# Phenotypic variation in hypocotyl elongation among elite sand rice (Agriophyllum squarrosum) lines

## TL;DR

This study examines how different sand rice lines vary in hypocotyl growth traits and how these traits are influenced by climate factors.

## Contribution

The study identifies elite sand rice lines with superior hypocotyl traits and links climate factors to trait variability using PLSPM.

## Key findings

- Significant phenotypic variation was observed in hypocotyl traits among six elite sand rice lines.
- The elite line Aerxiang (AEX) showed superior emergence and survival, making it a prime candidate for cultivation.
- Climate factors like temperature and precipitation significantly correlate with hypocotyl length.

## Abstract

Sand rice (Agriophyllum squarrosum), widely distributed in Central Arid Asia and prevalent in the sand dunes of northern China, presents a promising potential as a climate‐resilient crop. The plasticity of hypocotyl growth is the key trait for sand rice to cope with wind erosion and sand burial, ensure seedling emergence, and determine plant architecture. In this study, we assessed the overall hypocotyl phenotype of six sand rice elite lines, which were collected from different regions of northern China, and selected by our group over past decade through common garden trials. Significant phenotypic variations were observed in thousand‐seed weight (TSW), seedling emergence percentage, hypocotyl length and diameter, and seedling fresh weight among the lines. The elite line Aerxiang (AEX) exhibited excellent agronomic performance with superior and synchronous emergence, and high survival percentage, distinguishing itself as a prime candidate for further large‐scale cultivation. Contrastingly, the lines from the arid regions showed markedly lower performance. Partial Least Squares Path Modeling (PLSPM) was used to assess the impact of seed provenance climate factors, including annual mean temperature (AMT) and annual mean precipitation (AMP), on trait variability among lines. The findings indicate a significant correlation between climate factors and hypocotyl length, highlighting the intricate adaptation of sand rice to local climate. The comprehensive understanding of the mechanisms behind phenotypic variations offers valuable insights for sand rice de novo domestication and innovative germplasm resources, and lays the foundation for ecological restoration in sandy areas.

Sand rice presents a promising potential crop due to its wide distribution, comprehensive nutritional profile, and adaptability to extreme arid desert. Since 2010, our group has dedicated extensive efforts to the domestication and breeding of sand rice, resulting in the selection of several elite lines from 75 natural populations. This study analyzed the hypocotyl traits of six elite lines, revealing significant differences both among and within the lines. Partial Least Squares Path Modeling (PLSPM) analysis indicated a significant correlation between climate factors and hypocotyl length, exposing the intricate adaptation of sand rice to local environment.