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28 May 2022, Volume 29 Issue 3 Previous Issue    Next Issue
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Letter

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Effect of Roasting Temperature on Production of Functional Wild-Rice Tea and Factors Influencing Purchase Intention Towards Wild-Rice Tea Hyun Yi Jung, Kyoung Rim Han, Geon Lee, Joong Kyun Kim 2022, 29(3): 197-200.  DOI: 10.1016/2022.01.008 Abstract ( )   HTML ( )   PDF (5323KB) ( )

Review

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Rice Germination and Its Impact on Technological and Nutritional Properties: A Review Lucas Ávila do Nascimento, Abhilasha Abhilasha, Jaspreet Singh, Moacir Cardoso Elias, Rosana Colussi 2022, 29(3): 201-215.  DOI: 10.1016/j.rsci.2022.01.009 Abstract ( )   HTML ( )   PDF (8158KB) ( )   Grain germination is a process involving numerous factors that influence the biochemical processes inside the plant cells. This review covered the abiotic factors that lead to the germination and significantly impact the nutritional properties and digestion behavior of rice grains. The macro- and micro-nutrients can be changed depending on the intensity of the applied variables during germination. For instance, germination time can increase the protein content in the grain and concurrently reduce its protein digestibility. In most cases, the number of bioactive compounds present in rice grains are increased regardless of germination conditions. Germination can promote the complexation of nutrients and thus negatively interfere with the digestibility of macronutrients. This review highlighted the influence of the germination process on the nutritional quality of rice grains, providing information about the germination conditions and their impacts on the anabolic and catabolic reactions of the grain, emphasizing the health benefits.

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Conservation and Utilization of Genetic Resources of Wild Rice in China Yang Ziyi, Xu Zhijian, Yang Qingwen, Qiao Weihua 2022, 29(3): 216-224.  DOI: 10.1016/j.rsci.2021.08.003 Abstract ( )   HTML ( )   PDF (3767KB) ( )   The abundant genetic resources of wild rice in China represent a key gene pool for modern rice breeding, contributing to food production and agricultural development in China and worldwide. Between the 1970s and the 2010s, two national wild rice surveys were carried out in China. More than 20 000 accessions of three species Oryza rufipogon, O. officinalis and O. meyeriana have been conserved ex situ. An in situ conservation system has also been set up to protect notable and endangered populations. This review summarized the geographical distribution of wild rice in China, the current status of conservation, the discovery of elite genes, and the application of research into the origin and domestication of rice.

Research Paper

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Nucleus-Encoded Thylakoid Protein, OsY3IP1, Confers Enhanced Tolerance to Saline and Alkaline Stresses in Rice Hyeran Moon, Young-Ah Kim, Ryoung Shin, Chang-Jin Park 2022, 29(3): 225-236.  DOI: 10.1016/j.rsci.2021.08.004 Abstract ( )   HTML ( )   PDF (3083KB) ( )   Abiotic stress confers serious damage to the photosynthetic machinery, often resulting in plant growth inhibition. Hypothetical chloroplast open reading frame 3 (Ycf3)-interacting protein 1 (Y3IP1) is a nucleus-encoded thylakoid protein and plays an essential role in the assembly of photosystem I. The full-length cDNA over-expresser (FOX) gene-hunting system is an approach using systemically generated gain-of-function mutants. Among the FOX-rice lines, a line CE175 overexpressing rice Y3IP1 gene (OsY3IP1) displayed less inhibition of root growth under saline (NaCl) stress. The expression of OsY3IP1 was up-regulated under saline and alkaline (Na2CO3) stresses in the rice variety Kitaake. After saline and alkaline treatments, transgenic Kitaake overexpressing OsY3IP1-GFP (OsY3IP1-GFPox/Kit) displayed higher levels of chlorophyll content compared to Kitaake. Under the stress conditions, the maximum quantum yield of photosystem II photochemistry levels was higher in OsY3IP1-GFPox/Kit than in Kitaake. The increased tolerance conferred by OsY3IP1 overexpression correlated with reduced reactive oxygen species accumulation. Our data provide new insights into the possible role of OsY3IP1 in the pathway suppressing photooxidative damage under stress conditions. These features can be further exploited to improve saline and alkaline tolerances of rice plants in future.

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NRL3 Interacts with OsK4 to Regulate Heading Date in Rice Chen Wei, Cai Yicong, Shakeel Ahmad, Wang Yakun, An Ruihu, Tang Shengjia, Guo Naihui, Wei Xiangjin, Tang Shaoqing, Shao Gaoneng, Jiao Guiai, Xie Lihong, Hu Shikai, Sheng Zhonghua, Hu Peisong 2022, 29(3): 237-246.  DOI: 10.1016/j.rsci.2022.01.010 Abstract ( )   HTML ( )   PDF (3737KB) ( )   NRL3 is essential for the growth and development of rice leaves. In this study, we found that the loss function of NRL3 also delayed heading date under natural long daylight and short daylight conditions. The yeast two-hybrid and the bimolecular fluorescence complementation proved that NRL3 interacts with OsK4, a Snf1-related kinase. OsK4 localized to the nucleus and expressed in various rice tissues. The rhythmic expression pattern of OsK4 was similar to NRL3 under long daylight and short daylight conditions. Knock-out mutants of OsK4 exhibited early heading under long daylight conditions, indicating that it acts as a negative regulator of heading date in rice. Interestingly, the OsK4 mutant under the nrl3 mutant background rescued the late heading phenotype of nrl3 under long daylight conditions, suggesting that OsK4 functions downstream of NRL3. Moreover, both NRL3 and OsK4 controlled heading date through regulating the expression of Hd3a and RFT1 genes. These findings shed light on the heading date regulation in rice and provide a sound theoretical base to improve regional adaptability of rice.

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OsABT, a Rice WD40 Domain-Containing Protein, Is Involved in Abiotic Stress Tolerance Chen Eryong, Shen Bo 2022, 29(3): 247-256.  DOI: 10.1016/j.rsci.2021.07.012 Abstract ( )   HTML ( )   PDF (46665KB) ( )   Plant growth and crop productivity are severely affected by abiotic stress on a global scale. WD40 repeat-containing proteins play a significant role in the development and environmental adaptation of eukaryotes. In this study, OsABT, a stress response gene, was cloned from rice (Oryza sativa L. cv. Nipponbare). OsABT encodes a protein containing seven WD40 domains. Expression analysis revealed that the OsABT gene was first up-regulated and then down-regulated following treatment with abscisic acid (ABA) and NaCl, but was down-regulated when treated with PEG8000. Subcellular localization results showed that OsABT was located in the cytoplasm and nucleus of Arabidopsis roots. OsABT transgenic Arabidopsis showed significantly increased tolerance to ABA and salt stress during plant seedling development. However, the transgenic lines were more sensitive to drought stress. Moreover, OsABT can interact with OsABI2, a component of ABA signaling pathway. These results showed that OsABT plays a positive regulatory role in response to salt stress and a negative role in response to drought stress in Arabidopsis.

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Poaceae Orthologs of Rice OsSGL, DUF1645 Domain-Containing Genes, Positively Regulate Drought Tolerance, Grain Length and Weight in Rice Liu Kai, Li Minjuan, Zhang Bin, Yin Xuming, Xia Xinjie, Wang Manling, Cui Yanchun 2022, 29(3): 257-267.  DOI: 10.1016/j.rsci.2021.11.001 Abstract ( )   HTML ( )   PDF (12490KB) ( )   Grain yield is a polygenic trait that can be influenced by environmental factors and genetic compositions at all plant growth stages. Currently, the molecular mechanisms behind the coordination of the interaction between grain yield-related traits remain unknown. In this study, we characterized the function of four STRESS_tolerance and GRAIN_LENGTH (OsSGL) Poaceae ortholog genes that are transcribed into DUF1645 domain-containing proteins in relation to the grain length, grain weight, and drought stress-tolerance of rice. The transgenic plants with overexpressing or heterologous high levels of Poaceae OsSGL ortholog genes exhibited longer grain size than the wild type plants. Larger cells were seen in panicles of the four transgenic lines with paraffin sectioning and scanning electron microscopy analyses. In addition, four Poaceae OsSGL ortholog genes positively affected the drought tolerance of rice. Four transgenic plants displayed higher resistance to drought stress at the seedling and vegetative stages. RNA-sequencing and qRT-PCR results indicated that over- or heterologous-expression of four Poaceae OsSGL ortholog genes also affected the transcriptome of rice plants. These genes may play a role in auxin and cytokinin biosynthesis and their transduction pathways. Taken together, these results suggested that the four OsSGL orthologs have a conserved function in the regulation of stress-tolerance and cell growth by modulating hormonal biosynthesis and signaling.

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Three Genes Related to Trehalose Metabolism Affect Sclerotial Development of Rhizoctonia solani AG-1 IA, Causal Agent of Rice Sheath Blight Wang Chenjiaozi, Zhao Mei, Shu Canwei, Zhou Erxun 2022, 29(3): 268-276.  DOI: 10.1016/j.rsci.2021.09.004 Abstract ( )   HTML ( )   PDF (44514KB) ( )   Trehalose metabolism is related to the sclerotial development of Rhizoctonia solani AG-1 IA, the causal agent of rice sheath blight (RSB). Here, we further elucidated the functions of three genes Rstre, Rstps1 and Rstpp that encode three key enzymes trehalase (TRE), alpha, alpha-trehalose- phosphate synthase (TPS1) and trehalose 6-phosphate phosphatase (TPP) in the sclerotial development of R. solani AG-1 IA. Due to the lack of a stable genetic transformation system for R. solani, the heterologous expression of these three genes in Pichia pastoris GS115 was performed. The results showed that reactive oxygen species (ROS) contents and enzyme activities in R. solani decreased significantly in the treatments of the fermentation broths of Rstps1 and Rstpp transformants, and that in the treatment of the fermentation broth of Rstre transformant visibly increased. Furthermore, the fermentation broths of the transformants of all the three genes were added to potato dextrose agar (PDA) medium for the cultivation of R. solani, as a result, the dry weight of sclerotia in each PDA plate containing the fermentation broths of Rstps1 and Rstpp transformants significantly increased compared with the control, and that of Rstre transformant obviously decreased. Finally, 178 proteins were found to interact with RSTPS1, and 16 of them were associated with ROS. Taken together, the findings suggest that all these three genes related to trehalose metabolism play important roles in the sclerotial development of R. solani AG-1 IA, and can be used as new targets for the development of novel high-efficiency fungicides for the controlling of RSB.

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Dissecting Genetic Basis of Deep Rooting in Dongxiang Wild Rice Nie Yuanyuan, Xia Hui, Ma Xiaosong, Lou Qiaojun, Liu Yi, Zhang Anling, Cheng Liang, Yan Longan, Luo Lijun 2022, 29(3): 277-287.  DOI: 10.1016/j.rsci.2021.11.002 Abstract ( )   HTML ( )   PDF (4651KB) ( )   Deep rooting is an important trait in rice drought resistance. Genetic resources of deep-rooting varieties are valuable in breeding of water-saving and drought-resistant rice. In the present study, 234 BC2F7 backcross introgression lines were derived from a cross of Dongye 80 (an accession of Dongxiang wild rice as the donor parent) and R974 (an indica restorer line as the recurrent parent). A genetic linkage map containing 1 977 bin markers was constructed by ddRADSeq for QTL analysis. Thirty-one QTLs for four root traits (the number of deep roots, the number of shallow roots, the total number of deep roots and the ratio of deep roots) were assessed on six rice chromosomes in two environments (2020 Shanghai and 2021 Hainan). Two of the QTLs, qDR5.1 and qTR5.2, were located on chromosome 5 in a 70-kb interval. They were detected in both environments. qDR5.1 explained 13.35% of the phenotypic variance in 2020 Shanghai and 12.01% of the phenotypic variance in 2021 Hainan. qTR5.2 accounted for 10.88% and 10.93% of the phenotypic variance, respectively. One QTL (qRDR2.2) for the ratio of deep roots was detected on chromosome 2 in a 210-kb interval and accounted for 6.72% of the phenotypic variance in 2020. The positive effects of these three QTLs were all from Dongxiang wild rice. Furthermore, nine and four putative candidate genes were identified in qRDR2.2 and qDR5.1/qTR5.2, respectively. These findings added to our knowledge of the genetic control of root traits in rice. In addition, this study will facilitate the future isolation of candidate genes of the deep-rooting trait and the utilization of Dongxiang wild rice in the improvement of rice drought resistance.

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Carbon and Nitrogen Footprints of Major Cereal Crop Production in China: A Study Based on Farm Management Surveys Xu Chunchun, Chen Zhongdu, Ji Long, Lu Jianfei 2022, 29(3): 288-298.  DOI: 10.1016/j.rsci.2021.11.003 Abstract ( )   HTML ( )   PDF (2216KB) ( )   Greenhouse gas (GHG) emissions and reactive nitrogen (Nr) releases are central environmental problems, which are closely linked to climate change, environmental ecology and crop production. Sustainable development of agriculture plays an important role in GHG emissions and Nr loss. The life cycle assessment (LCA) method was used to calculate the product and farm carbon footprints (CFs) and nitrogen footprints (NFs) in rice, wheat and maize production in China based on farm survey data. The results pinpointed that the CFs of rice, wheat and maize were 0.87, 0.30 and 0.24 kg/kg. Meanwhile, the computed NFs were 17.11, 14.26 and 6.83 g/kg, respectively. Synthetic nitrogen fertilizer applications and methane (CH4) emissions were dominant CF sources, while ammonia (NH3) volatilization was the main NF contributor. Moreover, significant decreases in CF and NF by 20%-54% and 33%-61%, respectively, were found in large-size farms (> 20 hm2) when compared to small-size farms (< 0.7 hm2). Furthermore, the significantly positive relationships between CF and NF indicated the potential for simultaneous mitigation in the regions with high agricultural inputs, like amounts of fertilizer. Based on our results, some effective solutions would be favorable toward mitigating climate change and eutrophication of the major cereal crop production in China, especially optimizing fertilizer use and farm machinery operation efficiencies, as well as developing large-size farms with intensive farming.