However, viviparous germination had occurred because of in rainy season. In conclusion, it was presumed that an optimum harvest time for safe seed production in HV should be during 42 DAF ~ 54 DAF before the rainy season considering seed yield, 1,000-seed weight and germination.

A New High Grain Yielding Forage Rye Cultivar, “Seedgreen”

“Seedgreen” (Secale cereal L.), a new rye cultivar was developed by National Institute of Crop Science (NICS), RDA in 2013. It was developed from an open pollination from within 10 rye varieties or lines including “Chochun” in 1995. The line “SR95POP-S1-140-9-1-3-7-5-3” was selected for its excellent agronomic appearance, and was placed in yield trials for three years from 2008 to 2010. The new cultivar was designated “Homil50” and was placed in regional yield trials at the five locations around Korea from 2011 to 2013, during which time the name “Seedgreen” was given. This cultivar is an erect plant type and of a long size, with a dark-green leaf color, a yellowish-white colored, medium-diameter culm, and a brown-colored, medium-size grain. The heading and maturation dates of Seedgreen were April 22 and June 16, which were 3 days and 2 days earlier than that of “Gogu”, respectively. Seedgreen also showed better winter hardiness and a greater resistance to lodging and wet injury compared to those of the check cultivar. Over three years, the average dry matter yield of Seedgreen was 8.3 ton ha (fresh yield = 39.8 ton ha), which was harvested in late April and was lower than that of the check cultivar Gogu. The seed productivity of Seedgreen was approximately 4 ton ha, which was 16 % more than that of the check. Seedgreen was higher to than Gogu in term of protein content (10.5% and 9.7%, respectively), total digestible nutrients (TDN) (58.3% and 57%, respectively), and TDN yield ha (4.81 ton and 4.77 ton, respectively). This cultivar is recommended as a fall sowing crop in areas where the average daily minimum-mean temperatures are higher than -12°C in January, and as a winter crop for whole-crop forage before the planting of rice or green manure around Korea. (

Change of Weeds Occurrence, Early Growth and Yield of Soybean at Simultaneous Planting with Rye as Living Mulch

Introduction of rye living mulch in soybean production is important for labor-saving and reduction of herbicide usage for weeding by weed suppression and for soil conservation by mulching of rye. Soybean and rye were row-planted and broadcasted simultaneously at different planting times (May 15, May 25, June 5) and row widths (35 and 70 cm) in 2010, different soybean cultivars (Daepoong, Singi) and planting times (May 15 and June 1) in 2011, respectively, and investigated weed occurrence, early growth and yield of soybean. Acalypha australis, which is known to herbicide-resistant weed, could be controlled ecologically by rye living mulch. Occurrence of Acalypha australis was controlled effectively also by mixture of alachlor and linulon at no mulch in 2011. Early growth amount of soybean plant per area was increased by narrow row width (35 cm) at rye living mulch, which was helpful in the control of weeds, but grain yield of soybean with narrow row was decreased compared to conventional row width (70 cm) at the planting in early June. It is concluded that soybean planting as row width 70 cm in early June is proper at simultaneous planting with rye.

Production of Colchicine Induced Tetraploids in Rye (Secale cereale L.)

ABSTRACT This experiment was carried out to report some data such as survival rate, tetraploid production efficiency, and agronomic characteristics of offspring from the induced tetraploid by the colchicine treatment in rye. The colchicine was soaked with 0.05%, 12 hours in dark condition and at two growth stages (green seed and 2nd leaf stage) in diploid ryes. Flow cytometry (FC) was proved to be efficient and rapid tool for screening ploidy levels in rye, showing around 40 to 60 in DNA amount (DAP1) corresponding to diploid and 80 to 110 tetraploid. There were 18.5% of survival rate at green seed treatment and 78% at 2nd leaf stage in average of two rye cultivars, Gogu and Jogreen, but in reverse 50.9% and 1.1% in the ratio of tetraploid to total tillers among the plants survived, respectively, resulting in 9.42% of tetraploid production rate in green seed treatment and 0.86% at 2nd leaf stage, respectively. In green seed treatment, there were 33% of survival rate in Gogu, 4% in Jogreen in 1st year, but 56% in Gogu, 21% in Jogreen and 49% in Charmgreen, respectively. The rate of tetraploid to total spikes among survived was 53.7% in Gogu, 32.4% in Jogreen, and 50.9% in average in 1st year, and 64.1% in Gogu, 51.5% in Jogreen, 60% in Charmgreen, and 60.5% in average in 2nd year. In green seed treatment, tetraploid production rate (survival rate ×tetraploid ratio × 100) was 17.7% in Gogu and 1.3% in Jogreen and 9.42% in average in 1st year, and 35.9% in Gogu, 10.8% in Jogreen, 29.4% in Charmgreen, and 25.4% in average of three diploid rye cultivars. By the colchicine treatment with 0.05% for 12 hours in Gogu and Jogreen, 35 tetraploid plants were obtained and they produced 2,673 seeds with 148 spikes. There were 3.3-4.4 in the number of spikes per plant, 15.6-18.3 in grain number per spike, and 37.6 g in Gogu and 46.8 g in Jogreen in the 1,000-grain weight.