| The objects of this research are five important ephemearl plants of Cruciferae which distribute widely at north piedmont of Tianshan. They are Arabidopsis thaliana, Leptaleum filifolium, Malcormia africana, Alyssum desertorum and Tetracme quadricornis. The content of this research is the variation about phenological, morphological and fruit dehiscence character under precipitation at the artificial set of environmental conditions both wet and dry in Standard experimental field. We explore the reason and drive of phenotypic differentiation, contribution of the intensity of fruit dehiscence to the fitness of species and phylogenic regulations among species and populations through phenotypic traits and ITS sequencing molecular method of combining. The analyzing is followed:(1) The characteristics of phenotypic differentiation of each species:Under droughty condition, the flower and maturity time is advanced in different populations of every species, and among populations and treatments are both significant difference. The plasticity of the other four species'flower and maturity time has no significant genetic variation but A. thaliana. There are significant differences about morphological and phenological characteristics among populations and treatments of A. thaliana, A. desertorum and M. africana (except number of fruits). This indicates that these three species with higher phenotypic plasticity, and it may be the main reason which make them distribute widely. There are six traits indicative that plasticity genetic differentations in ten traits at A. thaliana(including fruit dehiscence force, branch number, number of fruits, fruit length, single fruit weight, shoot weight/root weight) and A. desertorum has two (number of fruits, fruit length) and M. africana has three(shoot height, branch number, shoot weight/root weight). There are approximately only half of characteristics among populations of L. filifolium reach significant level. T. quadricornis only fruit dehiscence force and shoot weight/root weight are also significant difference among populations, and shoot weight/root weight, shoot height, number of fruits, branch number are significant difference at different treatment.(2) The driving force is difference with different species to adapt to different environments:A. thaliana adapt to environment is a overall adaption upon interactions of several characteristics, regional heterogeneity precipitation has driven species get together within same environment. Precipitation is also the promoting factor of phenotypic differentiation among species of A. desertorum and L. filifolium, but it is also affected upon certain microenvironment. However, M. africana is affected distinctly upon local microenvironment, the relationship between phenotypic differentiation and regional precipitation is not obvious.(3) Among these five research species(involved A. thaliana, A. desertorum, M. africana, L. filifolium, T. quadricornis), four specise's fruit length is related distinctly with intensity of fruit dehiscence, and three species'fruit length is related with fitness. This reflects that fruit shape of ephemearl plants of Cruciferae are closely related with intensity of fruit dehiscence and fitness. To sum up, we presumption that ephemearl plants of Cruciferae have abundant fruit shapes and different fruit dehiscence extents so that they can adapt extensive environment.(4) We set up phylogenetic tree, based the ITS sequencing, and find that the same species'different populations with the closest relationship,belong to different species of the same genus, followed by. M. africana and Malcolmia scorpioides and L. filifolium, the closest relationship, second, the order is T. quadricornis and A. desertorum, finish up as A. thaliana. The hightest level of genetic differentiation is Qinghel in A. thaliana at northern Tianshan. On the local area, among different populations of the same location have genetic differentiation, such as Qinghel and Qinghe2, Aletail and Aletai2; Regionally, the population in different regions have different phenotype. But the arid regions of the genetic differences among populations is relatively low, wet areas have no genetic differentiation or very low. |
