Promotion of Sorghum Callus Growth by the s-Triazine Herbicides

Abstract

Growth-promoting action of simazine and other s-triazine herbicides was detected by the use of sorghum (Sorghum bicolor Several studies over a wide spectrum of economic crops showed that the application of the s-triazine herbicides (mainly simazine) to plants at sublethal levels may cause an increase in total protein content as well as alteration of certain biological activities such as nitrate reductase (17,18,21,26). Since all known cytokinin active compounds are found to be nucleotide derivatives (4, 5, 10, 11), and the s-triazine ring is pyrimidine-like in structure with the number 5 carbon atom replaced by a nitrogen atom, it is possible that the action of the s-triazines in increasing protein content is due to alteration in hormonal control similar to that caused by kinetin.No chemical method has been developed to detect cytokinins easily. There are many biological assay systems to detect them, of which the callus tissue system may be the most reliable (13). Sorghum callus tissue developed in our laboratories from the hybrid RS 671 grain sorghum (Sorghum bicolor [L]. Moench) was dependent on an external source of cytokinin, which made it an excellent material to use in bioassays to detect the suspected growth-promoting action of the s-triazines. This paper reports that the effect of sublethal levels of simazine and other s-triazines Soil applications of simazine were made to the containers 2.5 cm below the surface by removing the top 2.5 cm of soil, spraying the calculated dose suspended in sufficient amount of water, and then replacing the soil. The dose was calculated as a fraction of the recommended field application rate corresponding to the area of the container surface. The soil treatments of simazine were added at concentrations 0.25, 0.5, 0.75 and 1.00 times the recommended amounts for application as a herbicide in the field (1.12 kg/ha). The application took place immediately prior to planting. A foliar application was administered 4 weeks after planting at concentrations 0.25, 0.5, 0.75 and 1.00 times the simazine saturated solution of S ,ug/ml (25). The plants were sprayed once until completely soaked with the solution.Root Exudate Sampling. The aerial portions of the plants were removed 3.5 cm above the soil surface and a piece of parafilm rolled around the stubs which extended above the cut surfaces. The exudates were collected periodically by means of a syringe until 5 to 10 ml was accumulated from each exuding plant. The exudates were filtered through Whatman No. 1 filter paper and added to the callus growth medium to test for their growthpromoting action.Testing for Growth Promotion. Callus was induced from hybrid RS 671 on Murashige and Skoog medium (15) supplemented with 2 to 5 jAg/ml of 2,4-D and 1% (v/v)

Growth responses of inbred maize lines with high and low DIMBOA (benzoxazinone) contents to atrazine

“…The growth stimulation as shown in Figures 1 to 3 could have been the result of cytokinin-like activity of atrazine (Bush & Ries, 1974;Copping, Davis & Pillai, 1972;Nadar, Clegg & Maranville, 1975) or a stimulation of cytokinin formation (Ebert & van Assche, 1969) in the presence of low atrazine concentrations. Differences in opinion exist as to whether atrazine may act as a plant hormone or enhance cytokinin formation.…”

Protoplast technology in relation to crop plants: Progress and problems

“…The growth rate of S . bicolor callus in the presence of 0.5 mg/I of zeatin is almost double of that in its absence (NADAR et al ., 1975) . Interestingly, a herbicide of the group Striazines, namely ametryne, is nearly as effective as zeatin in supporting growth of S. bicolor callus .…”

“…. 1974) and in Sorghum bicolor it is of the order of 7-or 13-fold in 4-5 weeks (NADAR et al ., 1975) . CHENG & SMITH (1975) have reported 125-175-fold increase in FW of barley callus in a period of 4 weeks .…”

The induction of callus in sugareane tissue cultures by selected chemicals

“…In addition to 2,4-D, IAA, and NAA, callus was induced in red clover by picloram [12], and in guayule by 2-(3,4-dichlorophenoxy) triethylamine [3]. Several s-triazine compounds maintain sorghum callus first induced by 2,4-D [11 ].…”