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The molecular mechanism for sensing and transducing the stress signals initiated by K deprivation in plants remains unknown. Here, we found that the expression of AtHELPS, an Arabidopsis DExD/H box RNA helicase gene, was induced by low-K, zeatin and cold treatments, and downregulated by high-K stress. To further investigate the expression pattern of AtHELPS, pAtHELPS::GUS transgenic plants were generated. Histochemical staining indicated that AtHELPS is mainly expressed in the young seedlings and vascular tissues of leaves and roots. Using both helps mutants and overexpression lines, we observed that, in the low-K condition, AtHELPS affected Arabidopsis seed germination and plant weight. Interestingly, the mRNA levels of AKT1, CBL1/9 and CIPK23 in the helps mutants were much higher than in the overexpression lines under low-K stress. Moreover, under low-K stress, the helps mutants displayed increased K influx, whereas the overexpression line of AtHELPS had a lower flux rate in the roots by the noninvasive micro-test technique. Taken together, these results provide information for the functional analysis of plant DEVH box RNA helicases, and suggest that AtHELPS, as an important negative regulator, plays a role in K deprivation stress. The Arabidopsis DExD/H box RNA helicase gene, AtHELPS, was mainly expressed in young seedlings and vascular tissues of leaves and roots. It was also induced by low potassium stress and down-regulated by high potassium stress. In the low potassium condition AtHELPS affected Arabidopsis seed germination and plant weight by affecting transcription of AKT1, CBL1/9 and CIPK23 and K influx rate [ABSTRACT FROM AUTHOR]

Enzymatic and non-enzymatic antioxidants play important roles in the tolerance of abiotic stress. To increase the resistance of seeds to oxidative stress, At2S3 promoter from Arabidopsis was used to achieve overexpression of the antioxidants in a seed-specific manner. This promoter was shown to be capable of driving the target gene to have a high level of expression in seed-related organs, including siliques, mature seeds, and early seedlings, thus making its molecular farming applications in plants possible. Subsequently, genes encoding Mn-superoxide dismutase ( MSD1), catalase ( CAT1), and homogentisate phytyltransferase ( HPT1, responsible for the first committed reaction in the tocopherol biosynthesis pathway) were overexpressed in Arabidopsis under the control of the At2S3 promoter. Double overexpressers co-expressing two enzymes and triple overexpressers were produced by cross pollination. Mn-SOD and total CAT activities, as well as γ-tocopherol content, significantly increased in the corresponding overproduction lines. Moreover, single MSD1-transgene, double, and triple overexpressers displayed remarkably enhanced oxidative stress tolerance compared to wild type during seed germination and early seedling growth. Interestingly, an increase in the total CAT activity was also observed in the single MSD1-transgenic lines as a result of MSD1 overexpression. Together, the combined increase in Mn-SOD and CAT activities in seeds plays an essential role in the improvement of antioxidant capacity at early developmental stage in Arabidopsis. [ABSTRACT FROM AUTHOR]