Dynamics of floret initiation/death determining spike fertility in wheat as affected by Ppd genes under field conditions

Abstract

Ppd-1a reduced the number of fertile florets due largely to lowering floret survival, and the effect was not proportional to the duration of the late reproductive phase.

Step-wise increases in FT1 expression regulate seasonal progression of flowering in wheat (Triticum aestivum L.)

“…The advanced induction of FT1 in the photoperiod-insensitive line potentially explains its ability to advance to terminal spikelet when daylengths were maintained at 10 h, relative to wild-type and ppd-1 that stalled at the lemma primordium stage. In addition to regulating spikelet number, photoperiod-insensitive alleles also reduce floret fertility; the increased expression of GNI1 at later stages in Ppd-D1a NILs, relative to wild-type, may explain the decrease in fertile florets (Prieto et al, 2018;Sakuma et al, 2019). Taken together with the seasonal analysis of FT1 expression, these results indicate that inflorescence development is intimately connected with the activity of floral signals generated in leaves, which dynamically respond to increasing daylengths.…”

“…Flowering-time genes respond to seasonal cues including daylength and temperature to coordinate seed production with favourable environmental conditions. Our understanding about the genes that regulate flowering of wheat mostly stem from work performed under controlled conditions different from those experienced by field-grown plants (Worland et al, 1998;González et al, 2005;Beales et al, 2007;Boden et al, 2015;González-Navarro et al, 2015;Prieto et al, 2018;Perez-Gianmarco et al, 2019). Here, we provide new knowledge about the seasonal regulation of flowering using natural photoperiods of a standard growing season.…”

“…Given photoperiod-insensitive alleles reduce yield potential by significantly decreasing spikelet number and the survival of floret primordia (i.e. floret fertility), it is vital that we learn more about the role of Ppd-1 in inflorescences of fieldgrown plants under natural daylengths to devise strategies for improving grain production (González et al, 2005;Fischer et al, 2014;González-Navarro et al, 2015;Prieto et al, 2018;Perez-Gianmarco et al, 2019).…”

Genetic pathways controlling inflorescence architecture and development in wheat and barley

“…Analysis of the dynamics of floret development and abortion have demonstrated that genetic variation for floret fertility exists in modern wheat, and that floret survival could be improved by two methods: (i) extending the period between completion of floret primordia development and initiation of floret degeneration, and (ii) optimizing assimilate distribution to spikelets and florets, which is supported by floret fertility being associated with ovary size at anthesis (Guo and Schnurbusch ; González‐Navarro et al ; Guo et al ; Guo et al ; Prieto et al ).…”

“…Although the genes that regulate floret survival remain largely unknown, photoperiod insensitive Ppd‐1 alleles, involved in promoting early flowering, reduce the number of fertile florets by effecting the developmental phase during which florets form, the rate of floret appearance and floret survival (González et al ; Prieto et al ) (Figure ). Moreover, a complex QTL analysis of multiple floret fertility‐related traits identified 52 loci, including regions on chromosomes 5B, 5D and 6A, which associate with traits including maximum floret primordia, grain number per spikelet, floret loss and grain survival (Guo et al ).…”