# RNA Interference-Mediated Suppression of GhSP (SELF-PRUNING) Modulates the Plant Architecture of Transgenic Cotton in a Dose-Dependent Manner

## TL;DR

Scientists used RNA interference to control cotton plant height, finding that mild suppression of a gene called GhSP leads to ideal plant architecture without harming yield or fiber quality.

## Contribution

This study demonstrates that precise RNAi-based suppression of GhSP can improve cotton plant architecture in a dose-dependent manner.

## Key findings

- Mild suppression of GhSP in cotton results in a semi-dwarf plant height of 70-100 cm without compromising agronomic traits.
- Severe suppression of GhSP causes excessive dwarfism and reduced fiber quality in transgenic cotton.
- RNAi-mediated GhSP silencing offers an efficient alternative to traditional plant height management methods in cotton cultivation.

## Abstract

To improve cotton architecture for field cultivation, this study employed RNA interference (RNAi) to achieve the graded suppression of GhSP (a key flowering repressor). Field trials revealed the dose-dependent effect of GhSP silencing on the determinate growth and final plant height of transgenic cotton. A mild suppression of GhSP in line GhSPi-#5 led to a semi-dwarf phenotype (70~100 cm) with preserved agronomic traits, which was ideal for cotton production compared to the indeterminate growth of the wild type and excessive dwarfism and compromised fiber quality in severely GhSP-suppressed cotton. These results demonstrate that the precise manipulation of GhSP expression enables targeted improvement in cotton plant architecture.

Cotton exhibits indeterminate growth potential at its apical meristem. In field cultivation, it is often necessary to restrict plant height by the foliar application of plant growth regulators or artificial topping. The genetic engineering of cotton architecture offers an efficient, environmentally friendly, and low-cost alternative to current field management. Our study aimed to improve the plant architecture of transgenic cotton by the suppression of GhSP, a key flowering repressor, via the RNA interference method. Sixteen independent transgenic lines were generated and classified as mildly, moderately, and severely suppressed, according to GhSP expression levels. Field evaluation revealed the dose-dependent effects of GhSP silencing on plant height. The mildly suppressed line GhSPi-#5 exhibited a semi-dwarf phenotype of approximately 70~100 cm in height. Negative phenotypes, including excessive dwarf plant architecture and inferior fiber quality and yield traits, were observed in severely GhSP-suppressed transgenic lines. Notably, the mild silencing of GhSP in GhSPi-#5 did not negatively affect leaf and flower organ growth, pollen fertility, major agronomic traits, or fiber quality compared with the wild type. These observations demonstrate the feasibility of manipulating the architecture of transgenic cotton via GhSP silencing.