Micronutrient Deficiencies Accelerate Leaf Senescence in Amomum villosum

微量元素缺乏加速砂仁葉片衰老

馮玉龍(Yu-Long Feng) ； 類延寶(Yan-Bao Lei) ； 李志(Zhi Li)

《Botanical Studies》 53卷3期 (2012/07) Pp. 345-352

摘要

栽培幾年後藥用植物砂仁（Amomum villosum）的果實產量逐漸降低，這常常被歸因於植株衰老。然而，至今砂仁衰老的原因還不清楚。本文研究了微量元素缺乏對砂仁葉片衰老的影響。我們假設微量元素缺乏可能通過干擾細胞代謝而導致氧化脅迫，進而導致砂仁葉片衰老以及生長減慢。銅、鋅和錳缺乏使砂仁葉片光飽和光合速率、葉綠素含量和可溶性蛋白質含量降低，丙二醛含量升高，表明發生了氧化脅迫和衰老。與缺銅和錳相比，缺鋅對砂仁的危害更大。缺少微量元素對葉綠體基質中CO2同化的負面影響大於對類囊體膜上電子傳遞的負面影響，導致葉綠體中過剩激發能增加。在大多數情況下，微量元素缺乏使砂仁葉片熱耗散能力和類胡蘿蔔素含量降低，減少過剩激發能的耗散，導致氧化脅迫，儘管此時抗氧化酶活性升高。本研究表明，缺少微量元素導致了砂仁葉片氧化脅迫，加速了葉片衰老，抑制了砂仁生長。

關鍵字

丙二醛 ； 光合作用 ； 抗氧化酶 ； 錳 ； 生長 ； 銅 ； 辛 ； 氧化脅迫 ； 葉綠素螢光

並列摘要

Fruit yield decreases gradually after several years of cultivation in Amomum villosum, an important Chinese medicinal herb, which is generally attributed to plant senescence. However, the reasons for plant senescence are still not clear until now. In this study, we investigated the effects of micronutrient deficiencies on leaf senescence. We hypothesized that micronutrient deficiencies may cause oxidative stress by disturbing cell metabolisms, which in turn leads to leaf senescence and decrease growth in A. villosum plants. Deficiencies of copper, zinc, and manganese decreased light-saturated photosynthetic rate and the contents of chlorophylls and soluble proteins but increased malondialdehyde content in A. villosum plants. The results indicated that oxidative stress and senescence occurred in leaves of A. villosum plants grown under micronutrient deficient conditions. Amomum plants were more susceptible to zinc deficiencies than to deficiencies of copper and manganese. The negative effects of micronutrient deficiencies on CO2 assimilation in chloroplast stroma were more serious than on electron transfer in thylakoids, increasing excess excitation energy. In most cases, micronutrient deficiencies decreased thermal dissipation of excess excitation energy and carotenoid content, leading to oxidative stress although antioxidant enzyme activities increased. Our results indicated that the micronutrient deficiencies caused oxidative stress, exacerbating leaf senescence and inhibiting biomass accumulation in Amomum plants.

並列關鍵字

Antioxidant enzymes ； Chlorophyll α fluorescence ； Copper ； Growth ； Malondialdehyde ； Manganese ； Oxidative stress ； Photosynthesis ； Zinc