Shunwu Yu, Fangwen Yang, Yuqiao Zou, Yunan Yang, Tianfei Li, Shoujun Chen, Yulan Wang, Kai Xu, Hui Xia, Lijun Luo

Front Plant Sci.; 2022 May 6;13:812279.  doi: 10.3389/fpls.2022.812279. eCollection 2022.

Abstract

Mosses are one of the earliest diverging land plants that adapted to living on land. The BURP domain-containing proteins (BURP proteins) are plant-specific proteins that appeared when plants shifted from aquatic environments to land. Phylogenetic analysis revealed that the BURP domain of higher plants is originated from lower land plants and divergent because of motif conversion. To discover the function of BURP protein in moss, rice transgenics with ectopic expression of PpBURP2 were subjected to different abiotic stresses treatments. The results revealed that the ectopic expression of PpBURP2 enhanced the tolerance to osmotic and saline stresses at the seedling stage and drought stress at the adult stage. Further ectopic expression of PpBURP2 improved the cadmium (2+) (Cd²⁺) tolerance and reduced Cd²⁺ accumulation in rice leaves. Transcriptomic analysis of the transgenic PpBURP2 plants showed that the differentially expressed genes were involved in the metabolism of secondary metabolites, energy, oxidation-reduction process, and defense-related genes. Further experiments showed that the photosynthetic efficiency and resistance against bacterial leaf blight were obviously improved in transgenic plants. Yeast two-hybrid and bimolecular fluorescence complementation (BiFC) assays revealed the physical interaction of BURP domain protein from rice and moss with mitogen-activated protein kinase kinase (MKK) from rice. Therefore, our findings demonstrate that overexpressing PpBURP2 in rice confers resistance to abiotic stresses and bacterial leaf blight. They also suggested that the regulatory role of BURP-like proteins across lower and higher plants was evolutionary conservation of responses of different classes of plants to different environmental challenges.

See https://pubmed.ncbi.nlm.nih.gov/35599889/

FIGURE 1

Phylogenetic relationship and motif structures of BURP domain-containing proteins from diverse species. (A) The unrooted tree was generated using the Molecular Evolutional Genetics Analysis version 5 (MEGA5) program by the Maximum-likelihood method. The bootstrap values were indicated at the lines. The abbreviations of species names are as follows: At, Arabidopsis thaliana; Os, Oryza sativa; Pp, Physcomitrella patens; Sm, Selaginella moellendorffii. (B) Multiple expectation maximizations for motif elicitation (MEME) motif search results. Conserved motifs are indicated in numbered, colored boxes. E-value is shown on the left. The accession number is shown in Supplementary Table 2.