Submitted to: Molecular Plant Microbe Interactions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/29/2004
Publication Date: 10/20/2004
Citation: He, L., Du, C., Covaleda, L., Xu, Z., Robinson, A.F., Yu, J., Kohel, R.J., Zhang, H. 2004. Cloning, characterization, and evaluation of the NBS-LRR-encoding resistance gene analogue family in polyploid cotton (Gossypium hirsutum L.). Molecular Plant Microbe Interactions. 17(11):1234-1241. Interpretive Summary: This article reports the isolation and analysis of a very large gene family that confer resistance to cotton diseases caused by bacteria, fungi, nematodes, and viruses. A sample of 150 DNA clones resulted in identification of 62 such likely resistance genes. Analyses from DNA sequencing and genetic mapping revealed abundant and diverse gene family members in cultivated cotton. This finding will help cotton researchers in understanding the organization and evolution of the gene family for its use in breeding disease resistant cotton cultivars.
Technical Abstract: The NBS-LRR-encoding gene family has attracted much research interest because approximately 75% of the plant disease resistance genes that have been cloned to date are from this gene family. We cloned the NBS-LRR-encoding genes from polyploid cotton by a PCR-based approach. A sample of 150 clones was selected from the NBS-LRR gene sequence library and sequenced, and 62 resistance gene analogues (RGAs) were identified. Sequence analysis revealed that RGAs are abundant and highly diverged in the cotton genome, and could be categorized into 12 distinct subfamilies based on the similarities of their nucleotide sequences. The numbers of members among different subfamilies vary many folds, and gene index analysis showed that each of the subfamilies is at different stages of RGA family evolution. Genetic mapping of a selection of the RGAs indicates that the RGAs reside on a limited number of the cotton chromosomes, with those from a single subfamily tending to cluster. The distribution of RGAs between the two subgenomes, A and D, of cotton is uneven, with the A subgenome being more abundant in RGAs than the D subgenome. The data provide new insights into the organization and evolution of the NBS-LRR-encoding RGA family in polyploid plants.