Real-time mapping of salt glands on the leaf surface of Cynodon dactylon L. using scanning electrochemical microscopy

Structural determinants of phytoremediation capacity in saltmarsh halophyte Diplachne fusca (L.) P. Beauv. ex Roem. & Schult. subsp. fusca

Micro and macro-morphological features contribute to plants' tolerance to a variety of environmental pollutants. The contribution of such structural modifications in the phytoremediation potential of Diplachne fusca populations collected from five saline habitats were explored when treated with 100 to 400 mM NaCl for 75 days along with control. Structural modifications in the populations from the highest salinity included development of aerenchyma in stem instead of chlorenchyma, absence of excretory hairs in stem, and exceptionally large trichomes on the leaf surface to help excretion of excess salt. Large parenchyma cells provided more space for water and solute storage, while broad metaxylem vessels were linked to better conduction water and nutrients, which ultimately excreted via glandular hairs, microhairs, and vesicular hairs. Broad metaxylem vessels and exceptionally long hairs observed in the populations collected from 52 dS m^-1. In conclusion, large stem aerenchyma, exceptionally large trichomes on the leaf surface, and tightly packed outer cortical region in roots with intensive sclerification just inside the epidermis accompanied with salt excretion via glandular hairs, microhairs, and vesicular hairs were the main anatomical modifications involved in the phytoremediation potential of D. fusca in hyper-saline environments.

Biological imaging with scanning electrochemical microscopy

Scanning electrochemical microscopy (SECM) is a powerful and versatile technique for visualizing the local electrochemical activity of a surface as an ultramicroelectrode tip is moved towards or over a sample of interest using precise positioning systems. In comparison with other scanning probe techniques, SECM not only enables topographical surface mapping but also gathers chemical information with high spatial resolution. Considerable progress has been made in the analysis of biological samples, including living cells and immobilized biomacromolecules such as enzymes, antibodies and DNA fragments. Moreover, combinations of SECM with comple-mentary analytical tools broadened its applicability and facilitated multi-functional analysis with extended life science capabilities. The aim of this review is to present a brief topical overview on recent applications of biological SECM, with particular emphasis on important technical improvements of this surface imaging technique, recommended applications and future trends.

Progress in Studying Salt Secretion from the Salt Glands in Recretohalophytes: How Do Plants Secrete Salt?

To survive in a saline environment, halophytes have evolved many strategies to resist salt stress. The salt glands of recretohalophytes are exceptional features for directly secreting salt out of a plant. Knowledge of the pathway(s) of salt secretion in relation to the function of salt glands may help us to change the salt-tolerance of crops and to cultivate the extensive saline lands that are available. Recently, ultrastructural studies of salt glands and the mechanism of salt secretion, particularly the candidate genes involved in salt secretion, have been illustrated in detail. In this review, we summarize current researches on salt gland structure, salt secretion mechanism and candidate genes involved, and provide an overview of the salt secretion pathway and the asymmetric ion transport of the salt gland. A new model recretohalophyte is also proposed.