Browsing by Author "Mercado, A"

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    Editing status of mat-r transcripts in mitochondria from two plant species
    (1998) Bégu, D; Mercado, A; Farré, JC; Moenne, A; Holuigue, L; Araya, A; Jordana, X
    The intronic mat-r ORF encodes a protein with significant homology to retroviral reverse transcriptases. Here, we describe the nucleotide sequence of potato mat-r and study the editing status of mat-r transcripts in two systems, potato and wheat, where the mat-r ORF is part of the trans-introns but in two different configurations relative to nadl exons d and e. In potato and wheat, 13 and 15 C-to-U transitions respectively were observed. Most transcripts were partially edited, but potato transcripts were edited more efficiently than wheat transcripts. As in functional mitochondrial genes, RNA editing increased the similarity between plant mat-r proteins and their homologous non-plant counterparts. Interestingly, editing of mat-r was clustered in the reverse-transcriptase (RT) and the maturase (X) domains, two well defined regions having known functions in other systems. These results, together with the integrity and sequence conservation of mat-r, strongly suggest that the encoded protein plays a functional role in plant mitochondria.
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    Regeneration of whole plants from apical meristems of Pinus radiata
    (2003) Prehn, D; Serrano, C; Mercado, A; Stange, C; Barrales, L; Arce-Johnson, P
    A methodology to regenerate whole plants of Pinus radiata from apical meristems of 3- and 7-year-old trees was developed. Meristematic domes with two or three leaf primordia were excised from surface-sterilized branch tips of field-grown plants and cultured in LP medium with half strength macronutrients (1/2 LP) and full strength micronutrients. The early growth of meristems required approximately 12 weeks, including a recovery stage during the first 2 weeks. After 8 weeks, some meristems developed abnormal phenotypes and died during the subsequent stages of development. However, healthy meristems elongated and formed shoots when they were transferred to LP medium supplemented with MS vitamins, 30 mg l(-1) casein hydrolysate, and 0.4 g l(-1) agar plus 2.85 g l(-1) Gelrite. Meristems that developed vigorous shoots were used for rooting experiments when they were 2 cm in length. Whole plants were obtained after 5 days of root induction in water-agar medium containing 8.2 muM IBA and 5.4 muM NAA and 1 month culture in LP medium with 10 g l(-1) sucrose. Plants regenerated from meristems were further propagated by rooting of cuttings. Of the rooted cuttings, 10% were morphologically juvenile.