Population Genetic Diversity and Structure of a Naturally Isolated Plant Species, Rhodiola dumulosa (Crassulaceae)

Aims: Rhodiola dumulosa (Crassulaceae) is a perennial diploid species found in high-montane areas. It is distributed in fragmented populations across northern, central and northwestern China. In this study, we aimed to (i) measure the genetic diversity of this species and that of its populations; (ii) describe the genetic structure of these populations across the entire distribution range in China; and (iii) evaluate the extent of gene flow among the naturally fragmented populations. Methods: Samples from 1089 individuals within 35 populations of R. dumulosa were collected, covering as much of the entire distribution range of this species within China as possible. Population genetic diversity and structure were analyzed using AFLP molecular markers. Gene flow among populations was estimated according to the level of population differentiation. Important Findings: The total genetic diversity of R. dumulosa was high but decreased with increasing altitude. Populationstructure analysis indicated that the most closely related populations were geographically restricted and occurred in close proximity to each other. A significant isolation-by-distance pattern, caused by the naturally fragmented population distribution, was observed. At least two distinct gene pools were found in the 35 sampled populations, one composed of populations in northern China and the other composed of populations in central and northwestern China. The calculation of Nei’s gene diversity index revealed that the genetic diversity in the northern China pool (0.1972) was lower than that in th

Role of Mineral Nutrients in Plant Growth Under Extreme Temperatures

Food productivity is decreasing with the drastic increase in population, while it is expected that the global population will be nine to ten billion in 2050. Growth, production, and development on whole plant, cell, and subcellular levels are extremely affected by environmental factors particularly with the extreme temperature events (high- or low-temperature stress). Increase in the fluidity of lipid membrane, protein accumulation, and denaturation are the direct effects of high temperature on a plant. Membrane integrity loss, protein deprivation, protein synthesis inhabitation, and inactivation of mitochondrial and chloroplast enzymes are the indirect effects of high temperature. Similarly, the oval abortion, alteration of the pollen tube, reduction in fruit set, pollen sterility, and flower abscission are the consequences of low temperature at the time of product development, which in turn lowers the yield. The judicious nutrient management is essential for improving the plant nutrition status to mitigate the drastic effects of temperature stress as well as for sustainable plant yield under extreme temperature events, because nutrient deficiency results in growth and development problems in 60% cultivars worldwide. Additionally, effective nutrient management increases the temperature stress tolerance in plants. Therefore, the appropriate nutrient application rates and timings are imperative for alleviating the heat stress in plants and can serve as an effective and decent strategy. To minimize the contrasting effects of the environmental stresses, particularly heat stress, several examples of the supplemental applications of N, P, K, Ca, Mg, Se, and Zn are given in detail in this study, to observe how these nutrients reduce the effects of temperature stress in plants. This study concluded that judicious nutrient management minimizes the heat stress and increases the growth and yield of plants