School of Plant Biology, Faculty of Natural and Agricultural Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
J Exp Bot. 2011 Jan;62(1):39-57. doi: 10.1093/jxb/erq271. Epub 2010 Sep 16.
O(2) deficiency during soil waterlogging inhibits respiration in roots, resulting in severe energy deficits. Decreased root-to-shoot ratio and suboptimal functioning of the roots, result in nutrient deficiencies in the shoots. In N(2)-flushed nutrient solutions, wheat seminal roots cease growth, while newly formed adventitious roots develop aerenchyma, and grow, albeit to a restricted length. When reliant on an internal O(2) supply from the shoot, nutrient uptake by adventitious roots was inhibited less than in seminal roots. Epidermal and cortical cells are likely to receive sufficient O(2) for oxidative phosphorylation and ion transport. By contrast, stelar hypoxia-anoxia can develop so that H(+)-ATPases in the xylem parenchyma would be inhibited; the diminished H(+) gradients and depolarized membranes inhibit secondary energy-dependent ion transport and channel conductances. Thus, the presence of two transport steps, one in the epidermis and cortex to accumulate ions from the solution and another in the stele to load ions into the xylem, is important for understanding the inhibitory effects of root zone hypoxia on nutrient acquisition and xylem transport, as well as the regulation of delivery to the shoots of unwanted ions, such as Na(+). Improvement of waterlogging tolerance in wheat will require an increased capacity for root growth, and more efficient root functioning, when in anaerobic media.
在土壤积水时，O(2)缺乏会抑制根部呼吸，导致严重的能量亏缺。根冠比下降和根系功能失调会导致地上部养分缺乏。在充氮气的营养液中，小麦初生根停止生长，而新形成的不定根则发育出气腔组织，并生长，但长度有限。当依赖地上部供应的内部 O(2)时，不定根的养分吸收受到的抑制小于初生根。表皮和皮层细胞可能会接收到足够的 O(2)用于氧化磷酸化和离子运输。相比之下，茎的缺氧-缺氧可能会发展，导致木质部薄壁细胞中的 H(+)-ATP 酶受到抑制；H(+)梯度的减少和膜去极化会抑制次级能量依赖的离子运输和通道电导。因此，存在两个运输步骤，一个在表皮和皮层中从溶液中积累离子，另一个在茎中向木质部装载离子，这对于理解根区缺氧对养分吸收和木质部运输的抑制作用以及对向地上部输送不需要的离子（如 Na(+)）的调节是很重要的。提高小麦的耐水淹能力需要在厌氧介质中增强根生长的能力和提高根系的功能效率。
