| 两个玉米品种灌浆期叶片氮转移效率差异的分子机制 |
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| 引用本文： | 郭松,孙文彦,顾日良,王章奎,陈范骏,赵秉强,袁力行,米国华. 两个玉米品种灌浆期叶片氮转移效率差异的分子机制[J]. 植物营养与肥料学报, 2018, 24(5): 1149-1157. DOI: 10.11674/zwyf.18001 |
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| 作者姓名： | 郭松 孙文彦 顾日良 王章奎 陈范骏 赵秉强 袁力行 米国华 |
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| 作者单位： | 1.中国农业大学资源与环境学院，北京 100193 |
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| 基金项目： | 国家自然科学基金项目（31272233）；欧盟项目（NUE-CROPS）；四川省科技计划（2016JY0012）资助。 |
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| 摘 要： | 【目的】提高玉米氮效率是实现农业高产高效的重要措施，而花后叶片的衰老和玉米的氮效率密切相关。为此，在田间条件下研究了叶片衰老过程与氮转移效率的关系，尤其是不同玉米品种氮转移效率差异的分子机制。【方法】田间试验选择中度绿熟玉米品种先玉335 (XY335) 和持绿玉米品种NE9为供试作物，设施N 45，120和240 kg/hm2三个水平。测定了玉米吐丝期以及吐丝后7 d、14 d、21 d、28 d、35 d、42 d和成熟期茎、叶、籽粒氮含量和花后绿叶面积，吐丝期及吐丝后14 d、28 d、42 d和成熟期叶片氮浓度，以及吐丝期和灌浆期叶片中SPAD、可溶性蛋白浓度、游离氨基酸浓度和ZmSee2β (玉米叶片中协同衰老的蛋白酶–豆荚蛋白的基因) 基因表达的变化，计算了叶片氮转移效率。【结果】品种XY335具有比品种NE9更高的产量，随施氮量的增加品种XY335的籽粒产量较品种NE9增加更加显著。虽然两个品种的收获指数没有差异，但是品种XY335的氮素收获指数高于品种NE9，并且品种XY335营养器官的氮转移效率高于品种NE9，整体高8.28个百分点 (P < 0.05)。品种XY335叶片氮转移效率比品种NE9高出12.89个百分点，而二者茎的氮转移效率没有差异。品种XY335花后叶片中氮浓度开始降低的时间早于品种NE9，在低氮条件下尤为明显。成熟期时，三个氮水平处理下品种XY335叶片中的氮含量均低于品种NE9。从吐丝期到灌浆期，品种XY335叶片中可溶性蛋白的降解率高于品种NE9，其中N45处理下高16.5个百分点，N120处理下高6.2个百分点。从吐丝期到灌浆期叶片中游离氨基酸的浓度不断增加，而品种XY335叶片中的增加幅度大于品种NE9。从吐丝期到灌浆期叶片中 ZmSee2β基因表达量增加，而随施氮量减少品种XY335叶片中表达量高于品种NE9，表明品种XY335叶片中蛋白降解得更加迅速。【结论】相对于绿熟品种NE9，品种XY335具有籽粒产量高和籽粒氮素积累强的特点。这不仅由于吐丝后品种XY335具有较强的氮素吸收能力，而且因为品种XY335有更高的叶片氮转移效率。品种XY335叶片氮转移效率高可能是因为控制蛋白质降解的ZmSee2β基因表达能力强，提高了叶片中蛋白质的降解速度。
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| 关 键 词： | 玉米 产量 籽粒氮浓度 氮转移 基因表达 |
| 收稿时间： | 2018-01-02 |
Differences in leaf nitrogen remobilization efficiency and related gene expression during grain filling stage of two maize hybrids |
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| GUO Song,SUN Wen-yan,GU Ri-liang,WANG Zhang-kui,CHEN Fan-jun,ZHAO Bing-qiang,YUAN Li-xing,MI Guo-hua. Differences in leaf nitrogen remobilization efficiency and related gene expression during grain filling stage of two maize hybrids[J]. Plant Nutrition and Fertilizer Science, 2018, 24(5): 1149-1157. DOI: 10.11674/zwyf.18001 |
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| Authors: | GUO Song SUN Wen-yan GU Ri-liang WANG Zhang-kui CHEN Fan-jun ZHAO Bing-qiang YUAN Li-xing MI Guo-hua |
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| Affiliation: | 1.College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China |
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| Abstract: | 【Objectives】Improving nitrogen (N) use efficiency of maize (Zea mays L.) is important for high-yielding and nutrient-efficient agriculture. The senescence of leaves after flowering stage is closely relevant to efficient N remobilization. The paper studied thus the molecular mechanism underlying genotypic difference in N remobilization efficiency of maize in field conditions.【Methods】In the field experiment, maize cultivars of XY335 (mediate stay-green) and the stay-green hybrid NE9 were used as tested materials, and three application levels of N 45, 120 and 240 kg/hm2 (named N45, N120, N240) were setup. We compared N accumulation of maize at silking and maturity, the dynamic changes of leaf area (at the silking stage, 7, 14, 28, 35 and 42 days after silking, and at the physiological maturity stage) and leaf nitrogen concentration (at the silking stage, 14, 28, and 42 days after silking, and at the physiological maturity stage) from silking to maturity, the SPAD value, the soluble protein concentration, the free amino acid concentration and the expression of genes associated with the N remobilization process.【Results】Grain yields of XY335 were greater than those of NE9 under all N levels. N concentrations were increased with the increase of N application level in grains, but that was similar in the N120 and N240 treatments in stems. No significant difference was observed in harvest index (HI) between the two genotypes. XY335 showed higher NHI than NE9, and higher N remobilization efficiency (increased by 8.28 percentage points), which can be mainly explained by the NRE from the leaf rather than the stem (increased by 12.89 percentage points, P < 0.05). The onset of N decrease in leaves was earlier in XY335 than in NE9, and even worse under low N application level (N45), suggesting that early N export from the source leaves occurred. At maturity, leaf N concentrations of XY335 were lower than those of NE9. From silking to 28 DAS (days after silking), the reduction of leaf soluble protein concentration of XY335 was more rapidly than that of NE9, the reduction rate was 16.5 and 6.2 percentage points higher under the N 45 and N120 treatments respectively. The concentration of total free amino acids was increased from silking to 28 DAS across genotypes and N treatments, and the increment of the acids of XY335 was greater than that of NE9 under the N45 and N120 treatments. ZmSee2β expression was decreased with increasing of N supply at both sampling stages in both hybrids, and its expression was increased from silking to 28 DAS in each genotypes. Correspondingly the expression level of ZmSee2β was higher in XY335 than that of NE9, which suggested protein degradation was more rapid in XY335.【Conclusions】Compared with stay-green NE9, XY335 has characteristics of greater grain yield and high grain nitrogen accumulation. This is not only due to the greater nitrogen uptake capacity of XY335 after silking, but also the higher nitrogen remobilization efficiency in the leaves. The genotypic difference in leaf N remobilization efficiency is related to the degradation of soluble proteins regulated by the expression of ZmSee2β. |
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