Storage Root Yield of Sweetpotato as Influenced by Sweetpotato leaf curl virus and Its Interaction With Sweetpotato feathery mottle virus and Sweetpotato chlorotic stunt virus in Kenya.

Bramwel W. Wanjala,Jan W. Low,Elijah M. Ateka,Douglas W. Miano,Jan F. Kreuze

doi:10.1094/pdis-06-19-1196-re

Abstract

In this study, the effect of a Kenyan strain of Sweetpotato leaf curl virus (SPLCV) and its interactions with Sweetpotato feathery mottle virus (SPFMV) and Sweetpotato chlorotic stunt virus (SPCSV) on root yield was determined. Trials were performed during two seasons using varieties Kakamega and Ejumula and contrasting in their resistance to sweetpotato virus disease in a randomized complete block design with 16 treatments replicated three times. The treatments included plants graft inoculated with SPLCV, SPFMV, and SPCSV alone and in possible dual or triple combinations. Yield and yield-related parameters were evaluated at harvest. The results showed marked differences in the effect of SPLCV infection on the two varieties. Ejumula, which is highly susceptible to SPFMV and SPCSV, suffered no significant yield loss from SPLCV infection, whereas Kakamega, which is moderately resistant to SPFMV and SPCSV, suffered an average of 47% yield loss from SPLCV, despite only mild symptoms occurring in both varieties. These results highlight the variability in yield response to SPLCV between sweetpotato cultivars as well as a lack of correlation of SPLCV-related symptoms with yield reduction. In addition, they underline the lack of correlation between resistance to the RNA viruses SPCSV and SPFMV and the DNA virus SPLCV.[Formula: see text] Copyright © 2020 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.

Highlights

Ranked seventh in global food crop production, sweetpotato (Ipomoea batatas) is the third most important root and tuber crop after potato and cassava
RT-PCR/PCR tests performed on bulk samples at the end of the experiment and just before harvest indicated that the following plots were contaminated with viruses with which they had not been preinoculated: Ejumula, plot 17; Kakamega, plot 24; and Kakamega, plot 18 (Table 1)
Our study confirmed the relative susceptibility of Ejumula to Sweetpotato virus disease (SPVD) and revealed that it expressed equal sensitivity to Sweetpotato feathery mottle virus (SPFMV) and Sweetpotato chlorotic stunt virus (SPCSV)

Summary

Introduction

Ranked seventh in global food crop production, sweetpotato (Ipomoea batatas) is the third most important root and tuber crop after potato and cassava. Sweetpotato is one of the traditional crops that play an important role in addressing food insecurity in most rural households in Africa (Gruneberg et al 2015). Orange-fleshed sweetpotato varieties have high b-carotene content (source of provitamin A) and have seen increased utilization in food and dietary programs aimed at addressing vitamin A deficiency, a global challenge in Sub-Saharan Africa (Kurabachew 2015). The crop is cultivated year-round in Kenya, producing high yields under marginal conditions. Sweetpotato yields differ from >25 t ha−1 with high input to

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