EFFECTS OF COLD STRATIFICATION AND GA3 ON GERMINATION OF ARBUTUS UNEDO SEEDS OF THREE PROVENANCES

Background:

Arbutus unedo is a valuable Mediterranean shrub as an ornamental plant as well as fruit tree. Fresh fruits of A. unedo are a good source of antioxidants, of vitamins C, E and carotenoids and also are characterized by the high content of mineral elements.

Materials and Methods:

The effects of gibberellic acid (GA₃) and cold stratification (CS) on seed germination performance were investigated in A. unedo seeds collected from three provenances in the Northern part of Greece. Seeds of each provenance were soaked in solutions of GA₃ (500, 1000 or 2000 ppm) for 24 h and subsequently were subjected to CS at 3 - 5°C for 0, 1, 2, and 3 months.

Results:

Non-stratified seeds of the three A. unedo provenances which were not treated with GA₃ solutions exhibited very low germination. However, seed germination was significantly improved after a one-month period of CS. Similarly, the non-stratified seeds of all three provenances became non-dormant after the treatment with 2000 ppm GA₃ and they germinated at high percentages. However, in untreated seeds with GA3, after a one-month CS period the seeds of the Pieria provenance exhibited higher germination percentage than that of Rodopi provenance seeds. Furthermore, in non-stratified seeds, the Pieria provenance seeds treated with GA3 germinated at higher percentages and more rapidly than those of the other two provenances.

Conclusion:

The results indicated that untreated seeds exhibited very low germination at 20/25°C. However, in all three provenances seed germinability was significantly improved by a one-month period of CS or treatment of seeds with 2000 ppm GA3. Furthermore, there was a considerable variability among seed provenances in response to the treatments which were applied.

Semi-quantitative analysis of transcript accumulation in response to drought stress by Lepidium latifolium seedlings

Cross-amplification of five Arabidopsis abiotic stress-responsive genes (AtPAP, ZFAN, Vn, LC4 and SNS) in Lepidium has been documented in plants raised out of seeds pre-treated with potassium nitrate (KNO 3) for assessment of enhanced drought stress tolerance. cDNA was synthesized from Lepidium plants pre-treated with KNO 3 (0.1% and 0.3%) and exposed to drought conditions (5% and 15% PEG) at seedling stage for 30 d. Transcript accumulation of all the five genes were found suppressed in set of seedlings, which were pre-treated with 0.1% KNO 3 and were exposed to 15% PEG for 30 d. The present study establishes that different pre-treatments may further enhance the survivability of Lepidium plants under conditions of drought stress to different degrees.