Night break effect is widely used in chrysanthemum production by applying incandescent (INC) lamps to inhibit flowering of chrysanthemum in order to obtain longer shoots. To save energy, LED lamps had been developed as a new light source and used in agriculture. Since there is limited research on chrysanthemums grown in LED light culture, we studied the night break effect by using several different wavelengths of LED lamps. Red (R) light from LED-630 and LED-660 had perfect inhibition on floral bud differentiation in 'Jimba,' but could not inhibit that in 'Iwa no hakusen' chrysanthemums. The far-red (FR) light of LED-735 had no effect on the inhibition of floral bud differentiation in 'Jimba,' but it was delayed in 'Iwa no hakusen.' Treatments of LED-690 and INC lamps inhibited floral bud differentiation in 'Jimba' and strongly delayed that in 'Iwa no hakusen.' Treatments of a combination of R light of LED-660 and FR light of LED-735 inhibited floral bud differentiation in both the cultivars.

Chrysanthemum morifolium Ramat 'Jimba' and 'Iwa no hakusen' were used as the plant materials. They flower in September and June under natural conditions in Japan. Shoots that were 10 cm in length were planted in plastic cases (32 cm 43 cm 10 cm) filled with BM2 (Berger Peat Moss Ltd., Canada). Each plastic case was divided

Background: Rose is one of most popular ornamental plants all over the world, it is of high economical value and great cultural importance. However, chilling damage restricts its application in cold area. To elucidate the metabolic response under low temperature stress, we conducted transcriptome and De novo analysis in Rosa xanthina f. spontanea.Results: A total of 124,106 unigenes from 9 databases were generated by De novo assembly, with mean length of 661bp under 4℃ and -20℃ stress (23℃ as control). Functional annotation and prediction of 55,084 unigenes were detected and 67.72% of these unigenes had significant similarity (Blast, E≤10-5) in the public databases. 468 DEGs were involved in three groups: biological process (64.84%), cellular component (9.38%) and molecular function (25.78%), KEGG analysis suggested that metabolic pathway, response to plant pathogen interaction, starch and sucrose metabolism, circadian rhythm plant and photosynthesis antenna proteins were significantly enriched under cold stress.Conclusions: Our study first reported response to cold stress at the transcriptome level in Rosa xanthina f. spontanea, which can provides a theoretical basis for further studies on the molecular mechanism of cold-resistance in rose. The results was shown that the expression trend of eight DEGs selected by qRT-PCR analysis at random was consistent with the results of high-throughput sequencing.

It has been attempted to develop multiple resistant rootstock against rose root rot (Pythium helicoides Drechsler) and crown gall disease (Rhizobium radiobacter (Beijerinck and van Delden, 1902) Young et al., 2001) using tetraploid Rosa multiflora 'Matsushima No.3' and R. 'PEKcougel'. However, hybrid identification based on conventional morphological characteristics is difficult, and establishment of hybrid diagnosis by DNA markers is desired. In this study, we attempted to develop specific DNA markers of R. multiflora. Three hundred 10 mer random oligonucleotide primers were screened, and a unique polymorphic fragment in R. multiflora amplified by OPAK16 primer was identified. This fragment could distinguish between roses with cross-fertilization genealogy with R. multiflora and roses with no relationship with R. multiflora. This specific fragment was cloned, sequenced and converted into a sequence characterized amplified region (SCAR) marker-SCAK16, which can amplify a 583 base pair (bp) fragment only in roses with relatedness to R. multiflora. This result indicated that SCAK16 583 was a species-specific marker of R. multiflora that could be used in a marker-assisted breeding program for hybrid identification of R. multiflora.

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