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10 May 2020, Volume 34 Issue 3 Previous Issue    Next Issue
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Reviews and Special Topics

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Current Status on Research and Utilization of Colored Rice Wenjian SONG, Zhong MEI, Yu LI, Wenhua XIA, Xiaoli SHU, Dianxing WU, Shufang MEI 2020, 34(3): 191-207.  DOI: 10.16819/j.1001-7216.2020.9137 Abstract ( )   HTML ( )   PDF (874KB) ( )   Colored rice is beautiful and edible. It can provide a new way for merging agriculture, tourism, education and culture together. Breeding and studying edible and ornamental colored rice can promote the combination of agriculture and tourism and the development of creative agriculture. In this paper, we summarized the germplasm improvement, major types, mutation mechanism, representative utilization of colored rice, and proposed the possible development trends of the colored rice in the future.

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Advances in the Effects of the Ability of Axillary Bud Germination on Grain Yield in Ratoon Rice Hao WANG, Qiang ZHANG, Wendi ZHANG, Siyu LI, Jian HUANG, An ZHU, Lijun LIU 2020, 34(3): 205-216.  DOI: 10.16819/j.1001-7216.2020.9097 Abstract ( )   HTML ( )   PDF (453KB) ( )   Ratoon rice can make full use of heat and light resources. It has the advantage of two harvests with one sowing, and it can increase multiple cropping index and grain yield per unit area, which has great importance to rice production and food security in our country. The effective panicle number plays a vital role in the yield formation in ratoon rice, which depends on the germination ability of regeneration buds. Therefore, improving the axillary bud germination ability of ratoon rice holds the key to increasing rice yield in regenerative season. In this paper, we outlined the current research advances in the mechanism of axillary bud germination and the influencing factors of the germination ability as well as the technical measures to improve axillary bud germination ability. We also proposed the research highlights in the future on enhancing axillary bud germination. It will lay a theoretical basis for higher yield in ratoon rice.

Research Papers

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Allelic Effects on Eating and Cooking Quality of SSⅡa and PUL Genes Under Wxmp Background in Rice Shu YAO, Yadong ZHANG, Yanqing LIU, Chunfang ZHAO, Lihui ZHOU, Tao CHEN, Qingyong ZHAO, Zhen ZHU, PILLAY Balakrishna, Cailin WANG 2020, 34(3): 217-227.  DOI: 10.16819/j.1001-7216.2020.9120 Abstract ( )   HTML ( )   PDF (1120KB) ( )   【Objective】Our aim is to analyze the genetic effects of soluble starch synthase gene SSⅡa and debranching enzyme gene PUL on eating and cooking quality under the same main gene background of Wxmp, so as to lay a theoretical basis for rice quality improvement. 【Method】In this study, a semi-glutinous rice line Ning 0145 and japonica rice variety Wuyunjing 21 were crossed to obtain F2 population and F3 lines. There was polymorphism in soluble starch synthase gene SSⅡa and debranching enzyme gene PUL but no polymorphism in other starch synthase related genes between the two parents. With molecular markers, some F2 plants and F3 lines containing Wxmp gene were selected and divided into four genotypes, SSⅡanPULn, SSⅡanPULw, SSⅡawPULnand SSⅡawPULw(n and w indicated that the genes were contributed by Ning 0145 and Wuyunjing 21, respectively). The allelic effects of SSⅡa and PUL genes on eating and cooking quality under the same Wxmp gene background was investigated by analyzing the eating and cooking quality and its differences among different genotypes. 【Result】There were significant differences for eating and cooking quality among genotypes of different parental origins. The allelic gene SSⅡaw and PULw from Wuyunjing 21 increased amylose content by 0.29%-1.00% and 0.62%-1.18% respectively, and the effect of PUL was greater than that of SSⅡa. There was interaction between SSⅡa and PUL genes. The SSⅡaw and PULw genes also decreased gel consistency and breakdown viscosity, increased hot paste viscosity, cool paste viscosity, setback viscosity and consistency viscosity, but had little effect on gelatinization temperature, peak viscosity and peak time. 【Conclusion】The genetic effects of SSⅡa and PUL genes on cooking and eating quality of rice under the background of Wxmp gene were clarified. The results lay a theoretical basis for improving rice quality by molecular marker-assisted selection of SSⅡa and PUL genes.

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Effects of Different Combinations of Wx and ALK Main Alleles on Rice Grain Quality Zhuanzhuan CHEN, Yong YANG, Linhao FENG, Ye SUN, Changquan ZHANG, Xiaolei FAN, Qianfeng LI, Qiaoquan LIU 2020, 34(3): 228-236.  DOI: 10.16819/j.1001-7216.2020.9140 Abstract ( )   HTML ( )   PDF (801KB) ( )   【Objective】Rice eating and cooking qualities are mainly controlled by two key genes, Wx and ALK. There are multiple alleles of both genes among rice cultivars. In this study, our aim is to clarify the effects of the main allelic variation combinations of Wx and ALK genes on rice grain quality.【Method】Three main alleles of Wx (Wxa, Wxb and wx) and two of ALK (ALKa and ALKc) were combined within a series of near-isogenic lines (NILs) in the japonica Nipponbare (Nip) background. The effects of different allelic combinations on grain quality were determined by measuring the physical and chemical characteristics of NILs.【Result】Gelatinization temperature (GT) was regulated by the major gene ALK and the minor gene Wx. Under the same ALK allele background, there was no significant difference in GT between rice lines carrying wx and Wxb alleles, but the GT of Nip-Wxa rice lines was significantly lower than that of Nip-Wxb and Nip-wx. The starch viscosity was greatly affected by the combination of Wx and ALK alleles. The breakdown value of Nip-Wxa rice line was lower and the setback value was higher (lower tasting value) than those of Nip-Wxb and Nip-wx. Under the same Wx allele background, ALK allelic variation mainly affected the pasting temperature of RVA curve, but had little effect on breakdown value and setback value. Nip-Wxa/ALKa and Nip-Wxa/ALKc rice grains had poor tasting value due to the high AC and breakdown value and low GC. But the protein content in above two NILs was higher than other rice lines. Nip-wx/ALKa and Nip-Wxb/ALka rice grains had better tasting value of hot cooked and cooled cooked rice due to the moderate AC, GC and protein content, as well as lower GT. Although the GT of Nip-Wxb/ALKc grains was higher, the moderate AC and high GC of this line resulted in a slight decrease in the tasting value of cooled cooked rice compared with hot cooked rice. The tasting value of hot cooked rice of Nip-wx/ALKc rice remained the same as those of Nip-wx/ALKa, Nip-Wxb/ALKa and Nip-Wxb/ALKc, but the tasting value of cooled rice decreased dramatically because of its high GT. 【Conclusion】Amylose content (AC) and gel consistency (GC) were mainly controlled by Wx gene; while ALK gene had no significant effect on AC, but a slight effect on GC.

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Effects of Phosphate Starvation Responses Gene OsSQD2.1 on Growth in Rice Lu LIU, Chuanshan XU, Yafei SUN, Zhi HU, Hao AI, Xiuli LIU, Xiaowen WANG, Shubin SUN 2020, 34(3): 237-244.  DOI: 10.16819/j.1001-7216.2020.9074 Abstract ( )   HTML ( )   PDF (1183KB) ( )   【Objective】This work aims at confirming the effects of gene OsSQD2.1, involved in phosphate starvation responses on rice growth so as to reveal its function. 【Method】The bioinformatics method was used to determine the OsSQD2.1 gene and its protein structure and the cis-acting elements on the OsSQD2.1 promoter. The expression of OsSQD2.1 under different deficiency conditions was measured by real-time PCR. For an insight into the effects of OsSQD2.1 on the growth and photosynthesis of transgenic plants, we determined the phenotype, phosphorus content and net photosynthetic rate of DNA insertion mutants and silencing interfering materials at different growth stages. 【Result】The coding region of the OsSQD2.1 gene is 3548 bp in length and it is located on chromosome 1, with 11 exons and 10 introns. OsSQD2.1 belongs to the glycosyltransferase family; OsSQD2.1 promoter contains multiple reported cis-acting elements responsive to phosphorus deficiency; OsSQD2.1 was induced by phosphorus deficiency and inhibited by sulfur deficiency. Compared with the wild type, the shoot length and primary root length during the vegetative growth period in the mutant or silencing materials were significantly lower than the wild type. During the reproductive growth, the plant height as well as 1000-grain weight of the mutant or silencing material was significantly lower than that of wild type, and there was no significant difference in seed setting rate; The total phosphorus contents in the leaves were not significantly different in the wild type under the phosphorus deficiency condition. In addition, the net photosynthetic rate of the seedling and mature mutants was significantly lower than that of the wild type, and it was presumed that OsSQD2.1 affected the net photosynthetic rate of rice. 【Conclusion】The results confirm that OsSQD2.1 is phosphorus deficiency-responsive and affects rice growth.

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Comparative Transcriptome Analysis of Transgenic Rice Line Carrying the Rice Blast Resistance Gene Pi9 Zhaomeng XU, Lihua LI, Xiaoqing GAO, Zhengjie YUAN, Xin LI, Xudan TIAN, Lanlan WANG, Shaohong QU 2020, 34(3): 245-255.  DOI: 10.16819/j.1001-7216.2020.9126 Abstract ( )   HTML ( )   PDF (1601KB) ( )   【Objective】The purpose of the study is to analyze the mechanism behind Pi9 gene-mediated rice blast resistance at the transcriptional level, and to lay a theoretical basis for breeding disease-resistant rice cultivars. 【Method】Rice cultivar Nipponbare (NPB) and NPB-transgenic line carrying the Pi9 rice blast resistance gene (NPB/Pi9) were inoculated with Magnaporthe oryzae. Leaf tissues were sampled at 0 h, 12 h, 24 h, and 36 h after inoculation, respectively. Gene-chip transcriptome analysis of 12503 rice genes was performed using the rice samples, and the microarray data were verified by qRT-PCR of a set of differentially expressed genes (DEGs). 【Result】7754 DEGs were identified by comparing the gene expression levels in the resistant NPB/Pi9 line at 12 h, 24 h and 36 h after inoculation, respectively, to that at 0 h after inoculation. Accordingly, 7385 DEGs were identified in the susceptible rice NPB at the same time points. At 36 h after inoculation, the DEG number of NPB/Pi9 was significantly higher than that of NPB. 4065 DEGs were identified by comparing the gene expression levels in NPB/Pi9 and NPB at the same time points; there were significantly more DEGs at 36 h after inoculation than at 0 h, 12 h or 24 h after inoculation. Therefore, NPB/Pi9 exhibited more intensive defense responses to Magnaporthe oryzae. Gene Ontology (GO) and KEGG analyses were carried out on the DEGs between NPB/Pi9 and NPB at the same time points. The GO terms classifications related to extracellular regions, plant response to stimuli, transcriptional regulation, redox activity, ion binding activity, secondary metabolism and plant hormones were significantly enriched for the time points post inoculation. The KEGG pathways of phenylalanine metabolism, flavonoid biosynthesis and plant hormone signaling were enriched significantly at the time points post inoculation. Distinctive gene expression patterns were observed between NPB/Pi9 and NPB at the same time points for the genes of the effector-triggered immunity (ETI) related salicylic acid signaling pathway and chitinase, and the PAMP-triggered immunity (PTI) related extracellular regions, response to stimuli, and lignin biosynthesis. Moreover, distinctive gene expression patterns were observed between NPB/Pi9 and NPB at the same time points for the genes of WRKY transcription factors, MAPK kinases, jasmonate and ethylene signaling pathways that were utilized by both PTI and ETI. Based on all the results, the differential expression patterns between NPB/Pi9 and NPB are related to ETI and PTI, which are involved with each other and play important roles in the Pi9-mediated rice blast rice resistance. 【Conclusion】 Compared with NPB, the resistant genotype NPB/Pi9 showed more intensive defense responses against Magnaporthe oryzae. Transcription factors, kinases, NBS-LRR genes, chitinases, salicylic acid-, jasmonic acid-, and ethylene-signaling pathways, and plant secondary metabolism play important roles in Pi9 gene-mediated rice blast resistance.

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Phosphorus Accumulation Characteristics of Medium-maturity Yongyou japonica/indica Hybrid Rice After Transplanting and Its Modeling Tianyao MENG, Jialin GE, Xubin ZHANG, Huanhe WEI, Guisheng ZHOU, Qigen DAI 2020, 34(3): 256-265.  DOI: 10.16819/j.1001-7216.2020.9098 Abstract ( )   HTML ( )   PDF (1036KB) ( )   【Objective】This study was conducted to quantitatively describe the dynamic changes of phosphorus accumulation of medium-maturity japonica/indica hybrids (MJIH) after transplanting based on simulation equations. 【Method】Yongyou 2640 and Yongyou 1640 were used as the test materials, and the japonica conventional rice (JC) cultivar Yangjing 4038 and Yangjing 4227, and indica hybrid rice (IH) Xinliangyou 6380 and Yangliangyou 6 were used as controls to study phosphorus accumulation characteristics after transplanting, and the differences in phosphorus uptake and utilization characteristics after transplanting among different rice types were compared. 【Result】Grain yield and total phosphorus accumulation at maturity of MJIH were both significantly higher than JC and IH. Compared with JC and IH, MJIH had higher grain phosphorus accumulation, while lower phosphorus grain productivity. MJIH showed lower phosphorus translocation from leaf after heading compared with JC and IH, and its phosphorus translocation from stem after heading fell in between. Gompertz equation was used to simulate phosphorus accumulation after transplanting of MJIH, while logistic equations for JC and IH. MJIH showed higher maximum nitrogen accumulation rate than JC and IH. The maximum phosphorus accumulation rate of MJIH was observed at 50–52 d after transplanting, 59–60 d after transplanting for JC, and 61–63 d for IH, respectively. Compared with JC and IH, MJIH had higher phosphorus accumulation at the middle and late stages, while lower phosphorus accumulation at the early stage. The higher phosphorus accumulation at the middle and late stages of MJIH was attributed to its longer duration and higher accumulation rate, relative to JC and IH. 【Conclusion】Our results indicated that compared with JC and IH, MJIH had superior grain yield and total phosphorus accumulation. The advantage in phosphorus accumulation of MIJH over JC and IH was seen at the middle and late stages, mainly owing to its longer duration and higher accumulation rate.

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Effects of Reducing and Postponing Nitrogen Application on Population Quality and Grain Yield of japonica Rice Under Paddy-upland Crop Rotations in Yunnan Plateau Qiongmei XIA, Jiaquan HU, Linbo DONG, Wenjuan QIAN, Yongfu HE, Guiyong LI, Ruiping LONG, Haiping ZHU, Congdang YANG 2020, 34(3): 266-277.  DOI: 10.16819/j.1001-7216.2020.9091 Abstract ( )   HTML ( )   PDF (1580KB) ( )   ：【Objective】The objective is to study the effect of reducing and postponing nitrogen application from earlier stage to later stage on population quality and yield, and to improve the nitrogen utilization efficiency for japonica rice on paddy-upland crop rotation in Yunnan Province.【Method】With two conventional japonica rice varieties(Huijing 17 and Chujing 28) as materials, a field plot experiment was carried out at six nitrogen application levels (270 kg/hm2, 243 kg/hm2, 216 kg/hm2, 189 kg/hm2 and 162 kg/hm2 with the corresponding basal, tillering, spikelet-promoting and spikelet-sustaining nitrogen ratios of 5:5:0:0, 3:3:2:2, 2.5:2.5:2.5:2.5, 0:2:5:3, 0:0:6:4, 0:0:0:0).【Result】The yield, over 8 t/hm2 at zero nitrogen fertilizer level in 2016 and 2017, increased significantly with rising nitrogen application level. As compared with conventional fertilization treatment (270 kg/hm2 and 5:5:0:0), with the increasing ratio of spikelet-promoting fertilizer while reduced total nitrogen application rate, an increasing trend was observed in yield and nitrogen agronomic efficiency. The optimum treatment was a reduction of 40% in nitrogen application rate. With the reduction of nitrogen application rate, the yield increased by more than 20% and the nitrogen agronomic efficiency increased from less than 10 kg/kg to more than 20 kg/kg. After reducing and postponing nitrogen application from earlier stage to later stage, the period of young panicle differentiation was prolonged. With longer functional leaves, the ordinal number of leaf length from the top of 2-3-1-4, the efficient leaf area ratio more than 80%, and appropriate leaf area index at full heading stage, the high photosynthetic efficient population formed, which promoted the differentiation of spikelets. At the same time, the panicle-bearing tiller percentage increased, with a higher population growth rate and dry matter accumulation after heading. 【Conclusion】Optimizing the nitrogen fertilizer management can effectively reduce the application amount of nitrogen fertilizer in paddy field and improve grain yield and the utilization rate of nitrogen fertilizer of japonica rice in Yunnan. Among them, spikelet-promoting nitrogen fertilizer application with zero basal-tiller fertilizer in the rice growing season required the least input but generated the most output.

Experimental Technique

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Absolute Quantification of Proteins in Rice Leaf Based on Multiple Reaction Monitoring Mass Spectrometry Mingxue CHEN, Huan YANG, Zhaoyun CAO, Youning MA, Zhenzhen CAO, Fangmin CHENG 2020, 34(3): 278-286.  DOI: 10.16819/j.1001-7216.2020.9056 Abstract ( )   HTML ( )   PDF (1531KB) ( )   【Objective】An absolute quantitative method for proteins in rice leaf based on multiple reaction monitoring (MRM) mass spectrometry was established.【Method】The proteins in rice leaf were extracted with PBS buffer containing 1.0% sodium dodecyl sulfate(SDS), purified by acetone precipitation, and then digested by Trypsin. The enzymatic hydrolysate was separated by liquid chromatography, monitored by MRM mass spectrometry and quantified by external standard method.【Results】The addition of 1.0% SDS to the extraction buffer enhanced the extraction effect of 16 kinds of target proteins and total proteins in rice leaf. Total proteins precipitation with several solvents varied significantly (P<0.05), and the precipitation ability from strong to weak was acetonitrile>acetone>isopropanol>methanol>ethanol. Acetone performed best in the precipitation effect of 16 kinds of target proteins, followed by isopropanol and acetonitrile, and methanol and ethanol represented the worst precipitants. The relative standard deviations of the method were all less than 14% in three orders of magnitude range, with the quantification limit from 0.1 to 2.5 nmol/L, and the contents of 16 kinds of proteins in rice leaf during the grain filling stage ranged from 6.0 to 2818.1 μg/g.【Conclusion】SDS could significantly improve the extraction effect of proteins in rice leaf. Acetone and acetonitrile addition generated excellent precipitation effects of proteins, with slight difference in various proteins. Combined with MRM mass spectrometry technology, the absolute quantification method for proteins in rice leaf is featured by wide-linear range, high sensitivity and good repeatability.