Increased availability of tryptophan in 5-methyltryptophan-tolerant shoots of Catharanthus roseus and their postharvest in vivo elicitation induces enhanced vindoline production.
Ten 5-methyltryprophan (5-MT)-resistant multiple shoot culture lines in three genotypes of Catharanthus roseus were selected in vitro. The variant shoot lines displayed a differential threshold tolerance limit against the analogue stress, ranged from 20 to 70 mg/l 5-MT in the medium. The lines tolerant to 40 mg/l 5-MT stress were most stable and fast proliferating. All the selected lines in the presence of 5-MT stress recorded increased level of tryptophan in their free amino acid pool. Highest tryptophan accumulation occurred in lines P40, P30, D40, and N40 (i.e., 296.5, 241.0, 200.6, and 202.0 μg/g dry wt., respectively). A concomitant increase in the total alkaloid content (2.3-3.8 % dry wt.) under the analogue stress was also noticed in these lines when compared to 1.0-1.58 % dry wt. in the respective wild-type shoot maintained on a stress-free medium. The HPLC analysis of the alkaloid extracts of the 5-MT-tolerant lines grown under analogue stress also revealed vindoline as a major constituent with maximum accumulation in lines N40, N30, D30, D40, and P40 (0.046, 0.032, 0.034, and 0.022 % dry wt., respectively). The rooted shoots of 5-MT-tolerant lines were successfully acclimatized under glasshouse environment wherein they grew normally and set seeds. Flowering twigs or leaves excised from 1-year-old glasshouse-grown plants of 5-MT variant lines upon postharvest in vivo elicitation with 30 mg/l 5-MT or 5.0 mg/l tryptophan registered an eight-to-tenfold increment in their vindoline content within 24-48 h.
Department of Plant Biotechnology, Council of Scientific and Industrial Research-Central Institute of Medicinal and Aromatic Plants (CSIR-CIMAP), PO CIMAP, Kukrail Picnic Spot Road, Lucknow 226015, India.
Priyanka
P
Verma
Ajay K
AK
Mathur
Karuna
K
Shanker
D030008:Catharanthus / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism; D014364:Tryptophan / Q000031:analogs & derivatives* / Q000378:metabolism*; D014747:Vinblastine / Q000031:analogs & derivatives* / Q000096:biosynthesis
C004182:5-methyltryptophan; C009667:vindoline; D014747:Vinblastine; D014364:Tryptophan