Efficient clonal seeds sorting for apomictic hybrid rice using a pollen-specific gene switch system

Area of Science:

• Plant Biotechnology
• Genetics
• Agricultural Science

Background:

• Apomictic hybrid rice development is hindered by challenges in inducing high rates of apomixis and distinguishing clonal from zygotic embryos.
• Accurate selection of clonal seeds is critical for advancing apomictic rice cultivation.

Purpose of the Study:

• To develop and validate a novel dual-fluorescence labelling gene switch system for distinguishing clonal seeds in apomictic hybrid rice.
• To assess the efficacy of the pollen-specific gene switch (PSGS) system in improving clonal seed purity.

Main Methods:

• Development of a pollen-specific gene switch (PSGS) system using Cre/LoxP + FRT recombination under a pollen-specific promoter.
• Co-transformation of PSGS vectors with apomixis vectors into hybrid rice varieties (Yongyou 2640 and Yongyou 4949) via Agrobacterium-mediated transformation.
• Analysis of seed fluorescence and ploidy in T1 and T2 generations to evaluate PSGS accuracy.

Main Results:

• The PSGS system successfully identified mutants capable of distinguishing between clonal and zygotic seeds.
• Specific lines (L47-4 and L151-1) produced non-fluorescent (diploid) seeds, indicating successful segregation.
• The PSGS system demonstrated a sorting accuracy rate of 80.2% to 88.9% for clonal seed selection.

Conclusions:

• The developed PSGS system is effective in differentiating clonal from zygotic seeds in hybrid rice.
• This technology is essential for enhancing clonal seed purity and facilitating the advancement of apomixis in rice breeding.
• PSGS offers a reliable tool for researchers and breeders working on apomictic rice development.