Molecular aspects of zygotic embryogenesis in sunflower (Helianthus annuus L.): correlation of positive histone marks with HaWUS expression and putative link HaWUS/HaL1L

Abstract

The link HaWUS/ HaL1L , the opposite transcriptional behavior, and the decrease/increase in positive histone marks bond to both genes suggest an inhibitory effect of WUS on HaL1L in sunflower zygotic embryos. In Arabidopsis, a group of transcription factors implicated in the earliest events of embryogenesis is the WUSCHEL-RELATED HOMEOBOX (WOX) protein family including WUSCHEL (WUS) and other 14 WOX protein, some of which contain a conserved WUS-box domain in addition to the homeodomain. WUS transcripts appear very early in embryogenesis, at the 16-cell embryo stage, but gradually become restricted to the center of the developing shoot apical meristem (SAM) primordium and continues to be expressed in cells of the niche/organizing center of SAM and floral meristems to maintain stem cell population. Moreover, WUS has decisive roles in the embryonic program presumably promoting the vegetative-to-embryonic transition and/or maintaining the identity of the embryonic stem cells. However, data on the direct interaction between WUS and key genes for seed development (as LEC1 and L1L) are not collected. The novelty of this report consists in the characterization of Helianthus annuus WUS (HaWUS) gene and in its analysis regarding the pattern of the methylated lysine 4 (K4) of the Histone H3 and of the acetylated histone H3 during the zygotic embryo development. Also, a parallel investigation was performed for HaL1L gene since two copies of the WUS-binding site (WUSATA), previously identified on HaL1L nucleotide sequence, were able to be bound by the HaWUS recombinant protein suggesting a not described effect of HaWUS on HaL1L transcription.

Genome-Wide Analysis of WOX Multigene Family in Sunflower (Helianthus annuus L.)

“…A WUS gene in Helianthus annuus ( HaWUS ) was previously characterized [ 42 ]. In particular, the lysine 4 (K4) methylation status and acetylation of histone H3 depend on HaWUS expression during the zygotic embryo development.…”

“…In particular, the lysine 4 (K4) methylation status and acetylation of histone H3 depend on HaWUS expression during the zygotic embryo development. The HaWUS recombinant protein [ 42 ] bound two copies of the WUS binding site (WUSATA), previously identified on the LEAFY COTYLEDON1-like ( HaL1L ) gene [ 43 ]. The interaction HaWUS / HaL1L showed opposite transcriptional behavior during zygotic embryo development.…”

“…The interaction HaWUS / HaL1L showed opposite transcriptional behavior during zygotic embryo development. The consequent decrease/increase in positive histone marks bond to both genes suggested an inhibitory effect of WUS on HaL1L in sunflower zygotic embryos [ 42 ]. Until now, HaWUS (here renamed HaWOX1 ) is the only member of the WOX family characterized in sunflower.…”

“…Many growth and development processes affect sunflower yield. Although WOX members have been shown to regulate many aspects of development in several plant species [ 37 , 38 , 39 , 40 ], only HaWOX1 was reported to regulate zygotic embryo development [ 42 , 43 ].…”

Homeobox genes encoding WOX transcription factors in the flowering parasitic plant Monotropa hypopitys

“…Центральная роль гена WUS в регуляции идентичности и поддержании плюрипотентных стволовых клеток в апи кальной меристеме побега показана для растений разных видов (Salvini et al, 2016;Segatto et al, 2016). Экспрессия WUS ограничена группой клеток, составляющих органи зующий центр, к которому прилегают стволовые клетки (Besnard et al, 2011;Sun, Ito, 2015), а подавление его экс прессии приводит к появлению эктопических меристем, преждевременно прекращающих свое развитие (Laux et al, 1996).…”