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Made available in DSpace on 2020-12-11T12:42:34Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-03-16 National Natural Science Foundation of China CAS President's International Fellowship Initiative (PIFI) China Postdoctoral Science Foundation SERB-Start-Up Research Grant (Young Scientist) Scheme, Department of Science and Technology, Government of India, New Delhi Antimicrobial activity of silver nanoparticles (AgNPs) has been well documented in earlier studies. As their efficient role in combating phytopathogens has begun recently, there is a huge scope to explore their effectiveness in agriculture. Considering the strong antifungal activity of biosynthesized AgNPs (as reported in our previous study), our main aim is to elucidate their antibacterial activity against bacterial plant pathogens to authenticate their wide range of agricultural applications. The present manuscript highlights the potential role of biosynthesized AgNPs against Xanthomonas oryzae pv. oryzae (Xoo) causing disastrous sheath blight disease of rice worldwide. We observed strong antibacterial activity of biosynthesized AgNPs (size similar to 12 nm) against Xoo at 20, 30 and 50 mu g/mL concentrations. The significant inhibitory impact of AgNPs on biofilm formation by Xoo was noted even at the lower dose of 5 mu g/mL (p = 0.001). Maximum biofilm inhibition (p = 0.000) was caused at 50 mu g/mL concentration of AgNPs in comparison to control. Furthermore, disease suppression by biosynthesized AgNPs was authenticated under greenhouse conditions. Foliar spray of AgNPs significantly reduced the blight symptoms in rice sheaths as shown by 9.25% DLA (% Diseased leaf area) as compared to 33.91% DLA in Xoo inoculated rice plants. Altogether, our data suggest that biosynthesized AgNPs based nanoformulation can be applied for successful management of blight disease of rice. In addition, the antibiofilm strategies instigated by AgNPs can be exploited against a wide range of bacterial phytopathogens. In light of rapidly emerging antibiotic-resistant microbial strains, the current work provides an alternate effective platform for the application of nanoformulation for augmenting sustainability in the agriculture. Chinese Acad Sci, Xishuangbanna Trop Bot Garden, CAS Key Lab Trop Forest Ecol, Menglun 666303, Yunnan, Peoples R China Banaras Hindu Univ, Dept Mycol & Plant Pathol, Inst Agr Sci, Varanasi 221005, Uttar Pradesh, India Sao Paulo State Univ, Lab Environm Nanotechnol, Inst Sci & Technol Sorocaba, Sao Paulo, Brazil Somvanshi Res Fdn, 13-21 Vikas Nagar, Lucknow 226022, Uttar Pradesh, India Sao Paulo State Univ, Lab Environm Nanotechnol, Inst Sci & Technol Sorocaba, Sao Paulo, Brazil National Natural Science Foundation of China: 31700457 CAS President's International Fellowship Initiative (PIFI): 2019PC0095 China Postdoctoral Science Foundation: 2018M631112 SERB-Start-Up Research Grant (Young Scientist) Scheme, Department of Science and Technology, Government of India, New Delhi: YSS/2015/000082

Background Xanthomonas oryzae pv. oryzae (Xoo) is the causal agent of Bacterial Leaf Blight (BB), an emerging disease in rice in West-Africa which can induce up to 50 % of yield losses. So far, no specific resistance gene or QTL to African Xoo were mapped. The objectives of this study were to identify and map novels and specific resistance QTLs to African Xoo strains. Results The reference recombinant inbred lines (RIL) mapping population derived from the cross between IR64 and Azucena was used to investigate Xoo resistance. Resistance to African and Philippine Xoo strains representing different races was assessed on the RIL population under greenhouse conditions. Five major quantitative trait loci (QTL) for resistance against African Xoo were located on different chromosomes. Loci on chromosomes 1, 7, 9, 10 and 11 explained as much as 13 %, 37 %, 13 %, 11 % and 15 % of resistance variation, respectively. A major novel QTL located on chromosome 7 explained 37 % of the phenotypic variance to the African Xoo corresponding to race A3 whereas that on chromosome 11 is effective to all African races tested. Together with genes and QTLs for resistance to bacterial blight previously described, the QTLs described here were mapped onto the reference O. sativa subs japonica (var. Nipponbare) physical map. Conclusion We characterized new resistance QTLs. While some co-localize with known resistance genes/QTLs to Asian strains, others are specific to African strains. We result with new information on genes and QTLs for resistance to bacterial blight that will be useful for controlling the disease.