Australian Centre for Plant Functional Genomics publications

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Browsing Australian Centre for Plant Functional Genomics publications by Author "Bacic, A."

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    Cell wall modifications in maize pulvini in response to gravitational stress
    (Amer Soc Plant Physiologists, 2011) Zhang, Q.; Pettolino, F.; Dhugga, K.; Rafalski, J.; Tingey, S.; Taylor, J.; Shirley, N.; Hayes, K.; Beatty, M.; Abrams, S.; Zaharia, L.; Burton, R.; Bacic, A.; Fincher, G.; Australian Centre for Plant Functional Genomics (ACPFG)
    Changes in cell wall polysaccharides, transcript abundance, metabolite profiles, and hormone concentrations were monitored in the upper and lower regions of maize (Zea mays) pulvini in response to gravistimulation, during which maize plants placed in a horizontal position returned to the vertical orientation. Heteroxylan levels increased in the lower regions of the pulvini, together with lignin, but xyloglucans and heteromannan contents decreased. The degree of substitution of heteroxylan with arabinofuranosyl residues decreased in the lower pulvini, which exhibited increased mechanical strength as the plants returned to the vertical position. Few or no changes in noncellulosic wall polysaccharides could be detected on the upper side of the pulvinus, and crystalline cellulose content remained essentially constant in both the upper and lower pulvinus. Microarray analyses showed that spatial and temporal changes in transcript profiles were consistent with the changes in wall composition that were observed in the lower regions of the pulvinus. In addition, the microarray analyses indicated that metabolic pathways leading to the biosynthesis of phytohormones were differentially activated in the upper and lower regions of the pulvinus in response to gravistimulation. Metabolite profiles and measured hormone concentrations were consistent with the microarray data, insofar as auxin, physiologically active gibberellic acid, and metabolites potentially involved in lignin biosynthesis increased in the elongating cells of the lower pulvinus.
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    Genetic variation in the root growth response of barley genotypes to salinity stress
    (C S I R O Publishing, 2013) Shelden, M.; Roessner, U.; Sharp, R.; Tester, M.; Bacic, A.; Australian Centre for Plant Functional Genomics (ACPFG)
    We aimed to identify genetic variation in root growth in the cereal crop barley (Hordeum vulgare L.) in response to the early phase of salinity stress. Seminal root elongation was examined at various concentrations of salinity in seedlings of eight barley genotypes consisting of a landrace, wild barley and cultivars. Salinity inhibited seminal root elongation in all genotypes, with considerable variation observed between genotypes. Relative root elongation rates were 60–90% and 30–70% of the control rates at 100 and 150 mM NaCl, respectively. The screen identified the wild barley genotype CPI71284–48 as the most tolerant, maintaining root elongation and biomass in response to salinity. Root elongation was most significantly inhibited in the landrace Sahara. Root and shoot Na+ concentrations increased and K+ concentrations decreased in all genotypes in response to salinity. However, the root and shoot ion concentrations did not correlate with root elongation rates, suggesting that the Na+ and K+ concentrations were not directly influencing root growth, at least during the early phase of salt stress. The identification of genetic diversity in root growth responses to salt stress in barley provides important information for future genetic, physiological and biochemical characterisation of mechanisms of salinity tolerance.