Isolation and molecular characterization of the FLOWERING LOCUS C gene promoter sequence in radish(Raphanus sativus L.)

Both bolting and flowering times influence taproot and seed production in radish. FLOWERING LOCUS C （FLC） plays a key role in plant flowering by functioning as a repressor. Two genomic DNA sequences, a 3 046-bp from an early- and a 2 959-bp from a late-bolting radish line were isolated and named as RsFLC1 and RsFLC2, respectively, for they share approximately 87.03% sequence identity to the FLC cDNA sequences. The genomic DNA sequences, 1 466-bp and 1 744-bp, flanking the 5＇-regions of RsFLC1 and RsFLC2, respectively, were characterized. Since both of them harbor the basic promoter elements, the TATA box and CAAT box, they were designated as PRsFLC1 and PRsFLC2. The transcription start site （TSS） was identified at 424 and 336 bp upstream of the start codon in PRsFLC1 and PRsFLC2, respectively, cis-regulatory elements including CGTCA （MeJA-responsive） and ABRE （abscisic acid-responsive） motifs were found in both promoters, while some cis-regulatory elements including TCAelement and GARE-motif were present only in PRsFLCI. These sequence differences lead to the diversity of promoter core elements, which could partially result in the difference of bolting and flowering time in radish line NauDY13 （early-bolting） and Naulu 127 （late-bolting）. Furthermore, to investigate the activity of these promoters, a series of 5＇-deletion fragment-GUS fusions were constructed and transformed into tobacco. GUS activity was detected in PRsFLCI-（1 to 4）-GUS-PSlaG-3 and PRsFLC2-（1 to 4）-GUS-PS1aG-3 transgenic tobacco leaf discs, and this activity progressively decreased from PRsFLC-1-GUS-PSlaG-3 to PRsFLC-5-GUS-PS1aG-3. Deletion analysis indicated that the cis-regulatory elements located at -395 bp to ＋1 bp may be critical for specifying RsFLC gene transcription.

雨生红球藻转录因子Whirly1的获得及其表达分析

Whirly转录因子广泛存在于植物中,参与植物生长发育进程和逆境胁迫耐受,对其功能的研究有助于我们理解雨生红球藻响应胁迫的机制。因此,先根据雨生红球藻192.80转录组测序数据,分离克隆到一个Whirly转录因子序列,并对其结构及表达进行分析。该转录因子的cDNA序列为924 bp,基因组序列为2556 bp,由有5个外显子和4个内含子组成,命名为HpWhirly1。HpWhirly1预测由244个氨基酸组成,拥有Whirly转录因子的保守结构域。HpWhirly1在醋酸钠和水杨酸胁迫早期表达上调,在强光-醋酸钠联合胁迫和缺氮胁迫条件下表达下调,表明其在雨生红球藻受到胁迫时发挥一定的作用。以上研究结果将有助于进一步研究Whirly转录因子的功能及其在雨生红球藻响应胁迫时的作用。