Yoneyama Kaori, Xie Xiaonan, Nomura Takahito, Yoneyama Koichi
Graduate School of Agriculture, Ehime University, Matsuyama, Japan.
PRESTO, Japan Science and Technology, Kawaguchi, Japan.
Front Plant Sci. 2020 May 20;11:438. doi: 10.3389/fpls.2020.00438. eCollection 2020.
Strigolactones (SLs) are essential host recognition signals for both root-parasitic plants and arbuscular mycorrhizal (AM) fungi in the rhizosphere, and SLs or their metabolites function as a novel class of plant hormones that regulate various aspects of plant growth through crosstalk with other hormones. Although nutrient availability is one of the important factors influencing SL production and exudation, and phosphate (Pi) deficiency significantly promotes SL production and exudation in host plants of AM fungi, how nutrient availability modulates SL production and exudation remains elusive. Cytokinin (CK), a canonical plant hormone, has extensively been studied as a shoot branching promoter and its biosynthesis is also influenced by mineral nutrients, especially nitrate, indicating that CK might be another key factor that affect SL production and exudation. In the present study, we show that CKs (-zeatin, benzyladenine, kinetin, and CPPU) applied to hydroponic culture media significantly suppressed the SL levels in both the root exudates and the root tissues of rice plants grown under Pi deficiency. In a split-root system, CK suppressed SL production locally, while Pi affected SL production systemically, suggesting that Pi and CK act on SL production independently in rice plants.
独脚金内酯（SLs）是根际中根寄生植物和丛枝菌根（AM）真菌识别宿主的关键信号，并且SLs或其代谢产物作为一类新型植物激素，通过与其他激素相互作用来调节植物生长的各个方面。尽管养分有效性是影响SLs产生和分泌的重要因素之一，且磷（Pi）缺乏会显著促进AM真菌宿主植物中SLs的产生和分泌，但养分有效性如何调节SLs的产生和分泌仍不清楚。细胞分裂素（CK）作为一种典型的植物激素，已被广泛研究为促进茎枝分枝的激素，其生物合成也受矿质养分尤其是硝酸盐的影响，这表明CK可能是影响SLs产生和分泌的另一个关键因素。在本研究中，我们发现，施加到水培培养基中的CKs（玉米素、苄基腺嘌呤、激动素和氯吡脲）显著抑制了缺磷条件下生长的水稻植株根系分泌物和根组织中的SLs水平。在分根系统中，CK局部抑制SLs的产生，而Pi对SLs的产生有系统影响，这表明在水稻植株中，Pi和CK对SLs产生的作用是独立的。
