Abstract
Heterosis has been widely accepted as an effective strategy to increase yields in plant breeding. Notably, the chemical hybridization agent SQ-1 induces male sterility in wheat, representing a critical potential tool in hybrid seed production. However, the mechanisms underlying the male sterility induced by SQ-1 still remain poorly understood. In this study, a cyclin-dependent kinase inhibitor gene, TaICK1, which encodes a 229 amino acid protein, was identified as a potential contributor to male sterility in common wheat. The expression of TaICK1 was upregulated during the development of anthers in Xinong1376 wheat treated with SQ-1. Meanwhile, the seed setting rate was found to be significantly decreased in TaICK1 transgenic rice. Furthermore, we identified two cyclin proteins, TaCYCD2;1 and TaCYCD6;1, as interactors through yeast two-hybrid screening using TaICK1 as the bait, which were validated using bimolecular fluorescence complementation. Subcellular localization revealed that the proteins encoded by TaICK1, TaCYCD2;1, and TaCYCD6;1 were localized in the cell nucleus. The expression levels of TaCYCD2;1 and TaCYCD6;1 were lower in Xinong1376 treated with SQ-1. A further analysis demonstrated that the expression levels of OsCYCD2;1 and OsCYCD6;1 were lower in transgenic TaICK1 rice lines as well. Taken together, these results suggest that the upregulation of TaICK1, induced by SQ-1, may subsequently suppress the expression of TaCYCD2;1 and TaCYCD6;1 in anthers, resulting in male sterility. This study provides new insights into the understanding of SQ-1-induced wheat male sterility, as well as the developmental mechanisms of anthers.
Highlights
Bread wheat (Triticum aestivum L.) is one of the most stable cereal crops and feeds nearly 40% of the world population, contributing to approximately 20% of the global total caloric intake [1,2,3]
It is worth noting that there are no evident interaction effects between most genotype varieties and SQ-1, nor negative effects on agronomic traits [12,13,14]. These results demonstrate that SQ-1 has tremendous application potential in wheat hybrid seed production
The full-length CDS sequence of TaICK1 was cloned into the expression vector pCAMBIA1301, which drives the expression of inserts through the 35S promoter
Summary
Bread wheat (Triticum aestivum L.) is one of the most stable cereal crops and feeds nearly 40% of the world population, contributing to approximately 20% of the global total caloric intake [1,2,3]. It is worth noting that there are no evident interaction effects between most genotype varieties and SQ-1, nor negative effects on agronomic traits [12,13,14] These results demonstrate that SQ-1 has tremendous application potential in wheat hybrid seed production. SQ-1-induced sterility lines showed lower expression levels of the PDH-E1α gene, which is essential for regulation of the tricarboxylic acid (TAC) cycle [24] This is consistent with a study showing that the inhibition of PDH-E1α expression in tobacco leads to male sterility [25]. It was reported that ICKs play an important role in the regulation of plant growth and development.
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