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玉米的叶片坏死斑点(lethal leaf-spot 1,Lls1)基因及其拟南芥中的同功能基因已证明编码叶绿素分解代谢中的关键酶脱镁叶绿酸氧化酶(pheide a oxygenase,PaO)．为了深入研究大豆叶片衰老过程中叶绿素分解代谢的调控机制,从大豆中克隆了玉米Lls1的同源基因,其cDNA全长1817bp,命名为GmLls1(GenBank登录号：DQ154009)．序列分析表明,该基因与拟南芥、玉米、豇豆和番茄等的Lls1及其同功能基因具有很高的同源性,其编码蛋白含有典型的Rieske[2Fe-2S]结构域、非亚铁血红素铁结合域和C-末端CXXC基序,这些都是PaO功能蛋白所具有的典型结构特征．RT-PCR结果显示,在大豆叶片自然衰老、人工黑暗诱导衰老和子叶衰老3个系统中,GmLls1基因都表现出明显的衰老上调趋势．进一步分析发现,在因敲减类受体蛋白激酶rlpk2基因而导致衰老延缓的大豆转基因叶片中,GmLls1的表达显著下降,而在因过表达rlpk2而导致加速衰老的转基因叶片中,GmLls1的转录本积累明显增加,暗示RLPK2介导的信号途径可能参与调控GmLls1在大豆叶片衰老过程中的表达,而rlpk2-RNAi转基因离体叶片光照下表现出lls1突变体典型的斑状失绿坏死表型则进一步支持了上述推论．
The lethal leaf-spot 1 (Lls1) gene of maize and its homologue gene in Arabidopsis have been shown to encode pheide a oxygenase (PaO), a key enzyme in chlorophyll catabolism. In order to further study the regulation mechanism of chlorophyll catabolism during soybean leaf senescence, a homologous gene of Lls1 was cloned from soybean. The full-length cDNA of Lls1 was named as GmLls1 (GenBank accession number: DQ154009). Sequence analysis showed that this gene has high homology with Lls1 and its homologues in Arabidopsis, maize, cowpea and tomato. The encoded protein contains the typical Rieske [2Fe-2S] domain, non-ferrous Heme iron binding domain and C-terminal CXXC motifs, all of which are typical structural features of PaO functional proteins. The results of RT-PCR showed that GmLls1 gene showed a significant upward trend in senescence, artificial dark-induced senescence and cotyledon senescence. Further analysis revealed that the expression of GmLls1 was significantly decreased in soybean transgenic leaves induced by the knockdown of the receptor-like protein kinase rlpk2 gene, whereas in the transgenic leaves induced by accelerated overexpression of rlpk2, the transcripts of GmLls1 Suggesting that RLPK2-mediated signaling pathway may be involved in the regulation of GmLls1 expression in senescence of soybean leaves, while the lpl1 mutant typical rlpk2-RNAi transgenic leaves showed further support for the typical macular degeneration-necrosis phenotype The above reasoning.