Volatile Compounds Governed by Single Recessive Gene Impart Aroma in Sponge Gourd (Luffa cylindrica L. Roem).

As a vegetable crop, sponge gourd is widely consumed worldwide due to its health promoting and nutraceutical value. This study describes genetics of an aromatic genotype VRSG-7-17 and deciphers the genetic control and volatile compound composition of sponge gourd. To study the inheritance of this trait, a cross was made between aromatic light-green-fruited VRSG-7-17 and non-aromatic dark-green-fruited VRSG-194 genotypes. The F1s were found to be non-aromatic and have a green fruit colour. Chi-square (χ2) analysis of backcross and F2 population segregating for aroma suggested that the inheritance of aroma in VRSG-7-17 is governed by a single recessive gene in a simple Mendelian fashion. The SPME-GC/MS analysis of the volatile compounds suggested that the compounds responsible for Basmati rice-like aroma were mainly hexanal, 1-octen-3-ol, 3-octanone and limonene. The aroma persists in the cooked VRSG-7-17 fruits, that did not lose fragrance traits at high temperatures. The inheritance of fruit colour was found to be controlled by a single gene with incomplete dominance. The segregation analysis showed that the aroma and fruit colour were not linked, and they segregated independently. The findings will lead to understanding the inheritance of the aromatic compounds in the sponge gourd and may be utilised in the breeding programmes for developing improved aromatic varieties.

Loop-mediated isothermal amplification assay for quicker detection of tomato leaf curl Joydebpur virus infection in chilli.

Chilli leaf curl disease caused by whitefly transmitted begomoviruses is an important constraint to chilli (Capsicum anuum L.) cultivation in India. Tomato leaf curl Joydebpur virus (ToLCJoV) was characterized and identified as incitant of leaf curl disease through rolling circle amplification (RCA) and PCR assay from the symptomatic samples collected from Uttar Pradesh, India. Although PCR assay provides the gold standard in diagnostics, this method consumes more time and requires convenient portable instruments. Therefore, a loop-mediated isothermal amplification (LAMP) assay was developed for the detection of ToLCJoV by targeting the AC1 and AC2 region. Detection has been achieved through a laddered pattern of amplification in agarose gel electrophoresis. The assay has detected ToLCJoV in a total DNA concentration of 1 × 10-1 ng indicating 200-fold higher sensitivity than that of the PCR. Further, the replacement of total DNA with leaf extracts using the grinding buffer and GES buffer coupled with LAMP assay also detected the presence of ToLCJoV in the infected chilli samples. With this assay, ToLCJoV can be detected in less than 2 h without DNA extraction. Besides, this assay will be highly useful in discriminating the leaf curl disease etiology by ToLCJoV from other begomoviruses and insects (thrips and mites). To the best of our knowledge, this is the first report of a LAMP assay for the detection of ToLCJoV.

Investigations on annual spreading of viruses infecting cucurbit crops in Uttar Pradesh State, India.

During 2018 an intensive study was conducted to determine the viruses associated with cucurbitaceous crops in nine agroclimatic zones of the state of Uttar Pradesh, India. Total of 563 samples collected and analysed across 14 different cucurbitaceous crops. The results showed the dominance of Begomovirus (93%) followed by Potyvirus (46%), cucumber green mottle mosaic virus (CGMMV-39%), Polerovirus (9%), cucumber mosaic virus (CMV-2%) and Orthotospovirus (2%). Nearly 65% of samples were co-infected with more than one virus. Additionally, host range expansion of CMV, CGMMV and polerovirus was also observed on cucurbit crops. A new potyvirus species, zucchini tigre mosaic virus, earlier not documented from India has also been identified on five crops during the study. Risk map generated using ArcGIS for virus disease incidence predicted the virus severity in unexplored areas. The distribution pattern of different cucurbit viruses throughout Uttar Pradesh will help identify the hot spots for viruses and will facilitate to devise efficient and eco-friendly integrated management strategies for the mitigation of viruses infecting cucurbit crops. Molecular diversity and evolutionary relationship of the virus isolates infecting cucurbits in Uttar Pradesh with previously reported strains were understood from the phylogenetic analysis. Diverse virus infections observed in the Eastern Plain zone, Central zone and North-Eastern Plain zone indicate an alarming situation for the cultivation of cucurbits in the foreseeable future.