Environmentally benign synthesis of phytochemicals-capped gold nanoparticles as nanopriming agent for promoting maize seed germination.

Elevated CO2 reduces the adverse effects of drought stress on a high-yielding soybean (Glycine max (L.) Merr.) cultivar by increasing water use efficiency.

Elevated CO2-induced changes in photosynthesis, antioxidant enzymes and signal transduction enzyme of soybean under drought stress

Cassava (Manihot esculenta) is valued mainly for high content starch in its roots. Our understanding of mechanisms promoting high starch accumulation in the roots is, however, still very limited. Two field-grown cassava cultivars, Huanan 124(H124) with low root starch and Fuxuan 01(F01) with high root starch, were characterised comparatively at four main growth stages. Changes in key sugars in the leaves, stems and roots seemed not to be strongly associated with the final amount of starch accumulated in the roots. However, when compared with H124, F01 exhibited a more compact arrangement of xylem vascular bundles in the leaf axils, much less callose around the phloem sieve plates in the stems, higher starch synthesis-related enzymatic activity but lower amylase activity in the roots, more significantly up-regulated expression of related genes, and a much higher stem flow rate (SFR). In conclusion, higher starch accumulation in the roots results from the concurrent effects of powerful stem transport capacity highlighted by higher SFR, high starch synthesis but low starch degradation in the roots, and high expression of sugar transporter genes in the stems. A model of high starch accumulation in cassava roots was therefore proposed and discussed.

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Characters related to higher starch accumulation in cassava storage roots

Drought is a severe abiotic stress that affects global crop production. A drought model was created for ‘Toyonoka’ Fragaria × ananassa, and the effects of drought stress on contents of proline, sugars, and antioxidant enzyme activities were investigated. Strawberry transplants with identical growth were chosen for the experiments and the randomized design included four replications (10 plants per block). The experimental sets differed in the moisture level of the culture medium relative to the range of moisture content as follows: control, 70-85%; mild drought stress, 50-60%; moderate drought stress, 40-50%; and severe drought stress, 30-40%. Drought stress was imposed by limiting irrigation. Plants were sampled and physiological parameters were measured on 0, 2, 4, 6, 8, and 10 days after the commencement of drought stress. The water potential of strawberry leaves decreased in the plants under mild, moderate, and severe stress during the course of the water stress treatment and exhibited a significant difference from the control. Strawberry leaves subjected to drought stress had higher accumulation of proline, sugars, and malondialdehyde, and higher activities of superoxide dismutase, peroxidase, and catalase than leaves of control plants. Malondialdehyde levels increased in parallel with the severity and duration of drought stress. By contrast, antioxidant enzyme activity displayed dynamic responses to drought stress, first increasing and subsequently decreasing as the severity and duration of drought stress increased. These results suggest that strawberry plants respond to drought stress by altering the activities of antioxidant enzymes and the levels of osmotically active metabolites. These biochemical response changes may confer adaptation to drought stress and improve the capacity of plants to withstand water-deficit conditions.

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Proline, Sugars, and Antioxidant Enzymes Respond to Drought Stress in the Leaves of Strawberry Plants

The purpose of this study was to examine the relationships between the soluble sugar content in the leaves and stems and the starch accumulation in the tuberous roots of four cassava cultivars: FuXuan01, GR891, SC124, and SC201. The results showed that the highest leaf soluble sugar content was in September, and the highest stem sugar content was in October, which played an important role in starch accumulation in the tuberous roots. The leaf and stem soluble sugar content and the tuberous root starch accumulation were positively correlated in the setting and growth stages but negatively correlated in the ripening stage. The soluble sugar content in the leaves went from high to low as the tuberous roots progressed from the setting stage to the ripening stage; starch accumulation in the root tubers followed the opposite pattern.

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Xinglu Luo

Papers

Relationships between Leaf and Stem Soluble Sugar Content and Tuberous Root Starch Accumulation in Cassava