Establishing In Vitro Screening Protocols Based on Phenotypic Plasticity of Amaranthus dubius and Galinsoga parviflora Seeds for Drought, Salinity, and Heat Tolerance

Abstract

The vulnerability of commercial crops under a changing climate has led scientists to consider wild crop species as alternative food sources. The aim of this study was to identify plastic physiological and morphological traits that could be used to in vitro screen Amaranthus dubius and Galinsoga parviflora seeds for drought, salinity, and heat tolerance. To establish the lethal dose/temperature, 50% (LD/T50), for each stress, seeds for both were subjected to various mannitol and NaCl stresses and a range of temperatures. Percentage seedling emergence was selected as the initial indicator of tolerance and used to establish the LD/T50 for in vitro screening for both species. Seeds of both were then screened at the LD/T50 concentrations/temperatures established, and seedlings that emerged after 21 days were measured for leaf area, root (RL), shoot length (SL), chlorophyll content (Chl), fresh, dry mass, and leaf number. Data for these were used to quantify plasticity in terms of Valladares’s phenotypic plasticity index. For A. dubius, three (viz. RL, SL, and Chl) showed some plasticity (≥0.53) and tolerance across all three stressors. For G. parviflora all traits except SL showed some plasticity (≥0.58) and tolerance across all three stressors. Both species had high phenotypic plasticity across all three stressors, which suggests that wild leafy vegetables may possess the ability to tolerate climate change-associated stressors and should be considered for future breeding programs.