The objective of this study was to investigate the variation of Chinese milk vetch(Astragalus sinicus L.; CMV) seed quality after flowering. We tagged individual open flowers of CMV at the day of maximum flowering(11 May) in Seoul, Korea. Seed samples were harvested serially at 15, 20, 25 and 30 days after flowering(DAF). To compare with dried seeds, non-dried seeds were tested immediately after harvest and the remaining seeds were placed at room temperature for 4 weeks. Seed length, 1000 seed weight, moisture content, germination rate(GR), mean germination time(MGT), germination speed(GS), germination performance index(GPI) and physical dormancy rate(PDR) were investigated. Seed length increased to 2.6 mm and 1000 seed weight reached up to 2.2 g until 25 DAF. Seed moisture content dramatically decreased from 20 to 25 DAF. Moisture content of non-dried seed(7.5%) was similar to that of dried seed(5.5%) at 25 DAF. The rate of seed viability reached up to 94% at 25 DAF. In case of dried seed, GR increased up to 39% at 25 DAF whereas GR of non-dried seed varied from 5 to 10%. GS and GPI of dried seed were significantly higher than those of non-dried seed since 25 DAF. PDR of dried seed has decreased since 20 DAF, whereas PDR of non-dried seed has increased. GR, GS and GPI increased as PDR decreased. Our results evidenced that PDR might be one of major factor in variation of seed quality, of which development was completed at 25 DAF.

In order to uncover gene regulatory networks clustering of co-expressing genes was performed using a rice micorarray dataset of 155 gene expression omnibus sample (GSM) plates in NCBI, generating a total of 1660 clusters. One cluster with 85 co-expressing genes was measured with the correlation coefficient between pairs, resulting in an average r value of 0.66 with a range of -0.08 to 0.98. This result might support the notion that genes included in each cluster play common functional role(s). We also retrieved 23 Affymetrix GeneChip spots IDs corresponding to each of candidate genes related to abiotic stresses obtained from the P1antQTL-GE database and subsequently detected 23 clusters including co-expressing genes with each of the genes. Expression profiles of co-expressing genes revealed some degree of tissue-specific expression patterns, probably reflecting the existence of, at least partial, parallel versions of stress-related networks with evolutionary process, such as subfuntionalization. The finding that several cis-elements related to abiotic stresses was detected by differences in frequency between co-expressing genes and randomly selected genes. Clustering, expression profiles, and putative cis-acting regulatory elements of co-expressing genes related to abiotic stresses may provide clues to shed further light on the gene regulatory network of stress-responsive pathway.

The genetic diversity was evaluated using RAPD and ISSR among natural populations and Korean wheat cultivars (Triticum aestivum). Understanding the genetic diversity of putative parental and wild stocks would be useful in wheat breeding programs. Ninety three populations were evaluated with fifty RAPD and three ISSR primers. A total of 185 RAPD and ISSR polymorphism were produced. These markers were considered to estimate the genetic distance among accessions. The genetic similarity ranged from 0.41 to 0.86. The dendrogram were constructed by using the UPGMA clustering algorithm based on genetic similarity. The genetic diversity within and among accession was assessed through Principal Component Analysis (PCA) for statistics analysis. In cluster analysis, four groups were clustered and 17 accessions were not clustered. The PCA was corresponded well to the result. This study provides basic information about the genetic relationships for breeding purposes.

In order to develop molecular markers related to stay green phenotype, AFLP analysis was conducted using near-isogenic lines for either stay green or non stay green trait. Both lines have characteristics of multi-ear and tillers (MET). Two out of 64 primer combinations of selective amplification identified three reproducible polymorphic fragments in MET corn with stay green. Both of E+AGC/M+CAC and E+AAG/M+CAA primer combinations produced two and one specific polymorphic fragments linked to stay green trait, respectively. For the conversion of AFLPs to sequence tag sites (STSs), primers were designed form both end sequences of each two polymorphic fragments. One fragment, which was amplified with E+AAG/M+CAA primer combinations, possessed 298 bp long and showed a 91~% homology with maize retrotransposon Cinful-l. One out of two polymorphic fragments produced with E+AGC/M+CAC primer combination had 236 bp long and matched a 96~% homology with an intron region of 22kDa alpha zein gene cluster in Zea mays. One out of two PCR fragments amplified with MET2 primer set in the stay green MET was not produced in the non-stay green MET. The developed AFLP and STS marker could be used as an efficient tool for selection of the stay green trait in the MET inbred.

The Hessian fly, Mayetiola destructor (Say), is known to be one of the major insect herbivores of wheat worldwide. In order to provide molecular events on interactions of the NIL with H21 and larvae of Hessian fly biotype L, the TaCR1 gene, Triticum aestivum cytokinin repressed 1, was isolated through the suppression subtractive hybridization, which was constructed using stems of the NIL with H21 at 6 days after infestation as tester and stems of the recurrent parent Coker797 without H21 at 6 days after infestation as driver. Transcript levels of TaCR1 mRNA in the NIL with H21 were highest at 6 days after infestation but in the Coker797 without H21 until 8 days were similar with those of non-infested plants. Expression of the TaCR1 gene was decreased at early time and then recovered after wounding or H2O 2 treatment as well as 6-BAP treatment. Transcripts levels of the TaCR1 gene was changed after MeJA, SA, ethephone, or ABA treatment. In drought treatment, the TaCRl gene were increased at early stage of stress and then decreased at late stage. Expression of the TaCRl gene was continued to decrease through 24 h in the cold treatment. Although the TaCRl gene is increased through infestation in NIL with H21, further study was required to elucidate a role on resistance against larvae of Hessian fly. However, the TaCR1 gene could be used as marker gene on response of plants against abiotic stresses as well as application of plants with several hormones.

Hamlet (PI549276) possessing 2RL was obtained by cross between a wheat cultivar ND7532 (Froid/Centurk) and a rye cultivar Chaupon. Chaupon was known to have resistant gene to biotype L of Hessian fly [Mayetiola destructor (Say)] larvae. The wheat-rye translocation line (Coker797*4/Hamlet) was also known to be resistant to biotype L of Hessian fly larvae. We analysed a set of 96 ESTs from the wheat-rye translocation line (2BS/2RL). ESTs were classified by various physiological processings, such as primary metabolism, secondary metabolism, transcription, translation, transport, signal transduction, defense, transposable element, and others. Three sequences encoding thioredoxin peroxidase, 26S rRNA, and rubisco small subunits were homologous to registered genes in rye. Although limited number of clones were used to develop ESTs, these clones and their sequence information may be useful for researchers studying general physiology and molecular biology on the translocation line.