Rajeevan M S, Bassett C L, Hughes D W
Department of Agronomy, University of Georgia, Athens 30602.
Plant Mol Biol. 1991 Sep;17(3):371-83. doi: 10.1007/BF00040632.
To study the control of enhanced synthesis of enzymes associated with C4 photosynthesis relative to non-C4 plants, we investigated the expression of NADP-malic enzyme (NADP-ME) in different photosynthetic types of Flaveria. Complementary DNA clones encoding NADP-ME were constructed using poly(A)+ RNA from leaves of Flaveria trinervia (C4) and F. linearis (C3-C4) and identified by homology to a cDNA clone (500 bp) encoding NADP-ME from maize (Zea mays L. [39]). The sequence of one clone from each species was determined. The Flaveria clones were 90% homologous over a 564 nucleotide region encoding the carboxy terminal end of the derived polypeptide; sequence similarity to the maize transcript in this region was 71%. Both Flaveria clones detected a 2/3 kb transcript by hybridization to poly(A)+ RNA from expanding leaves of F. trinervia, F. linearis and F. pringlei (C3). The level of transcripts paralleled previously observed NADP-ME activity and abundance differences determined in these species, suggesting that control of the expression of NADP-ME in different photosynthetic types is predominantly at the transcriptional/post-transcriptional level. Southern analysis of genomic DNAs from F. trinervia, F. linearis and F. pringlei indicated a low copy number for this gene in all three species.
为了研究与C4光合作用相关的酶的增强合成相对于非C4植物的调控，我们调查了NADP - 苹果酸酶（NADP - ME）在不同光合类型的黄顶菊中的表达。利用来自三脉黄顶菊（C4）和线叶黄顶菊（C3 - C4）叶片的聚腺苷酸加尾RNA构建了编码NADP - ME的互补DNA克隆，并通过与来自玉米（Zea mays L. [39]）的编码NADP - ME的cDNA克隆（500 bp）的同源性进行鉴定。测定了每个物种的一个克隆的序列。来自黄顶菊的克隆在编码推导多肽羧基末端的564个核苷酸区域内有90%的同源性；该区域与玉米转录本的序列相似性为71%。两个黄顶菊克隆通过与来自三脉黄顶菊、线叶黄顶菊和普氏黄顶菊（C3）展开叶片的聚腺苷酸加尾RNA杂交，检测到一个2/3 kb的转录本。转录本水平与先前在这些物种中观察到的NADP - ME活性和丰度差异平行，这表明在不同光合类型中NADP - ME表达的调控主要在转录/转录后水平。对三脉黄顶菊、线叶黄顶菊和普氏黄顶菊基因组DNA的Southern分析表明，该基因在所有三个物种中均为低拷贝数。
