Geographical differences of leaf traits of the endangered plant Litsea coreana Levl.var.sinensis and its relationship with climate

Seventeen morphological and anatomical characteristics of the leaves were selected from five natural populations to explore the variation in leaf traits of Lits ea core ana var.sinensis and the effects of geographical environment on these variations.Nested analysis of variance,multiple comparisons,principal component analysis(PCA),and correlation analysis were conducted to explore the variations within and between populations and their correlation with geographical and climatic factors.Significant differences in the 17 leaf traits were observed within and among populations.On average,the relative contribution of within population variation to total variation was 24.8%,which was lower than among population variation(54.6%).The average differentiation coefficient of the traits was 65.8%,and the average coefficient of variation 11.8%,ranging from6.7%for main vein thickness to 21.4%for petiole length.The PC A results showed that morphological characteristics were divided into two categories,and the level of variation was greater than that of leaf anatomy.Most of the leaf traits were significantly correlated with geography and climate and showed a gradual variation with longitude,latitude,and altitude.In areas with high temperatures,less rainfall,and strong seasonal rainfall,the leaves are larger,longer and thicker.This study shows that variations in leaf traits of L.coreana var.sinensis mainly come from variations among populations.The level of trait differentiation among populations is high and the level of variation within populations low.These findings help further understand leaf morphological characteristics of this species and can provide a valuable reference for the protection and sustainable utilization of this natural resource.

Analysis of genetic diversity and prediction of Larix species distribution in the Qinghai–Tibet Plateau,China

Larix resources in the Qinghai-Tibet Plateau have important ecological and economic values.However,the lack of genetic diversity background and related research hinders the development of conservation strategies.In this study,genetic diversity and distribution of fi ve Larix species were investigated.Using 19 polymorphic microsatellite markers to study 272 representative individuals from 13 populations,the results show low genetic diversity at the population level,with variation explained mainly by diff erentiation among populations.The Larix populations were classifi ed into two clades,one formed by eight populations,including three of the species in this study,L.kongboensis,L.speciosa,and L.potaninii var.australis.The other clade consists of fi ve populations,including the other two species in this study,L.griffi thii and L.himalaica.Genetic distance of the species was aff ected by geographical isolation and genetic diversity was mainly aff ected by altitude.The area suitable for Larix spp.decreased during the Last Glacial Maximum compared to the current distribution according to the niche model,but should increase in future climate scenarios(2050s),expanding westward along the Himalayas.These results provide an important scientifi c basis for the development of conservation strategies and further the sustainable utilization of Larix resources in the Qinghai-Tibet Plateau.

Comparison of photosynthesis and antioxidative protection in Sophora moorcroftiana and Caragana maximovicziana under water stress

This study aims to investigate the protective roles of photosynthetic characteristics and antioxidative systems in the desiccation tolerance of Sophora moorcroftiana and Caragana maximovicziana as they adapt to arid environments. A variety of physiological and biochemical parameters in the leaves of two Leguminosae species were monitored for 1, 7, 14, 21 and 28 d of drought stress. Soil water content decreased from 38.58% to 7.33% after exposure to 28 d of water stress. The photosynthetic carbon-assimilation rates of the two Leguminosae plants decreased for non-stomatal limitation with processing water stress. The malondialdehyde content and cell membrane relative conductivity of the two species increased significantly from 1 to 21 d and then decreased. S. moorcroftiana showed higher superoxide dismutase and peroxidase activities than C. maximovicziana during the 28 d treatment period. However, the catalase activities and proline content of C. maximovicziana were higher than those of S. moorcroftiana before the water stress treatment reached 21 d. Nine physiological and biochemical parameters were selected to comprehensively evaluate the two species＇ drought-resistance by the membership function values（MFV）. The mean MFV indicated that S. moorcroftiana has a relatively stronger drought defense capability than C. maximovicziana. S. moorcroftiana mainly uses carbon-assimilation rate and osmotic adjustment to combat water deficiency.

Comparative study on the chloroplast genomes of five Larix species from the Qinghai-Tibet Plateau and the screening of candidate DNA markers

Five Larix species(L.griffithii,L.speciose,L.himalaica,L.kongboensis,and L.potaninii var.australis),have survived on the Qinghai-Tibet Plateau(QTP)under specific climate conditions for decades.The lack of genomic information seriously hinders research on the evolution,conservation and ecology of these Larix resources.In this study,complete chloroplast(cp)genomes of the 5 species were assembled and compared based on next generation sequencing technology combined with polymerase chain reaction validation.The results show that the 5 cp genomes are relatively conservative in size,gene content and arrangement,and border variation.Phylogenetic analysis showed that the species are closely related as well as to seven other species of the same genus.In addition,the 5 cp genomes contained few simple sequence repeats and relatively low nucleotide variability;thus,12 candidate polymorphic cp DNA markers will be helpful for further research on relevant population genetics.These results will provide valuable genetic information for the conservation,evolution and ecology of these species and their relatives.

Unraveling the nexus between cellular senescence and malignant transformation:a paradigm shift in cancer research

Cellular senescence, a natural process wherein cells cease division and undergo irreversible growth arrest, has long captivated the curiosity of scientists because of its many implications in aging and disease. Recent research has shed light on the nexus between cellular senescence and malignant transformation, thus leading to a paradigm shift in understanding cancer development and progression.