Shimosaka E, Sasanuma T, Handa H
Laboratory of Plant Genecology, Hokkaido National Agricultural Experiment Station, Sapporo, Japan.
Plant Cell Physiol. 1999 Mar;40(3):319-25. doi: 10.1093/oxfordjournals.pcp.a029544.
Sequencing and computer analysis revealed that a wcr (wheat cold-regulated) cDNA, wcr12, contained a 525 bp open reading frame encoding a polypeptide of 174 amino acids. The deduced WCR12 protein had a high sequence similarity with Early light-inducible proteins (ELIPs) which are known as nuclear-encoded chloroplast proteins induced by light stress. The accumulation of wcr12 transcripts was induced by low temperature below 8 degrees C and was also increased under a high light flux of 1,000 microEm-2 s-1, which are typical expression patterns of the genes for ELIPs in other plants. The dramatic increase in the level of wcr12 transcripts was detected at 4 degrees C even under a low light condition (50 microEm-2 s-1) and the level of transcripts became 20-fold higher than the control at 20 degrees C under a moderate light condition (250 microEm-2 s-1). Surprisingly, the accumulation of wcr12 mRNAs was also induced by cold treatment alone at 4 degrees C in the darkness. The level of wcr12 transcripts accumulated in the darkness at 4 degrees C reached the same level as that under a high light flux at 20 degrees C. These results indicate that light is not essential for the accumulation of wcr12 transcripts at a low temperature. To determine the chromosomal location of wcr12 gene, we performed Southern analysis using the nullitetrasomic lines. The data showed that the wcr12 gene or related homologues are located on the chromosomes of homoeologous group-5 in wheat.
测序和计算机分析表明，一个小麦冷调控（wcr）cDNA，即wcr12，包含一个525 bp的开放阅读框，编码一个由174个氨基酸组成的多肽。推导的WCR12蛋白与早期光诱导蛋白（ELIPs）具有高度的序列相似性，ELIPs是已知的受光胁迫诱导的核编码叶绿体蛋白。wcr12转录本的积累受8摄氏度以下低温诱导，在1000微摩尔光子·平方米⁻²·秒⁻¹的高光通量下也会增加，这是其他植物中ELIPs基因的典型表达模式。即使在低光照条件（50微摩尔光子·平方米⁻²·秒⁻¹）下，在4摄氏度时也能检测到wcr12转录本水平的显著增加，并且在中等光照条件（250微摩尔光子·平方米⁻²·秒⁻¹）下，20摄氏度时转录本水平比对照高20倍。令人惊讶的是，在黑暗中4摄氏度单独进行冷处理也能诱导wcr12 mRNA的积累。4摄氏度黑暗中积累的wcr12转录本水平与20摄氏度高光通量下的水平相同。这些结果表明，在低温下光对于wcr12转录本的积累不是必需的。为了确定wcr12基因的染色体定位，我们使用缺体四体品系进行了Southern分析。数据表明，wcr12基因或相关同源物位于小麦同源群5的染色体上。
