巴西橡胶Pto类抗病同源序列的克隆与系统发育重建

番茄Pto基因是一类可以编码丝氨酸/苏氨酸激酶(STK)序列的广谱抗性候选基因,其序列克隆与鉴定为深入了解番茄的抗病机制奠定了基础.在该研究中,一对依据Pto基因的保守序列设计的简并引物被用来扩增巴西橡胶中Pto基因抗病同源序列,扩增得到了一个约550 bp的基因片段,其随后被克隆并测序.序列分析发现,其中的7个抗病同源序列与Pto基因高度同源(BLASTX E value <3e-53),所以其被认为是Pto基因抗病同源序列(Pto-RGCs).通过巴西橡胶的Pto-RGCs多序列比对表明,这些序列包含了多个STKs保守的次级结构域.此外,系统发育分析也表明,巴西橡胶的Pto-RGCs属于Pto基因同源的R基因.该研究结果中Pto-RGCs可为巴西橡胶抗病的发展提供一个有效的基因资源.

Structural and phylogenetic analysis of Pto-type disease resistance gene candidates in Hevea brasiliensis

The tomato Pto gene encodes a serine/threonine kinase(STK)whose molecular characterization provides valuable insights into the disease resistance mechanism of tomato and it is considered as a promising candidate for engineering broad-spectrum pathogen resistance in this crop. In this study, a pair of degenerate primers based on conserved subdomains of plant STKs similar to the tomato Pto protein were used to amplify similar sequences in Hevea brasiliensis. A fragment of -550 bp was amplified, cloned and sequenced. The sequence analysis of several clones revealed twelve distinct sequences were highly similar to STKs. Based on their significant similarity with the tomato Pto protein(BLASTX E value <3e-53), seven of them were classified as Pto resistance gene candidates(Pto-RGCs). Multiple sequence alignment of the hevea Pto-RGC products revealed that these sequences contained several conserved subdomains in most STKs and also several conserved residues that are crucial for Pto function. Moreover, the phylogenetic analysis showed that the hevea Pto-RGCs were clustered with Pto suggesting a common evolutionary origin with this R gene. The Pto-RGCs isolated in this study represent a valuable sequence resource that could assist in the development of disease resistance in hevea.