过量表达中国水仙(Narcissus tazetta var.chinensis)NTAG1基因促进拟南芥早花和衰老

Ectopic Expression of an AGAMOUS Homolog NTAG1 from Chinese Narcissus Accelerated Earlier Flowering and Senescence in Arabidopsis

中国水仙有金盏银盘和玉玲珑两个品种,玉玲珑由于雄蕊瓣化而形成重瓣花,而目前人们对这种重瓣花的分子机理不清楚。根据重瓣花多与C类花器官特性基因相关,本文通过RT-PCR方法分别克隆和分析了两种花型水仙品中的AGAMOUS同源基因NTAG1基因,序列分析表明,两种水仙中该基因序列完全相同,RT-PCR半定量分析它们的表达模式也相同,都仅在花器官中表达。将NTAG1基因在拟南芥中过量表达,转基因植物T0代和T1代有C类基因过量表达的类似表型,叶片卷曲、植株矮小,开花提前,少数转化子萼片、雄蕊等花器官发育异常,T3代纯合子稳定遗传的表型中不再有花器官发育异常,但植株矮小、叶片卷曲,开花提前,侧枝增多,植物提前进入衰亡期。文中对NTAG1基因在基因工程应用方面的改进进行了探讨。

There are two cultivating varieties of Chinese narcissus, named as Yulinglong （Narcissus tazetta var. chinensis Roem. Florepleno） and Jinzhanyutai （Narcissus tazetta var. chinensis M. Roem.） well known in China. Yulinglong plants exhibit double flower resulted from petaloid stamens. However, the molecular basis of double flower formation is known little and unclear. Based on the flowering ABCDE model, double flower formation is commonly used to link to C functional genes. In this present paper, the isolation and characterization of NATG1 gene, an AGAMOUS homolog from Chinese narcissus varieties mentioned above are reported. Sequence and expression pattern of NATG1 gene exhibited the same in both tested varieties. It expresses only in the reproductive organs. Furthermore, functional analysis by using ectopic tests in Arabidopsis showed that NATG1 might be involved in the carpel identity and floral transition The effects of ectopic expression of NATG1 mainly include dwarfing, early flowering, losing inflorescence indeterminacy, branch number increasing, and advancing senescence, whereas some of homeotic phenotypes gradually sisappeared in higher generation of transgenic plants. The utilizations of NATG1 gene in the future gene engineering were also discussed in the paper.