College of Agronomy/National Engineering Research Center for Wheat, Henan Agricultural University, Zhengzhou 450002, China.
College of Agronomy/National Engineering Research Center for Wheat, Henan Agricultural University, Zhengzhou 450002, China; The National Key Laboratory of Wheat and Maize Crop Science, Henan Agricultural University, Zhengzhou 450002, China.
J Plant Physiol. 2018 Dec;231:182-191. doi: 10.1016/j.jplph.2018.09.017. Epub 2018 Sep 27.
In order to understand the effects of sugar metabolism on drought resistance in wheat, two wheat cultivars with different levels of drought resistance were used in this study. We investigated the accumulation pattern of water-soluble carbohydrates (WSC) and expression profiles of twelve fructan metabolism-related genes in peduncle (PED), penultimate (PEN), and lower internode (LOW) stem tissues under drought stress. LH7, a higher drought-resistance cultivar, contained a higher stem dry weight and higher content of WSC in PED, PEN, and LOW tissues, while XN979, a lower drought-resistance cultivar, contained lower values. The tissues from LOW internodes had the highest WSC content, while PED had the lowest. The mRNA levels of genes encoding fructan synthesis-related enzymes, sucrose: sucrose 1-fructosyltransferase (1-SST), sucrose: fructan 6-fructosyltransferase (6-SFT), and fructan: fructan 1- fructosyltransferase (1-FFT) showed higher expression levels at early time points following stress, whilst the genes encoding degradation-related enzymes, fructan exohydrolases (1-FEH), and invertase (INV), showed higher expression at a later time point. Compared with XN979, LH7 showed higher expression levels of genes encoding fructan synthesis-related enzymes at all growth stages, whilst the expression of 1-FEH-W3, 6-FEH, and INV3 were higher at a later stage; these expression levels would benefit fructan accumulation and remobilization at early and later stages, respectively. Drought stress induced most of fructan metabolism related genes expression level decreasing in LH7 PED, but enhancing in LH7 LOW part at early time points following stress. The results confirm that there are complex, coordinated expression patterns of fructan synthesis- and degradation-related genes in stems under drought stress. In summary, 1-SST-A2, 6-SFT, 1-FFT-A, 1-FEH-W3, 6-FEH, and INV3 play important roles in fructan accumulation. In addition, higher expression of genes related to fructan synthesis and degradation occurs during early and later stages of drought stress, respectively, enhancing the drought resistance of wheat cultivar LH7.
为了了解糖代谢对小麦抗旱性的影响,本研究选用了两个抗旱性不同的小麦品种。我们研究了在干旱胁迫下穗颈(PED)、倒数第二节间(PEN)和下位节间(LOW)茎组织中水溶性碳水化合物(WSC)的积累模式和 12 个与果糖代谢相关基因的表达谱。LH7 是一个抗旱性较高的品种,其 PED、PEN 和 LOW 组织的茎干重和 WSC 含量均较高,而 XN979 是一个抗旱性较低的品种,其含量较低。LOW 节间组织的 WSC 含量最高,而 PED 最低。编码果糖合成相关酶的基因,蔗糖:蔗糖 1-果糖基转移酶(1-SST)、蔗糖:果糖 6-果糖基转移酶(6-SFT)和果糖:果糖 1-果糖基转移酶(1-FFT)的 mRNA 水平在胁迫早期表达较高,而编码降解相关酶的基因,果糖外切酶(1-FEH)和转化酶(INV)的 mRNA 水平在后期表达较高。与 XN979 相比,LH7 在所有生长阶段都表现出较高的果糖合成相关酶基因表达水平,而 1-FEH-W3、6-FEH 和 INV3 在后期的表达水平较高;这些表达水平分别有利于早期和后期果糖的积累和再利用。干旱胁迫诱导 LH7 PED 中大多数果糖代谢相关基因表达水平降低,但在胁迫早期 LH7 LOW 部分增强。结果证实,干旱胁迫下茎中果糖合成和降解相关基因的表达存在复杂的、协调的模式。综上所述,1-SST-A2、6-SFT、1-FFT-A、1-FEH-W3、6-FEH 和 INV3 在果糖积累中起重要作用。此外,干旱胁迫早期和后期,与果糖合成和降解相关的基因表达水平升高,分别增强了小麦品种 LH7 的抗旱性。