Variation in Rice Plastid Genomes in Wide Crossing Reveals Dynamic Nucleo-Cytoplasmic Interaction.

Area of Science:

• Plant genetics
• Molecular biology
• Genomics

Background:

• Angiosperm plastid genomes (plastomes) are generally stable in size, structure, and gene content.
• Limited knowledge exists regarding plastome heredity and variation, especially in wide crosses.

Purpose of the Study:

• To investigate plastome heredity and variation in rice backcross inbred lines (BILs) derived from wide crosses.
• To understand the impact of wide crossing on plastome stability and gene content.

Main Methods:

• Analysis of plastomes from five representative rice BILs developed from *O. glaberrima* / *O. sativa* crosses.
• Characterization of plastome size, structure (LSC, SSC, IR regions), and gene content (protein, rRNA, tRNA genes).

Main Results:

• All analyzed rice plastomes maintained a stable size of approximately 134,580 bp and a quadripartite structure.
• Despite structural stability, significant changes were observed in repeat-mediated recombination, gene expression, and RNA editing between the maternal line and BILs.
• Identified 76 protein genes, 4 rRNA genes, and 30 tRNA genes across the plastomes.

Conclusions:

• Wide crossing in rice not only induces nuclear genomic recombination but also leads to substantial plastome variation.
• Plastome variation plays a critical role in coordinating nuclear-cytoplasmic interactions during plant breeding and evolution.
• These findings offer new insights into the genetic dynamics of interspecific hybridization in plants.