Browsing by Author "Pierre, J"

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Delivering a novel DNA-based diagnostic for root health to the sugar industry: final report 2015/042
(Sugar Research Australia Limited, 2017) Pierre, J
Plant root systems play many key roles including nutrients and water uptake, interface with soil microorganisms and resistance to lodging. Unfortunately, as for any other crop, large and systematic studies of sugarcane root systems have always been hampered by the opaque and solid nature of the soil. In recent years, methods for efficient extraction of DNA from soil and for species-specific DNA amplification have been developed. Such tools could be adapted for sugarcane and have the potential to greatly improve root phenotyping and health diagnostic capability in sugarcane. In this report, we present a fast and efficient method for the quantification of live sugarcane root mass in soil samples. First we demonstrated that this test is sensitive and specific to sugarcane. Then we established a universal calibration for the test to convert root DNA quantity to live root mass. Finally we validated our test on field samples and used it to answer the question of the fate of the root system after harvest. There we demonstrated that, two weeks after harvest, the sugarcane roots are still alive. It raises the question of the role that the former root system plays in the performance of the following crop and demonstrates how this test can be used to answer research question or to monitor crop root health.
Sugarcane root systems for increased productivity; development and application of a root health assay : final report 2015/002
(Sugar Research Australia Limited, 2018) Rae, A; Pierre, J
A better understanding of the sugarcane root system has the potential to improve productivity and overcome soil constraints. By adapting the digital methods that have been developed in other crops, we have developed a toolkit of reliable methods that enable analysis of large numbers of root samples. These methods have been used to provide a baseline understanding of the range and variation of root parameters for sugarcane, including root/shoot ratios, root opening angle, root length, proportion of fine roots, branching density, average diameter and diameter in each size class. We found a consistently high proportion of fine roots, but there was genetic variation for many other key traits amongst current commercial lines. Importantly, there were no significant reductions in root system size or quality in modern varieties compared to older varieties. The methods and baseline were then applied to test the response to stresses encountered in Australian growing environments. When comparing plants with or without YCS symptoms, we found no differences in root system structure, despite significant reductions in shoot mass. Limiting growth by removal of tillers or by restricting nitrogen availability identified plasticity in specific root traits that enabled the plants to adapt to the restrictions. Root system distribution by depth, and relative allocation of resources to the root system showed adaptations to stress while root angle appeared to be stable. With the new methods and knowledge of trait plasticity, we can now start to test which traits provide a benefit in various agronomic situations and develop an integrated understanding of root health which can be used to monitor soil health and promote the adoption of better agronomic practices.