Background The wild ancestors of domesticated rice had red seed, white rice being the result of a mutation in the rice domestication gene Rc . Many pigmented rice landraces are still grown by ethnic communities for their nutritional and cultural value. This study assesses the genetic diversity in a collection of pigmented rice accessions from the Philippines. Results We undertook an analysis of the genetic and colour variation in a collection of 696 pigmented rice accessions held at PhilRice in the Philippines. The collection was reduced to 589 genotypes after removal of accessions with limited passport data or with low SNP marker call rates. Removal of duplicate genotypes resulted in a final, core collection of 307 accessions, representing all administrative districts of the Philippines, and composed predominately of japonica and indica sub-species. No genetic structure was observed in the core collection based on geographic origin. A pairwise comparison of accessions by region indicating that both local and long-distance exchange of rice accessions had occurred. The majority of the genetic variation was within regions (82.38%), rather than between regions (10.23%), with the remaining variation being within rice accession variance (7.39%). The most genetically diverse rice accessions originated from the Cordillera Administrative Region (CAR) in the far north of the Philippines, and in the regions of Davao and Caraga in the southeast. A comparison with pigmented rice accessions from the neighbouring countries Taiwan, Laos, China and India revealed a close relationship between accessions from Taiwan, supporting the hypothesis of southward diffusion of Austronesians from Taiwan to the Philippine. The 14-bp deletion within the gene Rc , known to result in loss of red pigmentation, was found in 30 accessions that still had coloured pericarps. Multi-spectral phenotyping was used to measure seed geometric and colour-appearance traits in 197 accessions from the core collection. The purple and variable purple rice accessions had the lowest values for the seed colour parameters - lightness (L*), intensity, saturation, a* (green – red; redness) and b* (blue – yellow; yellowness). Conclusion These pigmented rice accessions represent a diverse genetic resource of value for further study and nutritional improvement of commercial rice varieties. Electronic supplementary material The online version of this article (10.1186/s12284-019-0281-2) contains supplementary material, which is available to authorized users.

Superior rice varieties tend to be highly adopted by farmers across the country. Over time, samples of a variety coming from different places may exhibit some differences. Morphological descriptors are traditionally used to determine these differences however; these descriptors are limited in number and suffer from drawbacks such as influence of environment on trait expression and could not differentiate morphologically identical varieties. The highly reproducible molecular marker assay offers a powerful alternative to establish true identity and discriminate morphologically identical varieties. A study was conducted to determine the identity of several rice varieties based on DNA fingerprinting using genome-wide SSR markers. Samples of NSIC Rc240 from four sources, Aromatic Rice from three sources, and IR64 from two sources, were included in the study. Genetic similarity was calculated as proportion of shared alleles and cluster analysis was conducted using UPGMA. Results showed that the genetic similarity of three NSIC Rc240 samples was 1.0 confirming that these three samples were 100% genetically similar with each other while a fourth NSIC Rc240 sample from another source was only 89% similar to the other three. On the other hand, the three Aromatic Rice samples formed separate clusters at a range of 71-80% similarity. Lastly, a farmer's "improved" IR64 was only 59.5% similar to the original IR64. The observed divergence of samples with the same names in the study could be a result of further selection, gene flow, drift, admixture, or a combination of these mechanisms. This study underscores the importance of DNA fingerprinting analysis in variety identification, variation arising from selection and possible protection biopiracy.

Rice tungro is one of the most economically damaging virus diseases in the Philippines, which is caused jointly by Rice tungro bacilliform virus (RTBV) and Rice tungro spherical virus (RTSV). The disease causes a significant effect on rice propagation and cultivation. This study aimed to determine the level of genetic diversity of RTBV coat protein gene sequences collected from tungro-hotspot areas in the Philippines and infer their phylogenetic relationships. A total of 144 RTBV coat protein gene sequences were analyzed from six provinces with 21 municipalities representing Luzon, Visayas, and Mindanao. The highest percentage of RTBV detected was in Camarines Sur at 78% while Nueva Ecija had the least at 45%. Among the provinces, nucleotide diversity and number of segregating sites of RTBV were highest in Camarines Sur (π = 0.010797, S = 145) and lowest in Laguna (π = 0.006233, S = 67). Phylogenetic analysis revealed six divergent groups but did not completely reflect geographical origin while principal coordinate analysis (PCoA) resulted in three major groups: Laguna, Negros Occidental, and Nueva Ecija (Luzon and Visayas); and Camarines Sur and North Cotabato plus Isabela (Luzon and Mindanao). These results could infer genetic differentiation is relevant that disease severity variation could be observed including some breaking in resistance in some areas. There is a need to re-design breeding such as location-specific breeding for RTBV-resistant rice varieties that would consider genetic variation within and between location. Other molecular approaches such as the use of next-generation sequencing could be recommended to support the findings from this study.

The Genetic Resources Division (GRD) of PhilRice collects and conserves rice genetic resources to ensure the future generations of available seeds needed to build better rice plants in facing climate change and growing population. At present, GRD maintains the national collection of rice genetic resources with 7,129 accessions. To effectively manage the germplasm collection, the search for, development of, and implementation of the best conservation strategies and innovation in technology have been the utmost priority of the GRD. Thus, georeference data such as latitude, longitude and elevation of germplasm origin during collecting mission were recorded using a handheld global positioning system (GPS) receiver. The e-Seedfile software was developed to provide virtual access of the reference collection for regenerated germplasm seed verification and valid type confirmation for new and old germplasm collection. Barcoding, on the other hand, facilitated accurate inventory of seed stocks, making the distribution and regeneration of germplasm more efficient. Moreover, paperless data collection using android application was implemented for immediate data validation and accurate data downloading from tablets to workstations, making it an ideal tool for germplasm characterization. Furthermore, the current database system was upgraded and adjusted to adopt the use of digital object identifier (DOI) through registration to the global information system (GLIS) on Plant Genetic Resources for Food and Agriculture (PGRFA). The DOI allows the use of material to be tracked, thus meeting the legal obligations of the SMTA and monitor the impact of genebank collections in utilization in research and breeding programs. These innovative technologies are of great importance to expand the toolbox for the management and conservation of the germplasm collection that will help enhance the long-term conservation of rice diversity and easy access to germplasm and germplasm-related information.

Rice is a major staple in the Philippines. The major goal of the rice sector in the country is to increase its productivity to meet the ever growing demand for rice. Breeding is one of the potential solutions to achieve rice self-sufficiency in the country. Rice variety development is led by research institutions such as PhilRice, IRRI, UPLB, and private companies and each adapts various breeding strategies. Rice variety normally takes 10-12 years of a journey from breeding to release and more than 300 varieties have been developed and released that were suited for various rice ecosystems. Sufficient varieties were available for production and this led to continuous in rice production for the past decade. However, yield increment has plateaued. To meet the increasing demand for rice, achieve self-sufficiency, and particularly, break the yield barrier (plateau) and achieve a leap in yield potential, breeding institutions particularly PhilRice should embrace new advances and technologies in rice breeding. The introduction of the concept of transforming breeding into a “factory line” type encouraging rapid generation advance, earlier multi-location trials, and increasing selection pressure, and employing genomic selection (GS) in handling a large quantity of materials/populations can improve breeding efficiency and outputs significantly.