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28 March 2014, Volume 21 Issue 2 Previous Issue    Next Issue
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Use of Major Quantitative Trait Loci to Improve Grain Yield of Rice GUO Long-biao1, YE Guo-you2 2014, 21(2): 65-82.  DOI: 10.1016/S1672-6308(13)60174-2 Abstract ( )   PDF (1508KB) ( )   Further improvement of rice productivity remains a challenge. Breeding is perceived as an important option to increase rice yield. However, the genetic progress of grain yield in most rice breeding programs was slow in the last decades. Although great progress in rice genomics and molecular biology has been achieved, the effect of such technological innovations on rice breeding is far small. Marker-assisted selection (MAS) for a few target quantitative trait loci (QTLs) has significant effects in improving qualitative traits, such as disease resistance. The success of MAS has therefore motivated breeders to identify and use major QTLs for yield and yield component traits. In this review, we summarized the recent methods in QTL identification, including novel statistical methods for linkage and association mapping, special population types, and whole-genome sequencing. We reviewed the successful application of marker-assisted gene introgression and gene pyramiding to improve grain yield and discussed the design of efficient MAS schemes to further increase the success rate of breeding programs. The use of well-characterized major QTLs through introgression and gene pyramiding is proven effective in improving grain yield, particularly yield under abiotic stress. Major QTLs that are stable across genetic background and growing environments are often found in less adapted germplasms, such as landraces and wild relatives. Advanced backcross QTL analysis and introgression lines, which integrate QTL discovery and utilization, are important methods for exploiting major QTLs contained in such germplasms. Next-generation sequencing substantially increases mapping resolution and accelerates the identification of casual genes underlying major QTLs. Practical guidelines derived from theoretical and empirical studies are given to guide the design of efficient marker-assisted gene introgression and pyramiding schemes.

Research Paper

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OsPIN1a Gene Participates in Regulating Negative Phototropism of Rice Roots XU Hua-wei, MO Yi-wei, WANG Wei, WANG Hai, WANG Zhong 2014, 21(2): 83-89.  DOI: 10.1016/S1672-6308(13)60168-7 Abstract ( )   PDF (26106KB) ( )   The complete open reading frame of OsPIN1a was amplified through reverse transcriptase- polymerase chain reaction (RT-PCR) based on the sequence deposited in GenBank to explore the relationship between the auxin efflux protein OsPIN1a and the negative phototropism of rice roots. Sequencing results showed that the GC content of OsPIN1a was 65.49%. The fusion expression vector pCAMBIA-1301-OsPIN1a::GFP containing the OsPIN1a gene and a coding green fluorescent protein (gfp) gene was constructed. The fusion vector was transferred into onion epidermal cells by Agrobacterium tumefaciens transformation. The transient expression of OsPIN1a-GFP was mainly located in the nucleus and cell membrane. Moreover, the transgenic plants were obtained by Agrobacterium-mediated genetic transformation. Molecular detection performed by using PCR and β-glucuronidase staining showed that the target construct was integrated into the genome of rice. The negative phototropic curvatures of the transgenic rice roots were higher than those of the wild type. Similarly, the expression levels of OsPIN1a in the transgenic plants were considerably higher than those in the wild-type plants. These results suggest that OsPIN1a is crucial in the negative phototropic curvature of rice roots.

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Genetic Characterization of Indigenous Rice Varieties in Eastern Himalayan Region of Northeast India Baharul Islam CHOUDHURY, Mohammed Latif KHAN, Selvadurai DAYANANDAN 2014, 21(2): 90-98.  DOI: 10.1016/S1672-6308(13)60173-0 Abstract ( )   PDF (64086KB) ( )   The eastern Himalayan region of Northeast (NE) India is home to a large number of indigenous rice varieties, which are traditionally classified as Oryza sativa subspecies indica, japonica or intermediate types. The classification based on traditional Cheng’s index is often inconclusive due to phenotypic plasticity of morphological characters, which are influenced by environmental conditions. We used molecular markers specific for indica and japonica subspecies to assess the degree of genetic relatedness of indigenous rice varieties in NE India. The results revealed that majority of upland (jum) and glutinous rice varieties, traditionally considered as japonica, were genetically close to the subspecies indica. All varieties of boro ecotype were found to be indica type, and only a few varieties cultivated in lowland and upland areas were japonica type. Some of the lowland varieties of the sali ecotype were intermediate between indica and japonica, and they showed a closer genetic affinity to O. rufipogon.

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Effects of Water Management, Arsenic and Phosphorus Levels on Rice Yield in High-Arsenic Soil-Water System A. S. M. H. M. TALUKDER, C. A. MEISNER, M.A.R. SARKAR, M. S. ISLAM, K. D. SAYRE 2014, 21(2): 99-107.  DOI: 10.1016/S1672-6308(13)60172-9 Abstract ( )   PDF (83425KB) ( )   Aerobic rice (Oryza sativa L.) cultivation is considered an alternative production system to combat increased water scarcity and arsenic (As) contamination in the food chain. Pot experiments were conducted at the Wheat Research Centre, Dinajpur, Bangladesh to examine the role of water management (WM), As and phosphorus (P) on yield and yield attributes of boro (variety BRRI dhan 29) and aman (variety BRRI dhan 32) rice. A total of 18 treatment combinations of the three levels of As (0, 20 and 40 mg/kg) and P (0, 12.5 and 25.0 mg/kg) and two WM strategies (aerobic and anaerobic) were investigated. Yield attributes were significantly affected by increasing As levels. Grain yields of BRRI dhan 29 and BRRI dhan 32 were reduced from 63.0 to 7.7 and 35.0 to 16.5 g/pot with increasing As application, respectively, indicating a greater sensitivity of BRRI dhan 29 than BRRI dhan 32. Moreover, As toxicity was reduced with aerobic compared to anaerobic WM for all P levels. During early growth stages, phytotoxic symptoms appeared on BRRI dhan 29 and BRRI dhan 32 rice stems with increasing As levels without applying P under anaerobic WM. Under anaerobic and As-contaminated conditions, BRRI dhan 29 was highly susceptible to straighthead, which dramatically reduced grain yields. There were significant relationships between the number of effective tillers per pot and root dry weight, grain yield, and number of fertile and unfertile grains per pot for both BRRI dhan 29 and BRRI dhan 32 (P < 0.001). Our findings indicate that rice could be grown aerobically in As-contaminated areas with a reduced risk of As toxicity and yield loss.

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Multi-Temporal Detection of Rice Phenological Stages Using Canopy Spectrum WANG Lin, ZHANG Fucun, JING Yuanshu, JIANG Xiaodong, YANG Shenbin, HAN Xiaomei 2014, 21(2): 108-115.  DOI: 10.1016/S1672-6308(13)60170-5 Abstract ( )   PDF (2488KB) ( )   Information on rice phenology is essential for yield estimation and crop management. To test the ability of remote sensing in detecting multiple phenological stages, paddy rice canopy spectrum was measured by a hand-held radiometer. Normalized difference vegetation index (NDVI) was calculated from spectrum, and the slope of NDVI was obtained as its difference. We evaluated the response of NDVI and its slope to rice growth with a comparison of two late-season rice cultivars. The results showed that NDVI and its slope curves had distinct variation corresponding to rice development and they could be used as cultivar-independent phenological indicators. The dates of flooding and transplanting, tillering, panicle development, heading and flowering, maturity, harvest stages, and even field management practices, could be deduced from these indicators. ‘NDVI ≤ 0’ could be used as a single threshold for the detection of flooding and transplanting. The largest spike in the curve of the NDVI slope indicated the duration of tillering stage. The next spike corresponded to panicle development. The heading and flowering stage was characterized by the maximum NDVI and the change of NDVI slope from positive to negative. At the maturity stage, NDVI decreased continuously, and its slope fluctuated just below zero. When rice grains were completely mature and ready for harvest, NDVI decline was accelerated. At harvest, NDVI slope reached its minimum value. The distinction between heading and maturity stages was obscure, most likely due to NDVI saturation at high biomass. The study might provide references for paddy rice phenology determination through remote sensing images.

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Influence of Moisture Content, Variety and Parboiling on Milling Quality of Rice Grains Abozar NASIRAHMADI, Bagher EMADI, Mohammad Hossein ABBASPOUR-FARD, Hamid AGHAGOLZADE 2014, 21(2): 116-122.  DOI: 10.1016/S1672-6308(13)60169-9 Abstract ( )   PDF (26329KB) ( )   The effects of moisture content (8%, 10% and 12%), variety (Tarom and Fajr) and parboiling on milling quality of rice as a function of milling recovery (MR), head rice yield (HRY), degree of milling (DOM) and whiteness were investigated. The parboiled grains was prepared with three soaking temperatures of 25 oC, 50 oC and 75 oC and three steaming times of 10, 15 and 20 min. As a result of parboiling, the increasing rates of MR and HRY values were 7.8% and 14.3% for Tarom and 9.8% and 10.0% for Fajr, respectively, and the decreasing rates for DOM and whiteness were 6.6% and 10.8% for Tarom and 6.8% and 10.5% for Fajr, respectively. Moreover, decreasing moisture content to 8% maximized MR (75.8% for Tarom and 74.3% for Fajr) and HRY (65.8% for Tarom and 57.0% for Fajr) while increasing that to 12% revealed maximum values of DOM (6.1% for Tarom and 6.2% for Fajr) and whiteness (24.8% for Tarom and 28.2% for Fajr).

Short Communication

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Introgression of Gene for Non-Pollen Type Thermo-Sensitive Genic Male Sterility to Thai Rice Cultivars TANEE Sreewongchai, WEERACHAI Matthayatthaworn, CHALERMPOL Phumichai, PRAPA Sripichitt 2014, 21(2): 123-126.  DOI: 10.1016/S1672-6308(13)60171-7 Abstract ( )   PDF (3658KB) ( )   For the two-line hybrid rice system, pollen sterility is regulated by recessive gene that responds to temperature. The recessive gene controlling thermo-sensitive genetic male sterility (TGMS) is expressed when the plants are grown in conditions with higher or lower critical temperatures. To transfer tgms gene(s) controlling TGMS to Thai rice cultivars by backcross breeding method, a male sterile line was used as a donor parent while Thai rice cultivars ChaiNat 1, PathumThani 1, and SuphanBuri 1 were used as recurrent parents. The BC2F2 lines were developed from backcrossing and selfing. Moreover, the simple sequence repeat (SSR) markers were developed for identifying tgms gene and the linked marker was used for assisting selection in backcrossing. The identification lines were confirmed by pollen observation. The results showed the success of introgression of the tgms gene into Thai rice cultivars. These lines will be tested for combining ability and used as female parent in hybrid rice production in Thailand.