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28 January 2022, Volume 29 Issue 1 Previous Issue    Next Issue
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Cold Plasma: A Potential Alternative for Rice Grain Postharvest Treatment Management in Malaysia Mohd Fadthul Ikmal Misnal, Norizah Redzuan, Muhamad Nor Firdaus Zainal, Norhayati Ahmad, Raja Kamarulzaman Raja Ibrahim, Linda Agun 2022, 29(1): 1-15.  DOI: 10.1016/j.rsci.2021.12.001 Abstract ( )   HTML ( )   PDF (22024KB) ( )   Use of pesticides, herbicides and fertilizers is among the techniques to control insect pests and fungal pathogens. However, the technique is the major contributor to severe environmental implications in terms of air, water and soil pollution. Besides, variable inconsistency becomes an important issue in the implementation of inclined bed dryers, leading to significant rice grain loss. Cold plasma technology has been widely proposed as a potential alternative for rice grain postharvest treatment management due to the presence of generated ionised gas that eventually produces reactive oxygen species or reactive nitrogen species. These species are used to decontaminate foodborne pathogens, mycotoxins and bacterial diseases. This review explores the current literature regarding cold plasma treatment technology, focusing on its efficiency as the microbial decontamination medium and insect pest mortality medium, and on the enhancement functional, nutritional and cooking properties, especially in rice grains. Previous studies have successfully demonstrated the ability of cold plasma treatment to significantly reduce the microbial count of foodborne pathogens, detoxify mycotoxins, and control seedborne rice seedling bacterial diseases. Previous studies have also proved that the implementation of cold plasma technology in postharvest management should be seriously considered for improving rice grain quantity and quality in Malaysia.

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Rice Drying, Storage and Processing: Effects of Post-Harvest Operations on Grain Quality Amanda Müller, Marcela Trojahn Nunes, Vanessa Maldaner, Paulo Carteri Coradi, Rosana Santos de Moraes, Samuel Martens, Andressa Fernandes Leal, Vladison Fogliato Pereira, Cristielle König Marin 2022, 29(1): 16-30.  DOI: 10.1016/j.rsci.2021.12.002 Abstract ( )   HTML ( )   PDF (54595KB) ( )   PDF（mobile） (868KB) ( 19 )   Various post-harvest processes of rice are commonly employed, especially during the off-season, to ensure its consumption feasibility, which often affect the grain quality. Different forms of drying, storage and processing of rice are evaluated to identify their effects on grain quality. Microwave drying has emerged as an alternative to the widely-used intermittent-drying and fixed-bed-dryer methods of drying paddy rice. Control of drying-air temperatures (between 40 ºC and 60 ºC) according to the rice variety can improve quality, especially for exotic varieties. Keeping stored grain in hygroscopic balance, with water content between 11% to 15%, at temperatures between 16 ºC and 20 ºC and with intergranular relative humidity near 60%, allows 12 months of storage in a controlled environment without significant deterioration. Other innovations, notably the application of artificial refrigeration to grain stored in bulk in vertical cylindrical silos and the use of impermeable packaging for storage, ensure the conservation of grain mass. The different stages and equipments used to obtain polished, brown and parboiled rice result in significant changes in the nutritional value of rice because of the removal of the outermost layers of the grains. Polishing reduces the nutritional value and physical homogeneity of rice. Brown rice retains more bioactive compounds and nutrients because it does not lose the outer layer of the grains in the polishing processes. Parboiled rice, although less nutritious than brown rice, has better grain integrity and milling yield and less loss of nutrients than white rice.

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Diversity of Sodium Transporter HKT1;5 in Genus Oryza Shalini Pulipati, Suji Somasundaram, Nitika Rana, Kavitha Kumaresan, Mohamed Shafi, Peter Civáň, Gothandapani Sellamuthu, Deepa Jaganathan, Prasanna Venkatesan Ramaravi, S. Punitha, Kalaimani Raju, Shrikant S. Mantri, R. Sowdhamini, Ajay Parida, Gayatri Venkataraman 2022, 29(1): 31-46.  DOI: 10.1016/j.rsci.2021.12.003 Abstract ( )   HTML ( )   PDF (87964KB) ( )   PDF（mobile） (1694KB) ( 14 )   Asian cultivated rice shows allelic variation in sodium transporter, OsHKT1;5, correlating with shoot sodium exclusion (salinity tolerance). These changes map to intra/extracellularly-oriented loops that occur between four transmembrane-P loop-transmembrane (MPM) motifs in OsHKT1;5. HKT1;5 sequences from more recently evolved Oryza species (O. sativa/O. officinalis complex species) contain two expansions that involve two intracellularly oriented loops/helical regions between MPM domains, potentially governing transport characteristics, while more ancestral HKT1;5 sequences have shorter intracellular loops. We compared homology models for homoeologous OcHKT1;5-K and OcHKT1;5-L from halophytic O. coarctata to identify complementary amino acid residues in OcHKT1;5-L that potentially enhance affinity for Na+. Using haplotyping, we showed that Asian cultivated rice accessions only have a fraction of HKT1;5 diversity available in progenitor wild rice species (O. nivara and O. rufipogon). Progenitor HKT1;5 haplotypes can thus be used as novel potential donors for enhancing cultivated rice salinity tolerance. Within Asian rice accessions, 10 non-synonymous HKT1;5 haplotypic groups occur. More HKT1;5 haplotypic diversities occur in cultivated indica gene pool compared to japonica. Predominant Haplotypes 2 and 10 occur in mutually exclusive japonica and indica groups, corresponding to haplotypes in O. sativa salt-sensitive and salt-tolerant landraces, respectively. This distinct haplotype partitioning may have originated in separate ancestral gene pools of indica and japonica, or from different haplotypes selected during domestication. Predominance of specific HKT1;5 haplotypes within the 3 000 rice dataset may relate to eco-physiological fitness in specific geo-climatic and/or edaphic contexts.

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UvWhi2 Is Required for Stress Response and Pathogenicity in Ustilaginoidea virens Meng Shuai, Qiu Jiehua, Xiong Meng, Liu Zhiquan, Jane Sadhna Jagernath, Lin Fucheng, Shi Huanbin, Kou Yanjun 2022, 29(1): 47-54.  DOI: 10.1016/j.rsci.2021.12.004 Abstract ( )   HTML ( )   PDF (7028KB) ( )   PDF（mobile） (1010KB) ( 4 )   Some stress response-related genes have been identified in Ustilaginoidea virens, but it is not clear whether and how defects of stress responses affect the pathogenesis processes of U. virens. In this study, we identified a general stress response factor UvWHI2 as a homolog of Saccharomyces cerevisiae Whi2 in U. virens. The relative expression level of UvWhi2 was significantly up-regulated during infection, suggesting that UvWHI2 may be involved in pathogenesis. Furthermore, knockout of UvWhi2 showed decreased mycelial growth, increased conidiation in the potato sucrose medium and a defect in pathogenicity. In addition, the RNA-Seq and phenotypic analysis showed that UvWHI2 was involved in response to oxidative, hyperosmotic, cell wall stress and nutrient limitation. Further studies revealed that the defects of stress responses of the ∆Uvwhi2 mutant affected the formation of secondary spores on the nutrient limited surface and the rice surface, resulting in a significant reduction of pathogenicity of U. virens. Our results suggest that UvWHI2 is necessary for fungal growth, stress responses and the formation of secondary spores in U. virens. In addition, the defects of stress responses can affect the formation of secondary spores on the rice surface, and then compromise the pathogenicity of U. virens.

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Fine Mapping of QTLs for Stigma Exsertion Rate from Oryza glaberrima by Chromosome Segment Substitution Tan Quanya, Zhu Haitao, Liu Hui, Ni Yuerong, Wu Shengze, Luan Xin, Liu Junwei, Yang Weifeng, Yang Zifeng, Zeng Ruizhen, Liu Guifu, Wang Shaokui, Zhang Guiquan 2022, 29(1): 55-66.  DOI: 10.1016/j.rsci.2021.12.005 Abstract ( )   HTML ( )   PDF (36856KB) ( )   PDF（mobile） (1357KB) ( 5 )   Stigma exsertion is an important trait for outcrossing ability in rice. Stigma exsertion rate (SER) of male sterile lines (MSLs) is a key factor affecting F1-seed production in hybrid rice. In this study, seven QTLs for SER were detected on five chromosomes using a set of single-segment substitution lines (SSSLs) derived from O. glaberrima. Three of the QTLs were mapped in the estimated intervals of 92.5-333.0 kb. qSER-5 was located in a substitution segment of 92.5 kb. qSER-1b and qSER-8b were respectively limited to 333.0 kb and 107.5 kb by secondary substitution mapping. qSER-1b and qSER-3 had bigger additive effects of 11.5% and 11.9%, respectively, while the other five QTLs had smaller additive effects from 5.7% to 8.6%. Open reading frames were identified in the regions of qSER-5 and qSER-8b in O. sativa and O. glaberrima genomes. Fine mapping of the QTLs laid a foundation for the cloning of genes, and QTLs for SER will be used to develop MSLs with strong ability of outcrossing.

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Simple Bioassay for PAMP-Triggered Immunity in Rice Seedlings Based on Lateral Root Growth Inhibition Wang Rui, Zhang Dandan, Li Shengnan, Gao Jinlan, Han Liebao, Qiu Jinlong 2022, 29(1): 67-75.  DOI: 10.1016/j.rsci.2021.12.006 Abstract ( )   HTML ( )   PDF (4866KB) ( )   PDF（mobile） (790KB) ( 18 )   Pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) is an essential layer of plant disease resistance. Robust bioassays for PTI are pre-required to dissect its molecular mechanism. In this study, we established that lateral root growth inhibition as a simple and robust measurement of PTI in rice seedlings. Specifically, flg22, a well-characterized PAMP from bacterial flagellin, was used to induce PTI in rice seedlings. While flg22 treatment induced PR gene expression and mitogen-activated protein kinase activation in the roots of rice seedlings to support the PTI triggered, this treatment substantially repressed lateral root growth, but it did not alter primary root growth. Moreover, treatments with chitin (i.e., a fungal PAMP) and oligogalacturonides (i.e., classical damage-associated molecular pattern) clearly inhibited the lateral root growth, although a priming step involving ulvan was required for the chitin treatment. The bioassay developed was applicable to various rice cultivars and wild species. Thus, lateral root growth inhibition represents a simple and reliable assay for studying PTI in rice plants.

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Ionomic Profiling of Rice Genotypes and Identification of Varieties with Elemental Covariation Effects Zhang Chengming, Nobuhiro Tanaka, Maria Stefanie Dwiyanti, Matthew Shenton, Hayato Maruyama, Takuro Shinano, Chu Qingnan, Xie Jun, Toshihiro Watanabe 2022, 29(1): 76-88.  DOI: 10.1016/j.rsci.2021.12.007 Abstract ( )   HTML ( )   PDF (77529KB) ( )   PDF（mobile） (196KB) ( 0 )   Ionomic profiles are primarily influenced by genetic and environmental factors. Identifying ionomic responses to varietal effects is necessary to understand the ionomic variations among species or subspecies and to potentially understand genetic effects on ionomic profiles. We cultivated 120 rice (Oryza sativa) varieties to seedling stage in identical hydroponic conditions and determined the concentrations of 26 elements (including 3 anions) in the shoots and roots of rice. Although the subspecies effects were limited by the genus Oryza pre-framework and its elemental chemical properties, we found significant differences in ionomic variations in most elements among the aus, indica and japonica subspecies. Principal component analysis of the correlations indicated that variations in the root-to-shoot ionomic transport mechanisms were the main causes of ionomic differences among the subspecies. Furthermore, the correlations were primarily associated with the screening of varieties for elemental covariation effects that can facilitate breeding biofortified rice varieties with safe concentrations of otherwise toxic elements. The japonica subspecies exhibited the strongest elemental correlations and elemental covariation effects, therefore, they showed greater advantages for biofortification than the indica and aus subspecies, whereas indica and aus subspecies were likely safer in metal(loid) polluted soils. We also found that geographical and historical distribution significantly defined the ionomic profiles. Overall, the results of this study provided a reference for further association studies to improve the nutritional status and minimize toxicity risks in rice production.

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Nitrogen Deep Placement Combined with Straw Mulch Cultivation Enhances Physiological Traits, Grain Yield and Nitrogen Use Efficiency in Mechanical Pot-Seedling Transplanting Rice Li Lin, Zhang Zheng, Tian Hua, Umair Ashraf, Yousef Alhaj Hamoud, Al Aasmi Alaa, Tang Xiangru, Duan Meiyang, Wang Zaiman, Pan Shenggang 2022, 29(1): 89-100.  DOI: 10.1016/j.rsci.2021.12.008 Abstract ( )   HTML ( )   PDF (5245KB) ( )   PDF（mobile） (995KB) ( 12 )   To assess the effects of straw return coupled with deep nitrogen (N) fertilization on grain yield and N use efficiency (NUE) in mechanical pot-seedling transplanting (MPST) rice, the seedlings of two rice cultivars, i.e., Yuxiangyouzhan and Wufengyou 615 transplanted by MPST were applied with N fertilizer at 150 kg/hm2 and straw return at 6 t/hm2 in early seasons of 2019 and 2020. The experiment comprised of following treatments: CK (no fertilizer and no straw return), MDS (deep N fertilization and straw return), MBS (broadcasting fertilizer and straw return), MD (deep N fertilization without straw return), MB (broadcasting fertilizer without straw return). Results depicted that the MDS treatment significantly increased the rice yield by 41.69%?72.22% due to total above-ground biomass, leaf area index and photosynthesis increased by 54.70%?55.80%, 38.52%?52.17% and 17.89%?28.40%, respectively, compared to the MB treatment. In addition, the MDS treatment enhanced the total N accumulation by 37.74%?43.69%, N recovery efficiency by 141.45%?164.65%, N agronomic efficiency by 121.76%? 134.19%, nitrate reductase by 46.46%?60.86% and glutamine synthetase by 23.56%?31.02%, compared to the MB treatment. The average grain yield and NUE in both years for Yuxiangyouzhan were higher in the MDS treatment than in the MD treatment. Hence, deep N fertilization combined with straw return can be an innovative technique with improved grain yield and NUE in MPST in South China.