Large-Scale Seedling Grow-Out Experiments Do Not Support Seed Transmission of Sweet Potato Leaf Curl Virus in Sweet Potato.

Kai-Shu Ling,D Michael Jackson,Livy H Williams,Andrea C Gilliard,Phillip A Wadl,Sharon A Andreason,Alvin M Simmons,Omotola G Olaniyi

doi:10.3390/plants10010139

Kai-Shu Ling, D Michael Jackson + Show 6 more

Open Access

https://doi.org/10.3390/plants10010139

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Abstract

Sweet potato leaf curl virus (SPLCV) threatens global sweet potato production. SPLCV is transmitted by Bemisia tabaci or via infected vegetative planting materials; however, SPLCV was suggested to be seed transmissible, which is a characteristic that is disputed for geminiviruses. The objective of this study was to revisit the validity of seed transmission of SPLCV in sweet potato. Using large-scale grow-out of sweet potato seedlings from SPLCV-contaminated seeds over 4 consecutive years, approximately 23,034 sweet potato seedlings of 118 genotype entries were evaluated. All seedlings germinating in a greenhouse under insect-proof conditions or in a growth chamber were free of SPLCV; however, a few seedlings grown in an open bench greenhouse lacking insect exclusion tested positive for SPLCV. Inspection of these seedlings revealed that B. tabaci had infiltrated the greenhouse. Therefore, transmission experiments were conducted using B. tabaci MEAM1, demonstrating successful vector transmission of SPLCV to sweet potato. Additionally, tests on contaminated seed coats and germinating cotyledons demonstrated that SPLCV contaminated a high percentage of seed coats collected from infected maternal plants, but SPLCV was never detected in emerging cotyledons. Based on the results of grow-out experiments, seed coat and cotyledon tests, and vector transmission experiments, we conclude that SPLCV is not seed transmitted in sweet potato.

Highlights

Sweet potato, Ipomoea batatas (L.) Lam., in the morning glory family Convolvulaceae, is the sixth most important food crop worldwide behind rice, wheat, potatoes, maize, and cassava [1]
We detected the presence of sweet potato leaf curl virus (SPLCV) on sweet potato whole seeds and seed coats as well as other vegetative tissues through real-time PCR detection, confirming
Seed transmission indicates that virus particles present on/in the seed could be transmissible to the offspring, resulting in a new infection in the geminated seedlings

Summary

Introduction

Ipomoea batatas (L.) Lam., in the morning glory family Convolvulaceae, is the sixth most important food crop worldwide behind rice, wheat, potatoes, maize, and cassava [1]. As a root vegetable high in nutritive value, sweet potato has been relied on during food security crises, serving as a staple crop when other primary crops have failed [2,3]. It boasts a wide range of cultivation purposes, from subsistence farming to sales in high-profit, health food markets [3]. As such, planting stocks (e.g., storage roots and plant vines) can accumulate pathogens and serve as inoculum for disease in young crops and as a source of pathogen dissemination

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