Organ homeostasis is orchestrated by time- and spatially restricted cell proliferation. Studies identifying cells with superior proliferative capacities often rely on the lineage tracing of a subset of cell populations, which introduces a potential selective bias. In this work, we developed a genetic system [proliferation tracer (ProTracer)] by incorporating dual recombinases to seamlessly record the proliferation events of entire cell populations over time in multiple organs. In the mouse liver, ProTracer revealed more hepatocyte proliferation in distinct zones during liver homeostasis, injury repair, and regrowth. Clonal analysis showed that most of the hepatocytes labeled by ProTracer had undergone cell division. By genetically recording proliferation events of entire cell populations, ProTracer enables the unbiased detection of specific cellular compartments with enhanced regenerative capacities.

Flowering time adaptation is a major breeding goal in the allopolyploid species Brassica napus. To investigate the genetic architecture of flowering time, a genome-wide association study (GWAS) of flowering time was conducted with a diversity panel comprising 523 B. napus cultivars and inbred lines grown in eight different environments. Genotyping was performed with a Brassica 60K Illumina Infinium SNP array. A total of 41 single-nucleotide polymorphisms (SNPs) distributed on 14 chromosomes were found to be associated with flowering time, and 12 SNPs located in the confidence intervals of quantitative trait loci (QTL) identified in previous researches based on linkage analyses. Twenty-five candidate genes were orthologous to Arabidopsis thaliana flowering genes. To further our understanding of the genetic factors influencing flowering time in different environments, GWAS was performed on two derived traits, environment sensitivity and temperature sensitivity. The most significant SNPs were found near Bn-scaff_16362_1-p380982, just 13 kb away from BnaC09g41990D, which is orthologous to A. thaliana CONSTANS (CO), an important gene in the photoperiod flowering pathway. These results provide new insights into the genetic control of flowering time in B. napus and indicate that GWAS is an effective method by which to reveal natural variations of complex traits in B. napus.

The plant-specific NAC (NAM, ATAF1/2, and CUC2) transcription factors (TFs) play a vital role in the response to drought stress. Here, we report a lipid-anchored NACsa TF in Medicago falcata. MfNACsa is an essential regulator of plant tolerance to drought stress, resulting in the differential expression of genes involved in oxidation reduction and lipid transport and localization. MfNACsa is associated with membranes under unstressed conditions and, more specifically, is targeted to the plasma membrane through S-palmitoylation. However, a Cys 26 -to-Ser mutation or inhibition of S-palmitoylation results in MfNACsa retention in the endoplasmic reticulum/Golgi. Under drought stress, MfNACsa translocates to the nucleus through de-S-palmitoylation mediated by the thioesterase MtAPT1, as coexpression of APT1 results in the nuclear translocation of MfNACsa, whereas mutation of the catalytic site of APT1 results in colocalization with MfNACsa and membrane retention of MfNACsa. Specifically, the nuclear MfNACsa binds the glyoxalase I (MtGlyl) promoter under drought stress, resulting in drought tolerance by maintaining the glutathione pool in a reduced state, and the process is dependent on the APT1-NACsa regulatory module. Our findings reveal a novel mechanism for the nuclear translocation of an S-palmitoylated NAC in response to stress.

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