RESUMEN
In this paper, we introduced an order parameter, named the local structure similarity (LSS), to measure the resemblance of a cluster structure in a liquid with respect to a perfect crystal. The LSS is based on a dot product of two bond orientational order complex vectors, with one vector associated with a particle in a liquid and the other vector with a particle in a crystal. The calculation of the LSS should scan the entire space of the Euler angles determined by the two coordinate frames describing individually the liquid and the crystal. The effectiveness of the LSS was examined by solid-like clusters in a Lennard-Jones (LJ) system near its liquid-solid phase transition and at solid states below its melting point, where the thermodynamic states of the LJ system were obtained by simulation annealing. The LSS measure was utilized to scrutinize the fcc-like, hcp-like, and bcc-like clusters classified by criteria based on W4 and W6 order parameters. As indicated by our results, the two ways of classification are consistent for fcc-like and hcp-like clusters, which are in a close resemblance to their crystalline counterparts. However, the classification with positive W6 for bcc-like clusters is inconsistent with the results of the LSS measure, which was confirmed by clusters in a LJ system confined between two parallel slabs of particles in the bcc structure arrangement.
RESUMEN
Starch paste viscosity plays an important role in estimating the cooking, eating, and processing quality of rice. The inheritance of starch paste viscosity in glutinous rice remains undefined. In the present study, 118 glutinous rice accessions were collected, and the genotypes of 17 starch synthesis-related genes (SSRG) were analyzed by using 43 gene-specific molecular markers. Association analysis indicated that 10 of 17 SSRGs were involved in controlling the rapid visco analyzer (RVA) profile parameters. Among these, the PUL gene was identified to play an important role in control of peak viscosity (PKV), hot paste viscosity (HPV), cool paste viscosity (CPV), breakdown viscosity (BDV), peak time (PeT), and paste temperature (PaT) in glutinous rice. Other SSRGs involved only a few RVA profile parameters. Furthermore, interactions between SSRGs were found being responsible for PeT, PaT, and BDV. Some of the RVA parameters, including PKV, HPV, CPV, CSV, and PaT, were mainly governed by single SSRG, whereas other parameters, such as BDV, SBV, and PeT, were controlled by a few SSRGs, functioning cooperatively. Further, three near-isogenic lines (NIL) of a japonica glutinous cv. Suyunuo as genetic background, with PUL, SSIII-1, and SSIII-2 alleles replaced with those of indica cv. Guichao 2, were employed to verify the genetic effects of the various genes, and the results were consistent with those obtained from the association analysis. These findings indicated that starch paste viscosity in glutinous rice had a complex genetic system, and the PUL gene played an important role in determining the RVA profile parameters in glutinous rice. These results provide important information for potentially improving the quality of glutinous rice.