Genome-wide analysis of the cellulose toolbox of Primulina eburnea, a calcium-rich vegetable

Abstract

Background Human-guided crop domestication has lasted for more than 10,000 years. In terms of the domestication and breeding of vegetables, cellulose content in edible tissues is one of the most important traits. Primulina eburnea is a recently developed calcium-rich vegetable with a high soluble and bioavailable calcium content in its leaves. However, the high cellulose content in the leaves hampers the taste, and no research has been reported on the genetic basis of cellulose biosynthesis in this calcium-rich vegetable. Results We identified 36 cellulose biosynthesis-involved genes belonging to eight gene families in the P. eburnea genome. The cellulose accumulated decreasingly throughout leaf development. Nineteen genes were considered core genes in cellulose biosynthesis, which were highly expressed in buds but lowly expressed in mature leaves. In the nitrogen fertilization experiment, exogenous nitrogen decreased the cellulose content in the buds. The expressing pattern of 14 genes were consistent with phenotypic variation in the nitrogen fertilization experiment, and thus they were proposed as cellulose toolbox genes. Conclusions The present study provides a strong basis for the subsequent functional research of cellulose biosynthesis-involved genes in P. eburnea, and provides a reference for breeding and/or engineering this calcium-rich vegetable with decreased leaf cellulose content to improve the taste.

Transcriptomic and Metabolic Analyses Elucidate the Metabolomic Variation in Leaf Development of a Calcium-Rich Vegetable (Primulina eburnea)

“…The content of most soluble sugars, except galactose and starch, decreased during leaf development (Figure 5). The decreased content of pectin (Figure 5) and cellulose [10] improved the taste of the mature leaves of calcium-rich vegetables. In addition to vegetable use, P. eburnea also has a long history as a source of medicine.…”

“…Raw reads were quality-filtered with the methods described by Zhang et al [10]. The clean reads were mapped to the P. eburnea reference genome [19] using HISAT2 v2.1.0 [20].…”

“…qRT-PCR was performed with three biological replicates and ran on a Bio-Rad CFX96 real-time PCR detection system (Hercules, CA, USA). According to the output data, the relative mRNA expression of each sample was calculated in relation to the reference gene, PebActin [10].…”

“…Primulina eburnea (Hance) Yin Z. Wang is a perennial herb in the Gesneriaceae family [7]. Due to the high content of soluble calcium (Ca 2+ ) in its leaves [8], P. eburnea has been developed as a calcium-rich vegetable [9,10]. Many efforts have been devoted to improving the taste of this vegetable, such as developing fertilization strategies to decrease the leaf cellulose content and identifying genes involved in cellulose biosynthesis [10].…”

“…Due to the high content of soluble calcium (Ca 2+ ) in its leaves [8], P. eburnea has been developed as a calcium-rich vegetable [9,10]. Many efforts have been devoted to improving the taste of this vegetable, such as developing fertilization strategies to decrease the leaf cellulose content and identifying genes involved in cellulose biosynthesis [10]. In addition, mass selection and recurrent selection in our lab have greatly increased the flavor and nutrition of this vegetable (unpublished data).…”