On-site single pollen metabolomics reveals varietal differences in phosphatidylinositol synthesis under heat stress conditions in rice
On-site single pollen metabolomics reveals varietal differences in phosphatidylinositol synthesis under heat stress conditions in rice
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DOI：
10.1038/s41598-020-58869-9
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发表时间：
2020-02-06
影响因子：
4.6
通讯作者：
Nakano, Hiroshi
中科院分区：
文献类型：
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作者：
Wada, Hiroshi;Hatakeyama, Yuto;Nakano, Hiroshi
尽管在全球气候变化下，代谢热反应导致的健康花粉粒损失被认为是热致小穗不育的主要原因，但由于技术限制，迄今为止还缺乏花粉水平的详细信息。本研究采用皮升压力探针电喷雾电离质谱法（picoPPESI-MS）直接测定了耐热品种N22和热敏品种光光（Koshihikari）热处理后单成熟花粉粒的代谢物。N22和Koshihikari的小穗热致育率分别为90.0%和46.8%。虽然不同处理对花粉的体外活力没有影响，但在成熟花粉中检测到磷脂酰肌醇（PI）（34:3）和其他106种代谢物的差异。N22和Koshihikari花粉的PI含量均高于其他处理，Koshihikari花粉的PI含量高于其他处理。相比之下，两个品种的单个成熟花粉粒中几乎没有检测到磷酸肌苷。结果表明，picoPPESI-MS分析可以有效地鉴定完整单粒花粉的代谢物。由于PI是磷酸肌苷的前体，可诱导花粉萌发和管状生长的多种信号，因此萌发前PI的活性合成（34:3）可能与即使在高温下也能维持小穗的育性密切相关。
Although a loss of healthy pollen grains induced by metabolic heat responses has been indicated to be a major cause of heat-induced spikelet sterility under global climate change, to date detailed information at pollen level has been lacking due to the technical limitations. In this study, we used picolitre pressure-probe-electrospray-ionization mass spectrometry (picoPPESI-MS) to directly determine the metabolites in heat-treated single mature pollen grains in two cultivars, heat-tolerant cultivar, N22 and heat-sensitive cultivar, Koshihikari. Heat-induced spikelet fertility in N22 and Koshihikari was 90.0% and 46.8%, respectively. While no treatment difference in in vitro pollen viability was observed in each cultivar, contrasting varietal differences in phosphatidylinositol (PI)(34:3) have been detected in mature pollen, together with other 106 metabolites. Greater PI content was detected in N22 pollen regardless of the treatment, but not for Koshihikari pollen. In contrast, there was little detection for phosphoinositide in the single mature pollen grains in both cultivars. Our findings indicate that picoPPESI-MS analysis can efficiently identify the metabolites in intact single pollen. Since PI is a precursor of phosphoinositide that induces multiple signaling for pollen germination and tube growth, the active synthesis of PI(34:3) prior to germination may be closely associated with sustaining spikelet fertility even at high temperatures.