Identification and Gene Cloning of A New MaizePermanent chlorosis Mutantchs10

HOU Yuwei，YUE Yujing，LI Chuan，SU Shuai，YI Hongyang，CAO Moju*

Abstract

【Objective】 This study is aiming at genetically analyzing， gene mapping， and preliminarily  analysze the function of the candidate genes of a new maize leaf color mutant obtained by treating the inbred  line Qi 319 with 60Co-γ rays. 【Method】 The mutant was used as the parent to construct a genetic analy⁃sis population and a gene mapping population； the key candidate genes were obtained by map cloning；the structure and evolutionary relationship of the key candidate genes were analyzed by bioinformatics；the expression of the candidate genes in different tissues was detected by qRT-PCR； and the subcellular  localization of the candidate genes was analyzed by using the tobacco transient expression technology.  【Result】 A maize permanent chlorosis mutant chs10（Permanent chlorosis 10） was identified. Startig  from the V2 stage， the leaves of chs10 gradually turn from green to yellow from the base to the top of the  seedling， During the later growth and development process， they no longer return to green， and the  whole plant， including leaf sheaths， leaf rings， stems， bracts， and tassel， was also yellow. This mutation  is controlled by a pair of recessive nuclear genes， and can be stably inherited. The plant growth and develop⁃ment are normal， and it can be pollinated and fruited normally. The mutated gene is located within the  range of approximately 0.17 Mb between the long arm markers SNP-2 and SNP-3 on maize chromosome  10， revealing Zm00001d025860 as the key candidate gene. qRT-PCR results showed that  Zm00001d025860 was expressed in the maize roots， stems， leaves， and leaf sheaths， but was highly ex⁃pressed in the leaves. Subcellular localization results showed that the target protein was localized in the  cell membrane and chloroplasts. Using STRING prediction，Zm00001d025860 was found to interact with  the porphyrin-binding protein GUN4， and GUN4 has a feedback regulation with magnesium ion chela⁃tase （MgCh） in chlorophyll synthesis. 【Conclusion】 Mutations in the Zm00001d025860 gene lead to  changes in leaf color of mutant chs10， and Zm00001d025860 may regulate leaf color changes by participat⁃ing in the chlorophyll synthesis pathway. The discovery of mutant chs10 not only enriches the genetic re⁃sources for the study of leaf color mutants in maize， but also lays a material foundation for the analysis of  the mechanism of magnesium ion chelatase in the chlorophyll synthesis pathway.  

Keywords

 maize； genetic analysis； leaf color mutant；chs10； map-based cloning