Ygl1

Function

 Yellow-green leaf1 (ygl1), was isolated, which showed yellow-green leaves in young plants with decreased Chl synthesis, increased level of tetrapyrrole intermediates, and delayed chloroplast development.The mutant plant exhibits a yellow-green leaf phenotype, decreased level of Chl, and delayed chloroplast development.

Expression

 Genetic analysis demonstrated that the phenotype of ygl1 was caused by a recessive mutation in a nuclear gene. The ygl1 locus was mapped to chromosome 5 and isolated by map-based cloning. Sequence analysis revealed that it encodes the Chl synthase and its identity was verified by transgenic complementation. A missense mutation was found in a highly conserved residue of YGL1 in the ygl1 mutant, resulting in reduction of the enzymatic activity. YGL1 is constitutively expressed in all tissues, and its expression is not significantly affected in the ygl1 mutant. Interestingly, the mRNA expression of the cab1R gene encoding the Chl a/b-binding protein was severely suppressed in the ygl1 mutant. Moreover, the expression of some nuclear genes associated with Chl biosynthesis or chloroplast development was also affected in ygl1 seedlings.

Evolution

 The rice YGL1 was more closely related to Chl synthase from the monocotyledon plant oat than to those of other species. Not surprisingly, YGL1 has a phylogenetically much closer relationship to Chl synthases of the higher plant species than to bacteria proteins. In addition, it is interesting to note that bacteriochlorophyll synthases lack a motif (WAGHDF-197) that exists only in the Chl synthase. Analysis with the transmembrane calculation programs revealed that the ygl1 mutation site occurred at or close to the end of a transmembrane helix.

Labs working on this gene

 1.National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing, China
 2.National Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing, China

References

 1.Wu, Z., Zhang, X., He, B., Diao, L., Sheng, S., Wang, J., & Wan, J. (2007). A chlorophyll-deficient rice mutant with impaired chlorophyllide esterification in chlorophyll biosynthesis. Plant physiology, 145(1), 29-40.
 2.Shalygo, N., Czarnecki, O., Peter, E., & Grimm, B. (2009). Expression of chlorophyll synthase is also involved in feedback-control of chlorophyll biosynthesis. Plant molecular biology, 71(4-5), 425-436.
 3.Wu, Z. M., Zhang, X., Wang, J. L., & Wan, J. M. (2014). Leaf chloroplast ultrastructure and photosynthetic properties of a chlorophyll-deficient mutant of rice. Photosynthetica, 1-6.