Sweetpotato leaf curl virus decreased storage root yield and quality of edible sweetpotato in China.

Sweetpotato leaf curl virus (SPLCV) causes leaf curl symptoms in sweetpotato [Ipomoea batatas (L.) Lam]. These symptoms disappear under high temperature. Previous studies have shown that SPCLV reduces storage root yield in sweetpotato. However, knowledge of SPLCV's effect on root quality is limited. In this study, we surveyed the effect of SPLCV on storage root yield and quality in edible sweetpotato. Quantitative real‐time reverse transcriptase–polymerase chain reaction and leaf paraffin section results showed that the SPLCV mRNA level and the distribution density of spongy mesophyll cells in SPLCV‐infected plants were significantly higher than in healthy control plants (CK). Leaf net photosynthetic rate, vine length, and storage root yield were reduced in SPLCV‐infected plants during the growing period, and the shoot/root ratio was significantly increased compared with CK. Additionally, root abscisic acid, auxin, and zeatin riboside contents under SPLCV infection were higher than the CK, whereas root gibberellic acid content was lower. Root dry matter, starch, and carotenoid contents were lower in the infected plants than in the CK. Moreover, SPLCV‐infected plants showed reduced expression of starch and carotenoid metabolitic genes, such as ADP‐glucose pyrophosphorylase‐ß, granule‐bound starch synthase I, starch branching enzyme I and II, and carotenoid isomerase, and increased expression of α‐amylase, ß‐carotene hydroxylase, and zeaxanthin epoxidase. These results suggest that sweetpotato infected by SPLCV had decreased storage root yield and decreased starch and carotenoid contents through reducing photosynthetic capacity, regulating starch and carotenoid degradation, and changing endogenous hormone contents. Therefore, effective management should be taken to prevent SPLCV epidemics during sweetpotato production. [ABSTRACT FROM AUTHOR]