The Physalis floridana genome provides insights into the biochemical and morphological evolution of Physalis fruits

The fruits of Physalis(Solanaceae)have a unique structure,a lantern-like fruiting calyx known as inflated calyx syndrome(ICS)or the Chinese lantern,and are rich in steroid-related compounds.However,the genetic variations underlying the origin of these characteristic traits and diversity in Physalis remain largely unknown.Here,we present a high-quality chromosome-level reference genome assembly of Physalis floridana(~1.40Gb in size)with a contig N50 of~4.87Mb.Through evolutionary genomics and experimental approaches,we found that the loss of the SEP-like MADS-box gene MBP21 subclade is likely a key mutation that,together with the previously revealed mutation affecting floral MPF2 expression,might have contributed to the origination of ICS in Physaleae,suggesting that the origination of a morphological novelty may have resulted from an evolutionary scenario in which one mutation compensated for another deleterious mutation.Moreover,the significant expansion of squalene epoxidase genes is potentially associated with the natural variation of steroid-related compounds in Physalis fruits.The results reveal the importance of gene gains(duplication)and/or subsequent losses as genetic bases of the evolution of distinct fruit traits,and the data serve as a valuable resource for the evolutionary genetics and breeding of solanaceous crops.

Short Panicle 3 controls panicle architecture by upregulating APO2/RFL and increasing cytokinin content in rice

Inflorescence architecture is a major determinant of spikelet numbers per panicle, a key component of grain yield in rice. In this study, Short Panicle 3(SP3) was identified from a short panicle 3(sp3) mutant in which T-DNA was inserted in the promoter of SP3, resulting in a knockdown mutation. SP3 encodes a DNA binding with one finger(Dof) transcriptional activator. Quantitative real time(q RT)-PCR and RNA in situ hybridization assays confirmed that SP3 is preferentially expressed in the young rice inflorescence, specifically in the branch primordial regions. SP3 acts as a negative regulator of inflorescence meristem abortion by upregulating APO2/RFL. SP3 both up-and downregulates expression of genes involved in cytokinin biosynthesis and catabolism, respectively. Consequently, cytokinin concentrations are decreased in young sp3 panicles, thereby leading to small panicles having fewer branches and spikelets. Our findings support a model in which SP3 regulates panicle architecture by modulating cytokinin homeostasis. Potential applications to rice breeding, through gene-editing of the SP3 promoter are assessed.