Anoxia tolerance in rice seedlings: exogenous glucose improves growth of an anoxia-'intolerant', but not of a 'tolerant' genotype
Anoxia tolerance in rice seedlings: exogenous glucose improves growth of an anoxia-'intolerant', but not of a 'tolerant' genotype
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DOI：
10.1093/jxb/erg252
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发表时间：
2003-10-01
影响因子：
6.9
通讯作者：
Colmer, TD
中科院分区：
文献类型：
--
作者：
Huang, SB;Greenway, H;Colmer, TD
本研究表明，水稻幼苗对缺氧耐受性的基因型差异仅在吸胀时缺氧时出现，而在吸胀后3天则不存在。当种子吸水并在缺氧条件下生长时，IR22（缺氧“不耐受”）比 Amaroo（缺氧“耐受”）生长慢得多，胚芽鞘和种子中的可溶性糖浓度也较低，而 Calrose 则处于中间水平。缺氧3天后，IR22中缺氧幼苗胚胎和胚乳中的糖浓度比Amaroo中低近4倍。 IR22 胚胎中的糖缺乏可能是由于糖动员的限制而不是运输能力，如缺氧 3 d 时 IR22 和 Amaroo 的胚胎和胚乳之间相似的糖积累比率 1.8 所示。当外源葡萄糖浓度为20 mol m(-3)时，IR22缺氧幼苗的胚芽鞘伸长和鲜重增量与其他两种基因型的幼苗非常接近，但IR22胚芽鞘的鲜重蛋白质浓度仍然最低；表明缺氧期间蛋白质合成对于能量分配的优先级低于对胚芽鞘延伸至关重要的过程。与吸胀时对缺氧的反应相反，当在通气 48 小时，然后进行 16 小时缺氧预处理后对幼苗施加缺氧时，IR22 对缺氧的耐受性几乎与 Calrose 和 Amaroo 相同。事实上，缺氧IR22的胚芽鞘比Calrose具有更高的糖浓度并且生长更快，并且外源葡萄糖对IR22的胚芽鞘延伸没有影响。用外源葡萄糖切除的 IR22 和 Amaroo 的胚芽鞘尖端具有相似的乙醇生产率，并且同样耐缺氧。总之，当IR22在缺氧中发芽时，其缺氧“不耐受”的大部分可归因于胚胎和胚芽鞘的底物可用性有限，这可能是由于胚乳中的淀粉水解缓慢所致。
This study demonstrated that, in rice seedlings, genotypic difference in tolerance to anoxia only occurred when anoxia was imposed at imbibition, but not at 3 d after imbibition. When seeds were imbibed and grown in anoxia, IR22 (anoxia-'intolerant') grew much slower and had lower soluble sugar concentrations in coleoptiles and seeds than Amaroo (anoxia-'tolerant'), while Calrose was intermediate. After 3 d in anoxia, the sugar concentrations in embryos and endosperms of anoxic seedlings were nearly 4-fold lower in IR22 than in Amaroo. Sugar deficit in the embryo of IR22 is presumably due to the limitation of sugar mobilization rather than the capacity of transport as shown by similar sugar accumulation ratios of 1.8 between embryo and endosperm in IR22 and Amaroo at 3 d in anoxia. With 20 mol m(-3) exogenous glucose, coleoptile extension and fresh weight increments in anoxic seedlings of IR22 were much closer to those in the two other genotypes, nevertheless protein concentration remained lowest on a fresh weight basis in the coleoptiles of IR22; indicating that protein synthesis has a lower priority for energy apportionment during anoxia than processes crucial to coleoptile extension. In contrast to these responses to anoxia imposed at imbibition, IR22 had nearly the same high tolerance to anoxia as Calrose and Amaroo, when anoxia was imposed on seedlings subsequent to 48 h aeration followed by 16 h hypoxic pretreatment. In fact, coleoptiles of anoxic IR22 had higher sugar concentrations and grew faster than Calrose, and exogenous glucose had no effect on the coleoptile extension of IR22. Excised coleoptile tips of IR22 and Amaroo with exogenous glucose had similar rates of ethanol production and were equally tolerant to anoxia. In conclusion, much of the anoxia 'intolerance' of IR22 when germinated in anoxia could be attributed to limited substrate availability to the embryo and coleoptile, presumably due to slow starch hydrolysis in the endosperm.