| By the tissue culture, four potato lines from International Potato Centre(CIP391047.34, termed as A; CIP385499.11, termed as B; CIP394611.112, termed as C; CIP391919.3, termed as D) as materials, we study the effects of growth physiological under different PEG-6000 and Na Cl concentrations.Detection the expression of the genes were related to Proline biosynthesis and catabolism metabolic at PEG-6000. The results have been obtained as follows:1. The new leaf number, root number, maximum root length, fresh weight of stem leaf and root, root-shoot ratio of four introduced resources were declined significantly compared with control under different Na Cl stress. Root number of all lines was dramatically impacted under 0.3% Na Cl stress, of which the line B was declined 17.79% and D was declined 33.25% compared with control. The formation and development of roots and leaves were severely suppressed under 0.9% Na Cl stress. The growth of plantlets in vitro was nearly stopped and there was no rooting of lines C and D under 1.2% Na Cl stress. The leaf area and cholophyll content of four lines increased with the rise of Na Cl concentration. Under 0.9% Na Cl stress, the leaf area and cholophyll content of line D were higher than line B by 15.84 and 1.93 fold, respectively. The content of proline, malondialdehyde and ratio of Na~+ and K~+ of 4 lines increased with the rise of salt concentration. Under 0.9% Na Cl stress, the content of proline, malondialdehyde and ratio of Na~+ and K~+ of line D were higher than line B by 2.67, 1.80 and 1.87 fold, respectively.2. The new leaf number, root number, maximum root length, fresh weight of stem leaf and root of both lines declined at different levels compared to that of controls under drought stress treatment induced by PEG-6000. The growth was the serious influence under 2.5% PEG-6000 stress, root number and maximum root length of all lines were significantly higher than control, new leaf number of other 3 lines were declined significantly compared with control, besides B line. The plantlets can cause serious injury under 7.5% PEG-6000 stress. The growth of plantlets was suppressed completely under 10.0% PEG-6000 stress. The leaf area and cholophyll content of four lines were declined significantly compared with control under different PEG-6000 stress. Compared with control, the leaf area of B line was declined 37.66%, the leaf area of D line was declined 55.67%, the cholophyll content of B line was declined 36.96% and the cholophyll content of D line was declined 67.74% under 2.5% PEG-6000 stress. The content of proline and malondialdehyde of four lines increased with the rise of PEG-6000 concentration, and reached the highest level under 10.0% PEG-6000 stress, of which the content of proline and malondialdehyde of line D was higher than line B by, respectively.3. P5 CS, OAT and P5 CR gene expression of 4 lines increased with the rise of PEG-6000 concentration, and instead, PRODH and P5 CDH gene expression of 4 lines declined with the rise of PEG-6000 concentration. The content of proline had significantly positive correlation with P5 CS, OAT and P5 CR gene expression, but negatively correlated with PRODH and P5 CDH gene expression of four lines.4. The threshold value of salt tolerance of 4 lines was 0.6%, the proline content can be used as an evaluation index under salt stress. Line B is salt tolerant and line D is salt sensitive. Root growth was much more inhibited compared to stem leaf under osmotic stress, line B is the strongest drought-resistant material and line D is the weakest drought-resistant material. The proline accumulation of potato plantlets in vitro rely on P5 CS, OAT and P5 CR gene expression level increased and PRODH and P5 CDH gene expression level decreased under drought stress treatment induced by PEG-6000. Drought-tolerant plantlets can be screened at the PEG-6000 concentration of 7.5% or 5.0%. At a PEG-6000 concentration of 10%, growth of plantlets in vitro was inhibited. |
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