Genome-scale mRNA and miRNA transcriptomic insights into the regulatory mechanism of cucumber corolla opening

‘Corollas and spines’ is an important trait for fresh market cucumber. In a unique cucumber line, ‘6457’, the super ovary is much larger and corolla opening is delayed by 4–5 days, thus the resulting fruit has a flower that remains on the tip,which has a high commodity value. In this study, to better understand the molecular basis of corolla opening, mRNA and miRNA transcriptome analyses were performed during corolla development of the super and normal ovaries. A total of 234 differentially expressed miRNAs(DEMs) and 291 differentially expressed target genes(DE-target genes) were identified from four developmental stages, and the greatest number of DEMs was found at the yellow bud stage. Thirty of the DE-target genes were regulated by more than five DEMs, among which, CsHD-Zip was regulated by 28 DEMs,followed by DD2X(18). In addition, the expression patterns of miRNA_104, miRNA_157, miRNA_349, miRNA_242, and miRNA_98 were similar during corolla development, and they shared the same target gene, CsCuRX. Moreover, several critical candidate DEMs and DE-target genes were characterized and profiled by a qRT-PCR experiment. Three of the miRNAs, miRNA_157-CsCuRX, miRNA_411-CsGH3.6, and miRNA_161/297/257-CsHD-Zip, might be responsible for corolla opening in the cucumber super ovary. This integrated study on the transcriptional and post-transcriptional profiles can provide insights into the molecular regulatory mechanism underlying corolla opening in the cucumber.

Panicle-Cloud:An Open and Al-Powered Cloud Computing Platform for Quantifying Rice Panicles from Drone-Collected Imagery to Enable the Classification of Yield Production in Rice

Rice(Oryza sativa)is an essential stable food for many rice consumption nations in the world and,thus,the importance to improve its yield production under global climate changes.To evaluate different rice varieties'yield performance,key yield-related traits such as panicle number per unit area(PNpM^(2))are key indicators,which have attracted much attention by many plant research groups.Nevertheless,it is still challenging to conduct large-scale screening of rice panicles to quantify the PNpM^(2)trait due to complex field conditions,a large variation of rice cultivars,and their panicle morphological features.Here,we present Panicle-Cloud,an open and artificial intelligence(AI)-powered cloud computing platform that is capable of quantifying rice panicles from drone-collected imagery.To facilitate the development of Al-powered detection models,we first established an open diverse rice panicle detection dataset that was annotated by a group of rice specialists;then,we integrated several state-of-the-art deep learning models(including a preferred model called Panicle-AI)into the Panicle-Cloud platform,so that nonexpert users could select a pretrained model to detect rice panicles from their own aerial images.We trialed the Al models with images collected at different attitudes and growth stages,through which the right timing and preferred image resolutions for phenotyping rice panicles in the field were identified.Then,we applied the platform in a 2-season rice breeding trial to valid its biological relevance and classified yield production using the platform-derived PNpM^(2)trait from hundreds of rice varieties.Through correlation analysis between computational analysis and manual scoring,we found that the platform could quantify the PNpM^(2)trait reliably,based on which yield production was classified with high accuracy.Hence,we trust that our work demonstrates a valuable advance in phenotyping the PNpM^(2)trait in rice,which provides a useful toolkit to enable rice breeders to screen and select desired rice varieties under field conditions.

Salicylic acid promotes quiescent center cell division through ROS accumulation and down-regulation of PLT1,PLT2,and WOX5

Salicylic acid(SA)plays a crucial role in plant immunity.However,its function in plant development is poorly understood.The quiescent center(QC),which maintains columella stem cells(CSCs)in the root apical meristem and typically exhibits low levels of cell division,is critical for root growth and development.Here,we show that the Arabidopsis thaliana SA overaccumulation mutant constitutively activated cell death 1(cad1),which exhibits increased cell division in the QC,is rescued by additional mutations in genes encoding the SA biosynthetic enzyme SALICYLIC ACID INDUCTION DEFFICIENT2(SID2)or the SA receptor NONEXPRESSER OF PR GENES1(NPR1),indicating that QC cell division in the cad1 mutant is promoted by the NPR1-dependent SA signaling pathway.The application of exogenous SA also promoted QC cell division in wild-type plants in a dose-dependent manner and largely suppressed the expression of genes involved in QC maintenance,including those encoding the APETALA2(AP2)transcription factors PLETHORA1(PLT1)and PLT2,as well as the homeodomain transcription factor WUSCHEL-RELATED HOMEOBOX5(WOX5).Moreover,we showed that SA promotes reactive oxygen species(ROS)production,which is necessary for the QC cell division phenotype in the cad1 mutant.These results provide insight into the function of SA in QC maintenance.