Weedy rice is a conspecific form of cultivated rice (Oryza sativa L.) that infests rice fields and results in severe crop losses. Weed strains in different world regions appear to have originated multiple times from different domesticated and/or wild rice progenitors. In the case of Malaysian weedy rice, a multiple-origin model has been proposed based on neutral markers and analyses of domestication genes for hull color and seed shattering. Here, we examined variation in pericarp (bran) color and its molecular basis to address how this trait evolved in Malaysian weeds and its possible role in weed adaptation. Functional alleles of the Rc gene confer proanthocyanidin pigmentation of the pericarp, a trait found in most wild and weedy Oryzas and associated with seed dormancy; nonfunctional rc alleles were strongly favored during rice domestication, and most cultivated varieties have nonpigmented pericarps. Phenotypic characterizations of 52 Malaysian weeds revealed that most strains are characterized by the pigmented pericarp; however, some weeds have white pericarps, suggesting close relationships to cultivated rice. Phylogenetic analyses indicate that the Rc haplotypes present in Malaysian weeds likely have at least three distinct origins: wild O. rufipogon, white-pericarp cultivated rice, and red-pericarp cultivated rice. These diverse origins contribute to high Rc nucleotide diversity in the Malaysian weeds. Comparison of Rc allelic distributions with other rice domestication genes suggests that functional Rc alleles may confer particular fitness benefits in weedy rice populations, for example, by conferring seed dormancy. This may promote functional Rc introgression from local wild Oryza populations.
INTRODUCTION: The knowledge of pre-existing medical illnesses and their follow up status among active pulmonary tuberculosis (PTB) subjects can help in tuberculosis (TB) control programme. The aims of our study were to examine: the prevalence of pre-existing chronic medical illnesses, the follow up status of known pre-existing co-morbid and to distinguish between diagnosed and undiagnosed preexisting tuberculosis related chronic medical illnesses among our active PTB subjects.
METHODS: We conducted a retrospective review of demographic and clinical data of active PTB subjects that were diagnosed between January 2015 and June 2017 in the district of Manjung, Perak, Malaysia. Among the 302 TB clinical notes reviewed, 253 patients were included. Subjects below the age of 18 years and whose follow up centres for their medical illnesses that were located outside of Manjung were excluded. Demographic and clinical data were collected using pre-tested data collection form by trained investigators. The data was analysed using SPSS Version 20.0.
RESULTS: We identified diabetes mellitus as the most prevalent pre-existing co-morbid (77 cases) and almost 90% (68 cases) of these diabetic subjects were diagnosed prior to active PTB diagnosis. This was followed by Human Immunodeficiency Virus and Hepatitis C infection which accounted for 12.0% (30 cases) of the study populations. Among 132 subjects who had pre-existing chronic medical illnesses, only 74 subjects (29%) were under regular follow up at healthcare facilities in Manjung prior to PTB diagnosis.
CONCLUSION: Overall, our research provides evidence on the existence of wide variation of clinical background among active PTB subjects.
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.