AbstractThe SHORT VEGETATIVE PHASE (SVP) gene encodes a MADS-box gene family of transcription factors that repress floral transition. To explore the function of the Brassica rapa SVP (BrSVP) gene during the flowering time of this species, a construct containing BrSVP under the control of the cauliflower mosaic virus 35S promoter was introduced into B. rapa via Agrobacterium-mediated transformation. The resulting transgenic plants showed delayed flowering time, and RT-PCR analyses further revealed that BrSVP repressed the expression of the floral integrator genes AGL20, AGL24, and FT during vernalization. Our data indicated that BrSVP acts as a negative regulator in the flowering time of B. rapa and that it may therefore be a useful genetic source for crop improvement with respect to flowering time regulation.

One of the most important events in the regulation of plant development is the transition from the vegetative to the reproductive phase. The precise control of this transition, which has a profound effect on grain production in annual temperate cereals such as wheat and barley, is determined mainly by seasonal changes in day length (photoperiod) and by winter-like temperatures (vernalization). Recent molecular and genetic analyses in wheat have revealed the molecular mechanisms underlying flowering responses of wheat to changes in photoperiod and cold temperature. Here, we describe genes related to vernalization, photoperiod, and earliness per se (eps), and the molecular mechanism regulating flowering time through vernalization and photoperiod genes in wheat.

It is important for radish to have late flowering characteristics especially in the case of spring and winter cultivars. To understand late flowering characteristics of radish at the molecular level the flowering time genes of two radish lines (NH-JS1 and NH-JS2) with different flowering time were compared by re-sequencing their genomes. There were a total of 872,587 SNPs and 194,637 INDELs between the two lines. The SNP density of each chromosome was relatively uniform throughout, but the region with low SNP density was found at the end of R3 and the middle of R9. To compare the flowering time genes of the two lines, we first looked for the flowering time genes in radish using Arabidopsis thaliana flowering time genes. As a result, homologs of radish were found for most flowering time genes, but FRIGIDA was not found. Among 224 radish flowering time gene-homologs found, 97 genes showed more than one sequence difference (SNP or INDEL) between the two lines, and 127 genes had no difference. In particular, no sequence differences were found in FT, CO, and FLC, core flowering time control genes. Rs350520 (FVE), Rs193800 (CURLY LEAF) and Rs255320 (ATX1) with more than 100 sequence variations were expected to have a significant effect on flowering time difference between the two lines. These results will be of great help in understanding the flowering timing difference between the two lines at the molecular level.

Flower bud differentiation by temperature and photoperiod was investigated in early-, medium-, and late-maturing cultivars of radish (Raphanus sativus L.). Flower bud differentiation was induced by only day-length extension treatment (18 hr light/day) in early - and medium-maturing cultivars. Therefore, the early- and medium-maturing cultivars of radish were advanced the time of the flowering by the 2 weeks low temperature duration with day-length extension (18 hr light/day). The vegetative growth of early- and medium-maturing cultivar was the best by only day-length extension (18 hr light/day). However, late-maturing cultivar was needed for the flower bud differentiation and optimal vegetative growth not only long-day but also low temperature during 4~6 weeks at least. Our results suggest the optimal condition for flower bud differentiation in the each early-, medium-, and late-maturing cultivars of radish, which will be useful to develop breeding materials of radish.

‘Jungmo 7002’ is a intermediate parent of rapeseed (Brassica napus L.) with flowering uniformity and lodging tolerance for the scenery and oil production. ‘Jungmo 7002’ was developed from the cross between ‘RS10//Erra/Tower’ as female parent and ‘RS10’ as male parent in 1984. A promising line, ‘84013-B-6-3-3-6’, was selected and designated as the name of ‘Mokpo116’. It was prominent and had good result from regional adaptation yield trials (RYT) for three years from 2011 to 2013 and was released as the name of ‘Jungmo 7002’. ‘Jungmo 7002’ has middle parted and dark-green leaf, Brownish-green stem, yellowish flower and black seed coat. The flowering date of ‘Jungmo 7002’ was 16th April and ripening date was 9th June. The yield of ‘Jungmo 7002’ was 247 kg/10a, which was 19% higher than ‘Hanlayuchae’ in regional adaptation trials. This intermediate parent showed high resistance to lodging tolerance. The oil content of ‘Jungmo 7002’ was 44.3%. In fatty acid composition of ‘Jungmo 7002’ , oleic acid content is 70.8%, which is 3.3% higher than ‘Hanlayuchae’. And ‘Jungmo 7002’ has no erucic acid. ‘Jungmo 7002’ will be adaptable to southwestern area including Jeonllanam-do, Jeollabuk-do and Gyeongsangnam-do and Jeju island of Korea.

The influence of seed maturity, stratification, and seed washing method on seed germination were investigated for establishment of seed propagation system in dropwort (Oenanthe stolonifera DC). Seed germination rate was increased as period of the seed ripening increased, especially the seed over 40 days after flowering showed the highest germination rate. The optimum period of cold stratification treatment to promote seed germination was about 8 weeks. The seed treated by a cold wet stratification with sand exhibited higher germination rate compared to the seed treated by a cold wet stratification without sand. The stratified seeds that were stored in the ground having fluctuating temperature were improved up to 19%, while stratification stored under constant temperature(4°C) did not improve germination rate. In addition, 8 weeks of stratification period under fluctuating temperature in the ground was most effective. Sodium hypochlorite, vital oxide, and distilled water were used as chemicals to remove the germination inhibitor of seed coat. Water washing of seed coat after soaking in 0.5% sodium hypochlorite and 0.0005% vital oxide for three minutes and 60 minutes respectively could effectively remove the germination inhibitors in the seed coat.

A cultivar Dendranthema grandiflourm ‘Dream Prince’ was developed at Gyeonggi-do Agricultural Research & Extension Services, Korea in 2012. The cultivar ‘Dream Prince’ was bred from the cross hybridized in 2009 between ‘Grand Pink’, a spray chrysanthemum cultivar with pink colored single type petals, and ‘Classy’, a spray chrysanthemum cultivar with early flowering trait. Trials were conducted from 2010 to 2012 for evaluation and selection of the cultivar, including a shading culture in spring and a retarding culture in summer. Finally, ‘Dream Prince’ was selected. The natural flowering time of ‘Dream Prince’ was October 24th, and year-round flowering is possible. Days to flowering of ‘Dream Prince’ under the short day treatment were about 48, 50 and 47 in the autumn, spring and summer, respectively. ‘Dream Prince’ has single type flower with yellow petals and the diameter of flower was 6.7cm. Number of flowers per stem was 19.6 and petals per flower were 29.0 in autumn. The plant variety protection right of ‘Dream Prince’ was granted on Korea Seed & Variety Service with No. 4876 in 2014.