Carbohydrate Accumulation in Leaves of Plants Treated with the Herbicide Chlorsulfuron or Imazethapyr Is Due to a Decrease in Sink Strength

Abstract

Herbicides that inhibit branched chain amino acid biosynthesis produce a rapid carbohydrate increase in leaves of treated plants. The relationship between these processes is not known nor is the importance of carbohydrate accumulation in the growth inhibition caused by these herbicides. This work analyzes carbohydrate concentration in sources and sinks after herbicide treatments in pea (Pisum sativum L.), as well as photosynthetic carbon assimilation, using two classes of chemicals, chlorsulfuron and imazethapyr, applied to roots or leaves. The most remarkable result was that, in addition to carbohydrate accumulation in leaves, accumulation of sucrose and/or starch in roots was detected. This pattern of carbohydrate accumulation was similar for both herbicides and independent of whether the herbicides were applied to leaves or roots. This indicates that root growth inhibition was not caused by sugar starvation in sinks. Nevertheless, the results are consistent with a decrease in sink strength, leading to the inhibition of photoassimilate translocation.

Does nitrate co-pollution affect biological responses of an aquatic plant to two common herbicides?

“…The significant decrease of the chlorophyll a to b ratio (chl a/b) (Table A1) supports this hypothesis. Slight reductions in chlorophyll and carotenoid are consistent with previous studies for MSM (Royuela et al, 2000;Turgut and Fomin, 2002) and can be explained by the accumulation of carbohydrates in leaves, with a negative feedback on RubisCO activity and CO 2 fixation, leading to reduced photosynthesis and pigment content (Scarponi et al, 1996;Zabalza et al, 2004). The reduced total chlorophyll content under high nitrate level irrespective of the concentration of either herbicide might represent a stress reaction to the very high nitrate levels, possibly related to the generally lower growth rates observed under NP-100.…”

“…This lack of effect on RGR-DW is generally explained by an accumulation of carbohydrates resulting from a disturbance of source-sink relationships between storage and metabolism of fixed carbon (Royuela et al, 2000;Zabalza et al, 2004). Flurprimidol increased starch content in M. spicatum from about 3% to a maximum of 13% based on dry mass (Nelson, 1996).…”

Impairment of carbon metabolism induced by the herbicide glyphosate

“…All rights reserved. doi:10.1016/j.jplph.2011.08.009 plants (Zabalza et al, 2004). In the roots of treated plants, carbon consumption is diverted to the low-efficiency fermentative pathway and the alternative respiratory pathway (Zabalza et al, 2005;Gaston et al, 2002Gaston et al, , 2003.…”

Análise do perfil eletroforético de proteínas citoplasmáticas para verificação do processo de desintoxicação do herbicida mesotrione em plantas de Zea mays

“…De fato, as fitointoxicações provocadas por herbicidas podem causar inibição do transporte de fotoassimilados das folhas para os outros órgãos da planta (Royuela et al, 2000;Zabalza et al, 2004). A depleção fotossintética provocada pelo mesotrione nos tecidos aéreos das plantas, até o quinto DAA, deve levar a uma redução do conteúdo de açúcares e de outros compostos orgânicos a serem transportados para os tecidos não clorofilados, afetando principalmente as reações biossintéticas nas raízes (Rajcan & Tollenar, 1999).…”