Genome-Wide Identification and Expression Profiling of Ascorbate Peroxidase (APX) and Glutathione Peroxidase (GPX) Genes Under Drought Stress in Sorghum (Sorghum bicolor L.)
Genome-Wide Identification and Expression Profiling of Ascorbate Peroxidase (APX) and Glutathione Peroxidase (GPX) Genes Under Drought Stress in Sorghum (Sorghum bicolor L.)
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DOI：
10.1007/s00344-018-9788-9
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发表时间：
2018-09-01
影响因子：
4.8
通讯作者：
Kontbay, Kubra
中科院分区：
文献类型：
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作者：
Akbudak, M. Aydin;Filiz, Ertugrul;Kontbay, Kubra
APX和GPX是两种重要的植物抗氧化酶。通过蛋白同源性检索，在高粱双色基因组中鉴定出9个APX成员和7个GPX成员。根据染色体定位对它们进行注释，分别为SbAPX1-9和SbGPX1-7。apx分布在高粱的6条染色体上，编码250 ~ 474个具有“过氧化物酶”结构域的多肽；gpx分布在5条染色体上，编码136 ~ 232个具有“GSHPx”结构域的蛋白质。sbapx的前1-90个氨基酸残基和sbgpx的前60-70个氨基酸残基的n端与传递肽相对应，构成了序列变异的主要来源。另一方面，APXs/GPXs在氨基酸序列水平上表现出显著的保守性。这些酶的活性和/或金属结合位点的残基也被揭示出来，从而推断出它们在拟南芥中的对应物。结合高粱-拟南芥APX和GPX系统发育，可以在跨物种水平上推断推定的高粱序列的功能作用。在高粱的数字RNA-seq数据中，与gpx相比，敏感基因型中的apx对干旱的响应相对更强。APX4上调和GPX2下调的差异表明它们的表现是协同的。采用实时荧光定量PCR （RT-qPCR）技术检测干旱暴露高粱根和叶中SbAPXs/GPXs的表达。干旱暴露的植株在形态上表现出茎/根伸长和大小的减少，植株生长迟缓，叶片竖立。APXs/GPXs在干旱暴露植物的地上部分（如叶片）表达上调，而在根中表达下调。叶片中的APX1和APX5以及根中的APX8、APX9、GPX5和GPX6表达量均发生显著变化；因此，应考虑它们在干旱时期的协同调控。
APX and GPX are two crucial plant antioxidant enzymes. By protein homology search, nine APX and seven GPX members were identified in Sorghum bicolor genome. They were annotated based on chromosomal localizations as SbAPX1-9 and SbGPX1-7. APXs were distributed on six Sorghum chromosomes and encoded polypeptides of 250-474 residues with characteristic "peroxidase" domain, whereas GPXs were on five chromosomes and encoded proteins of 136-232 residues characterized by a "GSHPx" domain. The first about 1-90 amino acid residues in SbAPXs and about 60-70 amino acid residues in SbGPXs from N-terminus corresponded to transit peptides, and formed the main source of sequence variations. On the other hand, APXs/GPXs appeared to be significantly conserved at the amino acid sequence level. Residues in active and/or metal binding sites of these enzymes were also revealed with inference to their Arabidopsis counterparts. The combined Sorghum-Arabidopsis APX and GPX phylogenies allowed inferring functional roles to putative Sorghum sequences at cross-species level. In digital RNA-seq data from Sorghum, APXs within sensitive genotypes were relatively more responsive to drought compared to GPXs. Differentially upregulated APX4 and downregulated GPX2 suggested that their performance was synergistic. SbAPXs/GPXs expression in drought-exposed sorghum roots and leaves were quantified by Real-Time quantitative PCR (RT-qPCR). Drought-exposed plants morphologically demonstrated reductions in stem/root elongation and size, retardation in plant growth, and erected leaves. Expressions of APXs/GPXs were mostly upregulated in aboveground parts of drought-exposed plants, e.g., leaves while they were downregulated in roots. Furthermore, APX1 and APX5 in leaves, and APX8, APX9, GPX5, and GPX6 in roots showed significant changes in expression levels; therefore, their synergetic regulation during drought should be considered.