Regulation of sucrose storage by amino acid arginine in sugarcane cell suspension cultures

Abstract

Sug ar cane cell cul tures were ob tained from cal lus formed on explants de rived from young ex pand ing leaves of two early ma tur ing sug ar cane va ri et ies viz "CoJ83" and "CoJ86". The cell cul tures were var ied with dif fer ent arginine con cen tra tions in the cul ture me dium. For each cultivar, su crose con tent with 20 µM arginine in the cul ture me dium de creased from 3 to 5 days and then in creased to 10 days af ter subculturing. Higher con cen tra tion of arginine in the cul ture me dium (60 µM) decreased the su crose con tent at dif fer ent days af ter subculturing and thus sig nif i cantly stim u lated su crose mo bi li za tion. The activ ity of su crose synthase and su crose phos phate synthase reached max i mum while the ac tiv ity of acid and neu tral invertase was min i mal in the cul ture me dium with 20 µM arginine. Thus arginine at low con cen tra tion (20 µM) en ables the cells to ac cu mu late the higher level of su crose. The op timum level of amino ac ids can be uti lized to reg u late the in vivo ac tiv ity of su crose synthase, su crose phos phate synthase and invertase to achieve max i mum su crose ac cu mu la tion in sug arcane stor age tis sue.List of ab bre vi a tions: EDTA: Eth yl ene diamine tetra-ace tic acid; Hepes: N-(2-hydroxyethyl) pipera zine-N`-(2-ethanesulphonic acid); DETC: sodium di ethyl dithiocarbamate; DAS: days af ter sub culturing; MS: Murashige and Skoog In tro duc tionSug ar cane is a good ex am ple of a plant which stores large amount of su crose .The stor age of sucrose in sug ar cane internodes is a de vel op men tally reg u lated pro cess dur ing which the pa ren chyma cells af ter a pe riod of growth and ex pan sion start to ac cu mu late su crose (Lingle 1997, Batta et al. 2002. The young internodes use in com ing su crose for growth whereas the older internodes store sucrose (Glasziou and Gayler 1972) so that it accounts for 50 % of to tal dry weight, reach ing a concen tra tion of 500 mol⋅m -3 .Since Nickell (1964) de vel oped the pro to col for sug ar cane cell sus pen sion cul tures, it has been used as a model sys tem to in ves ti gate sugar up take by the cells (Maretzki and Thom 1972, Komor et al. 1981, Ebrahim et al. 1999, trans port across tonoplast Maretzki 1985, Thom and Komor 1985) and su crose me tab o lism (Botha et al. 1992, Mello et al. 2001. The syn the sis of su crose oc curs via se quen tial ac tion of su crose phos phate synthase and su crose phosphatase. The deg ra dation of su crose oc curs by sev eral en zymes in cluding su crose synthase and neu tral invertase in cytosol (Goldner et al.1991) and sol u ble acid invertase in vac u ole. The net su crose stor age is reg -37 ACTA PHYSIOLOGIAE PLANTARUM