• ISSN 1008-505X
  • CN 11-3996/S

小麦高效吸收利用磷素机制研究进展

Progress on mechanism on the phosphorus-efficient absorption and utilization in wheat (Triticum aestivum L.)

  • 摘要: 小麦是需磷量大的粮食作物,其稳产高产依赖于大量磷肥的投入,但我国小麦磷肥当季利用效率仅为19%,提高磷的吸收利用效率是小麦养分管理研究领域的关键科学问题。低磷胁迫下,小麦主要通过根系形态重塑、有机酸分泌、体内磷再分配来提高磷的吸收和利用效率,这些过程是通过相关途径的基因表达水平变化或者信号等转录途径来实现的。本文较详细介绍了小麦高亲和磷转运蛋白基因(TaPHT1s)的类别及功能,以及在小麦磷信号转导通路中转录因子PHR1、TaMYB4等的功能。由于小麦磷高效表型指标的获得过程繁琐且数据过于粗糙,从正向遗传学方面定位与克隆小麦磷高效基因进展缓慢,目前多采用反向遗传学方法(转录组学、蛋白质组、代谢组等)挖掘出小麦磷高效候选基因(PAPs、PHO1、PHT1s、SPX等)。作者团队采用iTRAQ蛋白组学与靶向蛋白定量(PRM)技术在小麦根系内鉴定到一个高亲和磷转运蛋白TaPHT1;9,通过酵母突变体发现它具有磷转运功能,创制了TaPHT1;9基因的BSMV-VIGS瞬时沉默小麦植株、基因编辑小麦突变体、异源过表达水稻转基因植株等试验材料,通过水培和田间试验,发现该蛋白在磷吸收转运中发挥了重要功能;进一步在小麦品种间分析TaPHT1;9基因序列上的等位变异位点,鉴定出含有磷高效优异等位变异位点的单倍型品种,开发了用于鉴定磷高效小麦品种的分子标记,利用该分子标记筛选出了一批磷高效小麦品种。作者团队还挖掘了另一个高亲和磷转运蛋白TaPHT1;6基因的磷高效优异等位变异位点并开发了分子标记。近年来,作物分子生物学的研究方向已从分子调控网络末端的功能基因逐渐向中间的调控因子(转录因子、受体、激酶等)方面转移,这是由于多数调控因子能同时控制下游数个功能基因的表达,改变作物性状的效果大多显著高于单一功能基因。在分子调控机制方面,作者团队利用酵母单杂交等技术,克隆出1个调控TaPHT1;3-5BTaPHT1;6-5BTaPHT1;9-4BTaPHT1;10-4D高亲和转运蛋白基因表达的转录因子TaMYB4。最后从小麦高通量磷高效精准表型组的研发、磷从花后衰老器官向籽粒转移过程中关键PHTs基因的鉴定、小麦全基因组测序和高通量芯片的利用等方面展望了加快小麦磷高效基因克隆的主要途径。

     

    Abstract: Wheat is a phosphorus (P)-demanding cereal crop, and its stable and high yield relies heavily on substantial phosphorus fertilizer input. However, the seasonal utilization efficiency of phosphorus fertilizer in Chinese wheat production is only 19%, making the improvement of phosphorus absorption and use efficiency a critical scientific issue in wheat nutrient management research. Under low-P stress, wheat enhances P uptake and utilization primarily through root morphological remodeling, organic acid secretion, and internal P redistribution. These processes are regulated by changes in gene expression levels or transcriptional pathways involving signaling molecules. This review elaborates on the classification and functions of high-affinity phosphate transporter genes (TaPHT1s) in wheat, as well as the roles of transcription factors such as PHR1 and TaMYB4 in wheat P signaling pathways. Due to the cumbersome and coarse data acquisition process for P-efficient phenotypic indicators in wheat, progress in mapping and cloning P-efficient genes via forward genetics has been slow. Currently, reverse genetics approaches (transcriptomics, proteomics, metabolomics, etc.) are increasingly adopted to identify candidate genes for P-use efficiency (PUE) in wheat, including PAPs, PHO1, PHT1s, and SPX families. Our research team identified a high-affinity phosphate transporter, TaPHT1;9, in wheat roots using iTRAQ proteomics and targeted protein quantification (PRM) techniques. Yeast mutant assays confirmed its P transport function. We generated experimental materials including TaPHT1;9-silenced wheat plants via BSMV-VIGS (Barley Stripe Mosaic Virus-induced Gene Silencing), gene-edited wheat mutants, and heterologous overexpression transgenic rice lines. Hydroponic and field trials revealed that this protein plays a crucial role in P uptake and translocation. Further analysis of allelic variations in the TaPHT1;9 gene sequence across wheat cultivars identified haplotypes harboring superior alleles associated with P efficiency. We developed molecular markers for screening P-efficient wheat cultivars and utilized these markers to select a cohort of P-efficient lines. Additionally, we uncovered P-efficient superior allelic variants in another high-affinity transporter gene, TaPHT1;6, and developed corresponding molecular markers. In recent years, crop molecular biology research has shifted from focusing on downstream functional genes at the end of molecular regulatory networks to intermediate regulatory factors (transcription factors, receptors, kinases, etc.). This shift is driven by the observation that most regulatory factors can simultaneously control the expression of multiple downstream functional genes, often yielding significantly greater effects on crop trait improvement than single functional genes alone. By using yeast one hybrid and other techniques, we isolated a transcription factor TaMYB4, which regulates the expression of four TaPHTs (TaPHT1;3-5B, TaPHT1;6-5B, TaPHT1;9-4B, and TaPHT1;10-4D). Finally, we propose future directions to accelerate the cloning of P-efficient genes in wheat, including: (1) developing high-throughput precise phenotyping platforms for P efficiency; (2) identifying key PHT genes involved in P remobilization from senescing post-anthesis organs to grains; and (3) leveraging wheat genome sequencing data and high-throughput microarrays.

     

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