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Zhu X.-G.,State Key Laboratory of Hybrid Rice | Zhu X.-G.,CAS Shanghai Institutes for Biological Sciences | Zhu X.-G.,University of Illinois at Urbana - Champaign | Wang Y.,CAS Shanghai Institutes for Biological Sciences | And 3 more authors.
Plant, Cell and Environment | Year: 2013

Photosynthesis is arguably the most researched of all plant processes. A dynamic model of leaf photosynthesis that includes each discrete process from light capture to carbohydrate synthesis, e-photosynthesis, is described. It was developed by linking and extending our previous models of photosystem II (PSII) energy transfer and photosynthetic C3 carbon metabolism to include electron transfer processes around photosystem I (PSI), ion transfer between the lumen and stroma, ATP synthesis and NADP reduction to provide a complete representation. Different regulatory processes linking the light and dark reactions are also included: Rubisco activation via Rubisco activase, pH and xanthophyll cycle-dependent non-photochemical quenching mechanisms, as well as the regulation of enzyme activities via the ferredoxin-theoredoxin system. Although many further feedback and feedforward controls undoubtedly exist, it is shown that e-photosynthesis effectively mimics the typical kinetics of leaf CO2 uptake, O2 evolution, chlorophyll fluorescence emission, lumen and stromal pH, and membrane potential following perturbations in light, [CO2] and [O2] observed in intact C3 leaves. The model provides a framework for guiding engineering of improved photosynthetic efficiency, for evaluating multiple non-invasive measures used in emerging phenomics facilities, and for quantitative assessment of strengths and weaknesses within the understanding of photosynthesis as an integrated process. Although the process of photosynthesis from light capture to carbohydrate synthesis has been largely known for some time, a complete dynamic process model representing each discrete step has been lacking. e-Photosynthesis described here provides this platform and is shown to reproduce in silico, quantitatively and qualitatively, responses of leaf gas exchange, electron transport, chlorophyll fluorescence and biochemical fluxes observed in vivo. The model provides a design engineering tool for selecting targets in a system of over 100 potential targets and many thousands of permutations. © 2012 John Wiley & Sons Ltd.

Huang M.,Hunan Agricultural University | Zou Y.,Hunan Agricultural University | Zou Y.,State Key Laboratory of Hybrid Rice | Jiang P.,Hunan Agricultural University | And 4 more authors.
Field Crops Research | Year: 2012

No-tillage (NT) is an alternative cropping system for saving costs and conserving soils relative to conventional tillage (CT). However, NT effects on paddy soil and rice growth are still controversial or not fully understood. A fixed field experiment was conducted to compare soil and crop properties between NT and CT wet-seeded flooded super hybrid rice in Changsha, Hunan Province, China. After 6 years of continuous cropping, NT had higher contents of active organic carbon, NaOH hydrolysable N and NH 4OAc extractable K and higher activities of invertase, urease and acid phosphatase at 0-5cm soil depth, higher bulk density at 5-10cm soil depth, and higher contents of double acid P at 5-10cm and 10-20cm soil depths. NT or associated soil compaction caused an adverse root environment for NT rice at early growth stage, which resulted in a lower capacity of photosynthetic carbon metabolism and consequent reductions in number of tillers and aboveground biomass accumulation before heading. However, no reductions were observed in total aboveground biomass and grain yield in NT rice, because the negative effects of NT or associated soil compaction on aboveground biomass production before heading were compensated for by its positive effects on aboveground biomass accumulation after heading. On one hand, the reduction in growth before heading of NT rice made its population density lower but more suitable during heading to 20 days after heading, which led to a more appropriate leaf area index, a lower leaf senescence and a consequent increase in net assimilation rate. On the other hand, N uptake was delayed in NT rice, which was another critical factor in determining its low leaf senescence. Our study suggests that the negative effects of NT or associated soil compaction on crop growth at early growth stage do not necessarily become concerns in NT wet-seeded flooded rice production. © 2012 Elsevier B.V.

Long S.P.,Urbana University | Marshall-Colon A.,Urbana University | Zhu X.-G.,Chinese Academy of Sciences | Zhu X.-G.,State Key Laboratory of Hybrid Rice
Cell | Year: 2015

Increase in demand for our primary foodstuffs is outstripping increase in yields, an expanding gap that indicates large potential food shortages by mid-century. This comes at a time when yield improvements are slowing or stagnating as the approaches of the Green Revolution reach their biological limits. Photosynthesis, which has been improved little in crops and falls far short of its biological limit, emerges as the key remaining route to increase the genetic yield potential of our major crops. Thus, there is a timely need to accelerate our understanding of the photosynthetic process in crops to allow informed and guided improvements via in-silico-assisted genetic engineering. Potential and emerging approaches to improving crop photosynthetic efficiency are discussed, and the new tools needed to realize these changes are presented. © 2015 Elsevier Inc.

Hu J.,State Key Laboratory of Hybrid Rice
Plant signaling & behavior | Year: 2013

The microRNAs (miRNAs) are a new class of non-protein coding small RNAs that regulate gene expression at the post-transcriptional level in plants. Although thousands of miRNAs have been identified in many plant species, little studies have been reported about chickpea microRNAs. In this study, 28 potential miRNA candidates belonging to 20 families were identified from 16 ESTs and 12 GSSs in chickpea using a comparative genome-based computational analysis. A total of 664 miRNA targets were predicted and some of them encoded transcription factors as well as genes that function in stress response, signal transduction, methylation and a variety of other metabolic processes. These findings lay the foundation for further understanding of miRNA function in the development of chickpea.

Huang M.,Guangxi University | Jiang L.,Guangxi University | Zou Y.,Hunan Agricultural University | Zou Y.,State Key Laboratory of Hybrid Rice | Zhang W.,China National Rice Research Institute
Field Crops Research | Year: 2013

Low temperature often occurs at seedling stage in early rice-growing season in southern provinces of China. However, it is not clear whether the low temperature at seedling stage has an impact on early-season rice quality. This on-farm study was conducted to compare quality and growth traits of an early-season rice cultivar between two contrasting years with respect to temperature at seedling stage, 2009 (normal temperature) and 2010 (low temperature). The results showed that brown rice percentage, milled rice percentage, gelatinization temperature and gel consistency were significantly lower in 2010 than 2009, whereas 2010 had significantly higher percentage of chalky rice grains, degree of chalkiness and protein content than 2009. The yearly difference in rice quality was attributed to variation in rice structure. In 2010, a marked decrease of grain weight was observed, which was not accompanied by a decrease in rice length or width. Source capacity (aboveground biomass accumulation) did not explain the difference in grain weight between 2009 and 2010, because grain-filling rate was comparable in the two years. Shortened grain-filling duration, indirectly caused by the low temperature at seedling stage, was responsible for the decreased grain weight in 2010. These results suggest that low temperature at seeding stage can affect early-season rice quality through its indirect effect on grain-filling duration. © 2012 Elsevier B.V.

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