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The phytohormone ethylene regulates many aspects of plant growth and senescence as well as its environmental responses. Most lily flowers are sensitive to ethylene, which plays a significant role in the senescence mechanism of them. In an effort to understand the regulation of ethylene responses in flower senescence, we isolated and characterized three genes, LERS1、PLETR1 and LCTR1, which respectively exhibited high similarity to ERS1 、 ETR1 and CTR1 in Arabidopsis, using a combination of reverse transcription PCR and RACE techniques from lily petals (Z. ×L formolongi Hort. ) . It would create a new way of researching ethylene control in lily flower senescence. The main results were as follows.1. The method for extraction and purification of total RNA from petals of lily flower was developed.2. The cDNA was designated as lily Ethylene Response 1(LERS1, accession number is DQ408428). The length of cloned cDNA was 2324bp including an open reading frame of 1905bp, from No. 84 to No. 1989, encoding 635 amino acids that had a calculated molecular mass 70. 8kDa. The putative protein had three conserved regions, including three transmembrane regions in the amino-terminal, one GAF domain and one conserved histidine kinase domain in the carbon-terminal, but lacked a receiver domain. The LERS1 protein had 80%, 75% and 72% similarity to DSPPERS1, Arabidopsis ETR1 and ERS1 respectively. The analysis and function suggested this putative protein exhibits significant sequence homology to a class of its kinases known as two-component regulators. LERS1 contained 5 motifs of histidine protein domain (H, N, G1, F, G2). These motifs are arranged in the same relative order and spacing found in other ethylene receptor proteins.3. The partial cDNA was designated as lily CTR1 (LCTR1), a gene acting downstream of the ethylene receptor and showing similarity to the Raf family of serine/threonine protein kinases. The length of cloned cDNA was 1104bp including an open reading frame of 705bp, a 398bp 3-flanking sequence with a poly A~+ tract. The cDNA encoded 235 amino acids and had a calculated molecular mass 26. 95kDa. The LERS1 protein had 82%, 78% and 77% similarity to 0s- CTR1, LeCTRland At-CTR1, respectively.
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