Department of Protein Chemistry and Technology, CSIR-Central Food Technological Research Institute, Mysore, India.
Plant Physiol Biochem. 2012 Aug;57:245-53. doi: 10.1016/j.plaphy.2012.05.028. Epub 2012 Jun 12.
Lipolytic enzymes play an important role in plant growth and development. In order to identify their functional roles, the temporal expression profiling of lipase was carried out during rice seed germination, growth and development of caryopsis. Changes in specific activities during germination revealed that the lipolytic activity increased significantly until the end of germination. As the lipase activity increased, two different lipase species were observed, which were designated as Lipase-I and Lipase-II based on their relative mobility. Lipase-II was active during germination. Lipase-I was responsible for lipid mobilization, a requirement for the growth of root and shoot. In comparison with the endosperm, the lipolytic activity in roots was three fold higher. During rice caryopsis development, the lipolytic activity increased gradually from initial panicle development and reached maximum as the grain dried to harvest maturity. Quantitative real-time PCR analysis revealed that the Lipase-II was a stage specific expressing gene during reproductive growth. The transcript level of Lipase-II reached maximum with completion of germination, then decreased and remained stable during post-germinative growth. During caryopsis development, Lipase-II is predominantly expressed in the developing seeds. The transcript abundance increased gradually during initial stages of development and reached a maximum until seed maturation. The results implicate that the dynamic changes in the enzyme activity of the two isoforms of lipase and gene expression patterns are associated with the energy reserve mobilization during seed germination and reproductive growth.
脂肪酶在植物生长发育中起着重要作用。为了鉴定它们的功能作用，我们在水稻种子萌发、颖果生长发育过程中对脂肪酶进行了时程表达谱分析。萌发过程中比活的变化表明，脂肪酶活性在萌发结束前显著增加。随着脂肪酶活性的增加，观察到两种不同的脂肪酶，根据其相对迁移率分别命名为脂肪酶-I 和脂肪酶-II。脂肪酶-II 在萌发过程中具有活性。脂肪酶-I 负责脂质动员，这是根和芽生长的需要。与胚乳相比，根中的脂肪酶活性高 3 倍。在水稻颖果发育过程中，脂肪酶活性从最初的小穗发育开始逐渐增加，在谷物干燥到收获成熟时达到最大值。定量实时 PCR 分析显示，脂肪酶-II 是生殖生长过程中具有阶段特异性表达的基因。脂肪酶-II 的转录水平在萌发完成时达到最大值，然后在萌发后生长过程中下降并保持稳定。在颖果发育过程中，脂肪酶-II 主要在发育中的种子中表达。在发育的早期阶段，转录丰度逐渐增加，直到种子成熟达到最大值。结果表明，两种同工酶的酶活性和基因表达模式的动态变化与种子萌发和生殖生长过程中能量储备的动员有关。
