Abstract
Major latex proteins (MLPs) play critical roles in plants defense and stress responses. However, the roles of MLPs from apple (Malus × domestica) have not been clearly identified. In this study, we focused on the biological role of MdMLP423, which had been previously characterized as a potential pathogenesis-related gene. Phylogenetic analysis and conserved domain analysis indicated that MdMLP423 is a protein with a ‘Gly-rich loop’ (GXGGXG) domain belonging to the Bet v_1 subfamily. Gene expression profiles showed that MdMLP423 is mainly expressed in flowers. In addition, the expression of MdMLP423 was significantly inhibited by Botryosphaeria berengeriana f. sp. piricola (BB) and Alternaria alternata apple pathotype (AAAP) infections. Apple calli overexpressing MdMLP423 had lower expression of resistance-related genes, and were more sensitive to infection with BB and AAAP compared with non-transgenic calli. RNA-seq analysis of MdMLP423-overexpressing calli and non-transgenic calli indicated that MdMLP423 regulated the expression of a number of differentially expressed genes (DEGs) and transcription factors, including genes involved in phytohormone signaling pathways, cell wall reinforcement, and genes encoding the defense-related proteins, AP2-EREBP, WRKY, MYB, NAC, Zinc finger protein, and ABI3. Taken together, our results demonstrate that MdMLP423 negatively regulates apple resistance to BB and AAAP infections by inhibiting the expression of defense- and stress-related genes and transcription factors.
Highlights
Major latex protein (MLP) is a plant-specific protein that was first identified in opium poppy latex and is widely found in other plants [1,2]
In a previous study we analyzed the iTRAQ-based proteomics profiles of ‘Huayue’ apple leaves in response to alternata apple pathotype (AAAP) infection, and we found that MdMLP423 is a potential allergy related protein, that is involved in stress responses in fruit trees [21]
The phylogenetic analysis showed that the MdMLP423 protein (XP_008340001.1) was closely connected with AtMLP43 (Q9SSK5.1; Figure 1A) from A. thaliana, but shared only 35.85% identity with AtMLP43 (Figure S1)
Summary
Major latex protein (MLP) is a plant-specific protein that was first identified in opium poppy latex and is widely found in other plants [1,2]. The proteins encoded by genes that are homologous to MLP are known as MLP-like proteins, and had been identified and isolated from cucumber [3], peach [4], ginseng [5], Arabidopsis thaliana [6], melon [7], soybean [8], and grape [9]. The MLP protein contains a Bet v_1 structure and the MLP-like proteins make up the second largest family in the Bet v_1 protein superfamily [10]. The members of this superfamily respond to biotic and abiotic stresses and play important roles in plant growth and development, including disease resistance, stress tolerance, and development [11,12,13]. Bet v_1 proteins have a ‘Gly-rich loop (GXGGXG) domain and three-dimensional structure similar to the pathogenesis-related protein PR
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
