Heterotic patterns of primary and secondary metabolites in the oilseed crop Brassica juncea

Abstract

Heterosis refers to the superior performance of F1 hybrids over their respective parental inbred lines. Although the genetic and expression basis of heterosis have been previously investigated, the metabolic basis for this phenomenon is poorly understood. In a preliminary morphological study in Brassica juncea, we observed significant heterosis at the 50% flowering stage, wherein both the growth and reproduction of F1 reciprocal hybrids were greater than that of their parents. To identify the possible metabolic causes or consequences of this heterosis, we carried out targeted LC-MS analysis of 48 primary (amino acids and sugars) and secondary metabolites (phytohormones, glucosinolates, flavonoids, and phenolic esters) in five developmental tissues at 50% flowering in hybrids and inbred parents. Principal component analysis (PCA) of metabolites clearly separated inbred lines from their hybrids, particularly in the bud tissues. In general, secondary metabolites displayed more negative heterosis values in comparison to primary metabolites. The tested primary and secondary metabolites displayed both additive and non-additive modes of inheritance in F1 hybrids, wherein the number of metabolites showing an additive mode of inheritance were higher in buds and siliques (52.77-97.14%) compared to leaf tissues (47.37-80%). Partial least regression (PLS) analysis further showed that primary metabolites, in general, displayed higher association with morphological parameters in F1 hybrids. Overall, our results are consistent with a resource-cost model for heterosis in B. juncea, where metabolite allocation in hybrids appears to favor growth, at the expense of secondary metabolism.

Metabolite Profiling and Transcriptome Analysis Provide Insight into Seed Coat Color in Brassica juncea

“…PAs are the most numerous and widely distributed polyphenols in plants and determine seed coat color in Arabidopsis thaliana [9][10][11], Medicago truncatula [19,20], sheepgrass (Leymus chinensis) [21], and B. napus [13,16,22]. In addition, advances in metabolomics technologies have led to numerous flavonoids being identified in B. oleracea [23], B. rapa [24], B. napus [14,25], and B. juncea [26,27]. However, the pathway of flavonoid biosynthesis has been well studied by the TT (TRANSPARENT TESTA) loci in model plant A. thaliana [18,[28][29][30][31][32][33][34], providing valuable resources and references for elucidating the mechanism of seed coat color.…”

Global insights into homoeolog gene expression in upland cotton under intraspecific hybridization

“…Metabolites are an essential component for adaptation, stress management, and regulation of different biological processes in plants (Kleessen et al 2014;Miller et al 2015). Modi cation of secondary metabolism is useful to growth heterosis in oilseed crop Brassica juncea (Bajpai et al 2019). Further, these researchers reported an additive mode of inheritance of metabolites in hybrids.…”

A cell suspension based uptake method to study high affinity glucosinolate transporters

“…HPLC chromatogram showing the peaks of purified glucosinolates used in this study. The identity of glucosinolates was based on similar retention time of peaks for sinigrin (SIN), sinalbin (4OHB) and gluconapin (GNA) using the method described in our recent study (Bajpai et al [1].…”

“…precipitated out through evaporation. The authenticity of the glucosinolate peaks has been described in our recent study [1] and a representative HPLC chromatogram has been provided as Additional file 1: Figure S1.…”