摘要
酰胺类除草剂拿草特对菟丝子幼苗生长具有强烈的抑制作用。采用石蜡切片法和细胞扫描分光光度法,通过测定对照及处理幼苗茎尖分生区的细胞分裂指数和核DNA含量,发现拿草特对菟丝子幼苗生长的抑制是由于它对分生区细胞有丝分裂的双重抑制作用:间期抑制和中期抑制。即它既可阻止有丝分裂的启动,又可象秋水仙素一样通过影响纺锤丝的功能而将细胞分裂阻止于中期,引起分生区细胞的多倍体化和径向膨大。这种生长受到抑制且茎尖粗肿的幼苗不能够在农作物上寄生。
Dodder (Cuscuta) is a troublesome parasitic weed for leguminous crops. One of the methods for the chemical control of this parasite is to use herbicides which would destroy the dodder seedlings before their attachment to the host plants.
Our previous work showed that pro-namide exerts a potent inhibitory effect on the growth of dodder seedlings. This paper deals with the mode of action of this compound on the mitosis in the shoot meristematic region of dodder seedlings.
The seeds of Cuscuta lupuliformis were allowed to germinate on wet filter paper in Petri dishes in the presence or the absence (control) of the herbicide. The evolution of the mitotic indices was examined in the control and in the herbicide-treated seedlings 3,6,9 and 15 days after sowing, and that of nuclear DNA contents was measured 9 and 15 days after sowing. The longitudinal axial sections (thickness: 14 nm) of the shoot meri-
stematic region were treated under strictly identical conditions by Feulgen reaction. According to the fact that the shoot meristem of dodder seedling is very long, the measurement of the mitotic indices and of the nuclear DNA contents were carried out on the 1400μm region beyond the apex. The DNA contents were estimated by microspectrophotometry; the reference values of 2 n and 4 n were obtained respectively by measurement of the absorbance of half-telophase and prophase or metaphase of dividing nuclei.
Pronamide exerts both a mitodepressi-ve and a mitoclasic action, inhibiting the entrance of the cells into division and the formation of spindle microtubules. This herbicide thus blocks the cell cycle and induces the endopolyploidisation of the meristematic cells. Such effects lead to the arrest of elongation and result in the radial swelling of the apical zone of the stems. The treated seedlings are then unable to attach to the host.
出处
《实验生物学报》
CSCD
1995年第2期209-214,共6页
Acta Biologiae Experimentalis Sinica
