X.F. Li et al LANT是 A凹,r",,L个叫上p, Momth Similar to Arabidopsis F,BFT2 function is needed for fower- 20 31 10 20 30 10 20 31 10 20 30 10 ay ing. The vernalization response suppresses BvFTI expression and releases its inhibition against BvFT2 to induce fowering Storage under natural conditions FLC, other FT orthologs and more of the relevant genes in 30℃for40d Chinese narcissus need to be characterized in order to elucidate the regulation of NFT1 expression in the SM. 120 Heat treatment is beneficial to the adjustment of the flowering time of Chinese narcissus Heat accumulation was not only necessary for flowering initi- ation in the 3-year-old bulbs, but also promoted fowering in the 2-year-old bulbs Chinese narcissus is characterized by 2 year juvenile phases before the first fower is formed. During farming 3-year-old bulbs were selected as flowering plants according to their sizes. Our data also showed that the fowering percentage 6.9 6.23 7.7 7.21 8.4 8.20 9.2 Date in the 2-year-old bulbs increased with longer high-temperature treatment. In addition, treatment at 30oC for 80 d significantly No. 1 increased fowering percentage(86. 1% vS. 25% under natural temperature)(Fig. 3B). Setting the heat accumulation of one summer equal to the treatment at 30oC for 40 d was necessary FTI to induce flowering initiation in the 3-year-old bulbs. the Row- ACTIN ering capability in most 2-year-old bulbs treated at 30C for 80 Fig. 7 NFT1 expression in the bulb apices was induced by high tem- d was due to the heat accumulation, equivalent to two summer perature. (A)Effect of temperature on the NFT1 expression profile in seasons. In addition to heat treatment combined with a short RT-PCR. The upper part illustrates the storage duration to improve the fiowering percentage, these different storage treatments of narcissus bulbs, with temperature re- results may have interesting applications in farming to adjust gimes shown below the corresponding date, and continuous lines fowering time. presenting periods between 22 and 25C. The two time points indicated by arrows are the beginning of flower transition in bulbs with relevant treatment. Relative expression levels indicate the data relative to those obtained on June 9 under natural temperatures. B) Materials and Method Effect of temperature on the change of NFT1 transcripts in bulb apices during storage, shown via RT-PCR Detailed temperature regimes are Plant materials and growth conditions shown in(A) Narcissus tazetta var. chinensis bulbs were commercially ob tained from Shanghai, China. Healthy bulbs of similar sizes (2-year-old bulbs, each with a 10+ 1 cm circumference, and and peak appeared earlier(Fig. 7A, B). These results there- 3-year-old bulbs, each with a 15+ 1 cm circumference)were fore suggest that the NFT1 transcription level in the SM may grouped and stored in natural or controlled conditions. a dry be a regulator of heat accumulation-induced flowering and ventilated warehouse with ambient light and temperature Reproductive onset in perennial poplar was also determined was used as the natural environment. by FT1 signaling, in response to winter temperature( Bohlenius Arabidopsis thaliana, ecotype Col, Ler and ft-3(SALK line et al. 2006, Hsu et al. 2011) cs185 in the Ler background) plants were grown in a green The nature of the upstream mechanism that controls NFT1 house under constant illumination(approximately 80 umol- expression in the SM remains an open question. FT expression $)at 22+2C. Seeds were surface sterilized, stratifed at 4C in Arabidopsis leaves is directly activated by the Co gene, which for 3d, plated on half-strength Murashige and Skoog acts as a sensor of photoperiod signals through the circadian (Murashige and Skoog 1962)medium containing 50 ug clock(Turck et al. 2008). The NFT1 gene in Chinese narcissus kanamycin, and grown under continuous fuorescent light at was also expressed in the leaves( Fig. 5), suggesting a possible 22 C to screen the transgenic plants role in flowering control during the photoperiod. However, the NFTI transcription level in the SM is an important regulator of Treatment method to affect flowering heat accumulation-induced fowering. The mechanism of ver- The flower differentiation during storage of the 3-year-old bulbs nalization in Arabidopsis is the release from FT inhibition by the at natural temperature, high temperature(300C)or low tem action of FLC FT duplication products(BvFT1 and BvFT2)have perature(150C Nos. CK, 1 and 2 in Fig. 1A) was analyzed via divergent functions in biennial sugar beet( Beta spp )(Pin et al. SEM to determine whether high or low temperatures favor 2010). BvFT1 represses reproductive onset and bolting fowering initiation. The average natural temperatures in 278 Plant Cell Physiol. 54(2): 270-281(2013)doi: 10.1093/pcp/pcs181 C The Author 2013and peak appeared earlier (Fig. 7A, B). These results there￾fore suggest that the NFT1 transcription level in the SM may be a regulator of heat accumulation-induced flowering. Reproductive onset in perennial poplar was also determined by FT1 signaling, in response to winter temperature (Bohlenius et al. 2006, Hsu et al. 2011). The nature of the upstream mechanism that controls NFT1 expression in the SM remains an open question. FT expression in Arabidopsis leaves is directly activated by the CO gene, which acts as a sensor of photoperiod signals through the circadian clock (Turck et al. 2008). The NFT1 gene in Chinese narcissus was also expressed in the leaves (Fig. 5), suggesting a possible role in flowering control during the photoperiod. However, the NFT1 transcription level in the SM is an important regulator of heat accumulation-induced flowering. The mechanism of ver￾nalization in Arabidopsis is the release from FT inhibition by the action of FLC. FT duplication products (BvFT1 and BvFT2) have divergent functions in biennial sugar beet (Beta spp.) (Pin et al. 2010). BvFT1 represses reproductive onset and bolting. Similar to Arabidopsis FT, BvFT2 function is needed for flower￾ing. The vernalization response suppresses BvFT1 expression and releases its inhibition against BvFT2 to induce flowering. FLC, other FT orthologs and more of the relevant genes in Chinese narcissus need to be characterized in order to elucidate the regulation of NFT1 expression in the SM. Heat treatment is beneficial to the adjustment of the flowering time of Chinese narcissus Heat accumulation was not only necessary for flowering initi￾ation in the 3-year-old bulbs, but also promoted flowering in the 2-year-old bulbs. Chinese narcissus is characterized by 2 year juvenile phases before the first flower is formed. During farming, 3-year-old bulbs were selected as flowering plants according to their sizes. Our data also showed that the flowering percentage in the 2-year-old bulbs increased with longer high-temperature treatment. In addition, treatment at 30C for 80 d significantly increased flowering percentage (86.1% vs. 25% under natural temperature) (Fig. 3B). Setting the heat accumulation of one summer equal to the treatment at 30C for 40 d was necessary to induce flowering initiation in the 3-year-old bulbs. The flow￾ering capability in most 2-year-old bulbs treated at 30C for 80 d was due to the heat accumulation, equivalent to two summer seasons. In addition to heat treatment combined with a short storage duration to improve the flowering percentage, these results may have interesting applications in farming to adjust flowering time. Materials and Methods Plant materials and growth conditions Narcissus tazetta var. chinensis bulbs were commercially ob￾tained from Shanghai, China. Healthy bulbs of similar sizes (2-year-old bulbs, each with a 10 ± 1 cm circumference, and 3-year-old bulbs, each with a 15 ± 1 cm circumference) were grouped and stored in natural or controlled conditions. A dry and ventilated warehouse with ambient light and temperature was used as the natural environment. Arabidopsis thaliana, ecotype Col, Ler and ft-3 (SALK line cs185 in the Ler background) plants were grown in a green￾house under constant illumination (approximately 80 mmol–2 s –1) at 22 ± 2C. Seeds were surface sterilized, stratified at 4C for 3 d, plated on half-strength Murashige and Skoog (Murashige and Skoog 1962) medium containing 50 mg ml–1 kanamycin, and grown under continuous fluorescent light at 22C to screen the transgenic plants. Treatment method to affect flowering The flower differentiation during storage of the 3-year-old bulbs at natural temperature, high temperature (30C) or low tem￾perature (15C; Nos. CK, 1 and 2 in Fig. 1A) was analyzed via SEM to determine whether high or low temperatures favor flowering initiation. The average natural temperatures in Fig. 7 NFT1 expression in the bulb apices was induced by high tem￾perature. (A) Effect of temperature on the NFT1 expression profile in the bulb apices shown via qRT-PCR. The upper part illustrates the different storage treatments of narcissus bulbs, with temperature re￾gimes shown below the corresponding date, and continuous lines representing periods between 22 and 25C. The two time points indicated by arrows are the beginning of flower transition in bulbs with relevant treatment. Relative expression levels indicate the data relative to those obtained on June 9 under natural temperatures. (B) Effect of temperature on the change of NFT1 transcripts in bulb apices during storage, shown via RT-PCR. Detailed temperature regimes are shown in (A). 278 Plant Cell Physiol. 54(2): 270–281 (2013) doi:10.1093/pcp/pcs181 ! The Author 2013. X.-F. Li et al. at East China Normal University on June 3, 2013 http://pcp.oxfordjournals.org/ Downloaded from