亚硒酸盐对旱稻吸收、转运砷及其氧化性胁迫的影响研究

Effect of selenite on arsenic uptake, translocation, and oxidative stress in upland rice

通过盆栽试验,以As低吸收旱稻(V1)和高吸收旱稻(V2)品种为材料,研究无污染(CK)及轻、中度As污染(65.2、83.9 mg·kg^(-1))土壤中,土施Se(0、1.0、5.0 mg·kg^(-1))对旱稻生长、As吸收转运及其氧化性胁迫的影响。结果显示:低、高Se处理在轻度As胁迫下,V1生物量较对照分别增加了3.50%和31.13%,V2分别增加了17.89%、34.95%;在中度As胁迫下,V1增幅分别为56.42%和122.96%,V2增幅分别为34.38%和38.73%。Se促进了根系As吸收,显著降低了As从根系向地上部转运,降低了茎叶As累积。在无、轻、中度As污染土壤中,高Se处理V1根As含量较对照分别增加了55.69%、27.08%和18.22%,茎As分别减少了18.89%、21.10%和30.93%,叶As分别减少了19.63%、27.68%和15.12%;V2根As含量分别增加了48.98%、23.82%和12.71%,茎As分别减少了17.02%、24.58%和16.16%,叶As分别减少了17.61%、20.52%和13.26%。Se在As胁迫下显著降低了叶MDA含量,低、高Se处理在轻度As胁迫下,V1叶MDA含量分别降低9.73%和13.26%,V2分别降低16.09%和20.68%;中度As胁迫下,V1分别降低9.29%和19.01%,V2分别降低14.80%和19.79%。V1在不同As胁迫下,Se显著提高了抗氧化酶(SOD、POD和CAT)活性,而V2在As胁迫增强下,Se对抗氧化酶活性先促进后抑制。本研究表明,Se能有效缓解旱稻As胁迫,低、高As吸收品种的差异与机制,主要体现在V2对As的吸收与转运远高于V1,以及V2体内的MDA含量、POD和CAT活性远高于V1。

Pot experiments were conducted to study the effects of different concentrations（0, 1.0, and 5.0 mg·kg^-1）of selenium（Se）on growth, arsenic（As）uptake and transport, and physiological parameters of upland rice under stress induced by different concentrations（20.1, 65.2, and 83.9 mg·kg^-1）of As. Low（V1）and high（V2）As-accumulating upland rice were selected as the experimental materials. V1 and V2 are different varities of the same species. The results showed that under low-concentration As stress, V1 biomass increased by 3.50%and 31.13%, compared with the control（CK）, in soils with low and high Se concentration , respectively , whereas V2 biomass increased by 17.89%and 34.95%, respectively. Under medium-concentration As stress, V1 biomass rose by 56.42%and 122.96%, and V2 by 34.38%and 38.73%at high and low Se concentrations, respectively. Se increased the As content in the roots but reduced As accumulation in stalks and leaves, and distinctly reduced As transport coefficients from root to stem. Under conditions of no, slight, and medium As stress in soil containing a high concentration of Se, As increased in the roots of V1 by 55.69%, 27.08%, and 18.22%, respectively, whereas it decreased in the stems by 18.89%, 21.10%, and, 30.93%, and in the leaves by 19.63%, 27.68%, and 15.12%, respectively. Under the same condi-tions, As increased in the roots of V2 by 48.98%, 23.82%, and 12.71%, whereas it decreased in the stems by 17.02%, 24.58%, and 16.16%, and in the leaves by 17.61%, 20.52%, and 13.26%, respectively. The malondialdehyde（MDA）content in leaves rose under As stress, but Se treatment resulted in a significant reduction in the MDA content. Under low-concentration As stress in soils with low and high Se concentrations, the MDA content in V1 leaves decreased by 9.73%and 13.26%, respectively, whereas that in V2 leaves decreased by 16.09%and 20.68%. Similarly, under medium-concentration As stress, the MDA content in V1 leaves decreased by 9.29%and 19.01%, respectively, whereas that in V2 decreased by 14.80%and 19.79%. In V1, Se clearly enhanced the activity of antioxidant enzymes（SOD, POD, and CAT）in leaves under different levels of As stress, whereas in V2, Se enhanced and inhibited antioxidant enzyme activity under low- and medium-concentration As stress, respectively. This study shows that Se can effectively relieve As stress in upland rice. Owing to differences in the As uptake mechanism of the low（V1）and high（V2）As-accumulating species, As uptake and transport in V2 are con-siderably more efficient than those in V1, and the MDA concentrations and POD and CAT activities of V2 are considerably higher than those in V1.