Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Titre : Introduction of genes for stress tolerance and their expression studies in potato Solanum tuberosum L cv Kufri Sutlej

Auteur : Awadhesh Kumar Pal

Université de soutenance : Guru Nanak Dev University

Grade : Doctor of Philosophy (PhD) in Biotechnology 2012

Résumé partiel
Potato is one of the most important crop plants due to its high productivity, high starch, vitamin C, potassium and protein content. It thus has ability to eliminate hunger of the rising population which will reach to about nine billion by 2050. Potato is very sensitive to abiotic stresses and suffers a great yield loss due to overproduction of reactive oxygen species or ROS that disturbs the cellular homeostasis of oxygen free radical production and quenching. In this context, we used a thermostable copper-zinc superoxide dismutase (PaSOD) gene from Potentilla atrosanguinea and ascorbate peroxidase (RaAPX) gene isolated from another high altitude plant Rheum australe for raising transgenics in potato cv. Kufri Sutlej and evaluated their performance under abiotic stresses. For protocol development, silver thiosulfate at 5 µM level in the medium was used to improve the health and quality of explants required for regeneration and genetic transformation experiments. Further, a cost effective regeneration protocol from internodes, based on the endogenous auxin level was achieved. Inclusion of TIBA in the medium countered high endogenous auxin level and reduced the requirement of zeatin for a regeneration response which occurred at the basal ends of the internodes only. Using standardized protocol, thirteen transgenic lines of PaSOD five of RaAPX and two of double (PaSOD + RaAPX) transgenics were produced. Evaluation of WT and two PaSOD transgenic lines under water stress of 30 days duration evinced that transgenic plants had relatively lower water potential and higher water content than the WT which led to delay in stress response and stress related damages. Transgenic plants showed enhanced net photosynthetic rates (PN) and stomatal conductance (gs) compared to that in the wild type (WT) plants under control (irrigated) as well as water stress conditions. Water stress declined leaf water potential, PN, gs, photosystem II activity and chlorophyll content, but increased proline and superoxide radical (O2 than in the transgenic potato plants. Significantly higher SOD activity in transgenic plants coincided well with lower O2 content, suggesting the role of SOD in maintaining higher gs and PN in transgenic potato plants. The tuber yield in transgenic plants was highest under severe stress. Furthermore, transgenic tuber slices showed more browning of the pulp with time as compared to the WT and also its starch granules were larger in size impacting the pasting property of the starch.

Présentation et version intégrale (Shodhganga)