Natural variation in Brassica FT homeologs influences multiple agronomic traits including flowering time, silique shape, oil profile, stomatal morphology and plant height in B. juncea

• Published in: Plant science (Limerick) 2018-12, Vol.277, p.251-266
• Main Authors: Tyagi, Shikha, Mazumdar, Pooja Anjali, Mayee, Pratiksha, Shivaraj, S.M., Anand, Saurabh, Singh, Anupama, Madhurantakam, Chaithanya, Sharma, Prateek, Das, Sandip, Kumar, Arun, Singh, Anandita
• Format: Article
• Language: English
• Subjects: Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis - physiology; Artificial microRNA; Brassica and Arabidopsis transformation; Brassica napus - genetics; Brassica napus - metabolism; Brassica napus - physiology; Fatty acid profile; Fatty Acids - metabolism; Flowering time; Flowers - genetics; Flowers - metabolism; Flowers - physiology; MicroRNAs - genetics; Mustard Plant - genetics; Mustard Plant - metabolism; Mustard Plant - physiology; Natural variation; Plant Stomata - genetics; Plant Stomata - metabolism; Plant Stomata - physiology; Pleiotropy; Quantitative Trait Loci - genetics; Silique and seed development; Stomatal morphology
• ISSN: 0168-9452; 1873-2259
• DOI: 10.1016/j.plantsci.2018.09.018

•Molecular models predict differential interaction of Brassica FT structural variants with AtFD.•BjuFT, predicted to interact strongly with AtFD, triggers a stronger floral acceleration in A. thaliana relative to BnaFT.•Overexpression and loss-of-function studies establish role of Brassica FT in multiple agronomic traits in B. juncea. Natural structural variants of regulatory proteins causing quantitative phenotypic consequences have not been reported in plants. Herein, we show that 28 natural structural variants of FT homeologs, isolated from 6 species of Brassica, differ with respect to amino-acid substitutions in regions critical for interactions with FD and represent two evolutionarily distinct categories. Analysis of structural models of selected candidates from Brassica juncea (BjuFT_AAMF1) and Brassica napus (BnaFT_CCLF) predicted stronger binding between BjuFT and Arabidopsis thaliana FD. Over-expression of BjuFT and BnaFT in wild type and ft-10 mutant backgrounds of Arabidopsis validated higher potency of BjuFT in triggering floral transition. Analysis of gain-of-function and artificial miRNA mediated silenced lines of B. juncea implicated Brassica FT in multiple agronomic traits beyond flowering, consistent with a pleiotropic effect. Several dependent and independent traits such as lateral branching, silique shape, seed size, oil-profile, stomatal morphology and plant height were found altered in mutant lines. Enhanced FT levels caused early flowering, which in turn was positively correlated to a higher proportion of desirable fatty acids (PUFA). However, higher FT levels also resulted in altered silique shape and reduced seed size, suggesting trait trade-offs. Modulation of FT levels for achieving optimal balance of trait values and parsing pair-wise interactions among a reportoire of regulatory protein homeologs in polyploid genomes are indeed future areas of crop research.