State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China.
Thomas H. Gosnell School of Life Sciences, Rochester Institute of Technology, Rochester, NY 14623, USA.
Int J Mol Sci. 2021 Jun 26;22(13):6877. doi: 10.3390/ijms22136877.
Recently, crop breeders have widely adopted a new biotechnology-based process, termed Seed Production Technology (SPT), to produce hybrid varieties. The SPT does not produce nuclear male-sterile lines, and instead utilizes transgenic SPT maintainer lines to pollinate male-sterile plants for propagation of nuclear-recessive male-sterile lines. A late-stage pollen-specific promoter is an essential component of the pollen-inactivating cassette used by the SPT maintainers. While a number of plant pollen-specific promoters have been reported so far, their usefulness in SPT has remained limited. To increase the repertoire of pollen-specific promoters for the maize community, we conducted a comprehensive comparative analysis of transcriptome profiles of mature pollen and mature anthers against other tissue types. We found that maize pollen has much less expressed genes (>1 FPKM) than other tissue types, but the pollen grain has a large set of distinct genes, called pollen-specific genes, which are exclusively or much higher (100 folds) expressed in pollen than other tissue types. Utilizing transcript abundance and correlation coefficient analysis, 1215 mature pollen-specific (MPS) genes and 1009 mature anther-specific (MAS) genes were identified in B73 transcriptome. These two gene sets had similar GO term and KEGG pathway enrichment patterns, indicating that their members share similar functions in the maize reproductive process. Of the genes, 623 were shared between the two sets, called mature anther- and pollen-specific (MAPS) genes, which represent the late-stage pollen-specific genes of the maize genome. Functional annotation analysis of MAPS showed that 447 MAPS genes (71.7% of MAPS) belonged to genes encoding pollen allergen protein. Their 2-kb promoters were analyzed for -element enrichment and six well-known pollen-specific -elements (AGAAA, TCCACCA, TGTGGTT, [TA]AAAG, AAATGA, and TTTCT) were found highly enriched in the promoters of MAPS. Interestingly, JA-responsive -element GCC box (GCCGCC) and ABA-responsive -element-coupling element1 (ABRE-CE1, CCACC) were also found enriched in the MAPS promoters, indicating that JA and ABA signaling likely regulate pollen-specific MAPS expression. This study describes a robust and straightforward pipeline to discover pollen-specific promotes from publicly available data while providing maize breeders and the maize industry a number of late-stage (mature) pollen-specific promoters for use in SPT for hybrid breeding and seed production.
最近，作物育种者广泛采用了一种新的基于生物技术的过程，称为种子生产技术（SPT），以生产杂交品种。SPT 不会产生核雄性不育系，而是利用转基因 SPT 保持系来授粉雄性不育植物，以繁殖核隐性雄性不育系。晚期花粉特异性启动子是 SPT 保持系使用的花粉失活盒的重要组成部分。虽然迄今为止已经报道了许多植物花粉特异性启动子，但它们在 SPT 中的用途仍然有限。为了增加玉米群体中花粉特异性启动子的种类，我们对成熟花粉和成熟花药与其他组织类型的转录组图谱进行了全面比较分析。我们发现，与其他组织类型相比，玉米花粉的表达基因（>1 FPKM）要少得多，但花粉粒有一大组独特的基因，称为花粉特异性基因，这些基因在花粉中特异性表达或表达水平更高（100 倍）。利用转录丰度和相关系数分析，在 B73 转录组中鉴定出 1215 个成熟花粉特异性（MPS）基因和 1009 个成熟花药特异性（MAS）基因。这两个基因集具有相似的 GO 术语和 KEGG 途径富集模式，表明它们的成员在玉米生殖过程中具有相似的功能。在这两个基因集中，有 623 个基因是共享的，称为成熟花药和花粉特异性（MAPS）基因，这些基因代表了玉米基因组中晚期花粉特异性基因。对 MAPS 基因的功能注释分析表明，447 个 MAPS 基因（MAPS 的 71.7%）属于编码花粉过敏原蛋白的基因。分析了它们的 2-kb 启动子，发现六个著名的花粉特异性 - 元件（AGAAA、TCCACCA、TGTGGTT、[TA]AAAG、AAATGA 和 TTTCT）在 MAPS 启动子中高度富集。有趣的是，还发现 JA 反应元件 GCC 盒（GCCGCC）和 ABA 反应元件耦合元件 1（ABRE-CE1，CCACC）在 MAPS 启动子中富集，表明 JA 和 ABA 信号可能调节花粉特异性 MAPS 表达。本研究描述了一种从公开数据中发现花粉特异性启动子的稳健而直接的方法，同时为玉米育种者和玉米产业提供了许多晚期（成熟）花粉特异性启动子，用于 SPT 杂交育种和种子生产。
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