Spread of Sugarcane yellow leaf virus in sugarcane plants and fields on the island of Réunion

Abstract

The spread of Sugarcane yellow leaf virus (SCYLV) in sugarcane plants was studied on Réunion using virus-infected cuttings from four cultivars (R570, R575, R577 and R579). One month after the germination of cuttings in an insect-proof glasshouse, SCYLV was detected by reverse-transcription polymerase chain reaction (RT-PCR) and tissue-blot immunoassay (TBIA) in the leaves, shoots and roots of all cultivars. The distribution of SCYLV in the whole plant did not vary over a 10-to 11-month period of growth. In addition, the spread of SCYLV in sugarcane fields on Réunion was investigated during a survey conducted from 1998 to 2001. Samples were taken in three sugarcane-growing areas, and TBIA was used to detect SCYLV in the three major cultivars (R570, R575 and R579). The percentage of infected stalks varied according to cultivar and growing area, but remained relatively stable for a given cultivar in a given growing area over the 30-month survey period. Cultivar R575 was the most infected cultivar in all three growing areas (mean of 98% infected stalks). The percentage of infected stalks ranged from 16 to 94% in cv. R570 and from 21 to 92% in cv. R579. These results suggested that on Réunion: (i) infected sugarcane stools do not recover from the disease after harvesting; and (ii) the virus is mainly propagated by planting infected cuttings. SCYLV was detected by RT-PCR in the aphid Melanaphis sacchari , a potential vector of this virus. Two months after planting virus-free plants of susceptible cv. R575 in a field surrounded by sugarcane infected with SCYLV, 14% of plants were found infected with the virus. Four months later, 25% of plants were found infected with SCYLV, but no new infections were detected between 6 and 12 months after planting. In the first ratoon crop, 42% of plants were infected with SCYLV after 6 months of growth. Spatial distribution of infected plants suggested that, on Réunion, a small window of time (between 0 and 2 months after planting cuttings) exists during which primary infection can occur. Based on the results obtained in this study, the use of clean planting material for some cultivars and the use of tolerant cultivars should be an efficient means of controlling sugarcane yellow leaf on Réunion.

Quantification of sugarcane yellow leaf virus in sugarcane following transmission through aphid vector, Melanaphis sacchari

“…Screening of SCYLV in Hawaii revealed positive infection in all susceptible sugarcane cultivars but disease symptoms appeared only occasionally [14]. However, this nonsymptomatic stage can still lead to significant (20-30 %) yield decline [15]. These studies clearly indicated that nonsymptomatic plants still harbour very high titre for SCYLV.…”

“…Also, they found about 25 % of the plants within a plot were asymptomatic. Screening of SCYLV in Hawaii revealed positive infection in all susceptible sugarcane cultivars but disease symptoms appeared only occasionally [14]. However, this nonsymptomatic stage can still lead to significant (20-30 %) yield decline [15].…”

“…The present work showed high fluctuations in the aphid population ranging from trace to 484 per plant in May and up to 643 aphids in October, 2012 (Viswanathan, unpublished). Rassaby et al [14] reported virus-free susceptible cultivar planted near SCYLVinfected sugarcane resulted in 45 % of infection after 4 months. Schenck and Lehrer [17] reported that R. maidis can transmit SCYLV from sugarcane to cereal grasses.…”

“…These crops are not likely to be a source of infection for sugarcane infection as these crops are propagated by seeds and these viruses are not known to be seed-borne [6]. However, these cereals could become infected in the field by viruliferous M. sacchari or R. maidis from neighbouring sugarcane [14].…”

“…The virions of luteovirids are restricted to the phloem tissue of plants and are not transmitted mechanically [7]. Long range SCYLV transmission in sugarcane is achieved through infected seed canes and secondarily by aphids in a persistent manner [14]. Earlier, Schenck and Lehrer [17] reported three aphid species namely Melanaphis sacchari (sugarcane aphid), Rhopalosiphum maidis (corn leaf aphid) and R. rufiabdominalis (rice root aphid) as vectors of SCYLV in Hawaii.…”