Seed Storage Oil Mobilization Is Important But Not Essential for Germination or Seedling Establishment in Arabidopsis
Seed Storage Oil Mobilization Is Important But Not Essential for Germination or Seedling Establishment in Arabidopsis
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DOI：
10.1104/pp.111.181784
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发表时间：
2011-10-01
期刊：
影响因子：
7.4
通讯作者：
Eastmond, Peter J.
中科院分区：
文献类型：
--
作者：
Kelly, Amelie A.;Quettier, Anne-Laure;Eastmond, Peter J.
三酰甘油（TAG）是许多植物种子中的主要贮藏物质。我们先前鉴定了一种称为糖依赖性1（sdp 1）的TAG脂肪酶突变体，其在拟南芥（Arabidopsis thaliana）种子萌发后TAG水解受损（Eastmond，2006）。本研究的目的是确定额外的脂肪酶，占剩余的TAG水解观察sdp 1。在三个候选基因（SDP 1-LIKE [SDP 1 L]、脂肪糖甘油三酯脂肪酶样和比较基因标识符-58-LIKE）中分离突变体。双重，三重，四重突变体的分析表明，SDP 1 L是负责几乎所有的残留的TAG水解存在于sdp 1幼苗。从sdp 1 sdp 1 L幼苗纯化的油体膜缺乏TAG脂肪酶活性，但仍然可以水解二和单酰基甘油。SDP 1 L在幼苗中的表达不如SDP 1强烈。然而，SDP 1 L可以部分拯救TAG分解的SDP 1或35 S启动子的控制下表达时，在sdp 1幼苗和体外试验表明，SDP 1和SDP 1 L可以水解TAG，优先于甘油二酯或甘油单酯。种子萌发减慢sdp 1 sdp 1 L和发芽后幼苗生长严重受阻。幼苗建立的频率也降低，但sdp 1 sdp 1 L在正常的实验室生长条件下是不致命的幼苗。我们的数据表明，SDP 1和SDP 1 L一起占拟南芥种子中TAG水解速率的至少95%，并且这种水解对于种子萌发或幼苗建立是重要的但不是必需的。
Triacylglycerol (TAG) is a major storage reserve in many plant seeds. We previously identified a TAG lipase mutant called sugar-dependent1 (sdp1) that is impaired in TAG hydrolysis following Arabidopsis (Arabidopsis thaliana) seed germination (Eastmond, 2006). The aim of this study was to identify additional lipases that account for the residual TAG hydrolysis observed in sdp1. Mutants were isolated in three candidate genes (SDP1-LIKE [SDP1L], ADIPOSE TRIGLYCERIDE LIPASE-LIKE, and COMPARATIVE GENE IDENTIFIER-58-LIKE). Analysis of double, triple, and quadruple mutants showed that SDP1L is responsible for virtually all of the residual TAG hydrolysis present in sdp1 seedlings. Oil body membranes purified from sdp1 sdp1L seedlings were deficient in TAG lipase activity but could still hydrolyze di- and monoacylglycerol. SDP1L is expressed less strongly than SDP1 in seedlings. However, SDP1L could partially rescue TAG breakdown in sdp1 seedlings when expressed under the control of the SDP1 or 35S promoters and in vitro assays showed that both SDP1 and SDP1L can hydrolyze TAG, in preference to diacylglycerol or monoacylglycerol. Seed germination was slowed in sdp1 sdp1L and postgerminative seedling growth was severely retarded. The frequency of seedling establishment was also reduced, but sdp1 sdp1L was not seedling lethal under normal laboratory growth conditions. Our data show that together SDP1 and SDP1L account for at least 95% of the rate of TAG hydrolysis in Arabidopsis seeds, and that this hydrolysis is important but not essential for seed germination or seedling establishment.