甘蔗各家族SPS基因表达特性分析

Expression analysis of sucrose phosphate synthase gene family in sugarcane

【目的】通过时空表达特性分析,初步推测甘蔗各家族蔗糖磷酸合成酶（SPS）基因在甘蔗蔗糖积累途径中的功能,为研究甘蔗各家族SPS基因的生物学功能奠定基础。【方法】采用荧光定量PCR分析甘蔗4个家族SPS基因在高、中、低糖甘蔗品种未成熟叶片、成熟叶片和茎中的时空表达特性。【结果】在甘蔗伸长期、蔗糖积累前期和蔗糖积累后期,Sof SPSDⅢ基因在所有甘蔗品种的未成熟叶片、成熟叶片和茎中均高水平稳定表达,相对表达量在5.3-8.1;Sof SPSB基因在成熟叶片中几乎不表达,而以茎中表达量最高。在伸长期,Sof SPSC和Sof SPSA基因表达较强,相对表达量分别为7.3-14.2和1.5-4.4;在蔗糖积累前期,Sof SPSC基因表达稍有降低,但仍处于较高水平,相对表达量达为4.6-8.9,而Sof SPSA基因表达加强,相对表达量达3.8-6.9;在蔗糖积累后期,Sof SPSC基因在成熟叶片中的表达量比蔗糖积累前期下降4.0-7.2倍,且均比未成熟叶和茎中下降约6.0倍,而Sof SPSA基因在不同组织中的表达量比蔗糖积累前期下降1.8-5.7倍。各家族SPS基因在不同糖分甘蔗品种间的表达趋势一致。【结论】甘蔗D家族SPS基因维持甘蔗蔗糖合成的基本功能,通过调控C、A家族SPS基因的表达来调控蔗糖合成的强度,B家族SPS基因不参与甘蔗源叶中蔗糖合成而参与蔗糖的积累与利用。

【Objective】The role of each sucrose phosphate synthase gene（SPS） in regulation of sucrose accumulation in sugarcane was preliminary predicted by analyzing their spatial and temporal expression features in the present study, in order to lay the foundation for further accurately elucidating the biological functions of each SPS gene in sugarcane.【Method】The fluorogenic quantitative PCR was used for analyzing the spatial and temporal expression features of different SPS genes from four families in immature leaf, ＋2 mature leaf and ＋6 stalk of different sugarcane varieties with low, moderate and high sucrose content. 【Result】At elongation stage, earlier sucrose accumulation and later sucrose accumulation stages of sugarcane, a high level stable expression（ the relative expression between 5. 3- 8. 1） of Sof SPSDIII was detected in immature leaves, ＋2 mature leaves, and ＋6 stalks of all tested varieties; Sof SPSB gene was hardly expressed in mature leaves, but high expression was found in stalks. At elongation stage, the expression levels of Sof SPSC and SofSPSA were relatively higher, and their relative expression was 7.3-14.2 and 1.5-4.4, respectively. During the earlier sucrose accumulation stage, the expression level of Sof SPSC slightly decreased, but remained relatively higher as 4.6-8.9;whereas the expression level of Sof SPSA increased as reaching to 3.8-6.9. During later sucrose accumulation stage, the relative expression of Sof SPSC in mature leaves was 4.0-7.2 times less than that of earlier sucrose accumulation stage, and also decreased by 6.0 times as compared to those of immature leaves and ＋6 stalks; the relative expression of Sof SPSA in different tissues was found to decrease 1.8-5.7 times as compared to that of earlier sucrose accumulation stage. Furthermore, different SPS genes of all four families in sugarcane presented the same expressing trends in different sugarcane varieties with different sucrose contents. 【Conclusion】The SPS gene from family D of sugarcane may be maintain the basic functions of sucrose synthesis in sugarcane; and the intensity of sucrose synthesis is controlled by regulating the expressions of SPS genes from family C and family A. The SPS gene from family B may be not participate in the sucrose synthesis in source leaf but participate in sucrose accumulation and utilization in sugarcane.