Subtropical adaptation of a temperate plant (Brassica oleracea var. italica) utilizes non-vernalization-responsive QTLs

Abstract

While many tropical plants have been adapted to temperate cultivation, few temperate plants have been adapted to the tropics. Originating in Western Europe, Brassica oleracea vernalization requires a period of low temperature and BoFLC2 regulates the transition to floral development. In B. oleracea germplasm selected in Taiwan, a non-vernalization pathway involving BoFLC3 rather than BoFLC2 regulates curd induction. In 112 subtropical breeding lines, specific haplotype combinations of BoFLC3 and PAN (involved in floral organ identity and a positional candidate for additional curd induction variation) adapt B. oleracea to high ambient temperature and short daylength. Duplicated genes permitted evolution of alternative pathways for control of flowering in temperate and tropical environments, a principle that might be utilized via natural or engineered approaches in other plants. New insight into regulation of Brassica flowering exemplifies translational agriculture, tapping knowledge of botanical models to improve food security under projected climate change scenarios.

Genome sequencing sheds light on the contribution of structural variants toBrassica oleraceadiversification

“…10). We detected several previously described SVs in B. oleracea, including the two indels in BoFLC3 related to subtropical adaptation of broccoli (Lin et al, 2018), and the two indels in BoFRIa related to winter annual or biennial habit of cauliflower and cabbage (Irwin et al, 2012).…”

“…The MADS box transcription factor FLC, a flowering time integrator in the vernalization and autonomous pathways, acts as a repressor of flowering (Michaels and Amasino, 1999;Sheldon et al, 1999). Several studies have demonstrated the roles of FLC paralogues in flowering time in diverse B. oleracea morphotypes (Okazaki et al, 2007;Razi et al, 2008;Ridge et al, 2015;Irwin et al, 2016;Lin et al, 2018). A 3,371-bp insertion (SV_b_92666a) in the promoter of BoFLC1.1 in Korso was found under strong differential selection, present in 99% and 88% of the cauliflower and broccoli accessions, respectively, while only in 9% of cabbage accessions (Fig.…”

“…The Korso allele of BoFLC3 contains a 263-bp deletion (SV_w_24534) and a 49-bp insertion (SV_w_24533) in the first intron. The effect of the structure of the FLC first intron on flowering time has been reported in Arabidopsis and cruciferous crops (Sheldon et al, 2002;Lin et al, 2018;Wang et al, 2018).…”

Doubled haploid based parental lines are most suitable in predicting heterosis using microsatellites and in development of highly heterotic F1hybrids inBrassica oleracea

“…The DH based breeding populations have been instrumental in discovery and mapping of QTLs of economically important agronomic and quality traits in Brassica vegetables [35, 51, 72, 89]. DH based populations has also facilitated the construction of high-density genetic linkage map [90], mapping QTLs/genes for disease resistance [50, 70], identification of QTLs related to timing of curd induction, subtropical adaptation in Brassica oleracea crops [35, 46, 62]. Thus, realizing the utility of DH technology in accelerating the genetic improvement of B. oleracea crops, completely homozygous DH lines have been developed by our group previously through IMC in cauliflower [7-9].…”

Curd Initiation and Transformation in Tropical Cauliflower Cultivars under Different Temperature Treatments

“…A previous study indicated that BoFLCs polymorphisms existed in Brassica genus crops. The expression of Flowering Locus C (FLC) in Brassica oleracea includes BoFLC3 in broccoli (Lin et al, 2018) and BoFLC4 in cabbage (Lin et al, 2005). However, in Chinese kale and broccoli, BoFLC5 does not contribute to flowering time because of premature stop codons (Razi et al, 2008).…”