Control of seed coat rupture by ABA-INSENSITIVE 5 in Arabidopsis thaliana
Control of seed coat rupture by ABA-INSENSITIVE 5 in Arabidopsis thaliana
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DOI：
10.1017/s0960258519000059
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发表时间：
2019-06-01
影响因子：
2.1
通讯作者：
Graham, Ian A.
中科院分区：
文献类型：
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作者：
Barros-Galvao, Thiago;Vaistij, Fabian E.;Graham, Ian A.
在拟南芥中，种子萌发是一个两个阶段的过程，包括种皮破裂和胚根穿过珠孔胚乳的出现。在缺乏赤霉素的情况下，胚扩展会导致种皮破裂和种皮脱落，同时Della蛋白会阻止胚扩展。外源脱落酸(ABA)处理不能阻止种皮破裂，但能阻止胚根的萌发。我们利用外源ABA的这种有限效应来进一步研究它阻止以种皮破裂为标志的萌发开始的机制。我们发现，种皮的物理划痕导致外源ABA处理阻止种皮和胚乳破裂，这种阻止需要转录因子ABI3和ABI5，但不需要ABI4。此外，我们发现外源ABA抑制几个EXPANSIN基因(EXPA1、EXPA2、EXPA3、EXPA9和EXPA20)的表达需要ABI5。我们得出结论，ABI5通过阻止种皮破裂在ABA介导的萌发抑制中发挥重要作用，并认为这与ExPANSIN相关的控制细胞壁松动有关。
In Arabidopsis, seed germination is a biphasic process involving rupture of the seed coat followed by emergence of the radicle through the micropylar endosperm. Embryo expansion results in seed coat rupture and removal of seed coat imposed dormancy with DELLA proteins blocking embryo expansion in the absence of gibberellins. Exogenous abscisic acid (ABA) treatment does not block seed coat rupture but does block radicle emergence. We used this limited effect of exogenous ABA to further investigate the mechanism by which it blocks the onset of germination marked by seed coat rupture. We show that physical nicking of the seed coat results in exogenous ABA treatment blocking both seed coat and endosperm rupture and this block requires the transcription factors ABI3 and ABI5, but not ABI4. Furthermore, we show that the repression of expression of several EXPANSIN genes (EXPA1, EXPA2, EXPA3, EXPA9 and EXPA20) by exogenous ABA requires ABI5. We conclude that ABI5 plays an important role in the ABA-mediated repression of germination through prevention of seed coat rupture and propose that this involves EXPANSIN related control of cell wall loosening.