Chloroplast transformation with modified accD operon increases acetyl-CoA carboxylase and causes extension of leaf longevity and increase in seed yield in tobacco
Chloroplast transformation with modified accD operon increases acetyl-CoA carboxylase and causes extension of leaf longevity and increase in seed yield in tobacco
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DOI：
10.1093/pcp/pcf172
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发表时间：
2002-12-01
影响因子：
4.9
通讯作者：
Sasaki, Y
中科院分区：
文献类型：
--
作者：
Madoka, Y;Tomizawa, KI;Sasaki, Y
叶绿体中的乙酰辅酶A羧化酶(ACCase)是调节植物体内从头合成脂肪酸速率的关键酶。胞质ACCase由3个核编码亚基和1个胞质编码ACCD亚基组成。为了提高ACCase的水平，我们研究了ACCD的过度表达是否会提高ACCase的产量。我们利用同源重组的方法，将烟草叶绿体基因组中ACCD操纵子的启动子替换为叶绿体rRNA操纵子(Rrn)启动子，并成功地提高了叶绿体中ACCase的总水平。这一结果表明，ACCD亚单位的水平是ACCase水平的决定因素，酶水平部分地在转录后亚基组装水平上受到控制。转化子生长正常，叶片中脂肪酸含量显著增加，但种子中脂肪酸含量增加不明显。然而，转化子的叶片寿命延长了，种子产量比对照增加了一倍，最终转化子的单株脂肪酸产量几乎是对照和野生型植物的两倍。这些发现为提高植物生产力和石油产量提供了一种潜在的方法。
Acetyl-CoA carboxylase (ACCase) in plastids is a key enzyme regulating the rate of de novo fatty acid biosynthesis in plants. Plastidic ACCase is composed of three nuclear-encoded subunits and one plastid-encoded accD subunit. To boost ACCase levels, we examined whether overexpression of accD elevates ACCase production. Using homologous recombination, we replaced the promoter of the accD operon in the tobacco plastid genome with a plastid rRNA-operon (rrn) promoter that directs enhanced expression in photosynthetic and non-photosynthetic organs, and successfully raised the total ACCase levels in plastids. This result suggests that the level of the accD subunit is a determinant of ACCase levels, and that enzyme levels are in part controlled post-transcriptionally at the level of subunit assembly. The resultant transformants grew normally and the fatty acid content was significantly increased in leaves, but not significantly in seeds. However, the transformants displayed extended leaf longevity and a twofold increase of seed yield over the control value, which eventually almost doubled the fatty acid production per plant of the transformants relative to control and wild-type plants. These findings offer a potential method for raising plant productivity and oil production.