Work

LIKE EARLY STARVATION is involved in the regulation of starch initiation in potato tubers ( Solanum tuberosum cv. Désirée)

Year: 2025

Type: article

Abstract: Starch initiation has been intensively investigated, and in tubers of Solanum tuberosum it is controlled by a heteromultimeric isoamylase (ISA) complex composed of ISA1 and ISA2. In Arabidopsis, two non-catalytic starch binding proteins regulate leaf starch metabolism, namely EARLY STARVATION 1 (ESV1) and LIKE EARLY STARVATION 1 (LESV). These proteins both interact with starch glucans through a C-terminal antiparallel β-sheet domain and differ by the presence of a 115 amino acid N-terminal overhang in LESV. Here, we used CRIPSR/Cas9 to inactivate LESV or ESV1 in potato and characterized the resulting tuber starches. Starch from esv1 mutants was unaffected whereas granule diameter was severely reduced in tubers of lesv plants. This was negatively correlated with the number of granules, consistent with an altered starch-initiation phenotype. Strikingly, SEM of purified starches revealed that lesv plants phenocopy isa1 and isa2 antisense lines described 20 years ago. Using yeast two-hybrid assays, we confirmed that LESV interacts with ISA1 in potato, as previously demonstrated in rice, providing molecular evidence for their functional association in potato. This interaction supports the hypothesis that LESV acts in concert with the ISA1/ISA2 complex, probably regulating the early steps of glucan organization required for proper starch granule formation.

Source: Journal of Experimental Botany

DOI: 10.1093/jxb/eraf506