In the CIPK family, the CBL-interacting protein kinases have shown crucial roles in hormone signaling transduction, and response to abiotic stress in plant developmental processes. The CIPK family is characterized by conserved NAF/FISL (Asn-Ala-Phe) and PPI (protein-phosphatase interaction) domains in the C-terminus. However, little data has been reported about the CIPK family in apple. A total of 34 MdCIPK genes were identified from the apple genome in this study and were later divided into two groups according to the CIPK domains, characterized by gene structure and chromosomal distribution, and then mapped onto 17 chromosomes. All MdCIPK genes were expressed in the four apple tissues (leaf, root, flower, and fruit). In addition, the MdCIPK gene expression profile showed that five members among them revealed enhanced expression during the pollen tube growth stages. The MdCIPK4 was the most expressive during the entire fruit development stages. Under stress conditions 21 MdCIPK genes transcript levels were up-regulated in response to fungal and salt treatments. This suggested the possible features of these genes’ response to stresses in apples. Our findings provide a new insight about the roles of CIPK genes in apples, which could contribute to the cloning and functional analysis of CIPK genes in the future.

Pigeonpea is an important economic crop in the world and is mainly distributed in tropical and subtropical regions. In order to further expand the scope of planting, one of the problems that must be solved is the impact of soil acidity on plants in these areas. Based on our previous work, we constructed a time series RNA sequencing (RNA-seq) analysis under aluminum (Al) stress in pigeonpea. Through a comparison analysis, 11,425 genes were found to be differentially expressed among all the time points. After clustering these genes by their expression patterns, 12 clusters were generated. Many important functional pathways were identified by gene ontology (GO) analysis, such as biological regulation, localization, response to stimulus, metabolic process, detoxification, and so on. Further analysis showed that metabolic pathways played an important role in the response of Al stress. Thirteen out of the 23 selected genes related to flavonoids and phenols were downregulated in response to Al stress. In addition, we verified these key genes of flavonoid- and phenol-related metabolism pathways by qRT-PCR. Collectively, our findings not only revealed the regulation mechanism of pigeonpea under Al stress but also provided methodological support for further exploration of plant stress regulation mechanisms.

Sugar, acting as a signal, can regulate the production of some chemical substance during plant defense responses. However, the molecular basis and regulatory mechanisms of sugar in poplar and other forest trees are still unclear. Sorbitol is a sugar-signaling molecule associated with plant defense. In this study, the pathogen-infested status of poplar was alleviated after exogenous feeding of 50 mM sorbitol. We sequenced and analyzed the transcriptome of poplar leaves before and after inoculation. The results showed that the genes PR1, WRKY, ceramide kinases (CERK) and so on responded to sorbitol feeding and pathogen infestation. We screened for genes related to disease resistance such as PsWRKY25 and PsCERK1 and found that significant disease spots occurred on day six of strep throat infestation. Under sorbitol feeding conditions, the appearance of spots was delayed after the pathogen inoculation. Due to the overexpression of PsWRKY25, the overexpression of PsCERK1 triggered the defense response in poplar. This was also confirmed by PsWRKY25 overexpression experiments. These findings present new insights into the influence of sorbitol on Populus simonii Carr. disease resistance. These results emphasize the value of molecular phenotypes in predicting physiological changes.

To investigate the effect of sorbitol feeding on immune responses and its underlying mechanism, this study employed crabapple (Malus micromalus), a species native to China, as the experimental material. Detached leaves were subjected to sorbitol feeding experiments, with water feeding as the control. The dynamic changes in lesion area and cell membrane permeability were measured across four groups of leaves following feeding and fungal inoculation, and transcriptome sequencing was performed on these four groups. The results revealed that compared to the control group, leaves fed with sorbitol prior to inoculation exhibited significantly reduced lesion areas and decreased cell membrane permeability. Transcriptome and KEGG pathway analyses indicated that differentially expressed genes were significantly enriched in the phenylpropanoid biosynthesis pathway. HPLC results demonstrated that quercetin and isorhamnetin contents increased significantly after sorbitol feeding, and both compounds were shown to inhibit the mycelial growth of Alternaria alternata, thereby enhancing the disease resistance of crabapple leaves. Among the associated genes, MmF3H1, which regulates the synthesis of quercetin and isorhamnetin, showed the highest level of enrichment. Co-expression trend analysis and qPCR results revealed that MmNAC17 and MmbZIP1 exhibited strong co-expression relationships with MmF3H1 and responded to sorbitol regulation. Functional validation was conducted by constructing overexpression and silencing vectors for MmNAC17/MmbZIP1 and performing transient transformation, thereby elucidating the molecular and biochemical mechanisms underlying the response of M. micromalus to A. alternata. This study provides a theoretical reference for breeding crabapple varieties with enhanced resistance to leaf spot disease.