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Plant NAPDH oxidase (NOX) gene family members are critical producers of ROS and play crucial roles in plant signaling, development, and stress responses. Opisthopappus taihangensis is a pivotal wild genetic resource in Asteraceae. To date, little knowledge exists about the functions of NOXs in O. taihangensis. In this study, seven typical NOXs and seven ferric reduction oxidases (FROs) were identified in O. taihangensis. Dispersed duplication might play a critical role in the expansion of the NOX/FRO gene family in O. taihangensis, and most of the NOX/FRO homologous pairs have undergone purifying selection. Although the results of the collinearity analysis show that these genes were relatively conserved, the gain and loss of members in this gene family occurred frequently during the evolution of Asteraceae. Phylogenetic analysis indicated that the FROs are relatively ancient, and the earliest diverged branch was revealed by the maximum likelihood (ML) tree. The Asteraceae NOXs were divided into six subgroups according to their relationship with Arabidopsis and rice members. The transcriptome profile unveiled tissue-specific expression patterns and complex response modes under drought and salt stresses. OtNOX6 and OtNOX7 could be recognized as important candidates to respond to drought and salt stress. Our results provide clues and references for further in-depth exploration of NOX/FRO function in O. taihangensis and other horticulture plants. [ABSTRACT FROM AUTHOR]

Cold stress impacts woody tree growth and perennial production, especially when the temperature rapidly changes in late spring. To address this issue, we conducted the genome-wide identification of two important transcription factors (TFs), CBF (C-repeat binding factors) and ICE (inducers of CBF expression), in three walnut (Juglans) genomes. Although the CBF and ICE gene families have been identified in many crops, very little systematic analysis of these genes has been carried out in J. regia and J. sigillata. In this study, we identified a total of 16 CBF and 12 ICE genes in three Juglans genomes using bioinformatics analysis. Both CBF and ICE had conserved domains, motifs, and gene structures, which suggests that these two TFs were evolutionarily conserved. Most ICE genes are located at both ends of the chromosomes. The promoter cis-regulatory elements of CBF and ICE genes are largely involved in light and phytohormone responses. Based on 36 RNA sequencing of leaves from four walnut cultivars ('Zijing', 'Lvling', 'Hongren', and 'Liao1') under three temperature conditions (8 °C, 22 °C, and 5 °C) conditions in late spring, we found that the ICE genes were expressed more highly than CBFs. Both CBF and ICE proteins interacted with cold-related proteins, and many putative miRNAs had interactions with these two TFs. These results determined that CBF1 and ICE1 play important roles in the tolerance of walnut leaves to rapid temperature changes. Our results provide a useful resource on the function of the CBF and ICE genes related to cold tolerance in walnuts. [ABSTRACT FROM AUTHOR]

Allopolyploids exist widely in nature and have strong environmental adaptability. The typical allopolyploid Brassica napus L. is a widely cultivated crop, but whether it is superior to its diploid progenitors in abiotic stress resistance and the key genes that may be involved are not fully understood. Cystein-rich polycomb-like protein (CPP) genes encode critical transcription factors involved in the response of abiotic stress, including salt stress. To explore the potential molecular basis of allopolyploid adaptation to salt stress, we comprehensively analyzed the characteristics and salt stress response of the CPP genes in B. napus and its two diploid progenitors in this study. We found some molecular basis that might be associated with the adaptability of B. napus , including the expansion of the CPP gene family, the acquisition of introns by some BnCPPs , and abundant cis -acting elements upstream of BnCPPs. We found two duplication modes (whole genome duplication and transposed duplication) might be the main reasons for the expansion of CPP gene family in B. napus during allopolyploidization. CPP gene expression levels and several physiological indexes were changed in B. napus and its diploid progenitors after salt stress, suggesting that CPP genes might play important roles in the response of salt stress. We found that some BnCPPs might undergo new functionalization or subfunctionalization, and some BnCPPs also show biased expression, which might contribute to the adaptation of B. napus under saline environment. Compared with diploid progenitors, B. napus showed stronger physiological responses, and BnCPP gene expression also showed higher changes after salt stress, indicating that the allopolyploid B. napus had an adaptive advantage under salt stress. This study could provide evidence for the adaptability of polyploid and provide important clues for the study of the molecular mechanism of salt stress resistance in B. napus. [ABSTRACT FROM AUTHOR]