Increasing salinity leads to differential growth and H2O2 homeostasis in plants produced from heteromorphic seeds of the succulent halophyte Arthrocnemum indicum

Insights into the salinity tolerance of the succulent halophyte Arthrocnemum macrostachyum: comparative ecophysiology of plants from heteromorphic seeds

Introduction

Little is known about the similarities and differences in responses of plants grown from heteromorphic seeds, which are morpho-physiologically dissimilar seeds produced simultaneously on the same plant.

Methods

In this context, we studied how plants grown from heteromorphic (i.e. black and brown) seeds of the succulent halophyte Arthrocnemum macrostachyum respond to increasing salt levels during growth by modulating their physio-chemical processes.

Results

Plants germinated from both black and brown seeds did not show any significant growth reduction and chlorophyll a content decline at moderate salinity (300 mM NaCl) compared to non-saline controls. High salinity (900 mM NaCl), on the other hand, caused decreased growth and sap Ψs in plants derived from either seed type. In plants emerged from brown but not black seeds, high salinity increased the activity of all H2O2-detoxifying antioxidant enzymes as well as GSH level. Under conditions of high salinity, plants obtained from both types of seeds exhibited signs of lipid peroxidation in the form of elevated malondialdehyde levels.

Discussion

Our findings thus point to metabolic variability in A. macrostachyum plants growing from heteromorphic seeds under salt stress.

Water Content of Plant Tissues: So Simple That Almost Forgotten?

The aim of the present review was to reconsider basic information about various functional aspects related to plant water content and provide evidence that the usefulness of measuring absolute water content in plant sciences is undervalued. First, general questions about water status in plants as well as methods for determining water content and their associated problems were discussed. After a brief overview of the structural organization of water in plant tissues, attention was paid to the water content of different parts of plants. Looking at the influence of environmental factors on plant water status, the differences caused by air humidity, mineral supply, biotic effects, salinity, and specific life forms (clonal and succulent plants) were analyzed. Finally, it was concluded that the expression of absolute water content on a dry biomass basis makes easily noticeable functional sense, but the physiological meaning and ecological significance of the drastic differences in plant water content need to be further elucidated.