Foxtail millet [Setaria italica (L.) Beauv.] over-accumulates ammonium under low nitrogen supply
Foxtail millet [Setaria italica (L.) Beauv.] over-accumulates ammonium under low nitrogen supply
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DOI：
10.1016/j.plaphy.2022.05.031
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发表时间：
2022-05-31
影响因子：
6.5
通讯作者：
Li, Xuexian
中科院分区：
文献类型：
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作者：
Nadeem, Faisal;Mahmood, Rashid;Li, Xuexian
氮(N)缺乏是全球农作物生产的主要限制因素。在此之前，我们报道了水培谷子[Setaria italica(L.)Beauv.]以促进氮素限制下的氮素转运。在此，我们从水培条件下谷子体内氮素调节的角度研究了谷子地上部对低氮的适应性。研究结果表明，与对照(CK)相比，地上部N和硝酸盐(NO3-)浓度显著降低，但在低N(LN)条件下，地上部NH4+积累量过大。氮素缺乏导致SiPetA、SiccsA、SipsbA、SirpoB、SipsaA、SiatpA、Sirps16和SiPEPC的表达下调，从而破坏叶绿体功能和CO2同化提供碳骨架。缺碳和GS活性降低减缓了氨同化，并导致NH4+在LN地上部的过度积累，这表现为总氨基酸浓度较低。因此，提高GOGAT活性是为了同化NH4+，而提高过氧化氢酶(CAT)、超氧化物歧化酶(SOD)和过氧化物酶(POD)活性是为了清除NH4+毒害骨架中的活性氧(ROS)。弱化的叶绿体工厂最终使光合作用最小化，减少了LN新梢的干质量。地上部对氮素的这种调节，可能恢复了谷子在氮素限制下维持体内矿质状态的生理功能。
Nitrogen (N) deficiency is a primary limiting factor for crop production worldwide. Previously, we reported root system architectural modifications of hydroponically cultured foxtail millet [Setaria italica (L.) Beauv.] to facilitate N translocation under N limitation. Here, we investigated foxtail millet for its shoot adaptation to low N in terms of internal N regulation under hydroponic culture. The results of this study revealed that the shoot N and nitrate (NO3-) concentrations significantly declined as compared to control (CK); however, the shoot over accumulated ammonium (NH4+) under low N (LN). N shortage resulted in down-regulation of expressions of SiPetA, SiccsA, SipsbA, SirpoB, SipsaA, SiatpA, Sirps16, and SiPEPC which, undermined chloroplast functioning and CO2 assimilation for the provision of carbon skeleton. Carbon deficiency and lower activities of GS decelerated ammonia assimilation and led to over-accumulation of NH4+ in the LN-shoot, as indicated by lower concentrations of total amino acids. Thus, enhanced GOGAT activity was to assimilate NH4+ while, those of catalase (CAT), superoxide dismutase (SOD) and peroxidase (POD) were to scavenge reactive oxygen species (ROS) of NH4+ toxicity framework. The weakened chloroplast factory eventually minimized photosynthesis and reduced dry mass of the LN shoot. Such regulation of N by the shoot, perhaps, resurrected physiological functions which maintained internal mineral status under nitrogen limitation in foxtail millet.