Current Science

C. Chinnaraja ¹, R. Viswanathan ¹, M. Sathyabhama ¹, B. Parameswari ², K. Bagyalakshmi ¹, P. Malathi ¹, D. Neelamathi ³

Affiliations
1 Plant Pathology Laboratory, Karnal 132 001, IN
2 Sugarcane Breeding Institute Regional Centre (ICAR), Karnal 132 001, IN
3 Micropropagation Laboratory, Sugarcane Breeding Institute (ICAR), Coimbatore 641 007, IN

Abstract

Yellow leaf caused by Sugarcane yellow leaf virus (SCYLV) is a serious viral disease affecting production and productivity in many ruling sugarcane varieties in India. Usually the characteristic disease symptoms appear during maturity phases of the crop; also many of the infected varieties do not exhibit disease symptoms and disease expression is influenced by virus titre and other factors, including the prevailing climate. The present study was taken up to quantify and compare SCYLV in meristem-derived tissue culture raised in vitro plantlets and asymptomatic sugarcane plants in RT-qPCR by relative standard curve method. The standard curve was prepared with serial dilutions of plasmid standards from 3 × 10⁷ to 3 × 10³ copy numbers of virus target gene. In this assay, copy number of virus population in in vitro plantlets and asymptomatic plants was estimated from 20,314.58 to 4,330.87 and from 8.96 to 0.27 million copies of viruses respectively. Relative expression level of the virus between in vitro plantlets and asymptomatic plants was in the ratio 73.7 : 243,393.1 based on 2^{-(Δ ΔCt). The results clearly established that meristem-derived tissue culture significantly reduced SCYLV population and it is concluded that the relative standard curve method efficiently detects the copy numbers of the target virus in different sugarcane samples.}

Keywords

Asymptomatic Plants, In Vitro Plantlets, Sugarcane Yellow Leaf Virus, Viral Titre.

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N. Geetha ¹, R. Viswanathan ¹, T. Ramasubramanian ¹, K. P. Salin ¹, C. Yogambal ¹, P. Nirmala Devi ¹, S. Karthigeyan ², N. Chitra ³

Affiliations
1 Division of Crop Protection, ICAR-Sugarcane Breeding Institute, Coimbatore 641 007, India, IN
2 Division of Crop Improvement, ICAR-Sugarcane Breeding Institute, Coimbatore 641 007, India, IN
3 Department of Agricultural Entomology, Tamil Nadu Agricultural University, Coimbatore 641 003, India, IN

Abstract

In this study, we report Phenacoccus saccharifolii (green) on sugarcane in Tamil Nadu, India, though an earlier unre­ported isolated occurrence was observed by us in the farmers’ fields at Pugalur, Tamil Nadu. This pest has now become a major threat to sugarcane cultivation across the state as it can often kill the infested canes with or without the association of the fungal disease, pokkah boeng. Field observations revealed that the ratoon crop was affected more than the plant crop in the same locality. This species was found in large colonies, primarily between the –2 and +1 leaf of the sugarcane plant and hence, named as crown mealybug. Infestation leads to severe mottling in the leaf whorl and death of the central shoot. To the best of our knowledge, there are no earlier studies on the occurrence of this mealybug on Saccharum spontaneum L. Well-deve­loped colonies showed high activity of three encyrtid para­sitoids, viz. Aenasius phenococci (Ashmead), Aenasius arizonensis (Girault) and Leptomastix dactylopii Howard in the areas surveyed

Keywords

Encyrtid parasitoids, fungal disease, infestation, Phenacoccus saccharifolii, Saccharum spontaneum, sugar-cane.

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