Biology subjects

Schnurbusch, T.

Publications and source records attributed to Schnurbusch, T..

21 records · Page 2Linked to original sources

bioRxiv2020

Ppd-1 Remodels Spike Architecture by Regulating Floral Development in wheat

The determination of spike architecture is critical to grain yield in wheat (Triticum aestivum), yet the underlying mechanisms remain largely unknown. Here, we measured 51 traits associated with spike architecture and floral development in 197 wheat accessions with photoperiod sensitive and insensitive alleles. We included five distinct allele combinations at the Photoperiod-1 (Ppd-1) loci. A systematic dissection of all recorded phenotypes revealed connections between floral development, spike architecture and grain yield. Modifying the durations of spikelet primordia initiation did not necessarily affect spikelet number. In addition, Ppd-1 loci clearly influenced rachis dry weight, pointing to the rachis vascular system as a potential target for higher yield. Ppd-1 displayed opposite effects on the durations of pre and post-anthesis phases. Ppd-1 controlled carpel size, but not anther size. Finally, the photoperiod-insensitive alleles of Ppd-1 triggered floral degeneration. In parallel, we profiled the spike transcriptome at six stages and four positions in three Ppd-1 genotypes which consists of 234 samples. Integrating phenotypic and expression data suggested that loss of function in Ppd-1 loci delayed floral degeneration by regulating autophagy and extended floret development by regulating genes in different families. Therefore, we concluded that Ppd-1 remodels spike architecture by regulating floral development in wheat.

plant biology↗

bioRxiv2020

COMPOSITUM 1 (COM1) contributes to the architectural simplification of barley inflorescence via cell wall-mediated and meristem identity signals

Grasses have varying inflorescence shapes; however, little is known about the genetic mechanisms specifying such shapes among tribes. We identified the grass-specific TCP transcription factor COMPOSITUM 1 (COM1) expressed in inflorescence meristematic boundaries of different grasses. COM1 specifies branch-inhibition in Triticeae (barley) versus branch-formation in non-Triticeae grasses. Analyses of cell size, cell walls and transcripts revealed barley COM1 regulates cell growth, affecting cell wall properties and signaling specifically in meristematic boundaries to establish identity of adjacent meristems. COM1 acts upstream of the boundary gene Liguleless1 and confers meristem identity partially independent of the COM2 pathway. Furthermore, COM1 is subject to purifying natural selection, thereby contributing to specification of the spike inflorescence shape. This meristem identity pathway has conceptual implications for both inflorescence evolution and molecular breeding in Triticeae.

plant biology↗

bioRxiv2018

Unleashing floret fertility by a mutated homeobox gene improved grain yield during wheat evolution under domestication

Floret fertility is a key trait to determine the number of grains per inflorescence in cereals. During wheat (Triticum sp.) evolution, floret fertility has been increased and current bread wheat (T. aestivum L.) produces three to five grains per spikelet; however, little is known about the genetic basis controlling floret fertility. Here we identify the quantitative trait locus Grain Number Increase 1 (GNI1), encoding a homeodomain leucine zipper class I (HD-Zip I) transcription factor. GNI1 evolved in the Triticeae through gene duplication and functionalization. GNI1 was predominantly expressed in the most apical floret primordia and parts of the rachilla, suggesting that GNI1 inhibits rachilla growth and development. GNI1 expression decreased during wheat evolution, and as a consequence, more fertile florets and grains per spikelet are being produced. Genetic analysis revealed that the reduced-function allele of GNI1-A contributes to increase the number of fertile florets per spikelet. The knockdown of GNI1 in transgenic hexaploid wheat improved fertile floret and grain number. Furthermore, wheat plants carrying the impaired allele increased grain yield under field conditions. Our findings illuminate that gene duplication and functionalization generated evolutionary novelty for floret fertility (i.e. reducing floral numbers) while the mutations towards increased grain production were under selection during wheat evolution under domestication.\n\nSignificance StatementGrain number is a fundamental trait for cereal grain yield; but its underlying genetic basis is mainly unknown in wheat. Here we show for the first time a direct link between increased floret fertility, higher grain number per spike and higher plot-yields of wheat in the field. We have identified GNI1 gene encoding an HD-Zip I transcription factor responsible for increased floret fertility. The wild type allele imposes an inhibitory role specifically during rachilla development, indicating that expression of this protein actively shuts-down grain yield potential; whereas, the reduced-function allele enables more florets and grains to be produced. GNI1 evolved through gene duplication in Triticeae and its mutations were under parallel human selection during wheat and barley evolution under domestication.

plant biology↗