Professor Yong-Ling Ruan

Professor Yong-Ling Ruan focuses his research on identifying genetic bottlenecks that limit nutrient resource allocation to, and utilization within, major organs for improving plant fitness, fertility and food and fibre production.

Yong-Ling is a member of ARC College of Experts,  senior editor of Journal of Plant Physiology and editor of Molecular Plant and Frontiers in Plant Science.  He is the founding director of Aust-China Research Centre for Crop Improvement at UON.

He aims to:                      

(i) Elucidate mechanisms by which sugar metabolism, transport & signalling regulate plant development & stress tolerance;

(ii) Identify regulatory genes & pathways that control nutrient distribution between & within plant cells & organs;

(iii) Dissect molecular networks underpinning resource partitioning & reproductive output during evolution & domestication.

Prof Ruan has led his team to a sustained success with findings and insights published in top journals in Plant Biology such as Plant Cell, Nature Plants and Molecular Plant as well as in leading multidisciplinary journals including Nature Genetics and PNAS.  He is the leading and /or senior author for ~85% of all his publications, reflecting the major role he played in the work and his high weight to the citations of his papers.

His group has:

(1) Identified genetic bottlenecks limiting nutrient input into meristematic organs and established a “Ready-Set- Grow” model that provides novel insights into the control of seed & fruit set or their abortion;

(2) Discovered critical roles of invertase- mediated sugar metabolism & signalling in establishing male & female fertility & fiber cell patterning or growth;

(3) Demonstrated that elevation of invertase activity improves leaf longevity & seed yield & confers heat tolerance for fruit set, while enhancing the expression of Sus gene increased cotton fibre yield;

(4) Uncovered (a) roles of plasmodesmatal (PD) gating & coordinated expression of carriers for sugars and K+ in cell elongation and (b) the requirement of sterol homeostasis for maintaining PD function for cell-to-cell communication;

(5) Discovered evolution models of invertases, in which CWINs were co-evolved with seed plants, whereas cytosolic invertases were evolved under strong purifying selection for maintaining sugar homeostasis & cull function.         

The quality and impact of Prof Ruan's research has been internationally recognized as evidenced by, for example, having written multiple invited articles for world renowned Annual Review of Plant Biology and Trends in Plant Science, ranked first and second, respectively, among all 220+ Plant Biology journals. He has organized and/ or chaired many international conferences/ symposia and given invited talks worldwide. 

Key research expertise:

Plant Molecular Cell Biology, Plant Physiology, Gene Technology and Genetic Engineering.

Some highlights from the Ruan lab:

• Discovered contrasting evolutionary models between acid and alkaline invertase genes. The cytoplasmic invertase (CIN, the alkaline invertase) had undergone strong purifying selection and  remained very stable during evolution, probably reflecting its critical role for cellular function and viability. Cell wall invertase (CWIN) was evolved from vacuolar invertase (VIN) during the formation of vascular plants, likely as a functional component for phloem unloading (Wan et al 2018 Trends in Plant Sci).     

• Novel discovery that sterol homeostasis is essential for the opening of plasmodesmata (PD) by degrading callose in the neck region of PD and shutdown PD activates the expression of both energy-dependent and -independent sucrose transporters for cell growth  (Ruan*, Zhang* etc 2017 Plant Cell, * Equal 1st authors).

• First demonstration that vacuolar invertase (VIN) plays critical roles in the formation of both male and female fertility. Discovered that reduced expression of VIN in anthers delayed its dehiscence & decreased pollen viability, whereas suppressed VIN in seed coat resulted in programed cell death (PCD) in the endosperm and embryo (Wang & Ruan 2016 Plant Physiol).

• Discovered that elevation of cell wall invertase (CWIN) in tomato ovaries confers tolerance to moderate heat stress by suppressing PCD in a ROS independent manner, thereby sustaining fruit set under heat (Liu et al 2016 Plant Physiol). The work identified, for the first time, that plant reproductive organs respond to severe and moderate heat stress in ROS-dependent and independent ways, respectively.

• Novel finding that a substantial proportion of in planta (CWIN activity is capped by its inhibitor (INH1) and elevation of endogenous CWIN activity by silencing INH1increases seed weight and fruit sugar levels and delays leaf aging in tomato (Jin et al 2009 Plant Cell). Discovered that phloem-specific expression of CWIN and INH1 mRNAs in tomato fruit is developmentally-induced during ovary-fruit transition with the CWIN exhibiting activity burst during fruit set through posttranslational regulation (Palmer et al 2015 Mol Plant).

• Discovered the potential role of CWIN in endosperm nuclear division (Wang & Ruan 2012 Plant Physiol). This, together with early work on sucrose synthase (Sus; Ruan et al 2003 Plant Cell; 2008 Funct Plant Biol; Pugh et al 2010 Mol Plant), establishes a model where CWIN likely plays regulatory roles in early seed development through sugar signaling whereas Sus involves in late stage of seed development through impact on synthesis of cell wall and storage products (Wang & Ruan 2012 Plant Physiol; Ruan 2014 Annu Rev Plant Biol).

• Identified sucrose availability and its degradation by invertases as major cellular and biochemical bottlenecks for seed and fruit set and disruption of sucrose metabolism could cause abortion under abiotic stress (Ruan et al., 2010 Mol Plant; Ruan et al 2012 Trends Plant Sci; Li et al 2012 J Exp Bot), a view validated recently in our lab (Wang & Ruan 2016, Liu et al 2016 Plant Physiol) 

• Uncovered that VIN regulates cotton fibre and Arabidopsis root elongation through osmotic dependent and independent pathways, respectively (Wang et al 2010 Plant Physiol). Demonstrated that VIN could regulate cell differentiation (fiber initiation) by modulating expression of a subset of transcription factors and auxin signalling genes via sugar signalling (Wang et al 2014 Plant J).

• Dissected roles of Sus in seed maternal and filial tissue. Sus in maternal seed coat is essential for its own growth but not for filial development. By contrast, Sus in the filial tissue is required for both maternal and filial tissues (Ruan et al 1997, 1998 Plant Physiol; Ruan et al 2003 Plant Cell; 2005 J Exp Bot). Over-expression of Sus enhances cotton fibre and seed development (Xu et al 2012 Mol Plant; Jiang et al 2012 Plant Biotech J).

• Identified a novel Sus protein targets to cotton fibre cell wall matrix for intensive cellulose biosynthesis (Brill et al 2011 Plant Physiol).

• Discovered that reversible gating of plasmodesmata, modulated by callose turnover, coordinates plasma membrane sucrose and K+ carriers to control fibre elongation (Ruan et al 2001 Plant Cell; 2004 Plant Physiol). Similarly, developmental closure of symplasmic pathway coordinates expression of plasma membrane hexose carriers in tomato fruit (Ruan & Patrick 1995 Planta; Ruan et al1997 Plant Cell and Environ). Developmental switch of symaplsmic-to-apoplasmic pathways have now been shown to be a common feature in sinks including developing apple fruit and grape berries (e.g. Zhang et al 2006 Plant Physiol).

Teaching Expertise
Course Coordination and teaching roles:

BIOL1003 Professional Skills in Biological Sciences (~200 students).

BIOL2220 Plant Cell and Development (~60 students).

BIOL3330 Plant Development and Physiology (~30 students).

Administrative Expertise
UNIVERSITY EXPERTISE - Head of Biological Science Department/ Discipline, University of Newcastle (2013, 2014). - Director of Australia-China Research Centre for Crop Improvement (2008-). - Leader of Food Innovation Cluster, University of Newcastle (2014-). - Institutional Biosafety Committee Member (2010-2015). - ERA 2015 Cluster 7 Committee (2014-). - SACO, School of Environmental & Life Science (2009). - Biology Honours Committee Member (2010-2014).

PROFESSIONAL ACTIVITIES - Review Grants for top funding Bodies including NSF, USDA; EU, DFG, BILL & MELINDA GATES Foundation; - Review manuscripts for top journals including Plant Cell, Nature, Nature series; - Editorial duties for five international journals including Molecular Plant, Frontiers in Plant Science; Scientific Reports.

Appointed to ARC College of Experts (2019 ~ )

Collaborations
Prof Ruan has established productive and extensive collaborations worldwide, as evidenced by, for example, joint grant applications, co-organizing international conferences and publications of a large number of research papers with co-authors across Europe, North America and the Asia Pacific regions.