Activation of ribosomal and messenger RNA synthesis in excised Jerusalem artichoke tuber slices

Abstract

RNA synthesis was studied in Jerusalem artichoke (Helianthus tuberosus L.) tuber slices immediately following excision and during the early period of aging in water. Incorporation of [(3)H]adenosine into RNA was detected as early as 20 min after excision. Measurement of the specific activities of RNA (cpm/μg) and of ATP showed that RNA synthesis proceeded at a constant rate for the first several hours of aging and then increased moderately. [(3)H]adenosine was incorporated into polysomes throughout the aging period examined. Sucrose gradient fractionation of EDTA-dissociated polysomes showed that during the first 2 h of aging most of this incorporation was not into ribosome subunits but into presumed mRNA. Autoradiographic analysis of [(3)H]adenosine labelled nuclei showed that this was caused, at least in part, by a delay in the onset of rRNA synthesis synthesized during this time chromatographed as poly(A)-RNA on oligo(dT)-cellulose, indicating that a large part of the mRNA was not polyadenylated.

Effect of 2,4‐dichlorophenoxyacetic acid on polysomal profiles and polyadenylated RNA in excised tuber tissue of Jerusalem artichoke (Helianthus tuberosus)

“…It is known from previous studies that in storage organs of plants such as potato and Jerusalem artichoke tubers, most of the ribosomes are present in the form of monosomes (Byrne and Setterfield 1977,1978, Ishizuka et al 1981, Kahl 1971, Sato et al 1980, Sparkuhl et al 1976. Wielgat and Kahl 1979.…”

“…involves RNA and protein synthesis (Byrne and Setter-Changes in the profiles of ribosomes m these tissues field 1977 1978 Kahl 1971, Leaver andKey 1967, after wounding and hormone-treatment have been stud- Minocha andDiBona 1979, Sato et al 1980). Whereas ied by several workers (Byrne and Setterfield 1977, in tissues like potato, the wounding response involves 1978, Sato et al 1980, Wielgat andKahl 1979). Woiind-DNA synthesis and cell division (Watanabe and Imaseki ing causes a rapid aggregation of nbosomes to form 1973) in Jerusalem artichoke these events do not occur polysomes.…”

“…Although the synthesis of new mRNA is not unless auxin is supplied to the tissue after wounding. In a prerequisite for the formation of polysomes and the onset of protein synthesis (Byrne andSetterfield 1977, 1978), enhanced ribosomal activity at least partly depends upon the supply of new mRNA, which is transcribed actively after wounding.…”

Enhancement of Polyribosome Formation and RNA Synthesis of Gibberellic Acid in Wounded Potato Tuber Tissue

“…Leaver and Key (24) reported that the level of polyribosome formation in wounded carrot tissues depended on previous RNA synthesis. Rapid formation of polysomes was observed in slices of sugar beet (37) and during activation of artichoke tuber cells (5,32), and was correlated with protein synthesis (2,17,20).…”

“…The time-dependent development of responsiveness of a given tissue toward GA3 evidently is a widespread phenomenon (12,35,38,40,41 first 2 h after wounding sugar beet root (37) and Jerusalem artichoke tuber tissue (5). Later on, radioactivity is progressively incorporated into rRNA, also (5,16,37). Whereas GA3 has no effect in freshly wounded tuber tissue, it strikingly affects the incorporation of uridine into polysomes of tissue after 18 h of wound healing (Fig.…”