The tight regulators of fruit set initiation, gibberellin (GA) and auxin, have been applied for decades to induce parthenocarpy, fruit set without fertilization. The integration of GA and auxin signaling mediated by either GA or auxin application during parthenocarpy has been actively reported in tomato, and recently we reported that GA application at pre-bloom also activating auxin signaling and down-regulated negative regulators of fruit set initiation in grapevines. However, the activation of auxin signaling upon GA application without up-regulation of auxin biosynthesis is still unclear. In this study, expression patterns of three auxin efflux transporter genes, VvPIN1a, VvPIN2 and VvPIN4, were monitored during inflorescence development in ‘Tamnara’ grapevines with or without GA application. Without GA application, transcription levels of VvPIN1a and VvPIN4 gradually increased from 14 days before full bloom (DBF) to 2 and 5 days after full bloom (DAF), respectively, except down-regulation of VvPIN1a during 5 DBF to full bloom. However, VvPIN2 expression declined steadily after peaking at 10 DBF. With GA application, VvPIN1a did not show significantly different expression patterns when compared to no GA application, with the exception of 4-fold up-regulation at full bloom, but transcription of VvPIN4 was reduced between 5 and 2 DBF. In addition, VvPIN2 was down-regulated between 12 and 10 DBF by more than 50% compared to levels in the absence of GA application. These reductions of both VvPIN2 and VvPIN4 with GA application prior to pollination suggest that GA application might regulate auxin distribution, instead of auxin biosynthesis, to activating auxin signaling during parthenocarpic fruit initiation.

Rice blast (Magnaporthe oryza B.) is one of the most widespread and devastating diseases of rice. Screening of valuable genetic resources harboring resistance genes is one of the most efficient approaches against blast disease. Because the bioassay to rice blast in the field shows high variations, this study has performed to provide DNA profiles in the accessions of diverse countries using major blast resistant genes linked markers, identified and mapped in different genotypes of rice. Because durable resistance to blast is controlled by a combination of major resistance genes, we surveyed the distribution of blast resistant genes in the 1,500 accessions using major 12 blast resistance genes linked markers. These resistant genes found that the frequency distribution of Pi-39 (66.9%), Pik-m (41.9%), Pit (40.5%), Pii (21%), Pib (19.3%), Pi-d(t)2 (12.7%), but Pita, Pita/Pita-2, Pik, Piz-t, Pi5 genes were identified in less than 10% frequency. Most of accessions contain from 1 to 4 different resistant genes. Pi39 and Pik-m genes amplified in the 69.1% and 51.7% among 356 Korean accessions, Pi39 (79.6%) and Pib (55.8%) in 113 China, Pit (80.6%) and Pib (32%) in 103 Philippines, respectively. In this study, we evaluated the blast resistance degree and the information about the distribution of rice blast resistant genes in rice germplasm. This study will help to develop effective strategies for managing rice blast disease in rice germplasm.

Gibberellic acid (GA) is a well-characterized plant hormone, which plays a critical role in various plant growth and development. including stem elongation, floral indcution and seed development. GA is known to cause enlargement of ripening fruits and, especially in grapevines, GA shows a unique function: the induction of seedlessness in seeded grape varieties. However, despite extensive previous studies about GA, there has been no clear verification of the mechanism that induces seedlessness in grapes. To understand how GA treatment results in artificial parthenocarpy of seeded grapes at molecular levels, we analyzed transcriptional changes in seeded grapes with and without GA application in various inflorescence developmental stages using RNA-seq. At 14 days before flowering (DBF), seeded grapes were treated with 100 ppm GA and clusters were collected at three developmental stages: 7 DBF, full bloom, and 5 days after flowering (DAF). Of a total of 28,974 genes that were mapped to grape genome reference sequences, 7,013 and 9,064 genes were up- and down-regulated, respectively, in the GA-treated grape as compared to the non-GA-treated control at 7 DBF, full bloom, and 5 DAF. Clustering analysis revealed that these genes could be grouped into 9 clusters with different expression patterns. We also carried out functional annotation based on gene ontology categories. There were significant differences in the expression of the GA and auxin-related gene families. These findings expand our understanding of the complex molecular and cellular mechanisms of GA-induced parthenocarpy of grapes and provide a foundation for future studies on seed development in grapevines.

R genes are a key component of genetic interactions between plants and biotrophic bacteria and are known to regulate resistance against bacterial invasion. The most common R proteins contain a nucleotide-binding site and a leucine-rich repeat (NBS-LRR) domain. Some soybean NBS-LRR genes have also been reported to function in disease resistance. A total of 319 genes were determined to be putative NBS-LRR genes in the soybean genome. The number of NBS-LRR genes on each chromosome was highly correlated with the number of disease resistance QTL in the 2-Mb flanking regions of NBS-LRR genes. In addition, the recently duplicated regions contained duplicated NBS-LRR genes and duplicated disease resistance QTL, and possessed either an uneven or even number of NBS-LRR genes on each side. The significant difference in NBS-LRR gene expression between a resistant near-isogenic line (NIL) and a susceptible NIL after inoculation of Xanthomonas axonopodis pv. glycines supports the conjecture that NBS-LRR genes have disease resistance functions in the soybean genome. The number of NBS-LRR genes and disease resistance QTL in the 2-Mb flanking regions of each chromosome was significantly correlated, and several recently duplicated regions that contain NBS-LRR genes harbored disease resistance QTL for both sides. In addition, NBS-LRR gene expression was significantly different between the BLP-resistant NIL and the BLP-susceptible NIL in response to bacterial infection. From these observations, NBS-LRR genes are suggested to contribute to disease resistance in soybean. Moreover, we propose models for how NBS-LRR genes were duplicated, and apply Ks values for each NBS-LRR gene cluster.

Recent release of whole genome draft sequences in legume species have led comparative genome studies among legume plants including Glycine max, G. soja, Cajanus cajan and Medicago truncatula. The majority of comparative genomic researches have been conducted based on synteny of coding sequences and coding sequence variations may be one of major forces for speciation and evolution. However, non-coding sequences have been also reported to be important phenotypic regulators. Especially, since short sequence motifs in the promoter regions are highly conserved, they are suggested to be another resources of interests in comparative studies. In this study, we predicted the conserved short sequence motifs by BLASTN algorithm using dicot promoter database from Softberry (http://www.softberry.com). A total of 37,396 conserved short sequence motifs were identified onto 2 kb upstreams of 46,367 high confident gene model of G. max (cv. Williams 82). Meanwhile, whole genome of 7 soybean landraces (G. max) and 7 wild soybean genotypes (G. soja) were sequenced at low depth of less than ten using Illumina Hiseq 2000. Among these genotypes, nucleotide variations were identified in predicted conserved regulatory motifs by mapping of short reads to the reference genome sequence using the Samtools program (http://samtools.sourceforge.net/). Fifteen and two genes, which have SNPs in regulatory motifs and no SNP in coding sequence, were identified by comparisons of inter-species and intra-species, respectively. qRT-PCR experiments are in progress for investigating differences of these 17 genes expressions at transcriptional level.

As soybean (Glycine max) is known for its high nutritional value of oil and protein, soybean has been domesticated and cultivated by one specific character trait based on human selection. Importantly, tracing back in time where G. max and G. soja, the undomesticated ancestor of G. max have diverged plays an important role in studying of genetic diversity and in investigating the common ancestor of soybean. In this study, we sequenced 6 G. max and 6 G. soja using Illumina’s Hiseq 2000 with a low coverage sequencing technology to estimate the divergence of times between genotypes and populations. A total of the 12 genotypes were sequenced at the average depth of 6.5 and resulted 892.5 Mb and 903.3 MB consensus sequences with the coverage of 91.54% and 92.65% for G. max and G. soja, respectively. The whole genome SNP analysis showed that G. max had lower frequency levels of polymorphism (~0.1%) than G. soja (~0.25%). And, a high number of SNPs located in introns were found among 6 G. soja genotypes as SNPs were approximately twice than those found in 6 G max. The number of SNPs in G. max intronic regions was 53,134, whereas a total of 133,329 SNPs were discovered in G. soja introns. Almost an equal number of SNPs were discovered in 5’ UTR and exon regions; however, different numbers of SNP in CDS and 3′ UTR were identified. By the rate of nonsynonymous change, divergence of time between G. soja and G. max would be investigated.

Mutagenesis approach in combination with whole genome sequencing has become an import role in genetic and molecular biological study and breeding of crop plants. In this study, we screened the fast neutron M4 10,000 soybean mutant plants based on morphological phenotypes of agronomically important traits and characterized the mutant of interest using resequencing. Fast neutron radiation has been known to be a very effective mutagen to cause large deletion in genome. The screened mutant showed abnormal phenotypes in plant heights, seed sizes, color of leaves, number of leaves, maturity and number of branches etc. Among them, the mutant displaying short plant height and bush type of growth habit was selected for identification of the altered genomic regions. Analysis of deletion sites of genome in interesting soybean mutant was performed using next generation sequencer Illumina Hi-seq. Mutant sequence reads generated by paired-end shotgun library were mapped on a draft soybean reference soybean (G. max cv. Williams 82). The paired-end DNA sequences of 21.6 Gb produced by Illumina Hi-seq produced 21 fold sequence depth. Among the predicted deletion sites, total 3 deletion regions confirmed by PCR. Glyma03g02390 gene and Glyma03g03560 gene were involved in the deletion regions. Glyma03g02390 gene was related to AMP binding, catalytic activity, cofactor binding and metabolic process of cell growth and Glyma03g03560 gene was concerned to oxygen binding, defense response to bacterium, and especially process of indole acetic acid (IAA) biosynthesis. These genes detected in this mutant will be studied about their molecular function in stunted phenotype.