LightIt not only provides energy for plant photosynthesis, but also can better adapt to changes in the external environment and improve the efficiency of photosynthesis by affecting plant growth and development. Chlorophyll is an indispensable component of photosynthesis, and it is known that light can affect the chlorophyll content of plants by regulating the gene expression or enzyme activity of chlorophyll synthaseHow light affects chlorophyll synthesis and degradation, and the mechanism that regulates chlorophyll homeostasis under complex natural conditions is still unclear. N6 methylated adenosine(M6A) is the most widespread mRNA modification in eukaryotes, which affects RNA metabolism processes such as mRNA cleavage, nuclear transport, translation, and degradation. In 2021, Chentao Lin's research group will be innature plants(2021) It was reported that the blue light-induced blue light receptor Cry2 recruits the M6A "writer)" MTA complex into the liquid phase of Cry2 through blue-light-induced liquid-liquid phase separation, increases the concentration of MTA protein in the liquid phase of Cry2 and promotes M6A modification, regulates the mRNA stability of the M6A-modified circadian clock genes, and maintains the plant circadian clock rhythm. Recently, Fujian Agriculture and Forestry UniversityLin ChentaoThe professor's research group is again innature plantsPublished a post entitled :light-induced llps of the cry2/spa1/fio1 complex regulating mrna methylation and chlorophyll homeostasis in arabidopsisResearch**. The study found that blue light-induced slow liquid-liquid phase separation of the Cry2-SPA1-FiO1 complex directly enhanced the methyltransferase activity of the M6A "encoder" FiO1, promoted the regulation of chlorophyll homeostasis, and the M6a modification and translation efficiency of related genes, thereby affecting the chlorophyll homeostasis of plants under light. At the same time, Nature Plants also published a publication entitledlight-induced protein condensation regulates chlorophyll homeostasisThe research briefing, detailing the background and significance of the study. 
In a blue-light phenotypic screen of M6A "encoder" mutants, the authors found that M6A "encoder" FIO1 mutants of the Mettl16 type exhibited a chlorophyll-deficient phenotype similar to that of the blue light receptor CRY1Cry2 mutant under blue light, while mettl3 mutants exhibited a normal chlorophyll content phenotype under the same conditions. These results suggest that the specific M6a modification of Cry-FiO1 is crucial for the regulation of chlorophyll homeostasis. Subsequently, the authors performed multiomic analysis of WT, Cry1Cry2, FiO1, and MTA materials (RNA transcriptome, M6A methylation modification group, translationome, and proteomics) under blue light and dark conditions. The analysis showed that although blue light regulated the expression of some genes encoding chlorophyll metabolizing enzymes through crys, these genes did not show photoregulation of mRNA modification, translation and protein abundance independent of Crys and FiO1 but independent of MTA. At the same time, the multiomic analysis revealed that six nuclear genes encoding chloroplast proteins depended on Crys and FiO1 but were independent of MTA's mRNA modification, translation, and protein abundance photoregulation. Previous studies have shown that although these six genes are not directly involved in chlorophyll metabolism, they all have the function of positively regulating chlorophyll content in plants. Therefore, the authors named these six genes as CHR (Chlorophyll Homeostasis Regulator), i.e., chlorophyll homeostasis regulator genes, and CRY2-FIO mediates the mRNA modification and translation of blue light-regulated CHR genes to play a key role in maintaining chlorophyll balance under blue light. The authors further investigate how cry2-fio1 specifically regulates the M6a modification of chlorophyll homeostatic regulatory genes and promotes translation. Similar to Cry2-MTA, Cry2 and FIO1 also have non-blue light-dependent protein interactions, but surprisingly, FIO1 is not directly recruited into photosomes by Cry2 like MTA under blue light, but FIO1 can be significantly recruited into liquid-phase photosomes in the presence of blue light chaperone protein SPA1. In vitro enzyme activity experiments, the authors found that the CCE domain of Cry2 and the WD domain of SPA1 could significantly increase the methyltransferase activity of FIO1, and the two synergistically enhanced the methyltransferase activity of FIO1. The CCE domain of Cry2 and the WD domain of SPA1 are the key regions of their interaction with FIO, and the mutation of the key interaction site of the CCE domain cannot recruit FIO1 into the liquid phase of the Cry2 photosome, and it also cannot promote the methyltransferase activity of FIO1. 
Figure 1Blue light-induced cry2-spa1-fio1 liquid-liquid phase separation regulates chlorophyll homeostasis It is worth noting that this study is also the third study of Professor Lin Chentao's group on the regulation of plant growth and development by blue-light-induced liquid-liquid phase separation. Previously, Prof. Chentao Lin's group published that blue light-induced CRYS protein phase separation regulates the activity of M6A encoder MTA (Nature Plants, 2021) and chromatin-binding protein MAC3A 3B (Science Advances, 2023) affecting circadian clock rhythm and hypocotyl elongation。These studies revealed that blue light-induced phase separation directly regulates the activity of interacting proteins, providing a new explanation for understanding non-blue light-dependent interacting proteins in blue light receptor perception and signal transduction. The research group also recently reviewed and reported this new mechanism of action of cry blue light receptors in the Journal of Integrative Plant Biology (doi: 10.).1111/jipb.13578) 。Fujian Agriculture and Forestry UniversityJiang BochenPh.D. (now Postdoctoral Fellow, University of Chicago).Zhong ZhenhuiPh.D. (now UCLA Postdoc) andGu LianfengThe professor is the co-first author. Forestry Center, Straits Joint Research Institute, Fujian Agriculture and Forestry UniversityLin ChentaoProfessor,Wang XuPh.D. (now researcher Wang Xu, Institute of Modern Agriculture, Peking University) andJiang BochenPh.D. is the co-corresponding author. University of ChicagoHe ChuanProfessor and UC Riversidejulia bailey-serresThe professor has also made important contributions to the research. The research was supported by the National Natural Science Project, Fujian Agriculture and Forestry University Research Program, Taishan Scholars Young Expert Program, and Shandong Province Outstanding Youth Science Program (Overseas). Reference: Jiang B, zhong z., gu l., zhang x., wei j., ye c., lin g., qu g., xiang x., wen w., gateas m., bailey-serres j., wang q., chuan he c., wang x., and lin c. (2023). light-induced llps of the cry2/spa1/fio1 complex regulating mrna methylation and chlorophyll homeostasis in arabidopsis. nat. plants.jiang, b., zhong, z., su, j., zhu, t., yueh, t., bragasin, j., bu, v., zhou, c., lin, c., and wang, x. (2023). co-condensation with photoexcited cryptochromes facilitates mac3a to positively control hypocotyl growth in arabidopsis. sci. adv. 9, eadh4048. 10.1126/sciadv.adh4048.wang, x., jiang, b., gu, l., chen, y., mora, m., zhu, m., noory, e., wang, q., and lin, c. (2021). a photoregulatory mechanism of the circadian clock in arabidopsis. nat. plants 7, 1397-1408. 10.1038/s41477-021-01002-z.qu, g.，jiang, b., and lin, c. (2023). the dual-action mechanism of arabidopsis cryptochromes. j. integr. plant biol.**Links:
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