Background: Resistance Gene Analogues (RGAs) are an important source of disease resistance in crop plants and have been extensively studied for their identification, tagging and mapping of Quantitative Trait Loci (QTLs). Tracking these RGAs in sugarcane can be of great help for the selection and screening of disease resistant clones.

Objective: In the present study expression of different Resistance Gene Analogues (RGAs) was assessed in indigenous elite sugarcane genotypes which include resistant, highly resistant, susceptible and highly susceptible to disease infestation.

Methods: Total cellular DNA and RNA were isolated from fourteen indigenous elite sugarcane genotypes. PCR, semi-quantitative RT PCR and real time qPCR analyses were performed. The resultant amplicons were sequence characterized, chromosomal localization and phylogenetic analysis were performed.

Results: All of the 15 RGA primers resulted in amplification of single or multiple fragments from genomic DNA whereas only five RGA primers resulted in amplification from cDNA. Sequence characterization of amplified fragments revealed 86-99% similarity with disease resistance proteins indicating their potential role in disease resistance response. Phylogenetic analysis also validated these findings. Further, expression of RGA-012, RGA-087, RGA-118, RGA-533 and RGA-542 appeared to be upregulated and down regulated in disease resistant and susceptible genotypes, respectively, after inoculation with Colletotrichum falcatum.

Conclusion: RGAs are present in most of our indigenous genotypes. Anyhow, differential expression of five RGAs indicated that they have some critical role in disease resistance. So, the retrieved results can not only be employed to devise molecular markers for the screening of disease resistant genotypes but can also be used to develop disease resistant plants through transgenic technology.

背景：抗性基因类似物 (RGA) 是作物抗病性的重要来源，已被广泛研究用于其鉴定、标记和定量性状位点 (QTL) 的定位。跟踪甘蔗中的这些 RGA 对选择和筛选抗病克隆有很大帮助。

目的：在本研究中，评估了本地优良甘蔗基因型中不同抗性基因类似物 (RGA) 的表达，这些基因型包括抗性、高抗性、易感性和对疾病侵染的高度易感性。

方法：从十四个本土优良甘蔗基因型中分离出总细胞 DNA 和 RNA。进行了 PCR、半定量 RT PCR 和实时 qPCR 分析。对所得扩增子进行序列表征，进行染色体定位和系统发育分析。

结果：所有 15 种 RGA 引物均导致来自基因组 DNA 的单个或多个片段的扩增，而只有 5 种 RGA 引物导致来自 cDNA 的扩增。扩增片段的序列特征显示与抗病蛋白有 86-99% 的相似性，表明它们在抗病反应中的潜在作用。系统发育分析也证实了这些发现。此外，在接种镰状炭疽菌后，RGA-012、RGA-087、RGA-118、RGA-533 和 RGA-542 的表达似乎分别在抗病和易感基因型中上调和下调。

结论：RGA 存在于我们的大多数本土基因型中。总之，五种 RGA 的差异表达表明它们在抗病性中具有一些关键作用。因此，检索到的结果不仅可以用于设计用于筛选抗病基因型的分子标记，还可以用于通过转基因技术开发抗病植物。