Traditional Rice Landraces Research Articles

Identification of Arsenic Accumulator from Traditional Upland Rice Genotypes: A Field Survey in Interior Division, North Borneo

The Pan Borneo Highway provide traditional farmers better access to modern agronomic products that changes the rice agricultural management practices in rural areas. This study provides baseline data on selected heavy metal (As, Cd, Cr, Cu, Fe, Ni, Pb, Zn) concentration in rice and rhizosphere soil of four traditional rice landraces (Lantai, Tesik, Kembulaung & Sepulut) that was cultivated by the Dusun Minokok ethnic group residing in the small district of Sook, Interior Division, North Borneo. Heavy metals in soils and rice were determined by Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES). The soil pH value for all rice landraces except Lantai had increased in between the rice life cycle at the vegetative and reproductive phase. Certain heavy metals bioavailability had decreased at reproductive phase when soil pH had increased. Cd and Cr was not detected in any rice landraces grains. None of the heavy metals concentration for all rice landraces had exceed the maximum allowable limit of Malaysia Food Regulation 1985. However, arsenic was efficiently mobile from root to grain of the late-maturing rice landraces’ Kembulaung and Sepulut. The Kembulaung and Sepulut landrace is an accumulator of arsenic with Enrichment Factor value more than 11 and 2 respectively. Increase of As phytoavailability in this cultivation area might pose health hazard if not manage sustainably.

An approach to Climate resilient agriculture farming system using Rice landraces collected from Tamil Nadu

A field experiment was conducted to determine the physiological performance of traditional rice landraces under water stress given at vegetative and reproductive stages. Drought is one of the serious threats on rice productivity. Traditional rice landraces shows substantial adaptability to drought so Six popular rice land races, namely Rascadam, Kothamalli sambha, Kaattu sambha, Kallundai, Kuliyadichan and Milagu sambha from Tamilnadu, India and two popular rice check varieties, namely IR64 (susceptible check), N22 (tolerant check) were used to study the physiological performance for drought tolerance. These genotypes were subjected to drought under field condition at Agricultural Research Station, Bhavanisagar, TNAU, Coimbatore. The crops were imposed with drought during vegetative and reproductive stages by withholding irrigation till the soil moisture reaches below 20 per cent. The experimental design for the trial was factorial randomized block design (FRBD). Photosynthetic rate, Stomatal conductance, Transpiration rate, Fv/Fm ratio were measured.

Pan-genomic, transcriptomic, and miRNA analyses to decipher genetic diversity and anthocyanin pathway genes among the traditional rice landraces

Black rice is famous for containing high anthocyanin while Joha rice is aromatic with low anthocyanin containing rice from the North-Eastern Region (NER) of India. However, there are limited reports on the anthocyanin biosynthesis in Manipur Black rice. Therefore, the present study was aimed to understand the origin, domestication and anthocyanin biosynthesis pathways in Black rice using the next generation sequencing approaches. With the sequencing data, various analyses were carried out for differential expression and construction of a pan-genome. Protein coding RNA and small RNA sequencing analysis aided in determining 7415 and 131 differentially expressed transcripts and miRNAs, respectively in NER rice. This is the first extensive study on identification and expression analysis of miRNAs and their target genes in regulating anthocyanin biosynthesis in NER rice. This study will aid in better understanding for decoding the theory of high or low anthocyanin content in different rice genotypes.

Impact of Phyllosphere Methylobacterium on Host Rice Landraces.

ABSTRACTThe genus Methylobacterium includes widespread plant-associated bacteria that are abundant in the plant phyllosphere (leaf surfaces), consume plant-secreted methanol, and can produce plant growth-promoting metabolites. However, despite the potential to increase agricultural productivity, their impact on host fitness in the natural environment is relatively poorly understood. Here, we conducted field experiments with three traditionally cultivated rice landraces from northeastern India. We inoculated seedlings with native versus nonnative phyllosphere Methylobacterium strains and found significant impacts on plant growth and grain yield. However, these effects were variable. Whereas some Methylobacterium isolates were beneficial for their host, others had no impact or were no more beneficial than the bacterial growth medium on its own. Host plant benefits were not consistently associated with Methylobacterium colonization and did not have altered phyllosphere microbiome composition, changes in the early expression of plant stress response pathways, or bacterial auxin production. We provide the first demonstration of the benefits of phyllosphere Methylobacterium for rice yield under field conditions and highlight the need for further analysis to understand the mechanisms underlying these benefits. Given that the host landrace-Methylobacterium relationship was not generalizable, future agricultural applications will require careful testing to identify coevolved host-bacterium pairs that may enhance the productivity of high-value rice varieties.IMPORTANCE Plants are associated with diverse microbes in nature. Do the microbes increase host plant health, and can they be used for agricultural applications? This is an important question that must be answered in the field rather than in the laboratory or greenhouse. We tested the effects of native, leaf-inhabiting bacteria (genus Methylobacterium) on traditionally cultivated rice varieties in a crop field. We found that inoculation with some bacteria increased rice grain production substantially while a nonnative bacterium reduced plant health. Overall, the effect of bacterial inoculation varied across pairs of rice varieties and their native bacteria. Thus, knowledge of evolved associations between specific bacteria hosted by specific rice varieties is necessary to develop ways to increase the yield of traditional rice landraces and preserve these important sources of cultural and genetic diversity.

Effect of seedling age on productivity and profitability in traditional rice landraces

A field experiment was conducted at Tamil Nadu Agricultural University, with an objective to study the effect of seedling age on productivity and profitability in rice landraces under irrigated rice ecosystem. The experiment was laid out in split plot design with three replications. The treatments in main plot were three age of seedlings viz., 15, 20 and 25 days old seedlings and in sub plot eight rice landraces viz., Chandikar, Kuliyadichan, Kuruvaikalanjiyam, Norungan, Nootripathu, Black Kavuni, Red Kavuni, Njavara and CO(R) 50 (one high yielding variety). Observations were recorded on growth parameters such as plant height, tiller numbers and dry matter production. The yield attributes like productive tillers, total spikelet, filled grains, unfilled grains, spikelet sterility percentage, thousand grain weight, grain yield and straw yield were recorded at the time of harvest. From the study it was observed that 15 days old seedlings in all the eight rice landraces and one high yielding variety, recorded higher growth and yield attributes. In rice landraces, Red Kavuni recorded higher grain, straw yield and B:C ratio. Based on quality parameters, CO(R) 50 rice variety and landraces viz., Red Kavuni, Black Kavuni, Nootripathu, Chandikar recorded optimum values and were suitable for cooking purpose.

Synergistic Modulation of Seed Metabolites and Enzymatic Antioxidants Tweaks Moisture Stress Tolerance in Non-Cultivated Traditional Rice Genotypes during Germination.

Traditional rice landraces are treasures for novel genes to develop climate-resilient cultivars. Seed viability and germination determine rice productivity under moisture stress. The present study evaluated 100 rice genotypes, including 85 traditional landraces and 15 improved cultivars from various agro-ecological zones of Tamil Nadu, along with moisture-stress-susceptible (IR 64) and moisture-stress-tolerant (IR 64 Drt1) checks. The landraces were screened over a range of osmotic potentials, namely (−) 1.0 MPa, (−) 1.25 MPa and (−) 1.5 MPa, for a period of 5 days in PEG-induced moisture stress. Physio-morphological traits, such as rate of germination, root and shoot length, vigor index, R/S ratio and relative water content (RWC), were assessed during early moisture stress at the maximum OP of (−) 1.5 MPa. The seed macromolecules, phytohormones (giberellic acid, auxin (IAA), cytokinin and abscisic acid), osmolytes and enzymatic antioxidants (catalase and superoxide dismutase) varied significantly between moisture stress and control treatments. The genotype Kuliyadichan registered more IAA and giberellic acid (44% and 35%, respectively, over moisture-stress-tolerant check (IR 64 Drt1), whereas all the landraces showed an elevated catalase activity, thus indicating that the tolerant landraces effectively eliminate oxidative damages. High-performance liquid chromatography analysis showed a reduction in cytokinin and an increase in ABA level under induced moisture stress. Hence, the inherent moisture-stress tolerance of six traditional landraces, such as Kuliyadichan, Rajalakshmi, Sahbhagi Dhan, Nootripathu, Chandaikar and Mallikar, was associated with metabolic responses, such as activation of hydrolytic enzymes, hormonal crosstalk, ROS signaling and antioxidant enzymes (especially catalase), when compared to the susceptible check, IR 64. Hence, these traditional rice landraces can serve as potential donors for introgression or pyramiding moisture-stress-tolerance traits toward developing climate-resilient rice cultivars.

Growth, grain yield, and water productivity of traditional rice landraces from coastal Bangladesh, as affected by salt stress

ABSTRACT Salinity is a major abiotic stress limiting the growth, development, and productivity of rice (Oryza sativa L.) worldwide. A 10 × 4 factorial pot experiment consisting of 10 traditional aus rice (summer rice) landraces (Noyontara, Ratul, Rani Ratul, Sribalen, Mala, Kolmilata, Nayanmoni, Noncha, Kopilaice, and Kajollata) and four levels of water salinity (0.36 [control], 5, 10, and 15 dS m−1) was conducted to evaluate the salt tolerance of the popular traditional rice landraces. The results revealed that plant height, shoot dry matter, soil plant analysis development (SPAD) value, panicle number plant−1, filled-grain percentage, 1000-grain weight, grain yield, harvest index, and irrigation-water productivity were significantly affected by water salinity. The highest shoot dry matter, grain yield, and irrigation-water productivity were recorded for Noncha at the highest salinity level of 15 dS m−1, indicating its high salinity-tolerance ability. The 15 dS m−1 salinity level reduced shoot dry matter and grain yield of Kopilaice by 61% and 75%, respectively, relative to Noncha. The tested cultivars could be classified into three categories: (i) salt sensitive that cannot withstand salinity level above 5 dS m−1: Kopilaice, Noyontara, Ratul, Rani Ratul, and Sribalen, (ii) intermediate-salt tolerant that can withstand salinity below 10 dS m−1: Mala and Nayanmoni, and (iii) highly salt tolerant that can withstand salinity up to 15 dS m−1: Noncha, Kolmilata, and Kajollata. Noncha, Kolmilata, and Kajollata were considered promising salt-tolerant cultivars and can be used as valuable genetic resources for developing salinity-tolerant cultivars in the coastal salinity-affected region of Bangladesh.

The legacy of traditional rice cultivation by descendants of Indian contract laborers in Suriname

BackgroundSome 35,000 indentured laborers from India were recruited to work on plantations in Suriname between 1868 and 1916. It is likely that most were familiar with farming before they were shipped to this former Dutch colony in the Caribbean. Around 1900, those who did not return received a piece of land where most of them started growing rice as a staple crop. Agronomists characterized their traditional landraces as inferior and infested with weedy rice and started to ‘purify’ these landraces. No research has been done on whether these ancient rice varieties still exist. We aimed to document the rice varieties (both landraces and more modern cultivars) grown currently or in the recent past by (descendants of) Hindustani smallholders in Suriname, their origin, morphological and agronomic characters, local uses and cultural and spiritual relevance. Given the rapid decline in small-scale rice cultivation in the past 40 years, we wanted to know why people continued or abandoned rice farming and what aspects of traditional practices still survived.MethodsWe interviewed 26 (former) small-scale Hindustani farmers and asked about the varieties they cultivated and traditional agricultural practices. We collected seed samples, local names and associated information, and compared these to information from agricultural reports from the colonial period. We also interviewed 11 Maroons, one Javanese farmer, and three persons of mixed ethnicity, who were somehow involved in the cultivation of East Indian rice varieties.Results and discussionHindustani smallholders in Suriname largely lost their traditional rice landraces. Most of the interviewed farmers grew modern cultivars, developed after 2000. Some cultivars from the 1950s were still planted for fodder, but these were heavily mixed with weedy rice and other weeds. Maroon farmers in the interior, however, still actively cultivated varieties with names like ‘coolie rice’, which probably descend from landraces introduced by the Indian contract laborers, although this needs to be confirmed by molecular research. Although traditional cultivation practices seem to have been lost, smallholders still retain pleasant memories of the manual planting, harvesting, and processing of rice, as well as the gender-based practices and beliefs associated with the cultivation of the crop. The oral history of former rice farmers and traditional rice varieties (possibly obtained from Maroon fields) could play a role in museum settings as living vehicles for memories of the descendants of Asian contract labourers in Suriname and Guyana.

Genetic Structure and Geographical Differentiation of Traditional Rice (Oryza sativa L.) from Northern Vietnam.

Northern Vietnam is one of the most important centers of genetic diversity for cultivated rice. Over thousands of years of cultivation, natural and artificial selection has preserved many traditional rice landraces in northern Vietnam due to its geographic situation, climatic conditions, and many ethnic groups. These local landraces serve as a rich source of genetic variation—an important resource for future crop improvement. In this study, we determined the genetic diversity and population structure of 79 rice landraces collected from northern Vietnam and 19 rice accessions collected from different countries. In total, 98 rice accessions could be differentiated into japonica and indica with moderate genetic diversity and a polymorphism information content of 0.382. Moreover, we found that genetic differentiation was related to geographical regions with an overall PhiPT (analog of fixation index FST) value of 0.130. We also detected subspecies-specific markers to classify rice (Oryza sativa L.) into indica and japonica. Additionally, we detected five marker-trait associations and rare alleles that can be applied in future breeding programs. Our results suggest that rice landraces in northern Vietnam have a dynamic genetic system that can create different levels of genetic differentiation among regions, but also maintain a balanced genetic diversity between regions.

Exploration of traditional rice (Oryza sativa L.) land races: Scope for the future sustainable food production

Traditional landraces have more complex genetic backgrounds, abundant genetic diversity and heterogenecity, as well as strong adaptability to the environment and are the primary source an excellent resistance genes donors for various important pest and diseases. They provide new alleles for the improvement of commercially valuable traits in rice. Global climate change emphasizes the need to use better adapted cultivars of the main crops and traditional landraces as potential donors of useful genes. Traditional rice landraces are pest and disease resistance, and also resistance or tolerance to drought, water logging and flood situation. The traditional rice landraces are being gradually replaced by the incorporation of modern rice cultivars, thereby threatening the existence of many invaluable traits present in such local varieties. A large number of landraces of rice have disappeared from the irrigated field since the adoption of high yielding varieties (HYVs).Existing indigenous traditional rice can play an important role in the development of sustainable agriculture and also valuable for agronomical, social and cultural practices. Conventional breeding techniques are not alone to tap the genetic potential of rice landraces for commercial varietal improvement programme in rice. Molecular breeding programme is highly helpful into the breeders to elucidate the novel genes and QTLs from traditional rice landraces. These genes and QTLS will be introgressed into commercial rice verities through marker aided selection and using other biotechnological tools. This paper reviews the research findings related to improvement in yield, biotic and abiotic stress tolerance in traditional rice landraces.

Spectrum and frequency of macro and micro mutations induced through gamma rays in traditional rice landraces of Chhattisgarh

Mutation breeding offers a simple and effective means of inducing genetic variation followed by trait selection to improve the traditional rice landraces. Gamma ray induced mutagenesis is most commonly used to obtain chlorophyll mutants and economically useful mutants in many crops. In the present study, gamma ray induced (300Gy) mutagenesis was carried out in the three rice landraces viz., Samundchini, Vishnubhog and Jhilli to study the frequency and spectrum of macro and micro mutations. Macro mutations including four categories of chlorophyll mutations along with many viable mutations viz. mutants with reduced height, reduced maturity duration, high tillers, clustered grain type, dark green leaves, strong stem and grassy types were identified in the M2 population. A total of 81, 98 and 51 putative macro mutants were observed in Samundchini, Vishnubhog and Jhilli with mutation frequency (%) 0.591, 0.796 and 0.434, respectively. Furthermore, 45, 56 and 32 chlorophyll mutants with the 0.382, 0.455 and 0.272 mutation frequency percentages were observed in the M2 population of Samundchini, Vishnubhog and Jhilli, respectively. In addition, 36, 42 and 19 viable morphological mutants with the mutation frequency percentages (based on M2 population) 0.263, 0.341 and 0.162 were identified in Samundchini, Vishnubhog and Jhilli, respectively. Also, variations in mean, widening of the range and increase in the coefficient of variation for most of the quantitative traits in mutagen treated populations as compared to control depicts the existence of micro-mutation and release of polygenic variability in all the three mutagenic populations. Many economically important mutants were identified in all three landraces which could be further advanced for varietal development and use in the breeding program. Key words: Rice landraces, gamma rays, mutation breeding, mutation frequency, macro and micro mutations

Studies on genetic diversity in selected rice (Oryza sativa L.) landraces of Tamil Nadu

A total of 50 traditional rice landraces of Tamil Nadu were characterised for 12 biometric traits and the data were subjected to principal component analysis and cluster analysis to determine the contribution in variation, diversity level and the strength of association prevailing between grain yield and its related traits. Out of 12 Principal components, four exhibited more than 1.0 eigenvalues and contributed to 73.58 per cent of the total variability. PC1 alone accounts for about 39.15 per cent, while PC2, PC3, PC4 contributed 14.39, 11.00 and 9.04 per cent for total variability, respectively. Through agglomerative clustering, the landraces were grouped into five clusters. The landraces present in cluster I (G1, G18, G23, G26, G31, G32, G36, G39, G43, G44, G45) and cluster V (G30 and G45) were found to be with contrasting characters making them ideal parents for further utilization in rice breeding programmes. Key words: Rice, Landraces, Principal Component Analysis, Cluster Analysis

Comparative analyses of the nutraceutical potentialities of selected Indian traditional black rice (Oryza sativa L.) landraces

The present investigation aims to explore the importance of some traditional black rice varieties with their nutraceutical properties. The beneficial properties of these varieties remain unknown to the majority of the population due to the inadequate data. Decorticated rice grains of four black rice varieties were evaluated and compared with two commonly consumed white rice varieties - Gobindabhog (traditional aromatic) and BPT 5204 (modern high yielding variety). The sugars and total lipid levels were similar in Gobindabhog and BPT 5204. The black rice varieties, however, had considerably greater protein, thiamin, riboflavin, pantothenic acid, pyridoxine, and antimicrobial activities compared to the two selected white rice varieties. The ICPMS analysis of black rice grains showed that the former also had higher levels of Mn, Fe, and Zn than the white rice varieties. However, BPT 5204 contained a greater amount of Cu than the black rice varieties. Total flavonoid and phenolic content, as well as antioxidant potentiality of black rice varieties were also considerably higher than those of the white rice varieties.

Genetic differentiation and restricted gene flow in rice landraces from Yunnan, China: effects of isolation-by-distance and isolation-by-environment

BackgroundUnderstanding and identifying the factors responsible for genetic differentiation is of fundamental importance for efficient utilization and conservation of traditional rice landraces. In this study, we examined the spatial genetic differentiation of 594 individuals sampled from 28 locations in Yunnan Province, China, covering a wide geographic distribution and diverse growing conditions. All 594 accessions were studied using ten unlinked target genes and 48 microsatellite loci, and the representative 108 accessions from the whole collection were sampled for resequencing.ResultsThe genetic diversity of rice landraces was quite different geographically and exhibited a geographical decline from south to north in Yunnan, China. Population structure revealed that the rice landraces could be clearly differentiated into japonica and indica groups, respectively. In each group, the rice accessions could be further differentiated corresponded to their geographic locations, including three subgroups from northern, southern and middle locations. We found more obvious internal geographic structure in the japonica group than in the indica group. In the japonica group, we found that genetic and phenotypic differentiation were strongly related to geographical distance, suggesting a pattern of isolation by distance (IBD); this relationship remained highly significant when we controlled for environmental effects, where the likelihood of gene flow is inversely proportional to the distance between locations. Moreover, the gene flow also followed patterns of isolation by environment (IBE) whereby gene flow rates are higher in similar environments. We detected 314 and 216 regions had been differentially selected between Jap-N and Jap-S, Ind-N and Ind-S, respectively, and thus referred to as selection signatures for different geographic subgroups. We also observed a number of significant and interesting associations between loci and environmental factors, which implies adaptation to local environment.ConclusionsOur findings highlight the influence of geographical isolation and environmental heterogeneity on the pattern of the gene flow, and demonstrate that both geographical isolation and environment drives adaptive divergence play dominant roles in the genetic differentiation of the rice landraces in Yunnan, China as a result of limited dispersal.

Characterizing the diversity of grain phytic acid content in Indian rice landraces by multivariate genetic analyses

Phytic acid (PA) acts as chelator of cationic mineral elements iron (Fe) and zinc (Zn) and obstructs their absorption in the human gut. We have evaluated a set of 162 traditional rice landraces for phytic acid phosphorus (PA-P), inorganic phosphorus (Pi) and total phosphorus (TP). Wide variability was observed for PA-P, Pi and TP ranging from 1.12 to 3 mg/g, 0.004 to 0.16 mg/g and 1.17 to 3.04 mg/g respectively. The mineral micronutrients, Fe and Zn were not in correlation with PA-P, Pi and TP implicating the possibility of their independent improvement while PAP showed a significant positive correlation with TP and significant negative correlation with Pi. Principal component analysis (PCA) identified two principal components PC1 and PC2, explaining 50.6 % and 32.1 % of the total variation, respectively. Cluster analysis grouped the accessions into four clusters. The study has also led to the identification of promising donors such as P1490 and Gowri with low PA content to be utilized in rice biofortification programmes.

Colour based nutraceutical potential of some traditional rice (Oryza sativa L. ssp. indica) varieties of India

Consumption of unpolished grain, rather than polished grain has become a modern trend and consumers are mainly putting their thoughts and effort to consume products with more antioxidant capacity. Rice is the main staple food and apart from being considered as the main source of energy, it contains many nutraceutical properties because of its enriched secondary metabolites. This study is an effort to bring back the indigenous traditional rice landraces that almost disappeared from the farm fields after the advent of the Green Revolution in India. This article focuses on colour-based nutritional properties of six coloured and four non-coloured indigenous rice varieties based on antioxidant potential, total phenol and flavonoid content along with secondary metabolites profiling by high performance liquid chromatography. The biochemical uniqueness of these varieties has been explored that opens the gate for the conservation of more indigenous rice varieties for food security, as a cheap source of nutritional food and to construct a better niche for public health in developing country like India.

Investigation on frequency distribution of traditional rice landraces for drought tolerance at seedling stage

Drought is the major constraint, adversely affecting the rice productivity in India. Emerging climate change scenario demands potential donors to develop climate resilient genotypes in order to increase the productivity of rice. In the present study, 85 traditional rice landraces and 15 improved cultivars were screened for drought tolerance potential under hydroponics, along with IR 64 and IR 64 Drt 1 as drought susceptible and tolerant checks respectively. Moisture stress was induced using PEG 6000 over a range of osmotic potentialsviz.,(-) 1.0 Mpa, (-) 1.25 Mpa and (-)1.5 Mpafor a period of 30 days. Fifty two landraces survived under maximum osmotic potential of (-) 1.5 Mpa. Based on the phenotypic scores, six genotypes viz., Kuliyadichan, Rajalakshmi, Sahabhagidhan, Nootripathu, Chandaikar and Mallikar were identified to have higher degree of drought tolerance .. The investigation concluded that these six genotypes can serve as potential donors for developing drought resilient rice cultivars.

Phenotypic and Molecular Marker Based Screening of Coastal Rice Landraces under Salt Stress

Traditional rice landraces of coastal areas in Bangladesh are distinct in respect to their phenotypes, responses to salt stress and yield attributes. In characterization of coastal rice landraces, 46 rice genotypes were tested for salt tolerance at their seedling and reproductive growth stages. Through the cluster analysis following standard evaluation score (SES), genotypes were divided into five categories (highly susceptible, susceptible, moderately tolerant, tolerant and highly tolerant) at their seedling stage. Three coastal genotypes, viz. chorbindi, joyni and kedgrangal mota, were grouped as highly saline tolerant at their seedling stage. In studying reproductive stage salinity screening, based on mean score values obtained from different morphological and yield parameters (plant height, number of effective tillers/hill, number of filled grains, panicle length, 100-grain weight, and straw dry weight), kutiakon and kajolshail were identified as the salinity tolerant landraces while tulsimala, dudhkalom, birindi, bushihara, lalmota, chorboleshor, lalchikon and bashful chikon were found as moderately tolerant to salinity. Finally, the molecular characterization using two simple sequence repeat (SSR) markers, viz., RM493 and RM3412 revealed holde mota, dingamoni, kedgrangal mota, sada mota, laxmima, dishari, lal chikon, kalijira, kalo khaya, khaioz, chorbindi, kajolshail, kutiakon, bamonkhir, dudhmora, sakhorkhora, mota dhan, and sorbimaloti as tolerant landraces. These identified salt-tolerant landraces can be used as promising germplasm resources for breeding salt-tolerant high-yielding rice varieties in the future.

Traditional rice landraces in Lei-Qiong area of South China tolerate salt stress with strong antioxidant activity

ABSTRACTSalt stress, causing serious loss on crop productions, is one of the most important environmental stresses throughout the world. The aim of this study is to select salt-tolerant traditional rice resources collected from Lei-Qiong area of South China and investigate their physiological performances and biochemical regulations during salt stress response, together with two well-known international varieties, Nona Bokra (salt-tolerant sample) and IR29 (salt-sensitive sample). After comprehensive analyses, we discovered that two Lei-Qiong traditional salt-tolerant rice samples showed less growth inhibition by salt stress during both germination and seedling stage, in comparison with other rice samples. Moreover, there were less chlorosis symptoms in these two kinds of salt tolerant rice under salt stress, corresponding to their better water-holding capacity. We measured malondialdehyde and proline contents, and activities of CAT and POD of seedlings treated with 100 mM NaCl for 5 dand 10 d, respectively. Interestingly, less cellular membrane damage and stronger antioxidant enzyme system were found in the two Lei-Qiong rice samples. Our study suggests that traditional rice landrace growing onshore of Lei-Qiong area in China possesses good salt-tolerant capacity, which could be attributed to their efficient antioxidant enzyme system.

Genetic insights into fatty acid components of traditional Indian rice (Oryza sativa L.) landraces from Chhattisgarh

Knowledge about the contents and type of fatty acids (FAs) in rice bran is beneficial, particularly from a nutritional and health standpoint. An experiment was conducted to assess the genetic variability and diversity for FA components in 215 rice landraces during kharif 2015 and kharif 2016 by following the RCB design with two replications. Palmitic (C16:0), oleic (C18:1) and linoleic (C18:2) were the major fatty acids ranging from 12.59% to 20.25%, 37.60% to 49.17% and 31.55% to 44.67%, respectively. Analysis of variance revealed significant differences in all the FA components except for linolenic acid. Results showed that environmental factors play a significant impact on the expression of FA contents. Fatty acid components showed intermediate to low genotypic and phenotypic coefficient of variation, intermediate to high heritability and low to moderate genetic advance as percent of the mean. Oleic acid content was negatively correlated with palmitic acid, stearic acid, and linoleic acid contents. Principal component analysis and cluster analysis discriminated the 215 rice landraces into five main groups with a major contribution of oleic acid, linoleic acid, and palmitic acid contents. Landraces Kadamphool, Ratanchudi and Bathrash possessed the highest amount of oleic acid/linoleic acid ratio. Information generated through this study will be functionally useful in developing rice varieties having high-quality bran oil.