《植物生理学报》 2016, 52(9): 1397-1405

丝氨酸对光呼吸基因节律的影响机制初探

韩晓芳¹, 彭柯力¹, 吴海霞¹, 宋珊珊^1,2, 李亚辉^1,3, 朱晔荣¹, 白艳玲¹, 王勇^1,*

¹南开大学生命科学学院, 天津300071; ²罗斯托克大学植物生理学系, 德国罗斯托克D-18059; ³中国人民大学附属中学朝阳分校, 北京100020

通信作者：王勇；E-mail: wangyong@nankai.edu.cn

摘　要：

昼夜节律是植物为适应环境而做出的反应。有研究指出, 叶片内丝氨酸含量的变化能影响光呼吸基因的表达节律。影响昼夜节律的因素有很多, 其中最重要的是糖和生物钟。据此, 本研究比较了培养基中分别添加不同浓度(3%或5%)蔗糖和1 mmol•L^-1 l-丝氨酸后, 光呼吸基因在一天4个取样点的表达差异; 分别分析了外加蔗糖和l-丝氨酸对内源丝氨酸和内源蔗糖含量的影响; 并进一步分析了外源l-丝氨酸处理的野生型拟南芥叶片和羟基丙酮酸还原酶突变体(hpr1)叶片中生物钟基因的表达情况。实验结果显示, 从1%到3%再到5%蔗糖处理, 光呼吸基因的表达节律显示出了依赖糖浓度的规律性变化。叶片中蔗糖含量随处理浓度的升高而增加, 同时这种处理能够诱导丝氨酸含量的升高, 这可能与其影响了丝氨酸的合成有关, 但并不能影响其代谢节律的改变。1 mmol•L^-1的l-丝氨酸处理也能改变光呼吸基因的表达节律, 且与内源丝氨酸的代谢节律相吻合, 同时外源丝氨酸处理能轻微诱导内源蔗糖的积累, 这与突变体hpr1的结果类似。在培养基中同时添加1 mmol•L^-1的l-丝氨酸和1%的蔗糖后, 与只加1%蔗糖相比, 生物钟基因的表达出现了较大的差异: 虽然没有影响其节律的改变, 但强烈诱导了PRR7和PRR9在白天的表达水平, 从而轻微抑制了生物钟核心震荡基因CCA1和LHY在光照结束时的表达。同样, 在hpr1突变体中, 丝氨酸含量的积累对生物钟基因的表达也产生了类似的影响。

关键词：l-丝氨酸; 光呼吸基因; 节律; 蔗糖; 生物钟

收稿：2016-06-16   修定：2016-08-09

资助：国家自然科学基金(31270296)和中德合作科研项目(留金欧[2014]6013)。 致谢 德国罗斯托克大学植物生理学系Hermann Bauwe教授、Stefan Timm博士和Ramona Kern博士在实验中的指导与帮助, 以及中国科学院上海植物逆境生物学研究中心刘菲硕士在实验中的帮助。

A preliminary study on the mechanism of the effect of serine on the rhythm of photorespiration genes

HAN Xiao-Fang¹, PENG Ke-Li¹, WU Hai-Xia¹, SONG Shan-Shan^1,2, LI Ya-Hui^1,3, ZHU Ye-Rong¹, BAI Yan-Ling¹, WANG Yong^1,*

¹College of Life Sciences, Nankai University, Tianjin 300071, China; ²Department of Plant Physiology, University of Rostock, Rostock D-18059, Germany; ³RDFZ Chaoyang Branch School, Beijing 100020, China

Corresponding author: WANG Yong; E-mail: wangyong@nankai.edu.cn

Abstract:

Circadian rhythm is a response of plants for adaptation to the environment. It was reported that the change of serine content in leaves affects the expression rhythm of photorespiration-related genes. During many factors affecting the circadian rhythm, sugar and biological clock are the two most important factors for regulation of diurnal genes expression. In this report, Arabidopsis thaliana wild-type (wt) growing in plate containing 1%, 3% or 5% sucrose, or 1% sucrose plus 1 mmol•L^-1 l-serine, and hpr1 mutant plants growing in 1% sucrose plate were placed in normal air under a (10/14) h day/night regime. Leaf samples were harvested at four time points of a day for the analysis of expression patterns of photorespiration-related genes. At the same points, the effects of external sucrose and l-serine on levels of endogenous serine and sucrose were also analyzed, and the expression rhythms of circadian-associated genes in the wt with l-serine treatment and hpr1 mutant were further compared. It was shown that incubation with different amounts of sucrose (1%, 3% and 5%) could lead to the accumulated serine depending on the amounts of sucrose and a regular change on photorespiration-related genes. Besides, treatments also caused the endogenous sucrose significantly increased, which may be related to the synthesis of serine, but it could not alter metabolic rhythm of serine. One mmol•L^-1 serine treatment altered the accumulation rhythm of endogenous serine, which was in consistence with the expressing rhythm of photorespiration-related genes. Besides, it also induced a slight accumulation of endogenous sucrose, and those alterations were agreement with those in hpr1 mutant. One mmol•L^-1 l-serine supplementation in the growth medium induced significant changes of the expression levels of clock-related genes. Although the expression rhythms of genes were not changed, external l-serine supply strongly induced the expression of PRR7 and PRR9, which consequently slightly inhibited the expression of LHY and CCA1. The hpr1 mutant plants showed similar changes.

Key words: l-serine; photorespiration genes; rhythm; sucrose; circadian clock