Sugarcane brown rust, caused by Puccinia melanocephala, is one of the main diseases of sugarcane in China. The identification and discovery of new resistance genes have important theoretical and practical significance for preventing outbreaks of brown rust and ensuring the sustainable production of sugarcane. To screen for polymorphic simple-sequence repeat (SSR) molecular markers for localization of brown rust resistance genes, we used two populations that are suitable for genetic linkage map construction and mapping of new resistance genes to construct resistant and susceptible genetic pools. We then screened 449 pairs of primers to identify polymorphic SSR markers in the parental lines and the resistant/susceptible genetic pools. The results showed that 25 pairs of primers directed amplification of polymorphic DNA fragments between the parents of the cross combination ‘Yuetang 03-393’ × ‘ROC 24’, and 16 pairs of primers amplified polymorphic fragments between the parents of the cross combination ‘Liucheng 03-1137’ × ‘Dezhe 93-88’. Four pairs of primers (SMC236CG, SCESSR0928, SCESSR0636 and SCESSR2551) amplified polymorphic DNA fragments between the parental lines and the resistant/susceptible genetic pools in ‘Yuetang 03-393’ × ‘ROC 24’. The results of this study will establish a solid foundation for the mapping of new brown rust resistance genes, genetic linkage map construction and the development of closely-associated molecular markers in sugarcane.

We assessed inheritance of resistance to sugarcane brown rust (Puccinia melanocephala) in selfing F1 populations of wild sugarcane germplasm Erianthus rockii ‘Yundian 95-19’ and E. rockii ‘Yundian 95-20’. We tested parent and selfing F1 individuals for the brown rust resistance gene, Bru1, that has been shown to confer resistance to brown rust in sugarcane. The Bru1 gene was not detected in E. rockii ‘Yundian 95-19’, E. rockii ‘Yundian 95-20’ or their selfing F1 individuals, and we found there was segregation of resistance in the two selfing F1 populations (segregation ratio: 3:1). The results confirmed resistance in E. rockii ‘Yundian 95-19’ and E. rockii ‘Yundian 95-20’ to sugarcane brown rust is controlled by a novel, single dominant gene.

Electron microscopy was used to investigate microstructures of diamond single crystals prepared at high temperature and high pressure (HPHT) from the Fe–Ni–C system. Analysis through selected-area electron diffraction pattern suggests that the crystal structure of the HPHT-grown diamond is cubic; polycrystalline diamonds are contained in the diamond. Etch pits on the (111) surface of the diamond by scanning electron microscopy revealed the dislocation motion under the action of applied stress. An array of parallel dislocation lines taken with reflection of [110] was observed directly by transmission electron microscopy (TEM). Fringe distortions and concentric dislocation loops were examined by rotation moiré images, which arose from two overlapping (111) close-packed planes rotated with respect to each other at a 5° angle. The parallel dislocation lines, distorted fringes, and concentric dislocation loops might have derived from the micro-inclusions. The parallel layers with growth cellular interface by TEM provided direct evidence that the diamond grew from solution of carbon in the molten catalyst at HPHT and the growth interface diamond was not stable.