Recent Progress in Molecular Studies on Storage Root Formation in Sweetpotato (<i>Ipomoea batatas</i>)

Abstract

Elucidating the mechanisms underlying the formation of storage roots is important for further improvement of sweetpotato. Although the process of storage root formation in sweetpotato has been extensively studied anatomically and physiologically, the genetic and molecular mechanisms remain largely unknown. Recently, extensive gene expression analysis has identified numerous genes differentially expressed between fibrous and storage roots. The results of these analyses agreed with previous anatomical and physiological observations in that genes related to starch and storage protein biosynthesis were up-regulated, and those related to lignin biosynthesis were down-regulated in the storage roots. Also, molecular biological studies and analyses using transgenic sweetpotato plants have suggested that an expansin protein and several transcription factor genes, such as a Dof-type zinc finger protein, MADS-box proteins, and KNOXI proteins, are involved in the characteristic physiological process of storage root formation. Furthermore, ongoing whole-genome sequencing of sweetpotato and the related Ipomoea species is expected to identify genetic differences related to storage root formation. Although these studies are valuable as a first step in elucidating the critical genes and genetic network that control the formation of storage roots, further physiological, genetic, and molecular biological studies are needed to reveal the entire molecular process.

The wild sweetpotato (Ipomoea trifida) genome provides insights into storage root development

“…Understanding the mechanism of SR formation and development is of pivotal importance for further improving sweetpotato yield [6]. To date, sporamin proteins, Dof-type zinc finger proteins, MADS-box proteins and KNOX proteins have been shown to be associated with SR development [7–9]. The lack of genomic information has slowed research into SR development [7].…”

“…To date, sporamin proteins, Dof-type zinc finger proteins, MADS-box proteins and KNOX proteins have been shown to be associated with SR development [7–9]. The lack of genomic information has slowed research into SR development [7]. The candidate genes corresponding to many sweetpotato quantitative trait loci (QTL) remain elusive [10].…”

Effect of Partial Excision of Early Taproots on Growth and Components of Hydroponic Carrots

“…Given that C5 taproots contained more wounded parts compared with C10 and C15 plants, continuous wound stress at a root cut site may trigger higher production of phenolic compounds in C5 plants. In root vegetables, sink development is regulated by a variety of plant hormones such as auxin, cytokinin, and gibberellic acid [30][31][32][33]. In carrots, gibberellic acids function as negative regulators of taproot enlargement [34,35].…”

Gene Regulatory Network Guided Investigations and Engineering of Storage Root Development in Root Crops

“…Several well-known TFs were also identified, including IbMADS1, SHORTROOT (SHR), BEL1-LIKE HOMEODOMAIN 1 (BLH1), KNOX1 and ETHYLENE RESPONSE FACTORs (ERFs). Collectively, the summary by Tanaka (2016) indicated that important genes involved in sweet potato root formation are those related to carbohydrate metabolism, sugar signaling, lignin biosynthesis, cell division, development and transcription. More recently, Dong et al (2019) analyzed the transcriptome and proteome from the fibrous roots and four developmental stages of sweet potato storage roots, finding that genes related to meristem/cambium development, starch biosynthesis and hormones were differentially expressed during storage root formation.…”