Temporal and Spatial Distribution of Auxin Response Factor Genes During Tomato Flower Abscission
Temporal and Spatial Distribution of Auxin Response Factor Genes During Tomato Flower Abscission
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番茄花脱落过程中生长素响应因子基因的时空分布
DOI：
10.1007/s00344-013-9377-x
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发表时间：
2014-06-01
影响因子：
4.8
通讯作者：
Li, Tianlai
中科院分区：
文献类型：
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作者：
Guan, Xiaoxi;Xu, Tao;Li, Tianlai
脱落促进生长和繁殖，提高植物对病原体的防御能力。这个受到严格调控的过程是由环境信号和激素（如乙烯和生长素）触发的。由于生长素是植物生长的关键因子，因此生长素反应因子（ARF）可能在这一过程中发挥重要作用。在这里，我们研究了在番茄中的表达过程中基因的变化，侧重于调节基因编码的ARF。具体来说，我们分析了ARF基因表达的模式，在番茄花梗外植体处理乙烯，乙烯阻断剂1-甲基环丙烯（1-MCP），或生长素，以确定如何生长素和乙烯影响ARF基因的表达。此外，我们通过检查表达与GUS报告基因融合的IAA诱导型启动子的转基因番茄植物（P5：：GUS 'Chico III'系）来检查脱落期间IAA的空间和时间分布。从外植体上去除花后，乙烯迅速诱导外植体脱落，而外源生长素或1-MCP则抑制了乙烯的诱导。在植物早期休眠过程中，生长素（或1-MCP）调节各种ARF基因的表达，包括ARF 1、2、3、4、5、7、8 - 1、9、11、1,2、13、13 - 1、14和17，而乙烯则对大多数这些基因有相反的作用。进一步的分析表明，在此阶段，生长素可能介导ARF 8 - 1、9、11、12、13、13 -1和14的表达，而乙烯可能介导ARF 13 -1的表达。与未分化部位相比，在分化后期，ARF 2、8、10、11和19表达上调，8 - 1、12、13和13 - 1表达下调。荧光GUS分析表明，GUS酶活性在4 h时保持稳定，8h后急剧下降，直至酶解完全（32 h）。
Abscission facilitates growth and reproduction and improves plant defenses against pathogens. This tightly regulated process is triggered by environmental cues and hormones such as ethylene and auxin. Because auxin is crucial for abscission, auxin response factors (ARFs) may play important roles in this process. Here, we examined changes in gene expression during abscission in tomato, focusing on regulation of genes encoding ARFs. Specifically, we analyzed the pattern of ARF gene expression in tomato flower pedicel explants treated with ethylene, the ethylene blocker 1-methylcyclopropene (1-MCP), or auxin to determine how auxin and ethylene affect ARF gene expression. In addition, we examined the spatial and temporal distribution of IAA during abscission by examining transgenic tomato plants expressing an IAA-inducible promoter fused to the GUS reporter gene (the P5::GUS ‘Chico III’ line). Flower removal from the explants quickly induced abscission by ethylene, which was inhibited by exogenous auxin or 1-MCP. During early abscission, auxin (or 1-MCP) regulated the expression of various ARFs, includingARF1,2, 3,4,5,7,8-1,9,11,12,13,13-1,14, and17, whereas ethylene had the opposite effect on most of these genes. Further analysis shows that during this stage, auxin may mediate the expression ofARF8-1,9,11,12,13,13-1, and14, whereas ethylene may mediateARF13-1. During the later stage of abscission,ARF2,8,10,11, and19were upregulated, and8-1,12,13, and13-1were downregulated, compared with nonabscising parts of plants. Fluorometric GUS analysis indicated that GUS activity in the abscission zone remained stable at 4 h and sharply decreased after 8 h until abscission was complete (32 h).