Drought tolerance levels and antioxidant protection mechanisms were evaluated for 21 traditional rice varieties of Assam, India, along with Sahbhagi Dhan （drought tolerant） and IR64 （drought sensitive） as controls...Drought tolerance levels and antioxidant protection mechanisms were evaluated for 21 traditional rice varieties of Assam, India, along with Sahbhagi Dhan （drought tolerant） and IR64 （drought sensitive） as controls. Drought was imposed in hydroponic culture with polyethylene glycol 6000 （PEG6000） that was initially standardized with different concentrations. All the rice varieties showed apparent decreases in growth characteristics under drought stress （initially at 15% for 7 d followed by 20% PEG6000 for 7 d in Yoshida medium）. On the basis of standard evaluation score （SES）, eight rice varieties showed high drought tolerance which were carried forward for further biochemical analyses. Based on different morpho- physiological parameters, SN03 （Bora）, SN04 （Prosad Bhog）, SN05 （Kola Joha）, SN06 （Helash Bora）, SN08 （Salihoi Bao）, SN12 （Kola Amona）, SN20 （Ronga Bora） and SN21 （Sok-Bonglong） were identified as promising drought tolerant varieties. The non-enzymatic antioxidants activities viz., glutathione, ascorbate and enzymatic antioxidant activities such as superoxide dismutase （SOD）, catalase （CAT）, guaiacol peroxidase （GPX）, ascorbate peroxidase （APX）, glutathione reductase （GR） in shoots and roots of all the selected varieties revealed significant level of protection mechanisms as compared with controls. Enhancement in activities of the overall antioxidant enzymes including SOD, GPX, CAT, GR and APX under drought stress reflects their role in the adaptation process under water stress.展开更多
Arsenic （As）, a potentially toxic metalloid released in the soil environment as a result of natural as well as anthropogenic processes, is subsequently taken up by crop plants. In rice grains, As has been reported i...Arsenic （As）, a potentially toxic metalloid released in the soil environment as a result of natural as well as anthropogenic processes, is subsequently taken up by crop plants. In rice grains, As has been reported in Asia, North America and Europe, suggesting a future threat to food security and crop production. As3＋ by dint of its availability, mobility and phytotoxicity, is the most harmful species of As for the rice crop. Specific transporters mediate the transport of different species of As from roots to the aboveground parts of the plant body. Accumulation of As leads to toxic reactions in plants, affecting its growth and productivity. Increase in As uptake leads to oxidative stress and production of antioxidants to counteract this stress. Cultivars tolerant to As stress are efficient in antioxidant metabolism compared to sensitive ones. Iron and selenium are found to have ameliorating effect on the oxidative stress caused by As. Microbes, even many indigenous ones, in the plant rhizosphere are also capable of utilizing As in their metabolism, both independently and in association. Some of these microbes impart tolerance to As-stress in plants grown in As contaminated sites.展开更多
Assam of the northeastern region of India is unique in terms of its rich biodiversity and multiple ethnicity of its people. The impact of the resultant socio-religio-cultural diversity is also reflected in the diverse...Assam of the northeastern region of India is unique in terms of its rich biodiversity and multiple ethnicity of its people. The impact of the resultant socio-religio-cultural diversity is also reflected in the diverse traditional ways of silkworm farming. We report the genetic diversity of Persea bombycina “Som” from different locations of Goalpara district of Assam, India, where random amplified polymorphic DNA (RAPD) marker was used in this study. RAPD analyses of ten genotypes of “Som” from Goalpara district of Assam, India with B19 RAPD primer generated 86 bands, showing an average of 8.6 bands per sample and 30.2% (26 bands) of these were polymorphic. The number of bands per accession ranged from 5 to 10 with a mean of 8.6 and the size range of the amplified bands was 250 - 6000 bp. In a UPGMA phenetic dendrogram based on Jaccard’s coefficient, the P. bombycina accessions showed a high level of genetic variation, as indicated by genetic similarity and revealed 10 “Som” genotypes in to three major clusters. This study may be useful in identifying diverse genetic stocks of P. bombycina, which may then be conserved on a priority basis. The RAPD primer used in this study was able to distinguish all the 10 genotypes of “Som” plants, which can be used to assess genetic diversity.展开更多
基金supported by UGC,Maulana Azad National Fellowship for Minority Students,Government of India
文摘Drought tolerance levels and antioxidant protection mechanisms were evaluated for 21 traditional rice varieties of Assam, India, along with Sahbhagi Dhan （drought tolerant） and IR64 （drought sensitive） as controls. Drought was imposed in hydroponic culture with polyethylene glycol 6000 （PEG6000） that was initially standardized with different concentrations. All the rice varieties showed apparent decreases in growth characteristics under drought stress （initially at 15% for 7 d followed by 20% PEG6000 for 7 d in Yoshida medium）. On the basis of standard evaluation score （SES）, eight rice varieties showed high drought tolerance which were carried forward for further biochemical analyses. Based on different morpho- physiological parameters, SN03 （Bora）, SN04 （Prosad Bhog）, SN05 （Kola Joha）, SN06 （Helash Bora）, SN08 （Salihoi Bao）, SN12 （Kola Amona）, SN20 （Ronga Bora） and SN21 （Sok-Bonglong） were identified as promising drought tolerant varieties. The non-enzymatic antioxidants activities viz., glutathione, ascorbate and enzymatic antioxidant activities such as superoxide dismutase （SOD）, catalase （CAT）, guaiacol peroxidase （GPX）, ascorbate peroxidase （APX）, glutathione reductase （GR） in shoots and roots of all the selected varieties revealed significant level of protection mechanisms as compared with controls. Enhancement in activities of the overall antioxidant enzymes including SOD, GPX, CAT, GR and APX under drought stress reflects their role in the adaptation process under water stress.
文摘Arsenic （As）, a potentially toxic metalloid released in the soil environment as a result of natural as well as anthropogenic processes, is subsequently taken up by crop plants. In rice grains, As has been reported in Asia, North America and Europe, suggesting a future threat to food security and crop production. As3＋ by dint of its availability, mobility and phytotoxicity, is the most harmful species of As for the rice crop. Specific transporters mediate the transport of different species of As from roots to the aboveground parts of the plant body. Accumulation of As leads to toxic reactions in plants, affecting its growth and productivity. Increase in As uptake leads to oxidative stress and production of antioxidants to counteract this stress. Cultivars tolerant to As stress are efficient in antioxidant metabolism compared to sensitive ones. Iron and selenium are found to have ameliorating effect on the oxidative stress caused by As. Microbes, even many indigenous ones, in the plant rhizosphere are also capable of utilizing As in their metabolism, both independently and in association. Some of these microbes impart tolerance to As-stress in plants grown in As contaminated sites.
文摘Assam of the northeastern region of India is unique in terms of its rich biodiversity and multiple ethnicity of its people. The impact of the resultant socio-religio-cultural diversity is also reflected in the diverse traditional ways of silkworm farming. We report the genetic diversity of Persea bombycina “Som” from different locations of Goalpara district of Assam, India, where random amplified polymorphic DNA (RAPD) marker was used in this study. RAPD analyses of ten genotypes of “Som” from Goalpara district of Assam, India with B19 RAPD primer generated 86 bands, showing an average of 8.6 bands per sample and 30.2% (26 bands) of these were polymorphic. The number of bands per accession ranged from 5 to 10 with a mean of 8.6 and the size range of the amplified bands was 250 - 6000 bp. In a UPGMA phenetic dendrogram based on Jaccard’s coefficient, the P. bombycina accessions showed a high level of genetic variation, as indicated by genetic similarity and revealed 10 “Som” genotypes in to three major clusters. This study may be useful in identifying diverse genetic stocks of P. bombycina, which may then be conserved on a priority basis. The RAPD primer used in this study was able to distinguish all the 10 genotypes of “Som” plants, which can be used to assess genetic diversity.
