In order to understand the genetic diversity of germplasm resources of kumquats in Guangxi, 14 kumquat germplasm resources in Guangxi and 12 accessions from other provinces were analyzed by using SRAP markers. In total, 19 primer pairs with high stability, good reproducibility, and high polymorphism were chosen for analysis of all 26 kumquat genotypes. Among the 104 amplified bands, 90 (86.54%) were polymorphic. SRAP markers were analyzed by employing Principal Coordinate Analysis, Population Structure Analysis, and Hierarchical Cluster Analysis (UPGMA). The classification results showed that the 26 kumquat germplasm resources could be divided into 5 groups, including cultivated kumquat, intergeneric hybrid, wild kumquat from other provinces, wild kumquat, and hybrid kumquat from Guangxi. The Guangxi kumquat germplasm had high genetic diversity, and were clearly divided into three groups: cultivated kumquat, wild kumquat, and hybrid kumquat. Additionally, the eight cultivated kumquat varieties in Guangxi were further divided into two subgroups. Wild kumquat in Guangxi or in other provinces belonged to different groups; meanwhile, the Guangxi kumquat hybrid formed an independent group, thus indicating that Guangxi wild kumquat and hybrid kumquat possess certain specificity, or they possibly belong to different species. Among the tested 26 kumquat accessions, 23 unique genotype-specific SRAP markers were detected for 14 kumquat genotypes, which were positively identified. For the remaining 12 accessions without genotype-specific markers, they were distinguished by various combinations of markers. These results may have certain importance for kumquat genetic research and cultivar selection.

In order to understand the genetic diversity of germplasm resources of kumquat in Guangxi, 14 kumquat germplasm resources in Guangxi and 12 accessions from other provinces were analyzed by using SRAP markers. In total, 19 primer pairs with high stability, good reproducibility, and high polymorphism were chosen for analysis of all the 26 kumquat genotypes. Among the 101 amplified bands, 87 (86.14%) were polymorphic. SRAP markers were analyzed by employing Principal Coordinate Analysis, Population Structure Analysis and Hierarchical Cluster Analysis (UPGMA). The classification results showed that 26 kumquat germplasm could be divided into 5 groups, including cultivated kumquat, intergeneric hybrid, wild kumquat from other provinces, wild kumquat from Guangxi and hybrid kumquat from Guangxi. Guangxi kumquat germplasm occurred high genetic diversity, which were clearly divided into 3 groups like cultivated kumquat, wild kumquat and kumquat hybrid. And the 8 cultivated kumquat varieties in Guangxi were further divided into two subgroups. Wild kumquat in Guangxi and wild kumquat in other provinces belong to different groups, meanwhile the hybrids of Guangxi kumquat form independent groups, thus indicated that Guangxi wild kumquat and kumquat hybrid possessed certain specificity, or they maybe belonged to different species. Among the tested 26 kumquat accessions, 23 unique genotype-specific SRAP markers were detected for 14 kumquat genotypes, which made it possible to surely identify them. For the remaining 12 accessions without genotype-specific markers, they were distinguished by various combinations of markers. These results may have certain importance for kumquat genetic research and cultivar selection.

Citrus canker, caused by Xanthomonas citri subsp. citri (Xcc), is commonly managed with copper-based formulations, yet the performance of individual products may differ between laboratory and plant assays. We compared 16 commercial copper-containing formulations in plate-diffusion and root-drench assays, and inhibition zones varied among products. Thiosen Copper, however, produced no visible inhibition zone on agar but suppressed Xcc growth after root application. In sweet orange, this suppression appeared earlier than with Bordeaux Mixture at the same nominal total Cu concentrations. Thiosen Copper raised the leaf chlorophyll index without a significant increase in total leaf Cu, whereas Bordeaux Mixture led to greater leaf Cu accumulation. In separate experiments with Poncirus trifoliata, the two formulations produced different growth and tissue Cu responses, and root treatment altered PtCOPT transcript levels. Transient overexpression of CsCOPT4 in sweet orange leaves was accompanied by lower Xcc populations. These results reveal formulation-specific responses and nominate CsCOPT4 as a candidate for further study.