Genome-Wide Identification and Expression Analysis of the NAC Gene Family in Kandelia obovata, a Typical Mangrove Plant.

The NAC (NAM, ATAF1/2, and CUC2) gene family, one of the largest transcription factor families in plants, acts as positive or negative regulators in plant response and adaption to various environmental stresses, including cold stress. Multiple reports on the functional characterization of NAC genes in Arabidopsis thaliana and other plants are available. However, the function of the NAC genes in the typical woody mangrove (Kandelia obovata) remains poorly understood. Here, a comprehensive analysis of NAC genes in K. obovata was performed with a pluri-disciplinary approach including bioinformatic and molecular analyses. We retrieved a contracted NAC family with 68 genes from the K. obovata genome, which were unevenly distributed in the chromosomes and classified into ten classes. These KoNAC genes were differentially and preferentially expressed in different organs, among which, twelve up-regulated and one down-regulated KoNAC genes were identified. Several stress-related cis-regulatory elements, such as LTR (low-temperature response), STRE (stress response element), ABRE (abscisic acid response element), and WUN (wound-responsive element), were identified in the promoter regions of these 13 KoNAC genes. The expression patterns of five selected KoNAC genes (KoNAC6, KoNAC15, KoNAC20, KoNAC38, and KoNAC51) were confirmed by qRT-PCR under cold treatment. These results strongly implied the putative important roles of KoNAC genes in response to chilling and other stresses. Collectively, our findings provide valuable information for further investigations on the function of KoNAC genes.

Superior Wear Resistance in EBM-Processed TC4 Alloy Compared with SLM and Forged Samples.

The wear properties of Ti-6Al-4V alloy have drawn great attention in both aerospace and biomedical fields. The present study examines the wear properties of Ti-6Al-4V alloy as prepared by selective laser melting (SLM), electron beam melting (EBM) and conventional forging processes. The SLM and EBM samples show better wear resistance than the forged sample, which correlates to their higher hardness values and weak delamination tendencies. The EBM sample shows a lower wear rate than the SLM sample because of the formation of multiple horizontal cracks in the SLM sample, which results in heavier delamination. The results suggest that additive manufacturing processes offer significantly wear-resistant Ti-6Al-4V specimens in comparison to their counterparts produced by forging.