Functional aspects of early light-induced protein (ELIP) genes from the desiccation-tolerant moss Syntrichia caninervis

Authors: LIU, XIUJIN - Chinese Academy Of Sciences; ZHANG, YIGONG - Chinese Academy Of Sciences; YANG, HONGLAN - Chinese Academy Of Sciences; LIANG, YUQING - Chinese Academy Of Sciences; LI, XIAOSHUANG - Chinese Academy Of Sciences; Oliver, Melvin; ZHANG, DAOYUAN - Chinese Academy Of Sciences

Submitted to: International Journal of Molecular Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/14/2020
Publication Date: 2/19/2020
Citation: Liu, X., Zhang, Y., Yang, H., Liang, Y., Li, X., Oliver, M.J., Zhang, D. 2020. Functional aspects of early light-induced protein (ELIP) genes from the desiccation-tolerant moss Syntrichia caninervis. International Journal of Molecular Sciences. 21: Article 1411. https://doi.org/10.3390/ijms21041411.
DOI: https://doi.org/10.3390/ijms21041411

Interpretive Summary: Plants experiencing a drought in the summer months face a combination of both a water stress and high light stress that impact yield. Both stresses cause an increase in the production of reactive oxygen molecules (ROS) that damage plant cells and cause a breakdown of the photosynthetic machinery of the plant. Most plants use protective mechanisms to protect their chloroplasts during such times but they are not very efficient in most crops. One of the mechanisms involves a group of proteins call Early Light Inducible Proteins (ELIPs) that protect the chlorophyll binding apparatus of photosynthesis from damage by ROS. Plants that grow in highly stressful environments have many ELIP genes and the actual ELIP proteins appear to be more efficient at protecting photosynthesis than those from crops. ARS scientists, along with collaborators, isolated two ELIP genes from the desert plant Syntrichia caninaervis, a bryophyte that grows in the Gobi desert and also in the Western U.S., and investigated their ability to protect a sensitive plant from high-light stress. Both genes, when expressed in the model plant Arabidopsis, improved their ability to withstand high-light stress and protect their photosynthetic machinery. This work leads the way for the development of crops that are more tolerant of high-light stress and possibly the combination of high light and drought.

Technical Abstract: The early light-induced proteins (ELIPs) are postulated to act as transient pigment-binding proteins that protect the chloroplast from photodamage caused by excessive light energy. Desert mosses such as Syntrichia caninervis, that are desiccation-tolerant and homoiochlorophyllous, are often exposed to high-light conditions when both hydrated and dry ELIP transcripts are accumulated in response to dehydration. To gain further insights into ELIP gene function in the moss S. caninervis, two ELIP cDNAs cloned from S. caninervis, ScELIP1 and ScELIP2 and both sequences were used as the basis of a transcript abundance assessment in plants exposed to high-light, UV-A, UV-B, red-light, and blue-light. ScELIPs were expressed separately in an Arabidopsis ELIP mutant Atelip. Transcript abundance for ScELIPs in gametophytes respond to each of the light treatments, in similar but not in identical ways. Ectopic expression of either ScELIPs protected PSII against photoinhibition and stabilized leaf chlorophyll content and thus partially complementing the loss of AtELIP2. Ectopic expression of ScELIPs also complements the germination phenotype of the mutant and improves protection of the photosynthetic apparatus of transgenic Arabidopsis from high-light stress. Our study extends knowledge of bryophyte photoprotection and provides further insight into the molecular mechanisms related to the function of ELIPs.