Latitudinal and Longitudinal Trends of Seed Traits Indicate Adaptive Strategies of an Invasive Plant.

Lifeng Zhou,Li Chen,Jianqing Ding,Hongwei Yu,Kaiwen Yang,Wandong Yin

doi:10.3389/fpls.2021.657813

Abstract

Invasive plants may change their seed traits to adapt to the environment and facilitate their performance. Studies on variation in seed traits among populations of an invader along latitudes/longitudes may assist in revealing how invasive plants cope with variable climates. In this study, we collected seeds of 26 populations of the global invasive plant Ambrosia artemisiifolia along ranges spanning 23° latitudes and 20° longitudes that are highly correlated in its invasive range in China. We measured over 20 seed traits, including seed morphology, phytohormone, nutrients, and germination, and investigated how the climate along the latitudes affects those traits. We found that germination time was significantly delayed with increasing latitude and longitude, while the reversed patterns were true for the germination rate. From low to high latitude, seed size, abscisic acid, and fatty acid were increased, likely affecting seed germination. Our analysis further demonstrated that temperature is the dominant driver of the variability in seed traits and germination. Germination rates of larger seeds in cold ranges were lower, while smaller seeds from warm ranges germinated faster, likely indicating adaptive strategies of the invasive plant in seed trait functional ecology. Together, our findings provide new insights into understanding the seed adaptation strategies during the invasion process and the underlying physiological and biochemical mechanisms involved.

Highlights

Many invasive plants reproduce via seeds; seed traits are critical for invasive plant performance during their invasion process
The average time of T0 and T50 was prolonged by 3.41 days and 4.63 days, respectively, for every 10◦ increase in latitude (Figures 1A,B), the average germination rate and germination index were decreased by 28.1% and 1.03, respectively, for every 10◦ increase in latitude (Figures 1C,D)
Note due to the sampling sites were highly correlated in latitude and longitude coincidentally, in text we only showed figures for the effects of latitudes and those for the longitudes were presented in Supplementary Figures

Summary

INTRODUCTION

Many invasive plants reproduce via seeds; seed traits are critical for invasive plant performance during their invasion process. Variations in seed traits such as seed size, mass, and morphology between populations of a plant species could be driven by geographical or environmental variables, including temperature and precipitation (Soper Gorden et al, 2016; Jesús et al, 2017; Mojzes et al, 2018). Revealing adaptative strategies of invasive plant seed traits by examining their variation among populations in different latitudes/longitudes is important to understand the effects of geographic and environmental factors on seeds. As a response to various environmental conditions along latitudinal and longitudinal gradients, an invasive plant may adapt different strategies in germination, leading to intraspecific variation in seed traits (Leiblein-Wild and Tackenberg, 2014; Wu et al, 2018). In seed traits (mass, germination, nutrients, and biochemical property) among populations? (ii) If so, are there trends along latitudinal and longitudinal gradients? (iii) What are the major environmental drivers underlying the variation in seed traits for such trends?

MATERIALS AND METHODS

RESULTS

DISCUSSION

DATA AVAILABILITY STATEMENT