Changes in glycine betaine and related enzyme contents in Amaranthus tricolor under salt stress.
The glycine betaine (GB) and related enzymes contents, i.e., choline monooxygenase (CMO) and betaine aldehyde dehydrogenase (BADH), of seeds, roots, stems, cotyledons, leaves, and flowers in Amaranthus tricolor under salt stress were determined. GB content varied significantly among different organs. GB content in the leaves was higher at the beginning of unfolding stage and decreased during maturation and senescence. GB content in the roots was very low through the life of plant. GB content in the roots, stems, leaves and flowers increased by exposure to NaCl 300 mmol/L, except in the cotyledon where it was low and remained unchanged under salt stress. Induction of GB increase by salt stress was greater in mature and old leaves than in younger leaves. CMO protein content was low in the all organs, but that in stems and leaves was significantly increased by the addition of NaCl 300 mmol/L, and was concomitant with the accumulation of GB in their tissues. BADH protein was detected in all organs. But, the levels of BADH protein did not always vary among different organs as a result of salt stress. The effect of salt stress on BADH protein content was small and in consistent in mature and old leaves. Seeds after being soaked in water for 24 h were unable to synthesize GB. When the seeds started to germinate after being in water for 48 h, they showed an ability to synthesize GB under salt stress. This was accompanied with an increase in their CMO protein content, whereas their BADH protein level did not change. The present results indicate that CMO protein is important to GB synthesis when A. tricolor is under salt stress.
Wang
Yu-Mei
YM
Yingdong College of Biotechnology, Shaoguan University, Shaoguan 512005, China. wym990@vip.sina.com
Meng
Yu-Ling
YL
Nii
Naosuke
N
D027721:Amaranthus / Q000737:chemistry*; D001622:Betaine / Q000032:analysis* / Q000378:metabolism; D010105:Oxygenases / Q000032:analysis*; D012639:Seeds / Q000737:chemistry; D012965:Sodium Chloride / Q000494:pharmacology*
D001622:Betaine; D012965:Sodium Chloride; C105448:choline monooxygenase; D010105:Oxygenases