Influence of different auxins at varying concentrations on callus inductions and growth from embryo and leaf-tip explants in gramineae

Abstract

Experiments were conducted to determine the effectiveness of 2,4-dichlorophenxyacetic acid (2,4-D), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), α-2,4,5-trichlorophenoxypropionic acid (silvex), p-chlorophenoxyacetic acid ( pCPA), 3,6-dichloro- o-anisic acid (dicamba), 4-amino-3,5,6-trichloropicolinic acid (picloram), α-naphthaleneacetic acid (NAA) and indole-3-acetic acid (IAA) at molar concentrations of 5–60 μM on callus induction and growth of orchardgrass ( Dactylis glomerata L.), tall fescue ( Festuca arundinacea Schreb.) and annual ryegrass ( Lolium multiflorum Lam.) embryo explants. The effectiveness of 2,4-D, 2,4,5-T, silvex, dicamba, picloram and NAA on callus induction from leaf-tip explants was studied in annual ryegrass. Length of leaf from which tips were excised and whether or not the mesocotyl-tip node was included in the explant on the efficiency of callus induction were also studied in annual ryegrass. The three species responded differently with regard to different auxins and auxin concentrations for optimum callus induction and growth from embryos. In general, orchardgrass calli grew faster and attained a larger size during the 28-day incubation period than the other two species. Tall fescue calli exhibited the least growth. Dicamba and picloram were effective for inducing callus in all three species and were especially superior to 2,4-D in tall fescue. These auxins were also effective for inducing callus from leaf-tips in annual ryegrass but higher concentrations were needed than for embryos. Production of callus from leaf-tip was highly variable but tips from shorter leaves gave higher percentage of callus induction than those from longer leaves. Percent callus induction was 88% or above if the node were included in the explant regardless of initial leaf length or dicamba concentration.