Abreu Emanuel F M, Aragão Francisco J L
Embrapa Recursos Genéticos e Biotecnologia, Laboratório de Introdução e Expressão de Genes, PqEB W5 Norte, 70770-900, Brasília, DF, Brazil.
Ann Bot. 2007 Feb;99(2):285-92. doi: 10.1093/aob/mcl256. Epub 2006 Nov 30.
Myo-inositol-1l-phosphate synthase (MIPS) catalyses the conversion of d-glucose 6-phosphate to 1-l-myo-inositol-1-phosphate, the first and rate-limiting step in the biosynthesis of all inositol-containing compounds. Inositol phospholipids play a vital role in membrane trafficking and signalling pathways, auxin storage and transport, phytic acid biosynthesis, cell wall biosynthesis and production of stress-related molecules. In the present study, an MIPS cDNA from developing Passiflora edulis f. flavicarpa seeds was characterized and an investigation made into its spatial and differential expression, as well as changes in its transcription during exposure of growing plants to cold and heat stresses.
The MIPS-encoding gene was isolated by polymerase chain reaction (PCR) methods, and transcript levels were examined using semi-quantitative reverse transcription-PCR (RT-PCR) during seed development and in response to heat and cold stress. In addition, the copy number of the cloned PeMIPS1 gene in the genome of Passiflora edulis, P. eichleriana, P. caerulea, P. nitida and P. coccinea was determined by Southern blot analyses.
A full-length cDNA clone of the PeMIPS1 from P. edulis was isolated and characterized. Southern blot analyses indicated that the genomic DNA might have diverse sequences of MIPS-encoding genes and one copy of the cloned PeMIPS1 gene in the genomes of P. edulis, P. eichleriana, P. caerulea, P. nitida and P. coccinea. RT-PCR expression analyses revealed the presence of PeMIPS1 transcripts in ovules, pollen grains and leaves, and during the seed developmental stages, where it peaked at 9 d after pollination. The PeMIPS1 gene is differentially regulated under cold and heat stress, presenting a light-responsive transcription.
Experimental data suggest that PeMIPS1 transcription plays an important role in the establishment of developmental programmes and during the response of plants to environmental changes. The PeMIPS1 is differentially transcribed during cold and heat stress, presenting a light response pattern, suggesting that it is important for environmental stress response.
肌醇-1-磷酸合酶（MIPS）催化6-磷酸-D-葡萄糖转化为1-L-肌醇-1-磷酸，这是所有含肌醇化合物生物合成的第一步和限速步骤。肌醇磷脂在膜运输和信号通路、生长素储存和运输、植酸生物合成、细胞壁生物合成以及应激相关分子的产生中起着至关重要的作用。在本研究中，对西番莲黄果变种发育种子中的一个MIPS cDNA进行了表征，并对其空间和差异表达以及生长中的植物在冷应激和热应激下转录的变化进行了研究。
通过聚合酶链反应（PCR）方法分离出编码MIPS的基因，并使用半定量逆转录PCR（RT-PCR）检测种子发育过程中以及对热应激和冷应激反应时的转录水平。此外，通过Southern印迹分析确定克隆的PeMIPS1基因在西番莲、艾氏西番莲、蓝花西番莲、亮叶西番莲和红花西番莲基因组中的拷贝数。
分离并表征了来自西番莲的PeMIPS1全长cDNA克隆。Southern印迹分析表明，基因组DNA可能具有编码MIPS基因的不同序列，且克隆的PeMIPS1基因在西番莲、艾氏西番莲、蓝花西番莲、亮叶西番莲和红花西番莲基因组中各有一个拷贝。RT-PCR表达分析显示，PeMIPS1转录本存在于胚珠、花粉粒和叶片中，以及种子发育阶段，在授粉后9天达到峰值。PeMIPS1基因在冷应激和热应激下受到差异调节，呈现光响应转录。
实验数据表明，PeMIPS1转录在发育程序的建立以及植物对环境变化的响应过程中起着重要作用。PeMIPS1在冷应激和热应激期间差异转录，呈现光响应模式，表明其对环境应激反应很重要。
