六倍体普通油茶SPX基因家族的鉴定与表达分析OA

[Objective]Camellia oleifera in China is predominantly cultivated in acidic soils with prevalent phosphorus(P)deficiency.As core regulators of plant P signaling,the SPX gene family remains uncharacterized in hexaploid C.oleifera.The present study aimed to system-atically identify SPX family members and decipher their evolutionary and expression patterns,providing a theoretical foundation for P-efficient breeding.[Method]Based on the genomic sequence of hexaploid C.oleifera'Changlin 40',we performed genome-wide identification of SPX genes via bioinformatics approaches,followed by analyses of phylogenetic relationships,protein properties,cis-regulatory elements.Further-more,their tissue-specific expression profiles were determined using transcriptome sequencing and qRT-PCR.[Result]A total of 126 CoSPX genes were identified and classified into four subfamilies:SPX(47 members),SPX-RING(11),SPX-EXS(41)and SPX-MFS(27).The gene family exhibited 4.34-fold expansion compared to its diploid wild relative C.lanceoleosa(29 ClSPX genes),with strong purifying selec-tion(mean Ka/Ks=0.35±0.08).Physicochemical predictions revealed that 83.3％of CoSPX proteins were unstable hydrophilic mole-cules.Subcellular localization analysis showed that 79.4％(100/126)of members were localized to membranes/cytoplasm(62 membrane and 38 cytoplasmic),with significant subfamily localization preferences:97.6％(40/41)of SPX-EXS subfamily members localized to mem-branes,while all(11/11)SPX-RING subfamily members localized to nuclei.Cis-element analysis revealed that the SPX subfamily was sig-nificantly enriched in P1BS elements(89.4％of members contained ≥2 copies),with CoSPX23 and CoSPX20 harboring 10 and 6 proximal P1BS elements,respectively.This finding was consistent with their drastically up-regulated expression under low-Pi stress(nearly 140-fold in-duction after 30 days).Tissue-specific expression analysis revealed that SPX subfamily members were significantly highly expressed in leav-es,while 96.3％of SPX-MFS subfamily members were specifically expressed in embryos.Further qRT-PCR results clearly demonstrated that CoSPX4 and CoSPX18 from the SPX subfamily were leaf-preferential genes,whereas CoSPX19 and CoSPX22 were embryo-preferential genes,with their expression abundance in embryos far exceeding that in other tissues.[Conclusion]Compared to its diploid progenitor,the hexaploid C.oleifera genome exhibited extensive SPX family expansion coupled with functional diversification,reflected in subfamily-specific cis-element architectures and tissue expression biases.The study provides pivotal genetic resources and a theoretical framework for P-efficient breeding in C.oleifera.