文章编号：1003-935X（2016）01-0001-07
Abstract：Three lilyturfs，Ophiopogon japonicas （OJ），Liriope spicata （LS） and Liriope platyphylla （LP） were reported to have evolved high natural tolerance to glyphosate. The main mechanism is attributed to a combination of unique EPSPS structure and increased EPSPS gene copy number and expression. This target-site mechanism，however，appears insufficient to explain the differences in glyphosate-tolerance among those three lilyturfs with the highest level observed in LP and the lowest in OJ （LS has intermediate tolerance）. To further investigate the non-target site mechanisms conferring glyphosate tolerance in the three lilyturfs，microscopic and submicroscopic structure of leaf epidermis were observed using LM and SEM. The stomata mainly distribute in the lower leaf epidermis of the three species with stomatal densities of 376，36.2 and 23.9 mm-2 in OJ，LS and LP，respectively. Furthermore，there were more stomata in the upper epidermis of LP than that of LS. There are also differences in cell length，area，and length-width ratio of stomatal and non-stomatal bands in the three lilyturfs. The periclinal wall of epidermis cells around stomata forming obviously strumous protuberances resulted in sunken stomata on leaves of OJ. The periclinal wall of LS had wavy protuberances and the stomata were only partially sunken. On the contrary，the periclinal wall of LP almost had no protuberances and the stomata were not sunken. These features may contribute to the different tolerance to glyphosate in three lilyturf species.
Key words：
lilyturf；glyphosate tolerance；stomatal density；leaf epidermis；morphology
草甘膦[N-（膦羧基甲基）甘氨酸]是一种非选择性、广谱、内吸收传导的茎叶处理除草剂，由于其具有广谱、低毒、安全、无土壤残留的特点，一直被认为是迄今为止最为重要和最优秀的除草剂[1]。自1974年美国孟山都公司开发草甘膦以来，由于其非选择性的特点很长一段时间不能作为作物田的主要除草剂。但是，自1996开始，抗草甘膦转基因作物研制和商业化，使得草甘膦被广泛应用于农作物田杂草的防除，草甘膦的用量迅猛增长，成为除草剂市场中的主导产品[2]，而且随着全球抗除草剂转基因作物进一步发展，草甘膦在全球除草剂市场中的主导地位将更为加强，随之而来的是以草甘膦为主导的化学除草剂的单一化[3]。这加剧了人们对草甘膦抗性杂草问题的担忧。
植物对草甘膦的抗药性涉及到天然抗性和演化抗性[4]，前者是在没有接触过除草剂的情况下天生就有的在除草剂处理后能够生存和繁殖的能力。de Gennaro等在没有草甘膦使用历史的地区发现了草甘膦抗性生物型的田旋花（Convolvulus arvensis）[5]；1990年Boerboom等证实了百脉根（Lotus corniculatus）对草甘膦存在耐药性[6]；此后几年又陆续发现了饭包草（Commelina benghalensis）[7]、亚洲鸭跖草（Commelina communis）[7]、狗肝菜（Dicliptera chinensis）[9]、藜（Chenopodium album）[10]以及茼麻（Abutilon theophrasti）[4]对草甘膦的耐性。这些种群会占据转基因作物田中其他杂草的生态位，影响草甘膦除草效果，甚至对农作的生产造成巨大的威胁[11]。