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PubMed | Hainan University, Chinese Academy of Agricultural Sciences, Nanjing Agricultural University and State Key Laboratory of Hybrid Rice
Type: Journal Article | Journal: Proceedings of the National Academy of Sciences of the United States of America | Year: 2014

Success of modern agriculture relies heavily on breeding of crops with maximal regional adaptability and yield potentials. A major limiting factor for crop cultivation is their flowering time, which is strongly regulated by day length (photoperiod) and temperature. Here we report identification and characterization of Days to heading 7 (DTH7), a major genetic locus underlying photoperiod sensitivity and grain yield in rice. Map-based cloning reveals that DTH7 encodes a pseudo-response regulator protein and its expression is regulated by photoperiod. We show that in long days DTH7 acts downstream of the photoreceptor phytochrome B to repress the expression of Ehd1, an up-regulator of the florigen genes (Hd3a and RFT1), leading to delayed flowering. Further, we find that haplotype combinations of DTH7 with Grain number, plant height, and heading date 7 (Ghd7) and DTH8 correlate well with the heading date and grain yield of rice under different photoperiod conditions. Our data provide not only a macroscopic view of the genetic control of photoperiod sensitivity in rice but also a foundation for breeding of rice cultivars better adapted to the target environments using rational design.


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

The impact of climate warming on rice production has attracted considerable attention. In this study, we (1) analyzed trends in maximum and minimum temperatures and low temperature events from 1980 to 2010 for early season, (2) evaluated relationships between rice-yield attributes and maximum or minimum temperature by using data from field experiments conducted in early seasons of 1991-2004, and (3) compared grain yield among different rice establishment methods by using data from field experiments done in early seasons of two contrasting years (2009 and 2010) with respect to low temperature events in Changde, Hunan Province, China. The results showed that maximum and minimum temperatures in early season increased by 2.2. °C and 2.1. °C, respectively, during the period 1980-2010 and there was a significant relationship between early-rice grain yield and maximum temperature. Grain yield increased by 7% for each 1. °C increase in growing-season maximum temperature. The increase in grain yield with maximum temperature was driven from the increased daily yield rather than growth duration. However, stabilizing growth duration was critical to overcome the potential negative impact of future climate warming on early-rice production. On the other hand, the climate warming did not lead to significant decreases in low temperature events. In the year with low temperature events, direct seeding produced less grain yield than transplanting and seedling throwing by 32% and 23%, respectively. Our study suggests that direct seeding is a high risk establishment method for early-rice production and seedling throwing may be a more satisfactory method of establishing early-rice under current climate change scenarios. © 2013 Elsevier B.V.


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.


Huang M.,Guangxi University | Jiang L.,Guangxi University | Xia B.,Hunan Agricultural University | Zou Y.,Hunan Agricultural University | And 3 more authors.
Australian Journal of Crop Science | Year: 2013

China's super hybrid rice breeding project has developed many new cultivars with great yield potential. However, rice yield depends not only on genotype but also on environment. In 2008 and 2009, field experiments were conducted to compare super hybrid rice grown in Changsha (normal-yielding) and Guidong (high-yielding), Hunan Province, China. Eight super hybrid rice cultivars, namely II-you 084, II-youhang 1, D-you 527, Liangyoupeijiu, Nei-2-you 6, Y-liangyou 1, Zhongzheyou 1 and Zhunliangyou 527, were evaluated in each site. Grain yield and some yield attributes were determined for each cultivar. On the average across cultivars, Guidong produced higher grain yield than Changsha by 18% in 2008 and 41% in 2009. The higher grain yields were mainly attributed to a simultaneous increase in sink and source. For the sink, Guidong had both more panicles per m2 and larger panicle size (spikelets per panicle) than Changsha, which resulted in larger sink size (spikelets per m2). For the source, Guidong produced greater biomass than Changsha. Longer growth duration, more tillers (panicles) per m2 and higher biomass per unit tiller height were responsible for the greater biomass production in Guidong. Liangyoupeijiu and Zhunliangyou 527 performed well in both sites. Liangyoupeijiu was characterized by large panicle size, while Zhunliangyou 527 had high spikelet filling percentage and grain weight. Our study suggests that further improvement in both sink and source should be possible in the normal-yielding subtropical environments if new rice cultivars are to be bred by selection for tillering (tiller number and size), and developing cultivars with high spikelet filling percentage and grain weight may also be a feasible approach to achieve high rice yield.


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.


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.


Xing J.,Central South University | Xing J.,State Key Laboratory of Hybrid Rice | Jia Y.,Dale Bumpers National Rice Research Center | Correll J.C.,University of Arkansas | And 4 more authors.
Plant Disease | Year: 2013

The Pi-ta gene deployed in southern U.S. rice germplasm is effective in preventing the infection by strains of Magnaporthe oryzae isolates that carry the avirulence (AVR) gene AVR-Pita1. In the present study, 169 isolates from rice (Oryza sativa) cultivars, with and without Pi-ta, were analyzed for their genetic identity using an international differential system, repetitive element-based polymerase chain reaction (Rep- PCR), and sequence analysis of PCR products of AVR-Pita1. These isolates belong to the races IA1, IB1, IB17, IC1, and IC17 of M. oryzae. These isolates were further classified into 15 distinct groups by Rep-PCR. There was a predominant group within each race. Pathogenicity assays on 'Katy' (Pi-ta) and 'M202' (pi-ta) rice determined that IC1 was virulent to Katy and M202; IB17, IC17, and most of IA1 and IB1were avirulent to Katy and virulent to M202, suggesting that the Pi-ta gene in Katy is responsible for preventing infection by these isolates. Consistently, AVR-Pita1 was not amplified from 28 virulent isolates. One AVR-Pita1 allele was amplified by AVR-Pita1-specific primers in 78 avirulent isolates. Interestingly, different AVR-Pita1 alleles were found in each of the 12 avirulent isolates, as determined by DNA sequencing. Sequence analysis of 90 PCR products revealed 10 AVR-Pita1 haplotypes, 4 of which were new. In total, 12 amino acid changes were identified in the new variants when compared with the first described AVR-Pita sequence (AF207841). The finding of isolates with altered AVR-Pita1 from rice cultivars with and without Pi-ta suggests that these virulent isolates were adapted to the field environments in the southern United States. Further research will be needed to verify this prediction.


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.


Zhou H.,South China Agricultural University | Zhou M.,CAS Institute of Genetics and Developmental Biology | Yang Y.,University of Chinese Academy of Sciences | Li J.,State Key Laboratory of Hybrid Rice | And 20 more authors.
Nature Communications | Year: 2014

Thermosensitive genic male-sterile (TGMS) lines, which are male-sterile at restrictive (high) temperatures but male-fertile at permissive (low) temperatures, have been widely used in breeding two-line hybrid rice (Oryza sativa L.). Here we find that mutation of thermosensitive genic male sterile 5 (tms5) in rice causes the TGMS trait through a loss of RNase Z S1 function. We show that RNase Z S1 processes the mRNAs of three ubiquitin fusion ribosomal protein L40 (Ub L40) genes into multiple fragments in vitro and in vivo. In tms5 mutants, high temperature results in increased levels of Ub L40 mRNAs. Overaccumulation of Ub L40 mRNAs causes defective pollen production and male sterility. Our results uncover a novel mechanism of RNase Z S1-mediated Ub L40 mRNA regulation and shows that loss of this regulation produces TGMS in rice, a finding with potential applications in hybrid crop breeding.

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