Sporophyte formation and life cycle completion in moss requires heterotrimeric G-proteins

Flexible functional interactions between G‐protein subunits contribute to the specificity of plant responses

“…Furthermore, there seems to be some lineage‐specific effects of G‐proteins in plants, although the proteins are exceedingly similar at the sequence level. In the moss P. patens , a basal plant, G‐proteins are required for life‐cycle completion, as moss lacking G‐proteins cannot form sporophytes, the only diploid stage in this plant’s life cycle (Hackenberg et al , ). In plants such as maize or rice (and likely all monocots), some of the G‐proteins are essential for survival, for example plants lacking the Gβ or all XLG proteins are seedling lethal (Utsunomiya et al , ; Wu et al , 2018a,b).…”

“…It remains unknown if there are additional parallel pathways or unique proteins that exist in dicots, but are missing from the monocot lineage, or if there are fundamental differences in how G‐protein circuits are wired in different plant species (Pandey, ; Pandey, ). Extending this observation to a basal plant, the moss P. patens , showed that while the Gβ protein is not essential for its survival, it is required for the formation of a moss sporophyte, the only diploid stage in its life cycle (Hackenberg et al , ). Interestingly, while the Arabidopsis Gβ mutants exhibited no major defects during embryonic development, the AGB1 gene from Arabidopsis ( c. 60% similarity with AGB1) can fully complement the moss Gβ mutant phenotype (Hackenberg et al , ) .…”

“…Extending this observation to a basal plant, the moss P. patens , showed that while the Gβ protein is not essential for its survival, it is required for the formation of a moss sporophyte, the only diploid stage in its life cycle (Hackenberg et al , ). Interestingly, while the Arabidopsis Gβ mutants exhibited no major defects during embryonic development, the AGB1 gene from Arabidopsis ( c. 60% similarity with AGB1) can fully complement the moss Gβ mutant phenotype (Hackenberg et al , ) . These observations suggested that studies in other plant species, such as rice or maize or additional basal plants, in which some of the proteins are essential (Hackenberg et al , ), may uncover more partners or mechanistic modes that may not exist in Arabidopsis.…”

Physcomitrella patens Reute mCherry as a tool for efficient crossing within and between ecotypes

“…Hence, the crossing of such fluorescent mutants with wild types allows rapid detection of crossed sporophytes and permits assessment of male fertility through outcrossing rate evaluation, a method used successfully with mutants displaying fertility impairment (Hackenberg et al . ; Ortiz‐Ramírez et al . ).…”

“…Additionally, segregation analysis can also be performed visually on the resulting offspring, displaying the characteristic haploid 1:1 Mendelian segregation of the marker. Hence, the crossing of such fluorescent mutants with wild types allows rapid detection of crossed sporophytes and permits assessment of male fertility through outcrossing rate evaluation, a method used successfully with mutants displaying fertility impairment (Hackenberg et al 2016;Ortiz-Ram ırez et al 2017). The experimental crossing rate between and within the tested ecotypes (Vx, Gd and Ka) was low in all crosses, but one (Perroud et al 2011).…”