Transgenerational Plasticity Of Xanthium Strumarium And X. Sibiricum

Phenotypic plasticity is universal in plants.Attributed to the environmental information of the parents prefabricated in the offspring,some transgenerational plasticity(TGP)could improve the offsprings adaptation to environment of offsprings,which is transferred from parents to offspings by seeds.The role of TGP in plant invasion is unclear,even though the phenotypic plasticity is one of the important factors affecting plant invasion.As materials,the invasive species Xanthium strumarium L.and the native species X.sibiricum Patrin ex Widder were used to verify that TGP of invasive plant X.sibiricum is more efficient than X.sibiricum,which is conducive to faster adaptation of invasive plants to the environment and promote the invasion process through planting experiments.In the experiments,the changes of phenotypic plasticity and phenotypic plasticity of offspring at different water and nutrient levels were studied by used seeds germination bags to simulate homomorphism experiment.Several involved traits of offspring from different parents are compared with the different nutrients conditions.According to the characteristics of soil nutrients and soil moisture content in its main habitat,2 water gradients and 2 soil nutrient levels were set,it was four treatments totally.Using the theory of plant physiology ecology and mathematical statistics and the phenotypic plasticity to explore the characteristics of invasive plants under different conditions and enrich the theory of plant invasion.The main conclusions are as follows.1.No matter it's X.strumarium or X.sibiricum,except the parents under high nutrient conditions,the cotyledon thickness and germination rate of the offspring under high nutrient conditions are lower than the cotyledon thickness and germination rate under low nutrient conditions,and the parents under low nutrient conditions.The length of the lateral root of the offspring under high nutrient conditions is lower than that of the lateral root under low nutrient conditions,and the remaining indicators are whether the parents grow under high nutrient conditions or under low nutrient conditions.All the indexes of offspring are those of higher than lower nutrients For X.strumarium,all the traits of high-nutrient progeny except the lateral root length performed better under high nutrient conditions.The four traits of low nutrient progeny such as germination rate,germination index,cotyledon length,and main root length performed better under low nutrient environment conditions,which prove that phenotypic plasticity exists in the germination and young seedling stages of X.strumarium.However,this phenomenon was not found in X.sibiricum,and it proved that the phenotypic plasticity transmitted between the generations was conducive to the invasion of X.strumarium.The long lateral root of the offspring growing under low nutrient conditions is not necessarily the expression of phenotypic plasticity that can be transmitted between generations,so it can not proved that phenotypic plasticity exists in the young seedling period of X.sibiricum.2.The biomass of X.strumarium is significantly larger than that of X.sibiricum under every water and nutrient treatment,and it increases with the increasing of water and nutrient amount,indicating that the phenotype plasticity of adaptability of X.strumarium has obvious advantages compared with X.sibiricum,which is conducive to invasion various habitats.The plasticity of other different fitness traits can also promote the invasion of X.strumarium at different water levels,such as plant height,crown width,net photosynthetic rate,and root crown ratio.It shows that with the increase of resources,invasive species can use resources more efficiently.In the environment of insufficient resources,the adaptive phenotype plasticity advantage is further expanded X.strumarium compared with X.sibiricum.In the stress environment,X.strumarium is more competitive than native species X.sibiricum and is more conducive to invasion.3.Both the mother of X.strumarium and X.sibiricum can "tell" their offspring of the environmental characteristics in some way.Compared with the memory to resource-richenvironment,the memory to the resource-poor environment is more profound.At a high level of resources,the memory that parent pass to offspring is functional characteristics such as plant height,basal stem,and crown width.At a low level of resources,the memory that parent pass to offspring is adaptive characteristics,such as biomass.The effect of X.strumarium is higher than X.sibiricum,which is more obvious in low resource level.4.There are indeed phenotypic plasticity that can be transmitted between generations in X.strumarium and X.sibiricum,but not all phenotypic plasticity can be transmitted between generations.The plasticity phenotypes that can be transferred between generations are different in different developmental stages of X.strumarium and X.sibiricum.Even at the same developmental stage,the plasticity phenotypes of X.strumarium and X.sibiricum can transmit between generations are not exactly as the same.Compared with X.sibiricum,when the resource level is low(low water and low fertilizer),the plasticity phenotypes transmitted between generations are all phenotypes that adapt to environment,such as the lateral root length of the seed germination period and the biomass of the seedling period.It is proved that in the bad environment,the mother can transfer the traits that adapt to this bad environment to their offspring,so that the offspring can adapt to this unfavorable environment as soon as possible,and form dominant populations rapidly.This transgenerational phenotypic plasticity of X.strumarium may be one of the mechanisms of its successful invasion.