Parental Rice Research Articles

Genomic atlases of introgression and differentiation reveal breeding footprints in Chinese cultivated rice

The long history of cultivation and breeding has left a variety of footprints in the genomes of Asian cultivated rice (Oryza sativa L.). In this study, we focus on two types of genomic footprints, introgression and differentiation, in a population of more than 1200 Chinese rice accessions. We found that a Xian/indica and a temperate Geng/japonica accession respectively contained an average of 19.3-Mb and 6.8-Mb alien introgressed chromosomal segments, of which many contained functional sequence variants, quantitative trait loci, or genes controlling flowering, grain, and resistance traits. Notably, we found most introgressions, including the known heterotic loci Hd3a and TAC1, were distributed differentially between the female and male parents of three-line indica hybrid rice, indicating their potential contribution to heterosis. We also found many differentiated regions between subgroups within a subpopulation contained agronomically important loci, such as DTH7, Hd1 for heading date, and qCT7 for cold tolerance, providing new candidates for studying local adaptation or heterosis. Tracing these footprints allows us to better understand the genetic exchange or differentiation underlying agronomic traits in modern Chinese rice cultivars. These findings also provide potential targets for rice genetic research and breeding.

Growth and production of sixth generation of brown rice mutants in a high altitude location

This paper presents the result of an experiment which aimed to determine the growth and production of some 6th generation Sinjai brown rice mutants (M6) in the highlands. The experiment was conducted in an irrigated paddy field with a height of 750 meters above sea level. The arrangement was a randomized block design (RBD). The treatments consisted of 8 brown rice mutant lines (g1, g2, g3, g4, g5, g6, g7, g8) and Sinjai brown rice parent as control (g9). The results showed that the mutant lines g2 and g3 produced the highest grain production of 3.10 tons ha−1 and 3.13 tons ha−1 respectively. Mutant strains g2 and g3 were short in plant height with a high number of productive tillers, flowering age and a faster harvest time, as well as highest grain length. g2 and g3 strains are the most potential lines to be developed in the highlands. The growth character and production components that have a real positive correlation to production per hectare are production per clump and presentation of filled grain per panicle.

Genetic behavior of rice (Oryza sativa) genotypes under normal and infested weed conditions

A field study was conducted at Sakha Agricultural Research Station, Kafr El-Sheikh, Egypt during 2016-17 summer, to estimate general (GCA) and specific (SCA) combining ability effects as well as identify type of gene action controlling the inheritance of the studied traits under normal and infested weed conditions. Seven a diverse rice (Oryza sativa L.) parent’s were crossed using half diallel cross method without reciprocals to produce 21 F1 crosses during 2016 season. The seven parents and their 21 F1 crosses were evaluated under normal and infested weed conditions using a randomized complete block design (RCBD) with three replications during 2017. Highly significant differences were observed among genotypes, parents and crosses for all the studied traits. Moreover, general combining ability (GCA) and specific combining ability (SCA) mean squares were highly significant for all the studied traits under both conditions. The best general combiner for earliness and short stature was Sakha 103 variety. The highest desirable SCA effects were obtained by the crosses; Egyptian Yasmin × Dullar, Sakha 104 × Egyptian Yasmin, Egyptian Yasmin × Rikuto Norin 22 and Giza 177 × Rikuto Norin 22 for flag leaf area, No. of panicles/plant and grain yield/plant. These crosses could be utilized in rice breeding program for improving grain yield trait under normal and infested weed conditions.

Identification of a Novel QTL for Chlorate Resistance in Rice (Oryza sativa L.)

Chlorate resistance analysis is an effective approach commonly used to distinguish the genetic variation between Oryza sativa L. ssp. indica and japonica, and predict the nitrogen use efficiency (NUE). This study aimed at investigating the response of a doubled haploid (DH) population derived from anther culture of 93-11 × Milyang352 exposed to 0.1% potassium chlorate (KClO3) at the seedling stage. The results revealed that the parental rice lines 93-11 (indica) and Milyang352 (japonica) showed distinctive phenotypic responses. The parental line 93-11 scored highly sensitive (0% survival) and Milyang352 scored resistant (66.7% survival) 7 days after treatment. The DH lines reflected the differential phenotypic response observed in parental lines. Interestingly, we identified a novel quantitative trait locus (QTL) for chlorate resistance on chromosome 3 (qCHR-3, 136 cM, logarithm of the odds—LOD: 4.1) using Kompetitive Allele-Specific PCR (KASP) markers. The additive effect (−11.97) and phenotypic variation explained (PVE; 14.9%) indicated that the allele from Milyang352 explained the observed phenotypic variation. In addition, shoot growth showed a significant difference between parental lines, but not root growth. Moreover, in silico analysis identified candidate genes with diverse and interesting molecular and physiological functions. Therefore, this study suggested that the QTL qCHR-3 harbors promising candidate genes that could play a role in the regulation of nitrogen metabolism in rice.

Exogenous Cry1Ab/c Protein Recruits Different Endogenous Proteins for Its Function in Plant Growth and Development.

Current risk assessments of transgenic crops do not take into consideration whether exogenous proteins interact with endogenous proteins and thereby induce unintended effects in the crops. Therefore, the unintended effects through protein interactions in insect-resistant transgenic rice merit investigation. Here, a yeast two-hybrid assay was used to evaluate interactions between Bacillus thuringiensis (Bt) protein-derived Cry1Ab/c insect resistance rice Huahui-1 and the endogenous proteins of its parental rice Minghui-63. The authenticity of the strongest interactions of Cry1Ab/c and 14 endogenous proteins involved in photosynthesis and stress resistance, which may be primarily responsible for the significant phenotypic differences between transgenic Huahui-1 and parental Minghui-63, were then analyzed and validated by subcellular co-localization, bimolecular fluorescence complementation and co-immunoprecipitation. As the exogenous full-length Cry1Ab/c protein was found to have self-activating activity, we cleaved it - into three segments based on its three domains, and these were screened for interaction with host proteins using the yeast two-hybrid assay. Sixty endogenous proteins related to the regulation of photosynthesis, stress tolerance, and substance metabolism were found to interact with the Cry1Ab/c protein. The results of bimolecular fluorescence complementation and co-immunoprecipitation verified the interactions between the full-length Cry1Ab/c protein and 12 endogenous proteins involved in photosynthesis 23KD, G, PSBP, Rubisco, Trx, THF1 and stress resistance CAMTAs, DAHP, E3s, HKMTs, KIN13A, FREE1. We used a combination of yeast two-hybrid, bimolecular fluorescence complementation, and co-immunoprecipitation to identify Cry1Ab/c interacting with rice proteins that seem to be associated with the observed unintended effects on photosynthesis and stress resistance between Huahui-1 and Minghui-63 rice plants, and analyze the possible interaction mechanisms by comparing differences in cell localization and interaction sites between these interactions. The results herein provide a molecular analytical system to qualify and quantify the interactions between exogenous proteins and the endogenous proteins of the recipient crop. It could help elucidate both the positive and negative effects of creating transgenic plants and predict their potential risks as well as net crop quality and yield.

Allelic variations of the Wx locus in cultivated rice and their use in the development of hybrid rice in China.

To make better use of global germplasm resources for improving the eating quality of hybrid rice, using the resequencing data from the 3,000 rice genomes project (3K RGP), the allelic variations of the rice Wx locus were analysed. With the exception of five rare alleles discovered for the first time in our study, most of these alleles were known alleles of Wx. Furthermore, a set of Kompetitive allele-specific PCR (KASP) markers based on these Wx alleles have been developed, and thirty-six main parents of hybrid rice from 1976 to 2018 were selected for Wx genotyping. The results showed that only three Wx alleles existed in the main parents of hybrids, and the allelic combination of the hybrids changed from Wxa/Wxb and Wxlv/Wxb to Wxb/Wxb with the development of hybrid rice. Wxb is widely used in the male parents of hybrid rice. Wxa and Wxlv were used in the female parents of early hybrid rice, and they were gradually replaced by Wxb. In the future, more favourable Wx alleles from cultivated rice should be identified, introduced, and effectively used to improve hybrid rice quality.

Screening Out the Phytochemicals and Colour Values in White and Black Rice Lines and Its Interrelationship

Problem: Kavuni is a traditional black rice variety of Tamil Nadu, India it rich in nutritional and therapeutic properties. These traits it is not being cultivated widely, due to long duration, poor tillering and low yielding agronomic characters.
 Objectives: In the study, twenty three breeding rice lines from the cross between black kavuni and Co 50 were investigated for colour values and phytochemical viz., total phenols content (TPC), total flavonoids content (TFC) and total anthocyanin content (TAC).
 Methods: Twenty five rice samples were grouped as black and white rice based on colour of aleuronic layer by visual inspection. The color values expressed as L* (lightness), a* (redness), b* (yellowness), H° (hue) and C (chroma). TPC by the Folin–Ciocalteu method and expressed as milligram of gallic acid equivalent (mg GAE/g) per g. TFC by aluminum chloride method and expressed as mg catechin equivalent (mg CATE) per 100 g. TAC was measured by pH differential method, expressed as mg cyaniding 3-glucoside per 100 g (c3-glucoside/100 g).
 Main results: The black phenotype rice had low value in L*, b*, C, H° and high values in a* than the white color rice. In the black rice group, 145-6 breeding line had darker black aleuronic layer than other black rice. The TPC, TFC and TAC ranged between 0.74 -3.24 mg GAE/g, 12.79 – 82.58 mg CATE/100 g and 0.4-223.76 mg c3-glucoside/100 g, respectively. High level of TPC, TFC and TAC were recorded in black phenotypic rice, where as lower levels in white rice. The maximum amount of TPC and TAC were observed in 145-6 rice line, which on par with parent black kavuni rice. The maximum level TFC was observed in 144-2 rice line than the parent rice kavuni. The TPC, TFC and TAC were negatively correlated with L*, b*, C and H° values and positively correlated with a* values at 0.01 probability level. Among the 23 rice lines, based on TPC, TAC and TFC the superior breeding rice lines were 145-6 and 144-2 respectively. The results showed that dark black grain has higher phytochemicals than white grain.
 Main recommendation: The results indicate provide the opportunities to further increase the nutritional benefits of some food products from black rice in terms of therapeutic properties.

Chronic toxicity study in Sprague-Dawley rats on transgenic rice T1c-19 with cry1C* gene

In the present study, a novel transgenic rice line T1c-19 carrying cry1C* gene was evaluated in Sprague-Dawley (SD) rats by a 52-week feeding study, aiming at determining its unintended effects. The rice T1c-19 and its parental rice were prepared at a level of up to 60.75% in the growth diet and 66.75% in the maintenance diet, respectively. AIN-93 diet was used as a nutritional control. All the diets were nutritionally balanced. Each group, with 48 rats of both genders, was fed the corresponding diet for 52 weeks. The results of clinical signs, body weight and food consumption of the transgenic rice group were comparable to those of the parental rice group. Clinical measurements were made on weeks 13, 26 and 52, and statistical significances were observed in several hematological and serum biochemical indices between the two rice groups and were not considered as treatment-related. The terminal histopathological examination showed some spontaneous lesions in all groups with no significant difference among them. Taken together, the results of the present 52-week chronic toxicity study of transgenic rice T1c-19 exerted no unintended adverse effects on SD rats.

Screening of eight mutants of Sinjai lokal red rice (Oryza sativa) to salinity stress

The research aimed to determine the growth and tolerance of M7 brown rice mutant lines against stress by application of several doses of NaCl. The research was conducted at the Bio-Science and Biotechnology Laboratory for Plant Production, Agricultural Cultivation, Faculty of Agriculture of Universitas Hasanuddin. It was conducted from October 2018 to February 2019, which was compiled based on 2 factorial design patterns and a randomized block design as it’s environmental design. The first factor consisted of 9 genotypes, i.e. 8 red rice mutant lines namely g1, g2, g3, g4, g5, g6, g7, g8 and one comparison line g9 as red rice parent which was not mutated. The second factor consisted of 4 NaCl dosage levels namely 0 dS/m, 4 dS/m, 8 dS/m, 12 dS/m. The results of the NaCl treatment on several Sinjai local red rice mutant lines show that the g2 genotype had the highest average value on the parameters of the weight of the plants on a fresh and dry condition. It indicated the g2 genotype as a mutant genotype that has tolerance to salinity stress at the vegetative growth phase.

Effects of Pest Management Practices on Soil Nematode Abundance, Diversity, Metabolic Footprint and Community Composition Under Paddy Rice Fields.

The wide-scale adoption of transgenic crops has aroused public concern towards potential impacts to the ecological services of soil fauna, such as soil nematodes. However, few studies has examined whether the cultivation of transgenic rice would pose greater threats to soil nematode community and associated ecological functions than insecticides application. Moreover, what are determinants of soil nematode community in paddy fields remains unclear. During a 3-year field study, rhizosphere soil samples of transgenic-Bt rice, its counterpart non-Bt parental rice and not-Bt rice with insecticides application were taken at four times in the rice developmental cycle using a random block design with three replications for each treatment. We hypothesized that the effects of pest management practice on soil nematode abundance and metabolic footprint change with trophic group and sampling time. We also predicted there were significant differences in structure and composition of soil nematode community across the three treatments examined and sampling times. In agreement with our expectation, the effects of pest management practice on nematode abundance and metabolic footprints depend on trophic group and sampling time. However, pest management practice exerted no apparent effect on nematode diversity and community composition. Soil nutrient availability and C:N molar ratio are the primary regulating factor of soil nematode community in rice paddy fields. In conclusion, our findings implied that changes in abundance, diversity, metabolic footprints associated with the crop growth stage overweighed the application of Bt rice and insecticides. The cultivation of Bt rice Huahui-1 exerted no measurable adverse effect on soil nematode community in rhizosphere soil over 3 years of rice cropping.

Association analysis between constructed SNPLDBs and GCA effects of 9 quality-related traits in parents of hybrid rice (Oryza sativa L.)

BackgroundThe general combining ability (GCA) of parents in hybrid rice affects not only heterotic level of grain yield and other important agronomic traits, but also performance of grain quality traits of F2 bulk population which is the commodity consumed by humans. In order to make GCA improvement for quality traits in parents of hybrid rice by molecular marker assisted selection feasible, genome-wide GCA loci for quality traits in parents were detected through association analysis between the effects of GCA and constructed single nucleotide polymorphism linkage disequilibrium blocks (SNPLDBs), by using unhusked rice grains harvested from F1 plants of 48 crosses of Indica rice and 78 crosses of Japonica rice. GCA-SNPLDBs association analysis.ResultsAmong the 8 CMS and 6 restorer lines of indica rice subspecies, CMS lines Zhenpin A, Zhenshan97 A, and 257A, and restorers Kanghui98, Minghui63 and Yanhui559 were recognized as good general combiners based on their GCA effect values for the 9 quality traits (brown rice rate, milled rice rate, head rice rate, percentage of chalky grains, chalky area size, chalkiness degree, gelatinization temperature, gel consistency and amylose content). Among the 13 CMS and 6 restorer lines of japonica rice subspecies, CMS 863A, 6427A and Xu 2A, and restorers C418, Ninghui8hao and Yunhui4hao showed elite GCA effect values for the 9 traits. GCA-SNPLDB association analysis revealed 39 significant SNPLDB loci associated with the GCA of the 9 quality-related traits, and the numbers of SNPLDB loci located on chromosome 1, 2, 3, 4, 5, 8, 9, 11 and 12 were 1, 4, 3, 9, 6, 5, 5, 4 and 2, respectively. Number of superior GCA alleles for the 9 traits among the 33 parents ranged from 1 to 26.ConclusionsThirty-nine significant SNPLDBs loci were identified associated with the GCA of 9 quality-related traits, and the superior SNPLDB alleles could be used to improve the GCA of parents for the traits in the future by molecular marker assisted selection. The genetic basis of trait GCA in parents is different from that of trait itself.

Enhanced yield performance of transgenic cry1C* rice in saline-alkaline soil

ABSTRACTChina has a large area of saline-alkaline land that can be utilized for the cultivation of transgenic rice. Therefore, the growth and reproductive behavior of transgenic rice are not only a problem for production that needs to be resolved, but also an important aspect of environmental risk assessment for saline alkali soil. In the present study, an insect-resistant transgenic cry1C* rice, T1C-19, was grown in farmland and saline-alkaline soils. The transcription and translation of the exogenous cry1C*, and vegetative and reproductive fitness, such as plant height, tiller number, biomass, filled grain number and weight per plant, were assessed. Our findings indicated that the transcription and translation of exogenous cry1C* gene in T1C-19 rice grown in saline-alkaline soil were lower than that grown in farmland; however, the correlation was not significant. The vegetative and reproductive growth abilities of T1C-19 were lower than that of the parental rice, Minghui63 (MH63), in farmland. In alkaline-saline soil, except for tiller number and biomass, there were no significant differences between T1C-19 and MH63 in other vegetative indices. In contrast, the reproductive indices of T1C-19 were significantly higher than those of MH63. The results suggested that T1C-19 had a strong reproductive capacity, and significantly reduced the loss of yield caused by insects, thereby leading to a higher yield than that of MH63 grown in saline-alkaline soils. This may promote the cultivation of saline-alkaline soil to permit farming of T1C-19 in China in the future, despite the possible increased ecological risks.

Improving Parental Lines for Hybrid Rice Development in Indica / Japonica Rice Crosses

The present study was done at the Experimental Farm of Sakha Agricultural Research Station, Kafr El-Sheikh, Egypt, during 2016 and 2017 seasons to study combining ability, gene action and heterosis for grain yield and some agronomic traits in some lines to be utilized in hybrid rice development. The experiment comprised 30 crosses derived from six varieties/lines namely; Dular, Jip 5, O2428, Nekken 1, Giza 181 and Giza182. A complete diallel cross set was done among these six rice parents including reciprocals. General combining ability and specific combining ability were found to be highly significant for all studied traits. This indicated the importance of both additive and non-additive genetic variances in determining inheritance of grain yield and related traits. While, highly significant reciprocal effects were detected for most studied traits indicating presence of the maternal effects in controlling of studied traits except panicle length and panicle weight for these rice crosses. The ratio of GCA/SCA was more than unity for all studied traits, indicated the preponderance of additive gene effects in the expression of these traits. Rice varieties; Dular, O2428 and Nekken 1 showed highly spikelets fertility (> 70%) when they crossed with both japonica and indica cultivars indicated that these lines can be identified as wide compatible genotypes. Moreover, the three crosses of Nekken 1 X Giza 182, Giza 181 X Giza 182 and Nekken 1 X Giza 181 were the best specific combiner for grain yield.

Analysis on fertility and inheritance of hybrid male sterility of indica rice 9814HS-1

Hybrid rice has generally a yield-increasing heterosis of 10%−15% compared with inbred parents. Food and Agriculture Organization (FAO) has recommended hybrid rice as one of the best choices for solving the food shortage in the developing countries. Male sterility provides a basic genetic tool for hybrid rice breeding. Hybrid male sterility refers to the phenomenon that F1 hybrid from two parents is abnormal or nonfunctional in the development of male organs. A new germplasm source of hybrid male sterility is valuable for establishing a novel system for using heterosis by hybrid breeding of three-way crossing, which helps to develop elite hybrid rice with better comprehensive traits. To date, hybrid male sterility occurs commonly from the crosses between species (e.g. Oryza rufipogon × Oryza sativa ) or subspecies (e.g. indica rice × japonica rice). Nevertheless, it is not clear if the hybrid male sterility could be induced from a cross within a subspecies. Here, we reported firstly the hybrid male sterility resulted from a cross between two indica rice parents, i.e., two WA-type maintainer lines of indica rice T98B and M114B. The InDel marker analysis showed that T98B and M114B had an indica -genotype frequency at 0.94 and 1.00, respectively, indicating both of them belong to indica rice. Field observation showed that 9814HS-1, the F1 hybrid of T98B (as female parent) and M114B (as male parent), was eco-typically male sterile. The pollens of 9814HS-1 were completely aborted, resulting in a seed setting rate at 0.00% when heading after early October at Changsha or before mid-March at Sanya, while both parents T98B and M114B were normally fertile under the same conditions. Interestingly, when T98B and M114B were crossed with eight other indica rice varieties, all of their F1 hybrids were normally fertile with a seed setting rate ranged from 80.35% to 91.87%, implying that the hybrid male sterility of 9814HS-1 is induced from the specific parental incompatibility between T98B and M114B. The restorability test showed that 9814HS-1 could be restored for fertility by all of six representative indica rice lines, with seed setting rates ranged from 85.24% to 93.21% in their F1 hybrids, indicating that the broad spectrum of restorability of 9814HS-1. This male sterility provides a good basis for hybrid breeding of three-way cross. Genetic analysis showed that both of the F1 hybrid and its reciprocal cross from T98B and M114B were male sterile, suggesting the hybrid male sterility was controlled by nuclear genes. The Chi-square test supported that the separation ratio of sterile: Fertile plants in both F2 and BC1F1 populations was confirmed to be 1:3, which we infer that the hybrid male sterility in 9814HS-1 is controlled by two pairs of non-allelic nuclear genes and occurs only when they are in a heterozygous state. This study provides a new perspective for re-recognizing rice reproductive barriers and opens up a new way for the multiple-line hybrid rice breeding.

Effects of Stem Cutting Time and Height on Yield Components and Yield of Rice Ratun System (Oryza sativa L.)

Ratun is the ability of the rice plant to regenerate new tillers after harvest, so it can be increased rice productivity. The aim of this research was to compare the yield components and yield between rice ratun with the parent rice, to analyze influence of stem cutting time and height on yield components and yield of rice ratun system and also to determine optimum cutting time and height for the yield components and yield of rice ratun. This research was heald in Pusat Inovasi Agroteknologi (PIAT) of Gadjah Mada University, Kalitirto, Berbah, Sleman, Yogyakarta on March to June 2017. The experiment used split-plot design with cutting time as the main plot and cutting height as sub plot with 3 blocks as replication. The cutting time consisted of 3 levels i.e. at harvest time, 7 days after harvest time, and 14 days after harvest time. Meanwhile, cutting height consisted of 4 levels i.e. 3 cm, 13 cm, 23 cm, and 33 cm above the ground.The research showed that the yield components and yield of rice ratun lower than the parent rice. Cutting time at harvest time, 7, 14 days after harvest time with the cutting height close to the ground increase yield component and yield of rice ratun but delay the generative phase. The highest yield components and yield of rice ratun achieved at harvest time cutting time with cutting height 3 cm above the ground.

The effects of internal endosperm lipids on starch properties: Evidence from rice mutant starches

The mechanism responsible for the effects of endogenous lipids on starch functionality is not fully understood. In this study, a high-lipid rice mutant (GZ1), a low apparent amylose content (AAC) mutant (GZ93) and parent rice (R7954) were employed to study the effect of the removal of starch lipids (SL) and non-starch lipids (NSL) on the physicochemical properties of starch and resistant starch (RS) and the rice gel texture. GZ1 had a lipid content of 2.52%, of which 61.1% was NSL. Removal of NSL only had a slight impact on the AAC, RS content, gelatinization temperature, swelling power and paste viscosity, but further removal of SL significantly increased the AAC and RS contents. For R7954 and GZ93, removal of SL decreased Tp, ΔH, PKV, CPV, and BDV but significantly increased the swelling power (SP). In GZI, the removal of SL resulted in significant increases in ΔH, PKV, HPV, CPV, SBV and the hardness of the gel texture. These results suggested that SLs had a much greater influence on the starch physicochemical properties and gel texture than NSLs. The results may be helpful in designing breeding programs for new rice varieties with better functionality.

Strategies for pollen harvest and storage for increasing pollination and yield in hybrid rice seed production of Mestiso 19 cultivar

Attainment of high seed yield in hybrid rice seed production is a function of the amount of pollen that the male parent can shed during pollination. Low pollen load of the male parent (TG101M) of hybrid rice, Mestiso 19 leads to low seed yield which limits the number of hybrid rice seed growers engaged in its hybrid seed production. Artificial pollination, through collection and storage of sufficient amount of pollen may provide a solution to the problem. Additional pollen artificially loaded onto stigmas of female parent of Mestiso 19 (PRUPTG101) may increase seed yield. The study was conducted during wet and dry season of year 2016 and 2017 at Phil Rice Central Experiment Station to develop technique in pollen collection and storage of TG101M. Pollens were collected at anthesis, 30 minutes and 1 hour after anthesis, then stored in amber glass, paper and ziplock plastics and stored for 24, 48 and 72 hours in 280C, 50C, -50C. Pollens were grown in three different media for pollen viability and germination and viewed under the microscope for pollen tube growth. Pollen viability and germination was high at anthesis and decreased thereafter. Pollen grains grown in media 2 maintained pollen viability even after 1 hour after anthesis. Pollen germination decreased over time regardless of media used. Pollen tube length was consistently high at anthesis when pollen grains were grown in media 2 and 3 only. The length of pollen tube growth from medium 2 differed between 30 min and 1 hour. Less than 50% viable pollen was achieved after 24 hours of storage. Pollen viability and germination decreased beyond 24 hours. To increase the viability of collected pollen from TG101M for possible artificial pollination, grains must be collected at anthesis and stored immediately in amber glass under cold storage at negative 5°C.

OsNAC-like transcription factor involved in regulating seed-storage protein content at different stages of grain filling in rice under aerobic conditions

In this study, we show that NAC-like transcription factor (TF) has 90% sequence similarity with cDNA of the OsNac5 gene present in the NCBI database. Phylogenetic analysis of the NAC gene family was performed with inclusion of the highly diverse C-terminal sequences. We report that this gene is also found to be orthologous to Glycine max NAC8, NAC2, Triticum aestivum NAC6 and paralogous to OsNAC6. mRNA was purified from five recombinant inbred lines (RILs) and parents of rice at three different stages of grain filling under aerobic conditions, with grain protein content (GPC) spanning from 4 to 14%. The NAC-like TF encoding a protein was found to be upregulated at the S2 stage in the leaf (3.9-fold) and panicle (1.84-fold) of parent HPR14 and in five RILs (1.9 to 4.51-fold in leaves and 0.47 to 3.2-fold in panicles). Expression analysis of the NAC-like TF encoding a protein for the rice gene was found to be upregulated at the S2 stage in the leaf and panicle of parental line HPR14 and RILs with high protein content.

Diallel analysis of yield and its important components in aromatic rice (Oryza Sativa L.)

Eight parents of aromatic rice were crossed in half diallel mating design without reciprocal including parents. The parents were evaluated for eleven different characters. Genetic analysis was done through Griffing’s Method II Model I. Analysis of variance revealed highly significant differences among parents and their crosses for all the characters. Combining ability analysis revealed that gca and sca variance were highly significant for most of the characters studied in F1 generation. Amongst the parental lines, Basmati Kasturi was a good general combiner for plant height at maturity, total number of spikelets per panicle, total number of filled grains per panicle and grain yield per plant in F1 generation while the most promising specific combiners for grain yield per plant were Basmati x Chakhao Angangba and Basmati Kasturi x Basmati 370.

Feature of blast resistant near-isogenic lines using an elite maintainer line II-32B by marker-assisted selection

Rice plays a crucial role in food production worldwide as one of the most important cereal crops. Breeding blast disease resistant varieties is a long-term aim for sustainable rice production. II-32B is an elite maintainer line of II-32A which has been widely used as a hybrid rice parent in China. However, it is significantly susceptible to rice blast. In this study, multiple alleles, Pi-2 and Pi-9, and the chromosomal segment of blast resistance genes, Pi-1 and Pi-kh, were introgressed to receptor parents II-32B by marker-assisted backcross breeding. Eleven near-isogenic lines (NILs) with single Pi-gene and 12 pyramid lines containing double or three homozygous resistance genes were obtained. These improved lines were identified by inoculating Magnaporthe oryzae isolates in the field/greenhouses; the result showed that the resistance of pyramid lines containing three resistance genes was stronger than the lines with double or single gene, whereas the lines with double genes were stronger than the one with single-gene. Additionally, pyramiding of different Pi-genes was effective in obtaining the durable blast resistance in rice. This implies that gene pyramiding in rice can increase spectrum and strength of resistance to blast. Furthermore, three-line retention of sixteen improved NILs was kept well and the agronomic traits were consistence with II-32B. We conclude that gene pyramiding is an effective breeding approach for the improvement of rice varieties with durable resistance to blast in the future.