Fig. 2: The role of VEL3 in the control of endosperm development and maternal control of primary seed dormancy.

a VEL3 is important for seed dormancy establishment when seeds are set at low temperatures. vel3-1 seeds show a clear low-dormancy phenotype, which is complemented by transformation with the VEL3 gene sequence in 4 independent transgenic lines vel3-1 gVEL3. p-value is derived from the two-sided t-test. Boxplots indicate minimum and maximum values, as well as 25th, 50th and 75th percentiles. b Mutant vel3-1 seeds exhibit high-frequency seed abortion. Reciprocal crosses (always maternal x paternal in this paper) show that both the maternally derived and paternally derived VEL3 gene copies can act to promote normal seed development, and that complemented vel3-1 mutants (vel3-1 gVEL3) show normal seed development. Total number of seeds analyzed for each genotype are shown. c Representative DIC images of WT and vel3-1 seeds, demonstrating retardation of embryo development in vel3-1 (blue arrow) and an enlarged chalazal endosperm (red arrow). The experiments were repeated ten times. d Germination of freshly harvested seeds show that maternal VEL3 controls seed dormancy from the female gametophyte. Loss of maternal VEL3 is sufficient to affect seed dormancy whereas heterozygous mothers pollinated with WT pollen show an intermediate phenotype. Data represents minimum and maximum values as well we 25th, 50th and 75th quartiles of 9 to 10 biological replicates per genotype. p-values for significant differences using 2-tailed t-test are shown. e Confocal microscopy and corresponding brightfield image showing vel3 gVEL3-GFP in the central cell of the unfertilized emasculated ovule 1 day after anthesis. DAE: Days after emasculation. Scale bar 50 µm. The experiments were repeated three times. f Confocal microscopy and corresponding brightfield image showing transient vel3 gVEL3-GFP in the microspore, which was absent from mature pollen. Scale bars 10 µm. The experiments were repeated three times. g Confocal images of vel3 gVEL3-GFP seeds showing VEL3-GFP in the nuclei of the developing endosperm from homozygous plants, or in seeds derived from reciprocal crosses to show the activity of the maternally derived and paternally derived gene copies. Scale bars 50 µm. The experiments were repeated five times. h Expression of the paternally derived and maternally derived VEL3 gene copies during seed development, using F1 seeds generated by reciprocal crosses between WT and vel3-1 vel3 gVEL3-GFP by qRT-PCR. Mean and standard error of two to four biological replicates are shown (see source data), with p-values derived from 2-tailed t-tests. Seeds were standardized by embryo development stage, globular (glob), torpedo (torp), bent cotyledon (bent) mature dry seeds and 24 h after imbibition (24HAI).