英國一項最新研究發(fā)現(xiàn),，一種草本植物會在葉子中累積大量金屬元素，以避免病菌入侵,，如同給自己裝備了一層“金屬鎧甲”,。
英國牛津大學(xué)研究人員在新一期《科學(xué)公共圖書館—病原體》上報告說,，一種名為遏藍(lán)菜的植物會在葉子中累積高濃度的鋅、鎳,、鎘等金屬元素,，但此前并不清楚它累積金屬的用處。
為了解個中緣由,，研究人員在不同的金屬濃度環(huán)境中培養(yǎng)了遏藍(lán)菜,，并利用常在蘿卜等植物中引發(fā)疾病的丁香假單胞菌進(jìn)行實驗。結(jié)果顯示,，不論是鋅,、鎳還是鎘，只要遏藍(lán)菜體內(nèi)金屬濃度升高,，病菌入侵的程度就會變小,。
參與研究的蓋爾·普雷斯頓博士說，這表明遏藍(lán)菜是利用環(huán)境中的金屬元素給自己穿上“金屬鎧甲”,，以抵御病菌入侵,。
不過研究人員也發(fā)現(xiàn)，在遏藍(lán)菜裝備“堅盾”的同時,，也有一些細(xì)菌進(jìn)化出了“利矛”,。一些在金屬礦區(qū)發(fā)現(xiàn)的細(xì)菌已經(jīng)進(jìn)化出較高的金屬耐受性，因此有可能在具有較高金屬濃度的植物體內(nèi)存活,。研究人員說,，這就像一場“軍備競賽”，持續(xù)地發(fā)生在自然界中攻守雙方的互動進(jìn)化中,。（生物谷Bioon.com）
生物谷推薦英文摘要：
PLoS Pathog doi:10.1371/journal.ppat.1001093
Metal Hyperaccumulation Armors Plants against Disease
Helen Fones, Calum A. R. Davis, Arantza Rico, Fang Fang¤, J. Andrew C. Smith*, Gail M. Preston*
Metal hyperaccumulation, in which plants store exceptional concentrations of metals in their shoots, is an unusual trait whose evolutionary and ecological significance has prompted extensive debate. Hyperaccumulator plants are usually found on metalliferous soils, and it has been proposed that hyperaccumulation provides a defense against herbivores and pathogens, an idea termed the ‘elemental defense’ hypothesis. We have investigated this hypothesis using the crucifer Thlaspi caerulescens, a hyperaccumulator of zinc, nickel, and cadmium, and the bacterial pathogen Pseudomonas syringae pv. maculicola (Psm). Using leaf inoculation assays, we have shown that hyperaccumulation of any of the three metals inhibits growth of Psm in planta. Metal concentrations in the bulk leaf and in the apoplast, through which the pathogen invades the leaf, were shown to be sufficient to account for the defensive effect by comparison with in vitro dose–response curves. Further, mutants of Psm with increased and decreased zinc tolerance created by transposon insertion had either enhanced or reduced ability, respectively, to grow in high-zinc plants, indicating that the metal affects the pathogen directly. Finally, we have shown that bacteria naturally colonizing T. caerulescens leaves at the site of a former lead–zinc mine have high zinc tolerance compared with bacteria isolated from non-accumulating plants, suggesting local adaptation to high metal. These results demonstrate that the disease resistance observed in metal-exposed T. caerulescens can be attributed to a direct effect of metal hyperaccumulation, which may thus be functionally analogous to the resistance conferred by antimicrobial metabolites in non-accumulating plants.
