Analysis of Gene Regulatory Networks of Taro (Colocasia esculenta (L.) Schott.) Soluble Starch Synthase Based on DeGN and KASP Marker Development

TL;DR

This study identifies key genes and a new marker for starch synthesis in taro, which can help breed high-starch varieties.

Contribution

The study develops a KASP marker for starch content and identifies CeSS II and CeMyb108 as key genes in taro starch synthesis.

Findings

CeSS II is likely the key gene for soluble starch synthesis in taro corms.

CeMyb108 may negatively regulate starch synthesis.

The CeSS II-SNP KASP marker effectively distinguishes high- and low-starch taro varieties.

Abstract

Taro (Colocasia esculenta (L.) Schott.) is an important edible and economically valuable crop that is also a source of high-quality starch. Its quality is determined by the content and proportion of amylopectin. Based on transcriptome sequencing of corms at different growth stages (T1–T6), 34,603 transcripts and 1727 novel genes with functional annotation were obtained. In total, 11,865 differentially expressed genes (DEGs) were identified among six development stages, with 3836 and 3404 DEGs in T2 versus T3 and T3 versus T4, respectively. The regulatory network of taro starch synthesis was constructed on the DeGNServer. Among three cloned soluble starch synthase (SS) genes, CeSS II might be the key gene responsible for soluble starch synthesis in taro corm. The putative transcription factor CeMyb108 might play a negative role in starch synthesis. Sanger sequencing CeSS II gene revealed a single nucleotide polymorphism (SNP) between two variety groups with high and low starch content. A kompetitive allele-specific PCR (KASP) marker, namely, CeSS II-SNP, was developed and validated in a natural population of 89 taro accessions. The starch content of the C:T group amounts to 517.45 mg/g, which is significantly (22.3%) higher than its counterpart (T:T). This newly developed marker is proved to be effective and would facilitate marker-assisted breeding for taro with high starch content.

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