Rice endosperm, the major edible portion of the grain, plays an important role in regulating blood glucose and preventing intestinal diseases by increasing its resistant starch (RS) content. Previous studies have shown that suppressing amylopectin biosynthesis via genome editing can increase RS content. However, the influence of different Waxy (Wx) allelic backgrounds on RS accumulation in edited lines has not been systematically evaluated. In this study, we used glutinous rice Yunan Heixiangnuo (HXN) with a nonfunctional wx allele and indica rice Yixiang 1B (YX1B) with a weak Wxb allele as backgrounds. We simultaneously knocked out SSSIIIa, SBEI, SBEIIa, and SBEIIb using CRISPR/Cas9, and systematically analyzed changes in RS content, rice quality, and yield traits. The results showed that, in the HXN background, multigene knockout did not significantly alter amylose or RS content but largely maintained favorable eating quality. In contrast, in the YX1B background, quadruple-gene knockout lines exhibited an increase in amylose content from 17.7% to 53.7% and an increase in RS content to 2.48%, representing a 4.35-fold increase over the wild type, while gel consistency and seed-setting rate were significantly reduced. Scanning electron microscopy revealed that multigene knockout markedly remodeled starch granule structure, shifting from dense polygonal granules to loosely packed spherical particles and resulting in a floury endosperm. Collectively, enhancement of RS content through multigene editing was influenced by Wx gene function. Although the wx allele failed to increase RS content, it still participated in the regulation of grain quality and yield traits by modulating starch structure. This study provides a reference for breeding high-RS rice cultivars while balancing yield performance and eating quality.
Suting Yang, Yanxin Wang, Mengning Wang et al.· Rice· 0 citations
INTRODUCTION
Seed weight and nutritional composition (protein and oil content) are critical agronomic traits that collectively determine the yield and quality in soybean. However, the genetic architecture and regulatory mechanisms governing these traits remain poorly understood.
OBJECTIVES
This study aimed to identify the key genes and molecular mechanisms governing 100-seed weight and nutritional quality in soybean, providing a theoretical framework for the dual-enhancement of seed weight and protein content.
METHODS
A genome-wide association study (GWAS) was conducted using 1,702 diverse soybean cultivars to identify candidate loci associated with seed weight. Functional characterization was conducted through CRISPR-mediated knockout and overexpression analyses. Population genomic analyses were further performed to elucidate the evolutionary history and selection signals of the candidate gene.
RESULTS
We identified GmSW6 (Seed Weight 6), encoding a 2-oxoglutarate Fe(II)-dependent dioxygenase (2OGD), as a master regulator of 100-seed weight. Knockout of GmSW6 markedly enhanced seed weight and protein content while simultaneously reducing oil content. Mechanistically, we demonstrated that the transcription factor GmSW13 directly activates GmSW6 expression. This GmSW13-GmSW6 module, in turn, upregulates GmOLEO1 to coordinately modulate both seed weight and quality. Population genomic analysis revealed that the elite allele, GmSW6G, is significantly associated with increased seed weight and has undergone intense positive selection during soybean domestication and modern improvement.
CONCLUSION
Our findings elucidate a hierarchical genetic pathway governing soybean seed development and provide potent molecular targets for simultaneous improvement of seed weight and protein content in future 'designer' varieties.
Hao Zhang, Tianli Ge, Shiyu Guo et al.· Journal of Advanced Research· 0 citations
