Unfolded protein response in pollen development and heat stress tolerance

• Published in: Plant reproduction Vol. 29; no. 1-2; pp. 81 - 91
• Main Authors: Fragkostefanakis, Sotirios, Mesihovic, Anida, Hu, Yangjie, Schleiff, Enrico
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.06.2016; Springer
• Subjects: Agriculture; Biomedical and Life Sciences; Cell Biology; DNA binding proteins; Endoplasmic Reticulum - metabolism; Heat-Shock Response; Life Sciences; Plant Sciences; Pollen - growth & development; Pollen development and stress response; Protein Folding; Review; Stress, Physiological; Thermotolerance; Transcription (Genetics); Unfolded Protein Response; ER stress; Heat; Endoplasmic reticulum; Pollen tube; Male gametophyte; Unfolded protein response
• ISSN: 2194-7953; 2194-7961
• DOI: 10.1007/s00497-016-0276-8

Key message Importance of the UPR for pollen. Pollen is particularly sensitive to environmental conditions that disturb protein homeostasis, such as higher temperatures. Their survival is dependent on subcellular stress response systems, one of which maintains protein homeostasis in the endoplasmic reticulum (ER). Disturbance of ER proteostasis due to stress leads to the activation of the unfolded protein response (UPR) that mitigates stress damage mainly by increasing ER-folding capacity and reducing folding demands. The UPR is controlled by ER membrane-associated transcription factors and an RNA splicing factor. They are important components of abiotic stress responses including general heat stress response and thermotolerance. In addition to responding to environmental stresses, the UPR is implicated in developmental processes required for successful male gametophyte development and fertilization. Consequently, defects in the UPR can lead to pollen abortion and male sterility. Several UPR components are involved in the elaboration of the ER network, which is required for pollen germination and polar tube growth. Transcriptome and proteome analyses have shown that components of the ER-folding machinery and the UPR are upregulated at specific stages of pollen development supporting elevated demands for secretion. Furthermore, genetic studies have revealed that knockout mutants of UPR genes are defective in producing viable or competitive pollen. In this review, we discuss recent findings regarding the importance of the UPR for both pollen development and stress response.