Asynchrony of ovule primordia initiation in Arabidopsis

Abstract

Plant ovule initiation determines the maximum of ovule number and has a great impact on the seed number per fruit. The detailed processes of ovule initiation have not been accurately described although two connected processes, gynoecium and ovule development, have been investigated. Here we report that ovules initiate asynchronously. The first group of ovule primordia grows out, the placenta elongate, the boundaries of existing ovules enlarge and new group of primordia initiates from the boundaries. The expression pattern of different marker genes during ovule development illustrates that this asynchronicity continues throughout whole ovule development. PIN-FORMED1 polar distribution and auxin response maxima correlate to ovule primordia initiation asynchronous. We established computational modeling to show how auxin dynamics influence ovule primordia initiation. Brassinosteroid signaling positively regulates ovule number by promoting placentae size and ovule primordia initiation through strengthening auxin response. Transcriptomic analysis demonstrates numerous known regulators of ovule development and hormones signaling, and many new genes are identified to involve in ovule development. Taken together, our results illustrate the ovule primordia initiate asynchronously and the hormone signal involve in the asynchrony.

A digital 3D reference atlas reveals cellular growth patterns shaping the Arabidopsis ovule

“…Next, we dissected ovules from pistils of various lengths, determined the stage of the ovules for each pistil, and used the pistil growth curve for an estimate of the duration of the different ovule stages (see Materials and methods). It was previously noticed that early stage ovules do not develop synchronously within a pistil ( Schneitz et al, 1995 ; Wolny et al, 2020 ; Yu et al, 2020 ). In line with these results, we observed ovules of different stages within a given pistil ( Supplementary file 3 ).…”

Molecular Network for Regulation of Ovule Number in Plants

“…BRs affect ovule number and gynoecium size by modulating gene expression, like HLL and ANT , which exhibit similar effects on primordial ovule growth [ 12 , 14 , 62 ], and the AP2 gene, which affects ovule number determination and developmental specificity of the floral organ. As expected, the loss of function ant mutation affects carpel margin meristem and placenta development, resulting in abnormal lateral organs, and reduced fertility and number of ovules [ 31 , 41 , 106 ].…”

“…As expected, the loss of function ant mutation affects carpel margin meristem and placenta development, resulting in abnormal lateral organs, and reduced fertility and number of ovules [ 31 , 41 , 106 ]. Previous studies have demonstrated that BR affects ovule number via transcriptional control of primary ovule development genes ANT , HLL , and AP2 [ 12 , 50 ]. BZR1 activity was correlated with the upregulation of ANT and HUL genes, showing that BR signaling positively influences ovule number [ 50 , 57 ].…”

“…Ovule initiation and developmental processes have been extensively examined at the morphological, genetic, and molecular levels in Arabidopsis and other plant species [ 7 , 8 , 9 , 10 , 11 , 12 ]. These studies show the formation of a completely developed set of ovules through several fundamental processes, including three main stages.…”

Advances in the regulation of plant development and stress response by miR167

“…LEC2 is a positive regulator of selenium-induced YUC-mediated auxin biosynthesis in Arabidopsis thaliana somatic embryogenesis [81,82]. The overexpression of miR167c inhibited the formation of selenium and increases the expression of LEC2 [12], and at the same time interfered with PIN-FORMED1 (PIN1) in cell membrane of embryogenic callus affected auxin transport [83][84][85]. miR167 targeted ARF6 and ARF8, effects on auxin synthesis and local auxin transport in embryogenic callus, thus regulating Arabidopsis thaliana somatic embryogenesis.…”