Thaumatin-like Gene TLP1b Confers to Seed Oil Content and Resistance to Sclerotinia sclerotiorum in Arabidopsis

The synergistic optimization of yield and abiotic/biotic resistance is of great significance in plant breeding. However, the genomic mechanisms underlying the selection for environmental adaptation and yield-related traits remain poorly understood. In this study, we identified a thaumatin-like protein (TLP), AtTLP1b, which was shown to pleiotropically regulate seed oil content and resistance to <i>Sclerotinia sclerotiorum</i> by gene knockout and overexpressing experiments in Arabidopsis. The oil composition oleic acid (C18:1), linoleic acid (C18:2), linolenic acid (C18:3) and eicosenoic acid (C20:1) were altered significantly in overexpressing and knockout lines. RNA-seq analysis revealed that overexpression of <i>AtTLP1b</i> significantly downregulated the expression levels of genes involved in wax, suberin synthesis, oxylipin metabolism and plant-pathogen interaction. Furthermore, more than half of the genes involved in the circadian rhythm-plant pathway were differentially expressed in the overexpressing lines. We propose that <i>AtTLP1b</i> primarily inhibits fatty acid synthesis and plant immune responses via the circadian rhythm-plant pathway. Our findings suggest that <i>AtTLP1b</i> plays a vital role in simultaneous improvement of seed oil content and resistance to <i>S. sclerotiorum</i> and provides a valuable resource for molecular breeding.