砷对烤烟(Nicotiana tabacum L.)碳代谢的影响

Effects of arsenic on carbon metabolism in flue-cured tobacco (Nicotiana tabacum L.)

采用盆栽试验,系统地研究了砷对烤烟全生育期碳代谢及其过程的影响,结果表明,砷降低了烤烟整个生育期的叶绿素含量、光合速率、蔗糖合成酶(SS,合成方向)活性和现蕾以后的蔗糖磷酸合成酶(SPS)活性,提高了全生育期的SS(分解方向)活性和可溶性糖含量,因而抑制了碳的同化和蔗糖的合成,促进了蔗糖的分解,不利于碳向积累方向转化。砷提高了全生育期的腺苷二磷酸葡萄糖焦磷酸化酶(ADPG-PPase)活性,增加了团棵期和现蕾期淀粉的积累,降低了团棵期和采收期的可溶性淀粉酶(SSS)活性和采收期的淀粉含量,从而导致了碳积累代谢的紊乱,最终造成碳积累的减少。

Arsenic, a high toxic heavy metal, is one of the most serious contaminants in soil and potential threat to crop growth and human health. Carbon metabolism plays an important role in growing period and formation both of yield and quality in flue-cured tobacco. It is necessary to study arsenic toxicity to carbon metabolism in flue-cured tobacco. Therefore, a systematic experiment was conducted on the farm of Henan Agricultural University, Zhengzhou, China. Using Yunyan 85 planted in 400 mm× 340 mm plastic pots, treatments were layed out with 5 arsenic levels of 0 （CK）, 5, 20, 40, and 60 mg·kg^-1 [ added as sodium arsenate （ Na3 AsO4·12H2O ） ] to determine the effects of arsenic toxicity on metabolism of carbon. The results showed that arsenic toxicity significantly affected Carbon metabolism during the whole growing period. Chlorophyll content, photosynthetic rate and sucrose synthetase （SS, synthetic direction） activity of the leaves during the growing period, as well as activity of sucrose phosphate synthetase （SPS） after budding stage were all decreased. But activity of SS （decomposition direction） and content of soluble sugar during the growing period increased. The results suggested that carbon assimilation and sucrose synthesis in flue-cured tobacco be inhibited, and sucrose decomposition be accelerated as a result of arsenic toxicity, which was not favorable for carbon transformation. It was also indicated that activity of soluble starch synthetase （SSS） both at rosette stage and harvest stage, and accumulation of starch at harvest were inhibited, SSS activity at budding stage, activity of adenosine diphosphoglucose pyrophosphorylase （ ADPG- PPase） during the growing period, and starch content both＇ at rosette stage and budding stage were all increased by arsenic toxicity. Therefore, arsenic toxicity caused the disorder of carbon metabolism and decrease in starch content during the later part of the growing period.