The Future Science Leaders is a series of seminars that will run as a part of the QAAFI Science Seminar Series through out the year. These seminars are dedicated to showcasing early-career and student researchers. Each seminar will feature two students, from two different areas of research to encourage inter-disciplinary discussion across industries. 

Wheat endosperm cell walls: from isolation to a model
Ghanendra Gartaula, Centre for Nutrition and Food Sciences

The cell walls of cereal endosperms are a major source of fibre in diets, and wheat is one of the largest cereal crops grown and consumed worldwide. Whilst the composition and properties of cell walls from wheat flour have been extensively studied, less is known about starchy endosperm cell walls. Cell walls were isolated from both pure endosperm and milled flour, and compared structurally and chemically. 13C solid-state NMR in conjunction with methylation analysis, before and after acetic/nitric acid treatment, showed that, in addition to arabinoxylan (AX) and (1, 3; 1, 4)-β-glucan (MLG), wheat endosperm cell walls contain a significant proportion of cellulose (ca 20%) which is tightly bound to xylans and mannans. Microscopy showed that the cellulose was relatively evenly distributed across the grain endosperm. It was also found that the cell walls contain a fibrous acid-resistant structure laminated by matrix polysaccharides, as revealed by AFM imaging. A quantitative model for wheat endosperm cell wall’s structural organisation is proposed based on a network of cellulose and interacting non-cellulosic polysaccharides which anchors AX (with very occasional diferulic acid cross-linking) that in turn retains MLG through physical entanglement.

MicroRNA control of phase change in tropical/subtropical tree crops
Umair Ahsan, Centre for Horticultural Sciences

Unlike annual plants, horticultural tree crops are characterized by a long vegetative juvenile phase. This is an impediment to crop breeding and delays return-on-investment, as productivity depends on attaining reproductive phase. In the annual herb Arabidopsis thaliana, vegetative to reproductive phase transition is regulated by two microRNAs: miR156 and miR172. The high abundance of miR156 is implicated in juvenility by downregulating SQUAMOSA promoter binding protein-like (SPL) genes as well as miR172, while miR172 promotes flowering by downregulating members of the APETALA2-like gene family. In horticultural trees, such as avocado (Persea americana), mango (Mangifera indicia) and macadamia Macadamia integrifolia, a possible role for these microRNAs in phase transition has not been comprehensively investigated. In this study, the activity of miR156 and mir172, and their putative targets was quantified in these tree species over development. Youngest fully expanded leaves were collected from seed-grown trees at distinct ages, from one month to >10 years old.
The abundance of miR156 was highest in young seedlings of all species, and was downregulated at the mature/flowering stage. This downregulation occurred much earlier for macadamia and mango (within 6 months), than for avocado (>1.5 years). These results are consistent with findings in annual plants and suggests miR156 may play a role in vegetative identity in these crops. On the other hand, miR172 abundance remained largely unchanged over time, except in avocado where its expression was low in seedlings and high in mature/flowering trees, consistent with Arabidopsis. Target gene quantification (SPL4, SPL9 and AP2) revealed that SPL4 was anticorrelated with miR156, while SPL9 and AP2 showed varied expression patterns with little anticorrelation to microRNAs. Taken together, this data suggests a conserved role for the miR156: SPL4 module in phase transition between annual species and these horticultural tree crops.

About the speakers

Ghanendra Gartaula - Centre for Nutrition and Food Sciences

Ghanendra Gartaula is a final year PhD Student with Prof Mike Gidley at QAAFI Centre for Nutrition and Food Sciences, the University of Queensland. He is working on a project funded by ARC Centre of Excellence in Plant Cell Walls, aimed at increasing the swelling capacity of wheat endosperm cell walls. After his PhD, he wants to contribute more to the field of grain science, especially dietary fibres and starch and their role in satiety and physiological benefits.

Umair Ahsan - Centre for Horticultural Science
Umair Ahsan is a current HDR student at QAAFI, working on molecular aspects of phase transition/flowering in horticultural tree crops under Small tree high productivity initiative.
He has completed MS in Genetics from Istanbul while BS in Agriculture from the University of Agriculture Faisalabad Pakistan.
His previous research work includes working in Aarhus University Denmark on Candidate gene identification in Lotus japonicus using insertional mutagenesis and genetic mapping. While his research work in BOKU Vienna Austria was focused on “virus-induced gene silencing and phenotyping for resistance against Fusarium head blight in Wheat”.


About QAAFI Science Seminar Series

Queensland Alliance for Agriculture & Food Innovation (QAAFI) has been hosting a high-profile weekly seminar series across the disciplines of agriculture, food and nutrition science since 2014. With a range of speakers from Australia and abroad, the series explores how high-impact science will significantly improve the competitiveness and sustainability of the tropical and sub-tropical food, fibre and agribusiness sectors.

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Level 3 Qld Bioscience Precinct Building 80, St Lucia
Large Seminar Room (3.142)