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.

Sweet potato (Ipomoea batatas (L.) Lam.) is one of the most important crops with high storage roots yield. The formation and expansion rate of storage root (SR) plays a crucial role in the production of sweet potato. Lignin affects the SR formation; however, the molecular mechanisms of lignin in SR development have been lacking. To reveal the problem, we performed transcriptome sequencing of SR harvested at 32, 46, and 67 days after planting (DAP) to analyze two sweet potato lines, Jishu25 and Jishu29, in which SR expansion of Jishu29 was early and had a higher yield. A total of 52,137 transcripts and 21,148 unigenes were obtained after corrected with Hiseq2500 sequencing. Through the comparative analysis, 9577 unigenes were found to be differently expressed in the different stages in two cultivars. In addition, phenotypic analysis of two cultivars, combined with analysis of GO, KEGG, and WGCNA showed the regulation of lignin synthesis and related transcription factors play a crucial role in the early expansion of SR. The four key genes swbp1, swpa7, IbERF061, and IbERF109 were proved as potential candidates for regulating lignin synthesis and SR expansion in sweet potato. The data from this study provides new insights into the molecular mechanisms underlying the impact of lignin synthesis on the formation and expansion of SR in sweet potatoes and proposes several candidate genes that may affect sweet potato yield.

Background: Sweet potato (Ipomoea batatas (L.) Lam.) is a highly heterozygous autohexaploid crop with high yield and high anthocyanin content. Purple sweet potato is the main source of anthocyanins, and the mechanism of anthocyanin biosynthesis in storage roots has not been fully revealed. Results: In order to reveal the mechanism of anthocyanin biosynthesis and identify new homologous genes involved in anthocyanin biosynthesis in the storage roots of sweet potato, we used Ningzishu 1 and Jizishu 2 as parents to construct a F₁ hybrid population. Seven anthocyanin-containing lines and three anthocyanin-free lines were selected for full-length and second-generation transcriptome analyses. A total of 598,375 circular consensus sequencing reads were identified from full-length transcriptome sequencing. After analysis and correction of second-generation transcriptome data, 41,356 transcripts and 18,176 unigenes were obtained. Through a comparative analysis between anthocyanin-containing and anthocyanin-free groups 2329 unigenes were found to be significantly differentially expressed, of which 1235 were significantly up-regulated and 1094 were significantly down-regulated. GO enrichment analysis showed that the differentially expressed unigenes were significantly enriched in molecular function and biological process. KEGG enrichment analysis showed that the up-regulated unigenes were significantly enriched in the flavonoid biosynthesis and phenylpropanoid biosynthesis pathways, and the down-regulated unigenes were significantly enriched in the plant hormone signal transduction pathway. Weighted gene co-expression network analysis of differentially expressed unigenes revealed that anthocyanin biosynthesis genes were co-expressed with transcription factors such as MYB, bHLH and WRKY at the transcription level. Conclusions: Our study will shed light on the regulatory mechanism of anthocyanin biosynthesis in sweet potato storage roots at the transcriptome level.