Inhibition of BpEIN3 causes plaques in leaves of Betula platyphylla x B. pendula

摘要

Key message In this study, constructing BpEIN3 overexpression, inhibition expression vector, we transferred to birch to obtain BpEIN3 transgenic lines and study the function of this gene. EIN3 is an important transcription factor in the ethylene signal transduction pathway. It initiates the expression of a series of genes that regulate ethylene, positively regulating ethylene reaction, which affects the lesion mimic of plants through interacting ethylene signal and other signals in the signal transduction pathways. In order to reveal the function of BpEIN3 in Betula platyphylla, this study used birch as a genetic transformation receptor. Constructing BpEIN3 overexpression, inhibition expression vector, we transferred to birch to obtain BpEIN3 transgenic lines and study the function of this gene, which provided a reference for further revealing the molecular mechanism of BpEIN3 regulation of senescence and programmed cell death of birch leaves. In this study, the plant height, diameter and photosynthetic parameters of BpEIN3 transgenic lines were measured. The number of leaf lesions, histochemical staining, antioxidant enzymes, endogenous hormones and the expression of disease-related genes were also recorded. Results: We analyzed the expression of BpEIN3 by qRT-PCR, which was down-regulated in BpEIN3-inhibited expression lines and up-regulated in overexpression lines. The 2-year-old BpEIN3-RNAi lines exhibited brown spots on the leaves, leading to premature senescence and defoliation. The number of leaf spots is significantly different between different transgenic lines based on solid microscope. Photosynthetic parameters of BpEIN3-RNAi lines such as photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr) were significantly lower than wild type. The accumulation of H2O2 in the leaves of transgenic lines was more than WT. The content of endogenous salicylic acid (SA), abscisic acid (ABA), superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in BpEIN3-RNAi lines was higher than that in WT, except jasmonic acid (JA) content. Meanwhile, BpEIN3-RNAi lines showed strong resistance to Alternaria alternata. We analyzed the expression of genes which were involved in ABA, JA and SA biosynthesis, metabolism and senescence. The results showed that BpPYR9, BpPYL4, BpNPR1 and BpJAZ10 were up-regulated and BpSAG12, BpNAC2, BpPR1a and BpPR1b were abundantly expressed in the 6th and 7th leaves of the transgenic lines. We concluded that the suppression of BpEIN3 could lead to lesion and promote premature senescence.