soil salinity

The hunt for high salt tolerant barley crops gets closer

Barley-(optimised-for-web)

Soil salinity severely impacts crop growth and yield. Within minutes of exposure to salt, cell expansion, leaf expansion, photosynthesis, transpiration and tillering are reduced. When salts accumulate to toxic concentrations in the shoot, especially in older leaves, a secondary inhibition of growth occurs through damage to the plant’s metabolism and ion imbalances. These effects occur weeks to months following salt application.

Plants have evolved numerous mechanisms to detect and respond to the effects of salt stress including a range of signal transduction mechanisms. However, investigating the maintenance of growth under salt stress has been limited by the lack of techniques that allow nondestructive measurements of plant growth through time. The resources and technologies now exist to phenotype many genotypes and identify those with high shoot ion-independent and shoot ion-dependent tolerance under greenhouse conditions.

Barley is one of the more salt-tolerant crops, able to grow in higher concentrations of salt than wheat, rice or maize. However, the growth of barley is still significantly affected by salinity. A better understanding of the genetic variation for salinity tolerance mechanisms within barley cultivars is required for future breeding improvement.

In a study by Stuart Roy and his international collaborators, nondestructive and destructive measurements are used to evaluate the responses of 24 predominately Australian barley (Hordeum vulgare L.) lines at 0, 150 and 250 mM NaCl. Considerable variation for shoot tolerance mechanisms not related to ion toxicity (shoot ion-independent tolerance) was found, with some lines being able to maintain substantial growth rates under salt stress, whereas others stopped growing. Hordeum vulgare spp. spontaneum accessions and barley landraces predominantly had the best shoot ion independent tolerance, although two commercial cultivars, Fathom and Skiff, also had high tolerance. The tolerance of cv. Fathom may be caused by a recent introgression from H. vulgare L. spp. spontaneum.

This study shows that the most salt-tolerant barley lines are those that contain both shoot ion-independent tolerance and the ability to exclude Na+ from the shoot (and thus maintain high K+:Na+ ratios).

Read the full paper, ‘Variation in shoot tolerance mechanisms not related to ion toxicity in barley’, here (Functional Plant Biologyhttps://doi.org/10.1071/FP17049).

To find out how the Australian Plant Phenomics Facility can help facilitate your plant science research visit our website.

Taking the kinks out of curves

In a recent paper, researchers have developed a methodology suitable for analyzing the growth curves of a large number of plants from multiple families. The corrected curves accurately account for the spatial and temporal variations among plants that are inherent to high-throughput experiments.

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An example of curve registration.  a The salinity sensitivity (SS) curves of the 16 functions from an arbitrary family, b SS curves after the curve registration, and c the corresponding time-warping functions. The salinity sensitivity on the y-axis of a and b refers to the derivative of the relative decrease in plant biomass

 

Advanced high-throughput technologies and equipment allow the collection of large and reliable data sets related to plant growth. These data sets allow us to explore salt tolerance in plants with sophisticated statistical tools.

As agricultural soils become more saline, analysis of salinity tolerance in plants is necessary for our understanding of plant growth and crop productivity under saline conditions. Generally, high salinity has a negative effect on plant growth, causing decreases in productivity.  The response of plants to soil salinity is dynamic, therefore requiring the analysis of growth over time to identify lines with beneficial traits.

In this paper the researchers, led by KAUST and including Dr Bettina Berger and Dr Chris Brien from the Australian Plant Phenomics Facility (APPF), use a functional data analysis approach to study the effects of salinity on growth patterns of barley grown in the high-throughput phenotyping platform at the APPF. The method presented is suitable to reduce the noise in large-scale data sets and thereby increases the precision with which salinity tolerance can be measured.

Read the full paper, “Growth curve registration for evaluating salinity tolerance in barley” (DOI: 10.1186/s13007-017-0165-7) here.

Find out how the Australian Plant Phenomics Facility can support your plant science research here.

TPA_KAUSTproject

High-throughput phenotyping in the Smarthouse™ at the Adelaide node of the APPF

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Barley plants growing in the Smarthouse™