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High reproductive compatibility between crops and their wild relatives can provide benefits for crop breeding but also poses risks for agricultural weed evolution. Weedy rice is a feral relative of rice that infests paddies and causes severe crop losses worldwide. In regions of tropical Asia where the wild progenitor of rice occurs, weedy rice could be influenced by hybridization with the wild species. Genomic analysis of this phenomenon has been very limited. Here we use whole genome sequence analyses of 217 wild, weedy and cultivated rice samples to show that wild rice hybridization has contributed substantially to the evolution of Southeast Asian weedy rice, with some strains acquiring weed-adaptive traits through introgression from the wild progenitor. Our study highlights how adaptive introgression from wild species can contribute to agricultural weed evolution, and it provides a case study of parallel evolution of weediness in independently-evolved strains of a weedy crop relative. Genome-wide evidence to support that wild rice can contribute to weedy rice evolution by hybridization and adaptive introgression is very limited. Here, the authors sequence the weedy rice genomes and show reproductively compatible wild rice can contribute to weedy rice evolution. [ABSTRACT FROM AUTHOR]

Black rice has numerous health benefits and one of the well-known functional foods throughout the world. To encourage the increasing trend of the consumer interest in health-promoting functional foods, special varieties of rice have been developed offering greater nutrient values and exhibiting biological activities that are beneficial to the consumer. In this study, we aimed to evaluate the associations of the phytochemical contents, antioxidants, and anti-inflammatory properties among eight selected black rice germ and bran extracts (BR extracts) from 4 non-glutinous and 4 glutinous rice varieties. Accordingly, glutinous BR extracts possessed higher degree of Cyanidin-3-O-glucoside (C3G), Peonidin-3-O-glucoside (P3G) contents, antioxidant and anti-inflammatory properties than the non-glutinous BR extracts. Pearson's correlation indicated that the amount of C3G in the BR extracts had a strong positive association with the antioxidant properties (DPPH; r = 0.846, ABTS; r = 0.923, and FRAP; r = 0.958, p < 0.01). While P3G exhibited a strong positive association with the anti-inflammatory properties (r value = 0.717 and 0.797 for IL-6 and TNF-α inhibition, respectively, p < 0.05). Lastly, the principal component analysis (PCA) categorized the black rice varieties into three groups: Group A with high C3G content and superior antioxidant properties, Groups B with a high amount of P3G and potent anti-inflammatory properties, and Group C with a lower amount of phytochemical contents and less potent bioactivities. Overall, the outcomes of this study could provide vital information to food industries in selecting the variety of black rice for the functional food based on the anthocyanin contents that could benefit to consumers for new normal healthy lifestyle. [ABSTRACT FROM AUTHOR]

Background: In the almost century since the establishment of boron (B) as an essential plant nutrient, its roles in plant growth and development have been identified, and the mechanism for B transportation explained. Scope: This review relates the yield response of crops, measured as B efficiency i.e. productivity when B is limiting relative to when it is not, to the B supply logistics and requirement of different tissues and organs. Conclusions: Yield is depressed by B deficiency in graminaceous cereals primarily by impaired development and function of the stamen and pistil, but in dicots the adverse effects are expressed as structural damage to various organs. Boron-efficient cereal genotypes are readily identifiable by their successful grain set under limited B, while the quantitative trait loci associated with B efficiency provide a useful selection tool for dicots. The relevance to breeding for B efficiency of the numerous BOR1 and NIP genes controlling active B transport identified in many crops will depend on how close their up-regulation in a deficiency is associated with B efficiency. Understanding of the yield impact of B deficiency is useful in dealing with crop choice and the management of germplasm and B fertilizer. [ABSTRACT FROM AUTHOR]

Purple or black rice (Oryza sativa L.) is a culturally important germplasm in Asia with a long history of cultivation in northern Thailand. Purple rice is identified by the color of the rice pericarp, which varies from purple to black with the accumulation of phenolic acids, flavonoids, and anthocyanins. In the present study, we assessed molecular variation within and between wetland purple rice landraces germplasm from northern and northeastern Thailand using 12 microsatellite loci. All purple rice varieties surveyed showed high levels of homozygosity within varieties and strong genetic differentiation among varieties, indicating the fixation of genetic differences among them. This pattern is consistent with purple rice farming practices in northern Thailand, where a small portion of harvested seed is selected and replanted based on farmers' preferences. The reduced genetic diversity and high homozygosity observed for purple rice is also consistent with patterns expected for this inbreeding crop. Genetic differentiation among the varieties showed some degree of structuring based on their geographical origin. Taken together, these data highlight that the genetic diversity and structure of wetland purple rice landraces is shaped by farmer utilization and cultivation through local cultural practices, and that conservation should focus on ex situ conservation across its cultivation range, along with on-farm, in situ conservation based on farmers' seed-saving practices. In situ conservation may prove especially valuable for preserving the genetic identity of local varieties and promote adaptation to local environments. [ABSTRACT FROM AUTHOR]

Floral traits play an important role in mating systems in flowering plant species. In rice, variation in floral traits has been established in a wide range of germplasm, but the variability of floral traits in Thai rice remains uncharacterized. Sixty-seven rice varieties that are cultivated throughout the country and two accessions of common wild rice were evaluated for nine floral traits to assess the extent of variation, and the differentiation of floral traits among groups of rice (improved rice varieties, selected traditional varieties, local traditional varieties and wild rice). The range of variation of all traits examined in Thai rice varied within the extent of variation that has been reported in other rice germplasm. Most of the floral traits observed in Thai rice have mean values similar to other reports, except in stamen traits, percentage of stigma exertion and the length of spikelet, which exhibited higher mean values than other germplasm investigations. Since these floral traits have a large contribution on outcrossing potential, Thai rice might have a greater chance of natural outcrossing compared to other cultivated rice germplasm. There is no clear differentiation in floral traits among groups of cultivated rice, but there are obvious differences in most of the floral traits between cultivated rice varieties and common wild rice, illustrated in the transformation of rice floral structures during domestication. The results have implications for outcrossing and spontaneous gene flow as well as a potential use in the parental lines for hybrid rice seed production. [ABSTRACT FROM AUTHOR]

Phenotypic and Genetic Diversity of Local Perilla ( Perilla frutescens (L.) Britt.) from Northern Thailand. Perilla frutescens (L.) Britt., an important oil and culinary crop in Asia, is a valuable genetic resource. Despite its nutritional value and historic and cultural importance, research on Perilla has been scarce, particularly as far as its genetic diversity is concerned. The aims of the present study were to assess variability within and between 29 seed samples of P. frutescens collected from farmers in northern Thailand, and evaluation conducted of their genetic, morphological, and agronomic characteristics, and the seed composition, including polyunsaturated fatty acids omega-3, omega-6, and omega-9, and the vitamin E γ-tocopherols. Perilla frutescens (L.) Britt. of northern Thailand is genetically variable, and structured according to origin of collection which was the consequence of local adaptation. The discovery of high levels of polyunsaturated fatty acids, namely α-linolenic acid and γ-tocopherols, in some Perilla samples indicates the potential for utilizing Perilla for its high omega-3 content including as a vitamin E supplement for humans, a prospect that should be taken into account when planning conservation strategies or when Perilla variability is used in breeding programs. [ABSTRACT FROM AUTHOR]

Weedy rice ( Oryza sativa f. spontanea Baker) is one of the most serious weeds in direct-seeded rice production; adversely affecting rice areas and yield in Thailand. The objectives of this study were to evaluate the level of morphological and agronomical variation and the level and pattern of genetic diversity and population structure of weedy rice populations in Thailand. Sixty-three weedy rice populations collected from three rice production areas of Thailand were sampled over four rice cultivation seasons to study phenotypic characteristics, genetic diversity and population structure. All analysis included comparison with seven cultivated rice varieties and seven local common wild rice populations. The results demonstrated considerable genetic and morphological variation, population structure, and changing dynamics of Thai weedy rice populations, both within and between regions and growing seasons. Phenotypic and genotypic variations and population structure of weedy rice populations changed temporally, with a trend over five years toward greater similarity to companion crop rice varieties. The ongoing gene flow, combined with ecological conditions created by farmers' selection and agronomic practices, may enhance fitness and adaptability of weedy rice populations and stimulate the evolution of invasiveness in weedy rice plants. The adaptive evolution of weedy rice tended to parallel cultivated rice for high adaptation to the agronomic practices, possibly including selection for crop mimicry, which has led to the convergence of weedy populations phenotypically and genetically with the companion crop rice. [ABSTRACT FROM AUTHOR]

The gene pool of cultivated Asian rice consists of wild rice ( Oryza rufipogon Griff.), cultivated rice ( O. sativa L.) and a weedy form ( O. sativa f. spontanea). All three components are widespread in Thailand, frequently co-occurring within fields and providing the opportunity for gene flow and introgression. The purpose to this study is to understand the on-going evolutionary processes that affect the gene pool of rice by analysis of microsatellite variation. Results indicate that O. rufipogon, the wild ancestor of rice, has high levels of genetic variation both within and among populations. Moreover, the variation is structured predominantly by annual and perennial life history. High levels of variation are detected among cultivars indicating Thai cultivated rice has a broad genetic base with only a 20 % reduction in diversity from its wild ancestor. The weedy rice populations reveal varying levels of genetic variation, from nearly as high as wild rice to near zero. Weedy rice is genetically structured into 2 groups. Some populations of invasive weedy rice are the result of hybridization and gene flow between local wild rice and local cultivated rice in the regions of co-occurrence. Other populations of weedy rice are genetically nearly identical to the local cultivated rice. The diversity analysis indicates that the rice gene pool in Thailand is a dynamic genetic system. Gene flow is ongoing among its three main components, first between cultivated and wild rice resulting in weedy rice. Weedy rice in turn crosses with both cultivated varieties and wild rice. [ABSTRACT FROM AUTHOR]

Background and aims: The loss of iron and zinc during milling to produce white rice can have serious consequences for human health. Therefore, the objective was to evaluate Fe and Zn partitioning between the endosperm, bran and embryo, and the milling loss of these nutrients among Thai rice genotypes. Methods: Concentrations of iron and zinc and their partitioning to different parts of the grain were examined in 15 genotypes of Thai rice (10 belonging to the long-slender grain type) grown together under wetland condition. Results: The depression in grain Fe and Zn concentrations (24-60 and 10-58 %, respectively) on milling differed among rice genotypes and were affected by the extent of differential partitioning of Fe and Zn into different parts of the grain. For example, nearly 70 % of white rice Zn was allocated to the endosperm in contrast to only 43 % for Fe. Conclusions: Because of variation in milling loss of Fe and Zn, that can result from genotypic variation in the degree of milling and partitioning of Fe and Zn into different parts of the grain, we conclude that white rice Fe and Zn concentrations should not be inferred solely from brown rice concentrations of these nutrients. [ABSTRACT FROM AUTHOR]

Boron (B) deficiency depresses wheat, barley and triticale yield through male sterility. On the basis of field responses to B fertilization, maize ( Zea mays L.) is affected by B deficiency in five continents. In a series of sand culture trials with maize subject to B0 (nil added B) and B20 (20 μM added B) treatments, we described how B deficiency depressed maize grain yield while showing an imperceptible effect on vegetative dry weight. With manual application of pollen to the silk of each plant, B0 plants produced 0.4 grain ear compared with 410 grains ear in B20 plants. Symptoms of B deficiency was observed only in B0 plants, which exhibited symptoms of narrow white to transparent lengthwise streaks on leaves, multiple but small and abnormal ears with very short silk, small tassels with some branches emerging dead, and small, shrivelled anthers devoid of pollen. Tassels, silk and pollen of B0 plants contained only 3-4 mg B kg DW compared with twice or more B in these reproductive tissues in B20 plants. A cross-fertilization experiment showed that, although the tassels and pollen were more affected, the silk was more sensitive to B deficiency. Pollen from B20 plants applied to B0 silk produced almost no grains, while pollen from B0 on B20 silk increased the number of grains to 37% of the 452 grains plant produced from B20 pollen on B20 silk. Therefore, the silk of the first ear may be targeted for precise diagnosis of B status at maize reproduction, for timely correction by foliar B application, and even for B-efficient genotype selection. [ABSTRACT FROM AUTHOR]

daptability of traditional agricultural systems is suggested by their success over time, but documentation of how this happens is rare. This paper shows how genetic diversity in a rice landrace enables rice farming system of northern Thailand to adapt to a constraint of an insect pest, microenvironments of mountainous landscape and people's different tastes in rice. Resistance to laboratory-reared gall midge varied among accessions the rice landrace Muey Nawng and gall midge populations. Higher rice yield in farmers' fields reflected adaptation to local environment as well as resistance to gall midge. Microsatellite variation of the accessions correlated negatively with their gall midge resistance, but there was also variation in heading time and endosperm starch. Presence of non-waxy endosperm in glutinous rice provides opportunity to select for rice that is cooked into non-glutinous rice preferred by minority groups who live at higher elevations, where the gall midge is emerging as a new threat, possibly because of climate change. These data show how genetic diversity of a rice landrace coupled with seed management by farmers enabled a rice farming system to adapt to the varied microenvironment of a mountainous landscape under the constraint of an insect pest and people's different tastes in rice. [ABSTRACT FROM AUTHOR]

This experiment examined variation of iron (Fe) concentration in grain of local Thai rice varieties from Huai Tee Cha village, in northern Thailand. Seeds of 17 named varieties were collected from farmers in 66 accessions. Brown rice from each accession was stained individually with Perls’ Prussian blue, with IR68144 (high grain Fe) and KDML105 (low grain Fe) as checks. A wide range of grain Fe contents were found among different varieties, different seed lots with the same name and within individual accessions, notably BB, BGU and BK. The Fe concentrations in these varieties were confirmed by chemical analysis. Two accessions of each variety with most intense staining and highest average concentration of grain Fe were selected, and 20–40 seeds from each were sown for subsequent progeny testing. There was morphological variation between plants in 5 out of 6 accessions in characteristics such as pigmentation of the apiculus, pericarp and seed coat, while the sixth was externally uniform. Analysis for Fe concentration in seeds of individual lines found that the highest Fe lines were 40% to 50% higher than the lowest Fe lines. This range of grain Fe was found in all six accessions that were progeny tested, including BGU5 which was externally uniform in appearance ( H′ = 0). We have shown that variation in grain Fe concentration in local Thai rice may be found between different seed lots bearing the same name and within individual seed lot as well as between varieties. This level of genetic variation may need to be considered when assessing for traits such as grain Fe for breeding programs. [ABSTRACT FROM AUTHOR]

The genetic control of boron (B) efficiency in wheat (Triticum aestivum L.) was studied for three genotypes representing B inefficient (I, Bonza), moderately B inefficient (MI, SW 41) and B efficient (E, Fang 60) categories. Boron efficiency was expressed as a partially dominant character but the phenotypes of F1 hybrids, relative to parents, indicated genetic control varying from recessive to additive to completely dominant with different cross combinations and B levels. Major genes were identified from the evaluation of F2-derived F3 populations derived from intercrosses between the three parents. Monogenic segregation was found in Bonza × SW 41 and SW 41 × Fang 60 crosses and digenic segregation resulted in Bonza × Fang 60. Among the three wheat genotypes with widely different B efficiency, genetic variation for response to B could be accounted for by two genes, Bod1 and Bod2. [ABSTRACT FROM AUTHOR]