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Among the most important transcription factors in plants, the v-myb avian myeloblastosis viral oncogene homolog (MYB) regulates the expression network of response genes under stresses such as fungal infection. In China, the canker disease Valsa mali threatens the survival of Malus sieversii, an ancestor of cultivated apples. Using the M. sieversii genome, we identified 457 MsMYB and 128 R2R3-MsMYB genes that were randomly distributed across 17 chromosomes. Based on protein sequence and structure, the R2R3-MsMYB genes were phylogenetically divided into 29 categories, and 26 conserved motifs were identified. We further predicted cis-elements in the 2000-kb promoter region of R2R3-MsMYBs based on the genome. Transcriptome analysis of M. sieversii under V. mali infection showed that 27 R2R3-MsMYBs were significantly differentially expressed, indicating their key role in the response to V. mali infection. Using transient transformation, MsMYB14, MsMYB24, MsMYB39, MsMYB78, and MsMYB108, which were strongly induced by V. mali infection, were functionally identified. Among the five MsMYBs, MsMYB14 and MsMYB78 were both important in enhancing resistance to diseases, whereas MsMYB24 inhibited resistance. Based on the results of this study, we gained a better understanding of the MsMYB transcription factor family and laid the foundation for a future research program on disease prevention strategies in M. sieversii. [ABSTRACT FROM AUTHOR]

• AWC and photosynthesis decrease upon dehydration process. • Recovery from slow dehydration is more rapid in the rehydration process. • SOD and CAT are key scavenging enzymes responding to dehydration-rehydration process. • The increase of stress-related transcripts abundance is correlated with drying rates. Dehydration rates significantly impact the amount of damage and rate of recovery of desiccation-tolerant mosses and thus play a role in the ability of these plants to occupy desert ecosystems. The desiccation-tolerant moss Bryum argenteum Hedw. is a component of biological soil crusts in northwestern China and has been extensively studied, but the effects of dehydration rates on its physiological and molecular responses to desiccation and rehydration are still unclear. We evaluated the physiological, biochemical, and molecular responses of B. argenteum during and upon recovery from rapid dehydration, ambient air dehydration, and slow dehydration rates. Our results demonstrated that (1) photosynthesis decreased significantly in response to all dehydration rates and recovered to the control level following rehydration; however, recovery from slow dehydration was more rapid. Ultrastructural investigations revealed that chloroplasts did not degrade and remained intact during desiccation regardless of the dehydration rates. (2) The activities of antioxidant enzymes increased under all drying regimes. Superoxide dismutase (SOD) and catalase (CAT) were the main scavenging enzymes that responded during the dehydration and rehydration processes. The transcripts encoding these enzymes also increased in abundance during desiccation and rehydration. (3) The extent of the increase of the abundance of stress-related transcripts was correlated with the dehydration rates, and all the transcripts displayed decreased abundance throughout rehydration. The majority of the transcripts showed similar accumulation patterns under the rapid and air dehydration treatments; however, slow dehydration resulted in a greater increase in transcript abundance. Our work provides insights into how desiccation and rehydration play roles in the ability of B. argentum to endure harsh environments. [ABSTRACT FROM AUTHOR]