Comparative Study of Levels of Secondary Processing in Bulk mRNA from Dry and Germinating Wheat Embryos

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Abstract
There was no previous study of levels of secondary processing in the template-active RNA of dry seeds and embryos. Such information is needed to evaluate the role of transcription in changing the cell-free translational capacity of bulk RNA during early imbibition of water by dry wheat embryos. Although it probably contains a higher proportion of hidden breaks than bulk mRNA from imbibing embryos, bulk mRNA in dry wheat embryos is also capped by 7-methylguanosine at 5'' termini, devoid of unmethylated caps, methylated internally (N6-methyladenosine) and polyadenylated at 3'' termini. In contrast to other developing systems, there are apparently no signal changes in levels of secondary processing in the bulk mRNA populations which support change in cell-free translational capacity of RNA 1-5 h postimbibition of dry wheat embryos. Change in the pattern of protein synthesis 5-24 h postimbibition takes place without signal changes in levels of secondary processing in template-active RNA. The analytical data are evaluated in terms of difficulties allied with comparative analyses of poly(A)-rich RNA from dry and imbibing embryos, the former being refractory to, and the latter being most easily analyzed by, labeling in vivo.