Molecular transporters that drive plant responses to drought and salinity

April 25, 2014
Figure 1: In response to drought, ABA synthesized in leaf veins is transported into nearby ‘guard’ cells by specialized transporters. Credit: Y. Osakabe et al

Plants employ a remarkable range of mechanisms to sense and adapt to their environment and to maintain a strict biochemical balance across cells, tissues and organs. Understanding these mechanisms is crucial to developing crop varieties that can sustain high yields under poor growth conditions.

Through a review of recent discoveries relating to the complex network of signaling pathways associated with drought and salinity responses, Yuriko Osakabe and colleagues from the RIKEN Center for Sustainable Resource Science have drawn attention to several newly identified molecules involved in transport of the plant (ABA).

Central to the response of plants to drought and salinity is the transport of ions, compounds and hormones across cell membranes. The production of ABA is a pivotal component of this response, triggering the closure of pores, called stomata, and activating downstream, stress-related genes.

ABA was previously thought to be a long-distance messenger of stress, traveling from roots to shoots. However, studies now suggest that ABA is produced in the veins of the leaves themselves, where it acts on nearby stomata (Fig. 1). Specialized 'guard' cells, which close and open the stomata, are also able to produce ABA.

Once it enters a cell, ABA initiates a cascade of signals including the phosphorylation of key proteins, which is described by Osakabe and his colleagues as the 'molecular hub' of ABA signaling. Many phosphorylation targets are themselves channels or transporters in the cell membrane, and as a result ABA is able to influence ion transport and pressure inside each cell, known as turgor pressure. The researchers also found that ABA causes the production of that act as 'secondary messengers', regulating the flux of ions such as calcium, and in turn the electrical polarization of the , turgor pressure and guard-cell closure.

Under saline conditions, maintaining internal equilibrium with respect to ions such as sodium and potassium is crucial to plant survival. A number of genes involved in maintaining ion 'homeostasis', such as those in the ABA-controlled pathways, are subject to transcriptional regulation, providing not only tissue-specific expression but also expression in direct response to stress.

An improved understanding of the genes underlying stress-related cellular transport in plants opens the door to genetic modifications that could improve crop yields under drought and high-salinity conditions. "Modern technologies such as genome editing and gene targeting, together with basic cross-breeding, provide us with possible strategies to modify the functions of key genes," notes Osakabe.

Explore further: A new role for cytokinin plant hormones

More information: Osakabe, Y., Yamaguchi-Shinozaki, K., Shinozaki, K. & Tran, L.-S. P. "ABA control of plant macroelement membrane transport systems in response to water deficit and high salinity." New Phytologist 202, 35–49 (2013). DOI: 10.1111/nph.12613

Related Stories

A new role for cytokinin plant hormones

September 9, 2011

When plants, including crops, are exposed to environmental stresses such as drought or high salinity, abscisic acid (ABA), a stress-responsive hormone is synthesized to induce a protective response. At the same time, the ...

On guard against drought

October 28, 2011

Identification of a gene that helps plants to conserve water under drought conditions will bring biologists closer to understanding how plants tolerate drought. Researchers, led by Takashi Kuromori at Japan's RIKEN Plant ...

Improving crop yields in a world of extreme weather events

July 1, 2013

Farmers in the United States witnessed record-breaking extremes in temperature and drought during the last two summers, causing worldwide increases in the costs of food, feed and fiber. Indeed, many climate scientists caution ...

Recommended for you

Genomes uncover life's early history

August 24, 2015

A University of Manchester scientist is part of a team which has carried out one of the biggest ever analyses of genomes on life of all forms.

Rare nautilus sighted for the first time in three decades

August 25, 2015

In early August, biologist Peter Ward returned from the South Pacific with news that he encountered an old friend, one he hadn't seen in over three decades. The University of Washington professor had seen what he considers ...

Why a mutant rice called Big Grain1 yields such big grains

August 24, 2015

(Phys.org)—Rice is one of the most important staple crops grown by humans—very possibly the most important in history. With 4.3 billion inhabitants, Asia is home to 60 percent of the world's population, so it's unsurprising ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.