Artlip T S, Callahan A M, Bassett C L, Wisniewski M E
Appalachian Fruit Research Station, USDA-ARS, Kearneysville, WV 25430, USA.
Plant Mol Biol. 1997 Jan;33(1):61-70. doi: 10.1023/a:1005787909506.
A cDNA library was created from cold-acclimated bark tissue of peach and selectively probed using an antibody directed against the lysine-rich consensus region of dehydrin proteins. Several clones were thus obtained which had a high degree of sequence similarity to other dehydrin genes. Northern analysis, using clone 5a, indicated that a 1.8 kb transcript was seasonally expressed in sibling deciduous and evergreen genotypes of peach, and also inducible by water deficit in cv. Rio Oso Gem. The evergreen and deciduous genotypes differ significantly in both their ability to cold-acclimate and in the seasonal expression of the dehydrin transcript and protein. In both genotypes, the transcript was maximally expressed during winter and undetectable in May-July. The evergreen genotype (less cold-tolerant), however, displayed transcript accumulation which lagged behind and declined sooner than in the deciduous genotype. Protein expression was similar to transcript expression, however, protein expression in the evergreen genotype lagged considerably behind transcript accumulation in the fall. This indicates that several levels of regulation of dehydrin proteins may exist during cold acclimation. A genomic clone (G10a) was isolated which contained the full-length dehydrin gene, designated ppdhn1. The peach dehydrin gene encodes 472 amino acids with a predicted size of 50,020 Da. The encoded protein (PCA60) contains nine of the lysine-rich repeats characteristic of dehydrins and two DEYGNP motifs at the amino acid terminus. A genomic blot, probed with clone 5a under stringent conditions, indicated that one or two highly homologous genes are present in peach, whereas an additional member was detected under low-stringency conditions. It is suggested that several members of the dehydrin gene family may exist in peach that vary in their relation to ppdhn1.
从经冷驯化的桃树树皮组织中构建了一个cDNA文库，并使用针对脱水蛋白富含赖氨酸共有区域的抗体进行选择性筛选。由此获得了几个与其他脱水蛋白基因具有高度序列相似性的克隆。使用克隆5a进行的Northern分析表明，一个1.8 kb的转录本在桃树的落叶和常绿同属基因型中呈季节性表达，并且在‘Rio Oso Gem’品种中也可被水分亏缺诱导表达。常绿和落叶基因型在冷驯化能力以及脱水蛋白转录本和蛋白质的季节性表达方面均存在显著差异。在这两种基因型中，转录本在冬季表达量最高，而在5月至7月无法检测到。然而，常绿基因型（耐寒性较差）的转录本积累滞后，且比落叶基因型下降得更快。蛋白质表达与转录本表达相似，不过，常绿基因型中的蛋白质表达在秋季大大滞后于转录本积累。这表明在冷驯化过程中可能存在脱水蛋白的多个调控水平。分离出一个基因组克隆（G10a），其包含全长脱水蛋白基因，命名为ppdhn1。桃树脱水蛋白基因编码472个氨基酸，预测大小为50,020 Da。编码的蛋白质（PCA60）含有脱水蛋白特有的九个富含赖氨酸的重复序列以及位于氨基酸末端的两个DEYGNP基序。在严格条件下用克隆5a进行探针杂交的基因组印迹表明，桃树中存在一个或两个高度同源的基因，而在低严谨条件下检测到了另一个成员。有人提出，桃树中可能存在脱水蛋白基因家族的几个成员，它们与ppdhn1的关系各不相同。
