Identification and Expression Analysis of the Genes Involved in the Raffinose Family Oligosaccharides Pathway of Phaseolus vulgaris and Glycine max

Abstract

Raffinose family oligosaccharides (RFO) play an important role in plants but are also considered to be antinutritional factors. A profound understanding of the galactinol and RFO biosynthetic gene families and the expression patterns of the individual genes is a prerequisite for the sustainable reduction of the RFO content in the seeds, without compromising normal plant development and functioning. In this paper, an overview of the annotation and genetic structure of all galactinol- and RFO biosynthesis genes is given for soybean and common bean. In common bean, three galactinol synthase genes, two raffinose synthase genes and one stachyose synthase gene were identified for the first time. To discover the expression patterns of these genes in different tissues, two expression atlases have been created through re-analysis of publicly available RNA-seq data. De novo expression analysis through an RNA-seq study during seed development of three varieties of common bean gave more insight into the expression patterns of these genes during the seed development. The results of the expression analysis suggest that different classes of galactinol- and RFO synthase genes have tissue-specific expression patterns in soybean and common bean. With the obtained knowledge, important galactinol- and RFO synthase genes that specifically play a key role in the accumulation of RFOs in the seeds are identified. These candidate genes may play a pivotal role in reducing the RFO content in the seeds of important legumes which could improve the nutritional quality of these beans and would solve the discomforts associated with their consumption.

Seed Longevity in Legumes: Deeper Insights Into Mechanisms and Molecular Perspectives

“…The galactinol synthase enzymes of chickpea were identified to be encoded by two genes (CaGolS1 and CaGolS2), of which CaGolS1 revealed predominant expression in developing and mature seeds. Similar pattern of tissue-specific expression was also observed in few other species including Pisum sativum, soybean and Vicia hirsuta, where GolS1 gene was observed to be induced during seed development, enhancing seed desiccation tolerance (Peterbauer et al, 2001;Gojło et al, 2015;de Koning et al, 2021). Transgenic expression of the CaGolS1 gene triggered redox homeostasis through ROS scavenging, and restriction of both lipid peroxidation and cellular damage.…”

“…Valentine et al ( 2017 ) reported reduction in the content of raffinose (0.63%) as well as stachyose (3.79%) in soybean seeds of wild type to 0.11 and 1.21% respectively, using a silenced gene construct targeting an isoform of single RS gene i.e., Gm RS2. In analogy to the above reported studies, de Koning et al ( 2021 ) also reported six genes of GolS, three genes of RF and one gene of SS to be involved in RFOs production of soybean. In addition to this, the study reported three GolS genes ( Pv GolS1, Pv GolS2, and Pv GolS3), two RS genes ( Pv RS1 and Pv RS2) and one SS gene ( Pv SS) to be involved in the synthesis of RFOs in case of Phaseolus vulgaris .…”

“…The synthesis of RFOs depends on the influx of galactinol that acts as galactosyl donor. Along with galactinol, stachyose and galactosyl cyclitols could also be used as galactosyl donors (de Koning et al, 2021 ). The synthesis of galactinol, stachyose and galactosyl cyclitols has been identified to be catalyzed by the enzymatic activities of galactinol synthase (GolS) and stachyose synthase (SS) genes respectively.…”

Spatio-temporal expression pattern of Raffinose Synthase genes determine the levels of Raffinose Family Oligosaccharides in peanut (Arachis hypogaea L.) seed

“…Mutations as well as silencing of a raffinose synthase gene ( GmRS2 ) of soybean generated phenotypes with low raffinose content 26 , 27 . Similar studies on common bean ( Phaseolus vulgaris ) identified seed specific galactinol synthase ( PvGolS1 ) and raffinose synthase ( PvRS2 ) genes, making them interesting candidates to knock out towards nutritional quality 28 . A genome-wide analysis recently identified AdGolS3 as a candidate for drought tolerance in wild type peanut genotypes 29 .…”

Genome-wide association mapping of seed oligosaccharides in chickpea

“…Additionally, the genes involved in the RFO biosynthetic pathway have been identified in soybean ( Glycine max ) and common bean ( Phaseolus vulgaris ). de Koning et al. (2021) identified three galactinol synthase ( GolS ) genes in common bean, named PvGolS1, PvGolS2 , and PvGolS3 .…”