自然环境下不同秋眠型苜蓿PHYA和PHYBmRNA表达量的变化

为揭示光敏色素如何响应外界环境及作用机理，并探讨其与苜蓿（Medicago）秋眠性的关系，以田间自然生长条件下的不同秋眠类型紫花苜蓿标准对照品种Norseman（FD1）， Archer（FD5）和CUF101（FD9）为材料，应用RT-PCR测定在6月、8月、9月、11月采集的叶片PHYA和PHYB mRNA含量。结果表明：从6 月到11月，随着光照时间的逐渐缩短和温度的降低，3个不同秋眠类型紫花苜蓿品种PHYA和PHYB的mRNA含量均呈上升趋势，且PHYA mRNA含量比PHYB mRNA的含量高；除了6月份，其他月份均是随着紫花苜蓿秋眠性的提高，PHYA和PHYB mRNA表达呈上调趋势，且不同秋眠类型间的差距越来越大。据此推测PHYA和PHYB在苜蓿响应外界环境改变过程中起一定的作用，二者基因的转录受光周期与温度因子的调控，且随着光周期的缩短与温度的降低其mRNA量升高，PHYA和PHYB很可能参与了光周期与温度对紫花苜蓿秋眠性的调控。

Expression Levels of PHYA and PHYB mRNA in Different Fall Dormancy Alfalfa Varieties

The responses of phytochromes to external environment and its function mechanism as well as the relationships between them and different alfalfa varieties were investigated in this study. Leaves of three different alfalfa varieties including Norseman (FD1), Archer (FD5) and CUF101 (FD9) were collected in June, August, September and November. The mRNA contents of PHYA and PHYB in leaves were detected by RT-PCR. The results show that from June to November, the PHYA and PHYB mRNA contents of three different alfalfa varieties increase with the shortening of photoperiod and the decreasing of temperature, while the amount of PHYA is higher than that of PHYB. The mRNA expression levels of PHYA and PHYB increase from August to November with the dormancy of alfalfa deepening, and there are significant differences among different alfalfa varieties. These results indicate that PHYA and PHYB might be involved in the regulation of alfalfa fall dormancy induced by photoperiod and temperature.