查看更多>>摘要：Low pH is an important limiting factor for plant development in the south of China due to problems of acid red soil and boron (B) deficiency. Whereas, there is very limited information on the relationship between media pH and B distribution in plant, the physiological process changed by the interaction of pH and B in citrus growth also unclear. This experiment was conducted on trifoliate rootstock by employing two different concentrations of B (0 or 10 mu M B) under three pH levels: pH 4, pH 5, and pH 6. Our results illustrate that low pH inhibite plant growth and cause oxidative stress in the roots, resulting in cell membrane injury. The increase of pH and B addition reduce the accumulation of ROS (O(2)(center dot-)and H2O2) by regulating the activity of Class III peroxidases (CIII Prxs). Moreover, increased pH improves the internal circulation of B in plants and decrease the content of lignin and cellulose in cell wall (CW). In summary, our investigation demonstrated that the increase of pH in nutrient solution can accelerate the re-distribution of B by roots to promote citrus growth. The accumulation of B in roots can protect plants from the damage of ROS by regulating the activity of CIII Prxs as well as decrease the content of lignin and cellulose are to promotes roots elongation.
查看更多>>摘要：Carbohydrates remobilization in non-leaf organs has a potential association with the formation of cotton yield. However, our understanding of the physiological and molecular mechanisms regulating carbon remobilization during flowering is still limited. The objectives of the study were to: i) evaluate the potential of carbohydrate remobilization in stems and roots to yield formation; ii) unravel the carbon metabolism and transport associated gene expression patterns regulating carbon remobilization. Two cotton lines 4003-6 and 4003-10 were employed to examine leaf photosynthesis, reproductive biomass accumulation, and carbon dynamics in stems and roots during reproductive growth. The results showed that decreasing leaf photosynthetic capacity combined with rapidly increasing reproductive biomass and leaf area index is accompanied by the initiation of carbohydrate remobilization during first flowering to peak flowering. The proportion of sucrose to total nonstructural car-bohydrate was also decreased at that period. The upper and lower of stem recorded higher soluble sugars and starch concentrations, respectively compared to the two others. The gross contribution rate of carbon remobi-lization to seed cotton yield ranged from 2.83% to 7.12%. Key genes and sugar transporters related to starch and sucrose metabolism in the lower stem exhibited significant up-or down-regulated expressions indicating their important roles in carbon reserves remobilization. Three pivotal sugar transporters SWEET1, TMT2, and oD5 presented higher transcript levels at peak flowering suggesting more active sugar movement occurring at that stage. The present study provides potential target genes for engineering carbohydrate metabolism and transport to improve the remobilization efficiency of nonstructural carbohydrates.
查看更多>>摘要：Understanding the mechanisms underlying the activation of the abscission zone (AZ) responsible for organ separation from plant body in crop species will help improve their yielding and economic importance. Special attention has been given recently to the role of the INFLORESCENCE DEFICIENT IN ABSCISSION protein, particularly its functional fragment, EPIP peptide. Its stimulatory effect on abscission in different crops has been demonstrated. Recently we described the role of EPIP in the redox, lipid, and pectin-related events taking place in AZ of Lupinus luteus flowers, which undergo massive abscission in natural conditions. To further examine EPIP contribution in AZ functioning, here, we analyze its impact on the ultrastructural changes, synthesis of two hormonal abscission stimulators - abscisic acid (ABA) and ethylene (ET), and the appearance of phosphoproteins. As our results show, the response of flower AZ to exogenous EPIP involves the induction of distinct modifications related to the one hand with upregulation of cell activity but on the other hand degradation processes and possible autophagy. Furthermore, the EPIP stimulated biosynthesis pathways of ABA and ET precisely in AZ cells. In addition, progressive phosphorylation of proteins has been observed under EPIP influence. The highly accumulated ones were identified as those, related to primary metabolism and reactive oxygen species homeostasis, and their role in abscission has been discussed. To summarizing, the presented detailed description of EPIP action in AZ cells in combination with our previous data offers new insights into its regulatory function and provides opportunities to counteract excessive flower abscission in lupine.
NSTL
Elsevier