Prasad Sheo Mohan, Kumar Sushil, Parihar Parul, Singh Anita, Singh Rachana
Ranjan Plant Physiology and Biochemistry Laboratory, Department of Botany, University of Allahabad, Allahabad 211002, India.
Ranjan Plant Physiology and Biochemistry Laboratory, Department of Botany, University of Allahabad, Allahabad 211002, India.
Pestic Biochem Physiol. 2016 Mar;128:45-56. doi: 10.1016/j.pestbp.2015.10.006. Epub 2015 Oct 9.
The present study assessed the comparative responses of two agronomic species of Azolla (A.microphylla and A. pinnata) exposed to man-made and natural stressors by evaluating biomass accumulation, pigments (chlorophyll a and b and carotenoid contents), photosynthetic activity and nitrogen metabolism. The study was carried out in field where two species of Azolla were cultured and treated with various concentrations (5, 10 and 20 μg ml(-1)) of herbicide; pretilachlor [2-chloro-2,6-diethyl-N-(2-propoxyethyl) acetanilide] and enhanced levels (UV-B1: ambient +2.2 kJ m(-2) day(-1) and UV-B2: ambient +4.4 kJ m(-2) day(-1)) of UV-B, alone as well as in combination. Biomass accumulation, photosynthetic pigments; chlorophyll a, b and carotenoids, photosynthetic oxygen yield and photosynthetic electron transport activities i.e. photosystem II (PS II) and photosystem I (PS I) in both the species declined with the increasing doses of pretilachlor and UV-B radiation, which further declined when applied in combination. The lower doses (5 and 10 μg ml(-1)) of pretilachlor and UV-B (UV-B1 and UV-B2) alone, damaged mainly the oxidation side of PS II, whereas higher dose (20 μg ml(-1)) of pretilachlor alone and in combination with UV-B1 and UV-B2 caused damage to PS II reaction centre and beyond this towards the reduction side. A significant enhancement in respiration was also noticed in fronds of both the Azolla species following pretilachlor and UV-B treatment, hence indicating strong damaging effect. The nitrate assimilating enzymes - nitrate reductase and nitrite reductase and ammonium assimilating enzymes - glutamine synthetase and glutamate synthase were also severely affected when treated either with pretilachlor and/or UV-B while glutamate dehydrogenase exhibited a stimulatory response. The study suggests that both the species of Azolla showed considerable damage under pretilachlor and UV-B treatments alone, however, in combination the effect was more intense. Further, in comparison to A. pinnata, A. microphylla exhibited greater resistance against tested doses of both the stresses, either alone or in combination.
本研究通过评估生物量积累、色素（叶绿素a、b和类胡萝卜素含量）、光合活性和氮代谢，来评估两种农艺种满江红（小叶满江红和羽叶满江红）对人为和自然应激源的比较反应。该研究在田间进行，在田间种植了两种满江红，并分别用不同浓度（5、10和20μg/ml）的除草剂丙草胺[2-氯-2,6-二乙基-N-(2-丙氧基乙基)乙酰苯胺]以及增强水平（UV-B1：环境水平+2.2kJ m(-2)天(-1)和UV-B2：环境水平+4.4kJ m(-2)天(-1)）的UV-B单独处理以及联合处理。随着丙草胺和UV-B辐射剂量的增加，两种满江红的生物量积累、光合色素（叶绿素a、b和类胡萝卜素）、光合放氧量和光合电子传递活性，即光系统II（PS II）和光系统I（PS I）均下降，当联合使用时下降得更明显。单独使用较低剂量（5和10μg/ml）的丙草胺和UV-B（UV-B1和UV-B2），主要损伤PS II的氧化侧，而单独使用较高剂量（20μg/ml）的丙草胺以及与UV-B1和UV-B2联合使用时，会对PS II反应中心造成损伤，并进一步向还原侧扩展。在丙草胺和UV-B处理后，两种满江红的叶片呼吸作用也显著增强，因此表明有强烈的损伤作用。在用丙草胺和/或UV-B处理时，硝酸盐同化酶——硝酸还原酶和亚硝酸还原酶以及铵同化酶——谷氨酰胺合成酶和谷氨酸合酶也受到严重影响，而谷氨酸脱氢酶则表现出刺激反应。该研究表明，两种满江红在单独使用丙草胺和UV-B处理时均受到相当大的损伤，然而，联合使用时效果更强烈。此外，与羽叶满江红相比，小叶满江红对单独或联合测试剂量的两种胁迫均表现出更大的抗性。
