Photoperiod sensitivity of Canadian flax cultivars and 5-azacytidine treated early flowering derivative lines

Jia Sun,Megan A House,Lester W Young,Helen M Booker,Ketema Daba

doi:10.1186/s12870-019-1763-5

Abstract

BackgroundEarly flowering and maturing flax (Linum usitatissimum L.) cultivars are better adapted than lines with a longer reproductive phase for the short growing season of the northern Canadian Prairies. We examined the role of long days (LD) and short days (SD) on the time taken to flower in five established flax cultivars and three mutant-derived F10 lines. The photoperiod sensitivity of these eight different genotypes was determined using a reciprocal transfer experiment involving weekly transfers between LD and SD environments.ResultsThe genotypes tested had varying degrees of photoperiod sensitivity and demonstrated reduced time to flowering if exposed to LD environments prior to a critical time point. The duration of each of the three phases of vegetative growth differed among the genotypes studied. Transfers from SD to LD shortened the vegetative stage, reduced time to flowering, and extended the reproductive phase in the genotypes studied. Mutant-derived lines RE1/2/3 flowered significantly earlier compared to CDC Sorrel, CDC Bethune, Flanders, Prairie Thunder, and Royal. Modelling of the flowering times indicated that transferring the cultivars from SD to LD increased the photoperiod sensitive time; however, different reproductive phases for mutant lines were not defined as parsimonious models were not identified. Expression of the putative flax homologs for CONSTANS (CO), FLOWERING LOCUS T (FT), and GIGANTEA (GI) was examined in the leaves of Royal and RE1/2/3 plants at 10, 15, 19 and 29 days after planting. Expression of putative FT homologs was detected in all three early-flowering lines but expression was negligible, or not detected, in Royal.ConclusionsModels defining the three phases of reproductive development were established for the five cultivars studied; however, it was not possible to identify these phases for the three early flowering and photoperiod insensitive epimutant-derived lines. A putative flax homolog of FT, a key regulator of flowering time, is more highly expressed in RE plants, which may condition the day-length insensitivity in the early flowering ‘epimutant’ lines.

Highlights

Flowering and maturing flax (Linum usitatissimum L.) cultivars are better adapted than lines with a longer reproductive phase for the short growing season of the northern Canadian Prairies
Effect of short day and long day treatments on days to flowering All of the cultivars used in the experiment showed some degree of photoperiod sensitivity, as indicated by the difference between the DTF of control plants grown in non-inductive short days (SD) conditions compared to those under inductive long days (LD) (Table 2; triangles in Figs. 1 and 2, see Additional file 2)
Grown exclusively in SD conditions, had significantly longer DTF than controls grown under LD

Summary

Introduction

Flowering and maturing flax (Linum usitatissimum L.) cultivars are better adapted than lines with a longer reproductive phase for the short growing season of the northern Canadian Prairies. We examined the role of long days (LD) and short days (SD) on the time taken to flower in five established flax cultivars and three mutant-derived F10 lines. The development of earlier flowering and, earlier maturing flax would be beneficial to producers in the areas currently growing. Sun et al BMC Plant Biology (2019) 19:177 is divided into three phases [4]: the basic vegetative phase (BVP), known as the “pre-inductive stage” or “juvenile phase”; the photoperiod sensitive phase (PSP), known as the “inductive stage”; and the post-PSP phase (PPP), known as the “post-inductive stage”. A plant grows vegetatively under the most optimal day length during BVP [4, 5]

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