Developing markers for Sigatoka leaf spot disease (Mycosphaerella musicola Leach) resistance in banana (Musa spp.)

Sigatoka leaf spot (Mycosphaerella musicola Leach) disease is a limiting factor in banana production in India and other places. Breeding for resistance is the most effective method to control Musa diseases. However, Musa improvement using conventional methods has been hampered due to lack of genetic variability, resulting to biotechnological approaches. In this regard, marker-assisted selection has become a reliable method to improve disease resistance in Musa. The objective of this study was to identify markers that may be linked to Sigatoka leaf spot disease in Musa, using RAPDs and converting such into sequence characterized amplified region (SCAR). Consequently, a total of 102 oligonucleotide OPERON primer pairs were used to screen genomic DNA from two resistant cultivars: Calcutta 4 (Musa acuminate, AA) and Manoranjitham (AAA), and two susceptible cultivars Anaikomban (AA) and Grande Naine (AAA) with only 11 (10.8%) of the primers being polymorphic. Eventually, OPK 01 and OPK 11 primers in Calcutta 4 were eluted, but only OPK 11 was sequenced and cloned using pGEM-2T vector, resulting to a band size of 4.3 KB, and the development of two SCAR markers. A FASTA search in the Musa genome database could not identify corresponding gene sequences that show homology with the sequenced PCR fragment. Finally, the SCAR marker was used to amplify genomic DNA from the segregating population which could not discriminate between resistant and susceptible samples. This may be due to amplification conditions, limited number of primers and most importantly, the absence of tight linkage with the gene of interest. In conclusion, it may be necessary to screen the segregating population with more reliable and reproducible amplified fragment length polymorphism.Key words: Marker-assisted selection, disease resistance, Musa, random amplification of polymorphic DNA (RAPD), genetic improvement, SCAR

Not Available

Not AvailableCost-effective tissue culture protocols have been established for the commercial multiplication of three banana varieties, ‘Rasthali’ (AAB – Silk), ‘Grand Naine’ (AAA – Cavendish), and ‘Udhayam’ (ABB – Pisang Awak). Reverse osmosis water and 3% (w/v) table sugar were used as the low-cost water and carbon source, respectively. Six different gelling agent treatments were tested: sago alone (T1), Isabgol alone (T2), sago + agar (T3), Isabgol + agar (T4), sago + Isabgol (T5), and agar alone as a control (T6). Full-strength Murashige and Skoog (MS) medium supplemented with 3 mg l–1 6-benzylaminopurine (BAP) and 1 mg l–1 indole-3-acetic acid (IAA) were used for culture initiation and subculturing. Rooting was accomplished on low-cost MS medium containing 1.0 mg l–1 α-napthaleneacetic acid (NAA), 1.0 mg l–1 indole3-butyric acid (IBA), and 250 mg l–1 activated charcoal. Statistical analysis indicated that sago + Isabgol (T5) produced the maximum number of shoots (10 per explant) in ‘Udhayam’ and ‘Rasthali’, while sago alone (T1) produced the maximum number of shoots (6 per explant) in ‘Grand Naine’. The genetic stability of tissue-cultured banana plantlets produced using these low-cost substitutes was assessed using inter-simple sequence repeat (ISSR) markers. The results indicated that the ISSR profiles of the five treatments and the control (T6) were similar, indicating genetic stability using these cost-effective tissue culture protocols. Reductions in cost over the control (l–1 of MS medium) ranged from 65% to 86%, while the per plant production cost was reduced by 12.5%–20.0%. Adoption of these treatments (T1–T5) as lowcost tissue culture protocols for in vitro propagation would reduce production costs significantly, leading to an expansion of the area planted with tissue-cultured banana, thereby increasing productivity.ICAR, ICAR-NRC

Expression profiles of immune mediators in feline Coronavirus-infected cells and clinical samples of feline Coronavirus-positive cats

Abstract Background There are two biotypes of feline coronavirus (FCoV): the self-limiting feline enteric coronavirus (FECV) and the feline infectious peritonitis virus (FIPV), which causes feline infectious peritonitis (FIP), a fatal disease associated with cats living in multi-cat environments. This study provides an insight on the various immune mediators detected in FCoV-positive cats which may be responsible for the development of FIP. Results In this study, using real-time PCR and multiplex bead-based immunoassay, the expression profiles of several immune mediators were examined in Crandell-Reese feline kidney (CRFK) cells infected with the feline coronavirus (FCoV) strain FIPV 79–1146 and in samples obtained from FCoV-positive cats. CRFK cells infected with FIPV 79–1146 showed an increase in the expression of interferon-related genes and pro-inflammatory cytokines such as MX1, viperin, CXCL10, CCL8, RANTES, KC, MCP1, and IL8. In addition, an increase in the expression of the above cytokines as well as GM-CSF and IFNγ was also detected in the PBMC, serum, and peritoneal effusions of FCoV-positive cats. Although the expression of MX1 and viperin genes was variable between cats, the expression of these two genes was relatively higher in cats having peritoneal effusion compared to cats without clinically obvious effusion. Higher viral load was also detected in the supernatant of peritoneal effusions compared to in the plasma of FCoV-positive cats. As expected, the secretion of IL1β, IL6 and TNFα was readily detected in the supernatant of peritoneal effusions of the FCoV-positive cats. Conclusions This study has identified various pro-inflammatory cytokines and interferon-related genes such as MX1, viperin, CXCL10, CCL8, RANTES, KC, MCP1, IL8, GM-CSF and IFNγ in FCoV-positive cats. With the exception of MX1 and viperin, no distinct pattern of immune mediators was observed that distinguished between FCoV-positive cats with and without peritoneal effusion. Further studies based on definitive diagnosis of FIP need to be performed to confirm the clinical importance of this study