休眠期间油桃花芽碳水化合物代谢及其相关基因的表达变化

Changes in Carbohydrate Metabolism and Related Gene Expression in Nectarine Floral Buds during Dormancy

以十年生大田和三年生盆栽‘曙光’油桃花芽为材料,分别测定了其休眠期碳水化合物含量、糖代谢相关基因的季节性表达及低温处理下相关基因的表达变化,旨在探讨碳水化合物及低温与休眠的关系。结果表明:休眠期间可溶性糖(主要是蔗糖)含量逐渐增加,淀粉含量则呈相反趋势。糖代谢相关基因表达明显不同:腺苷二磷酸葡萄糖焦磷酸化酶基因(AGPase)无明显变化;组氨酸H3基因(HisH3)和己糖激酶1基因(HK1)在进入内休眠前有明显上升,蔗糖合酶基因(SuSy)则与之相反;尿苷二磷酸葡萄糖焦磷酸化酶(UGPase)表达总体上呈上调趋势,在进入内休眠后稍有下调。表明进入内休眠后,依赖HK1的糖信号转导途径起重要作用。在4℃处理后,与细胞分裂有关的基因HisH3含量急剧升高,而后下降,说明细胞分裂的减少并不是休眠期间抑制生长的原因;UGPase表现出与内休眠期一致的变化趋势,说明对低温有一定的适应性。

To determine relationships among carbohydrate, low temperature and dormancy, the carbohydrate content, the seasonal expression of sugar metabolism related genes and transcript expression of related genes under low temperature were examined using floral buds of ten-year-old field-grown and three-year-old potted ＇Shuguang＇ nectarine （Prunus persica vat. nectariana cv. ＇Shuguang＇）, respectively. The results indicated that soluble sugar （mainly sucrose） contents in floral buds increased gradually during dormancy; while starch con- tent showed an inverse decreasing pattern. The transcripts of genes involved in sugar metabolism were differen- tially regulated. The expression ofHisH3 （histone 113） and HK1 （hexokinase 1） was distinctly up-regulated before endo-dormancy, while SuSy （sucrose synthase） displayed a contrary expression pattern. The expression of AGPase （adenosine diphosphate glucose pyrophosphorylase） showed no significant change and the expression of UGPase （uridine diphosphate glucosepyrophosphorylase） was increased during dormancy. The results demonstrate that HKl-dependent sugar signaling pathway may play an important role after entering endo-dormancy. The expression of cell division related gene HisH3 increased dramatically and then decreased after low temperature treatment, indicating that inhibition of growth during endo-dormancy was not a consequence of reduced cell division availability. UGPase has an adaptability to low temperature to some extent for it shows a parallel trend between endo-dormant period and low temperature treatment.