Osa-miR167d facilitates infection of Magnaporthe oryzae in rice.

MicroRNAs (miRNAs) play important roles in rice response to Magnaporthe oryzae, the causative agent of rice blast disease. Studying the roles of rice miRNAs is of great significance for the disease control. Osa-miR167d belongs to a conserved miRNA family targeting auxin responsive factor (ARF) genes that act in developmental and stress-induced responses. Here, we show that Osa-miR167d plays a negative role in rice immunity against M. oryzae by suppressing its target gene. The expression of Osa-miR167d was significantly suppressed in a resistant accession at and after 24 h post inoculation (hpi), however, its expression was significantly increased at 24 hpi in the susceptible accession upon M. oryzae infection. Transgenic rice lines over-expressing Osa-miR167d were highly susceptible to multiple blast fungal strains. By contrast, transgenic lines expressing a target mimicry to block Osa-miR167d enhanced resistance to rice blast disease. In addition, knocking out the target gene ARF12 led to hyper-susceptibility to multiple blast fungal strains. Taken together, our results indicate that Osa-miR167d negatively regulate rice immunity to facilitate the infection of M. oryzae by downregulating ARF12. Thus, Osa-miR167d-ARF12 regulatory module could be valuable in improvement of blast-disease resistance.

miR396-OsGRFs Module Balances Growth and Rice Blast Disease-Resistance.

Fitness cost is a common phenomenon in rice blast disease-resistance breeding. MiR396 is a highly conserved microRNA (miRNA) family targeting Growth Regulating Factor (OsGRF) genes. Mutation at the target site of miR396 in certain OsGRF gene or blocking miR396 expression leads to increased grain yield. Here we demonstrated that fitness cost can be trade-off in miR396-OsGRFs module via balancing growth and immunity against the blast fungus. The accumulation of miR396 isoforms was significantly increased in a susceptible accession, but fluctuated in a resistant accession upon infection of Magnaporthe oryzae. The transgenic lines over-expressing different miR396 isoforms were highly susceptible to M. oryzae. In contrast, overexpressing target mimicry of miR396 to block its function led to enhanced resistance to M. oryzae in addition to improved yield traits. Moreover, transgenic plants overexpressing OsGRF6, OsGRF7, OsGRF8, and OsGRF9 exhibited enhanced resistance to M. oryzae, but showed different alteration of growth. While overexpression of OsGRF7 led to defects in growth, overexpression of OsGRF6, OsGRF8, and OsGRF9 resulted in better or no significant change of yield traits. Collectively, our results indicate that miR396 negatively regulates rice blast disease- resistance via suppressing multiple OsGRFs, which in turn differentially control growth and yield. Therefore, miR396-OsGRFs could be a potential module to demolish fitness cost in rice blast disease-resistance breeding.

Differential expression of microRNAs in dormant bud of tea [Camellia sinensis (L.) O. Kuntze].

KEY MESSAGE: Expression analysis of miRNAs and understanding their target genes function in dormant tea bud might be used to identify molecular network panel and novel approaches for modulating dormancy in tea. Tea [Camellia sinensis (L) O. Kuntze, Theaceae] is an important commercial beverage crop manufactured from the apical bud and two leaves immediately below the bud. The yield and quality of tea depend on the vegetative growth of shoots and bud dormancy. The dormancy of bud is being regulated by many factors, such as mechanical, environmental and molecular mechanisms. MicroRNAs (miRNAs) are a newly identified class of small non-protein coding regulatory RNAs in both plants and animals which regulates gene expression at post-transcriptional level either by cleavage or translational inhibition of targeted mRNA transcripts. With these importances, the expression pattern of tea miRNAs was analyzed in active and dormant bud using stem-loop pulse RT-qPCR method. The results demonstrated the following expression pattern for highly up-regulated miRNAs, cs-miR 414[csmiR 408[cs-miR782[cs-miR169, and down-regulated miRNAs, cs-miR828[cs-miR1864[cs-miR852[csmiR1425 in dormant bud of tea. Furthermore, the role of target transcripts regulated by these miRNAs in relation to bud dormancy was discussed in detail. Therefore, the present study on the miRNA expression in tea will provide basis and considerably broaden the scope of understanding the function of miRNAs within the bud tissues and can serve as an initial point for RNA interference-based controlling strategies of bud dormancy in tea.

Snakebite and its socio-economic impact on the rural population of Tamil Nadu, India.

BACKGROUND: Snakebite represents a significant health issue worldwide, affecting several million people each year with as many as 95,000 deaths. India is considered to be the country most affected, but much remains unknown about snakebite incidence in this country, its socio-economic impact and how snakebite management could be improved. METHODS/PRINCIPAL FINDINGS: We conducted a study within rural villages in Tamil Nadu, India, which combines a household survey (28,494 people) of snakebite incidence with a more detailed survey of victims in order to understand the health and socio-economic effects of the bite, the treatments obtained and their views about future improvements. Our survey suggests that snakebite incidence is higher than previously reported. 3.9% of those surveyed had suffered from snakebite and the number of deaths corresponds to 0.45% of the population. The socio-economic impact of this is very considerable in terms of the treatment costs and the long-term effects on the health and ability of survivors to work. To reduce this, the victims recommended improvements to the accessibility and affordability of antivenom treatment. CONCLUSIONS: Snakebite has a considerable and disproportionate impact on rural populations, particularly in South Asia. This study provides an incentive for researchers and the public to work together to reduce the incidence and improve the outcomes for snake bite victims and their families.