When cytosolic Ca²⁺ concentration is increased under salt stress， cells would activate Ca²⁺-regulated target enzymes or induce Ca²⁺ bind to Ca²⁺ high-affinity receptor proteins. Among them， plant Ca²⁺-ATPases are P-type ATPases， including endoplasmic reticulum Ca²⁺-ATPase（ECAs） and plasma membrane Ca²⁺-ATPase（ACAs）； they are able to translocate Ca²⁺ from the cytosol to apoplast or compartmentalize Ca²⁺ in organelles. Numerous studies have shown that salt tolerance of plants is largely related to their ability to maintain the activities of calcium pump， namely Ca²⁺-ATPases. The activities of Ca²⁺-ATPases in various plant species were sensitive to salt stress； exogenous Ca²⁺ application can alleviate cell injury by salt stress， suggesting that exogenous calcium -mediated Ca²⁺-ATPase might play an important role in intracellular calcium homeostasis and signal transduction. Therefore， this review summarized the types， structures and properties of plant Ca²⁺-ATPase， and the involvement of Ca²⁺-ATPase of subcellular localization in plant response to salt tolerance and the research progress of exogenous calcium and Ca²⁺-ATPase in regulation on plant salt tolerance. It emphasized potential roles of Ca²⁺-ATPases of plant plasma membrane， tonoplast， nuclear membrane， endoplasmic reticulum and Golgi in regulation of salt tolerance in plants， and presented an outlook in the field. This work provided help for a better understanding of physiological and molecular mechanisms of plant salt tolerance and provided new ideas for crop salt-tolerance cultivation.

Superoxide dismutase（SOD） widely presents in plants and can be mainly classified into three categories： Mn-SOD， Fe-SOD and Cu/Zn-SOD. They play different defense roles in cells and enhance plant tolerance. Additionally， Ni-SOD in blue cells and marine organisms remains to be explored. In this paper， the physicochemical properties and mechanisms of action of SOD were analyzed according to the different metal ions contained in SOD， and the role of SOD in plants under stress conditions such as drought， salinity and cold were elucidated， and the role of SOD in plant growth and development in future was prospected， and a reference for studying the mechanisms of plant growth and development under adverse environments was provided.

Rubber tree（Hevea brasiliensis） is one of the important tropical cash crops， and natural rubber（NR）， a secondary metabolite， is an important industrial raw material and strategic material in China. Phytohormones play important roles in regulating plant growth， development， germination， and environmental responses. Here， the research progress on application of four phytohormones， Ethylene， Abscisic acid， Brassinolides， and Gibberellin in the growth and development of rubber trees， NR biosynthesis， rubber yield， latex flow， and quality formation， was summarized in detail， and the application prospect of four phytohormones in mechanism research of improving rubber production and latex flow was looked forward to provide theoretical support for the rubber industry development.

Plant development is highly plastic. As ambient temperature increased， plant stems and petioles elongated， and promoted leaf surface cooling， the process known as thermomorphogenesis. High temperatures also triggered root elongation， which named as root thermomorphogenesis. There were many studies on the regulation of plant shoot thermomorphogenesis， but few investigations on the regulatory mechanisms of plant root thermomorphogenesis. In this review， we summarized the recent progresses in the field of plant root thermomorphogenesis， and proposed future research directions.

Rare and endangered plants are important plant resources in nature， and play a key role in the study of plant phylogeny， ecosystem restoration， plant stress resistance physiology， and the excavation of stress-resistance genes. However， the lack of genetic information has severely restricted the conservation and utilization in most endangered plant. Due to the large genomes， complex genetic information， and unclear genetic backgrounds of endangered plants， it is relatively difficult to sequence the genomes of endangered plants. In recent years， RNA-Sequencing could directly sequence non-reference genomic species， what makes it to be widely used in the study of endangeredplants. In addition， this paper presented the prospect of the application of RNA-Sequencing technology in the study of endangered plants and suggested the new ideas of transcriptome using in the endangered plants in future.

Root hairs are tubular extensions of plant root epidermal cells that play vital roles in soil fixation， water and inorganic salts absorption， and information exchange between plant roots and outside world. The developmental processes of root hair are highly plastic and might easily be affected by various plant hormones and environmental factors. Due to the structural and functional characteristics of root hair， it is often used as model to study apical growth and fate determination of plant cells. Therefore， the regulatory mechanism of root hair development has been a hot topic in the field of botany. The review summarized the research progress in the field of root hair development in the past two decades.

Since Linnaeus established the genus Populus， many taxonomic studies have been carried out about it and some taxonomic systems have been proposed， while the taxonomy of Populus is still in the stage of traditional morphological classification around the world. Although the taxonomic hierarchy of ‘genus-section-species’ is adopted in many countries， in which has Populus plant distributed， there are great differences in the classification of species， subspecies and varieties. The taxonomists of China and the United States are the representatives of splitter and lumper respectively， and there is a huge gap in poplar classification between them， but each has advantages and disadvantages. Even in China， there are still many problems to be solved. The existing phylogenetic studies about the genus Populus provide useful information to taxonomic revision， but the actual contribution is small yet. The ultimate aim on poplar classification is to establish a unified taxonomic system based on phylogeny in the world. It requires a comprehensive classification based on both population and the concepts of integrated species， which integrates morphology， ecology， biogeography， genomic bioinformatics and evolutionary biology.

Salt stress had a critical impact on plant growth and development， including osmotic stress and ion toxicity， which seriously damaged agricultural production and food security. Under salt stress， plant related receptors were stimulated to send Ca²⁺ enter the cytoplasmic matrix through the Ca²⁺ channels opened on the cell membrane and intracellular calcium storage membrane， resulting in the increase of intracellular Ca²⁺ concentration and calcium signal. Ca²⁺， as an important second messenger， transmited signals within and between plant cells， downstream， and caused a series of physiological responses to salt stress at different growth and development stages. Calcium signals mainly included calmodulin（CaM）， calmodulin like protein（CML）， calcium dependent protein kinase（CDPK） and calcineurin B-like protein（CBL） and CBL interacting protein kinase（CIPK）， and sensed and transmited specific calcium signal information to the downstream， and activated plant physiological response to salt stress. This paper reviewed how plants perceived salt stress stimulation and the mechanism of calcium signal regulation， and looked forward to the problems should be solved in this research field.