Roots are fundamental to the growth, development, and survival of plants. Beyond anchoring the plant, roots absorb water and nutrients, supporting the plant’s ability to grow and function normally. Root systems, originating from the apical meristem, exhibit significant diversity depending on the plant species. ROS are byproducts of aerobic metabolism, present in both above- and below-ground plant tissues. While ROS were once considered merely harmful byproducts of oxygen metabolism, they are now recognized as critical signaling molecules that regulate plant growth and development. Under stress conditions, plants produce elevated levels of ROS, which can inhibit growth. However, moderate ROS levels act as signals that integrate various regulatory pathways, contributing to normal plant development. However, there is still a lack of comprehensive and systematic research on how ROS precisely regulate root growth and development. This review provides an overview of ROS production pathways and their regulatory mechanisms in plants, with a particular focus on their influence on root development.

Sulforaphane is a natural isothiocyanate available from cruciferous vegetables with multiple characteristics including antioxidant, antitumor and anti-inflammatory effect. Single-molecule real-time (SMRT) sequencing has been used for long-read de novo assembly of plant genome. Here, we investigated the molecular mechanism related to glucosinolates biosynthesis in Chinese kale using combined NGS and SMRT sequencing. SMRT sequencing produced 185,134 unigenes, higher than 129,325 in next-generation sequencing (NGS). NaCl (75 mM), methyl jasmonate (MeJA, 40 μM), selenate (Se, sodium selenite 100 μM), and brassinolide (BR, 1.5 μM) treatment induced 6893, 13,287, 13,659 and 11,041 differentially expressed genes (DEGs) in Chinese kale seedlings comparing with control. These genes were associated with pathways of glucosinolates biosynthesis, including phenylalanine, tyrosine and tryptophan biosynthesis, cysteine and methionine metabolism, and glucosinolate biosynthesis. We found NaCl decreased sulforaphane and glucosinolates (indolic and aliphatic) contents and downregulated expression of cytochrome P45083b1 (CYP83b1), S-alkyl-thiohydroximatelyase or carbon–sulfur lyase (SUR1) and UDP-glycosyltransferase 74B1 (UGT74b1). MeJA increased sulforaphane and glucosinolates contents and upregulated the expression of CYP83b1, SUR1 and UGT74b1; Se increased sulforaphane; BR increased expression of CYP83b1, SUR1 and UGT74b1, and increased glucosinolates contents. The desulfoglucosinolate sulfotransferases ST5a_b_c were decreased by all treatments. We confirmed that NaCl inhibited the biosynthesis of both indolic and aliphatic glucosinolates, while MeJA and BR increased them. MeJA and BR treatments, conferred the biosynthesis of glucosinolates, and Se and MeJA contributed to sulforaphane in Chinese kale via regulating the expression of CYP83b1, SUR1 and UGT74b1.

Mustard, which belongs to the family Brassicaceae, is an annual or biennial herb and is considered as one of the most important native vegetables in China. Glucosinolates are important secondary metabolites containing sulfur and nitrogen in plants, which form a network with other metabolic pathways that play important roles in plant growth, development, and interaction with the environment. We studied varied phenotypic and glucosinolate contents of 60 mustard resources collected from various areas of China. The results showed both agronomic traits and glucosinolates varied greatly among mustard resources. We detected nine glucosinolates in mustard resources and the contents of total glucosinolates ranged from 1.2023 to 30.7310 μmol/g. Through the correlation analysis, we preliminarily found a significant negative correlation between leaf color and glucosinolate contents but needed further validation. For mustard resource JC 18-56, we analyzed the glucosinolate contents in different organs of different growth stages. The results indicated a significant difference among organs in both glucosinolates concentration and composition. The contents of glucosinolatess in alabastrums at bolting stage were highest, up to 140.1257 μmol/g dry weight (DW). We found that the main glucosinolates in roots were 4-methoxyglucobrassicin, while in other organs the glucosinolates were sinigrin. The contents of glucosinolatess in different organs of mustard were as follows: alabastrums > seeds > flowers > siliques > leaves > flower stems > stems > roots. This study provides important references for the selection and cultivation of high-quality mustard varieties.

Broccoli (Brassica oleracea var. italica Plenck) is an important vegetable crop, as it is rich in health-beneficial glucosinolates (GSLs). However, the genetic basis of the GSL diversity in Brassicaceae remains unclear. Here, we report a chromosome-level genome assembly of broccoli generated using PacBio HiFi reads and Hi-C technology. The final genome assembly is 613.79 Mb in size, with a contig N50 of 14.70 Mb. The GSL profile and content analysis of different Brassicas oleracea varieties, combined with a phylogenetic tree analysis, sequence alignment, and the construction of a three-dimensional model of the methylthioalkylmalate synthase 1 (MAM1) protein, which revealed that the gene copy number and amino acid sequence variation both contributed to the diversity of GSL biosynthesis in Brassica oleracea. The overexpression of BoMAM1 (BolI0108790) in broccoli resulted in high accumulation and a high ratio of C4-GSLs, demonstrating that BoMAM1 is the key enzyme in C4-GSLs biosynthesis. These results provide valuable insights for future genetic studies and nutritive component applications of Brassica crops.

Supplementation using selenium (Se) on plants is an effective and widely used approach. It can not only be converted to more Se rich compounds but promote the accumulation of glucosinolates (GSLs) with anti-carcinogenic properties. However, the molecular mechanism of Se in regulating GSLs synthesis remains unclear. In the present study, we analyzed the effects of Se treatment (50 μM sodium selenite) on GSLs, glucoraphanin (4MSOB), and sulforaphane compounds in broccoli tissues. The transcript levels of genes involved in sulfur absorption and transport, GSLs biosynthesis, translocation, and degradation pathways were also evaluated. The study showed that Se treatment remarkably promoted the accumulation of total sulfur and total Se contents and increased Trp-derived GSLs levels in roots by 2 times. The 4MSOB concentration and sulforaphane content in fresh leaves was increased by 67% and 30% after Se treatment, respectively. For genes expressions, some genes involved in sulfate uptake and transporters, GSLs biosynthesis, and transporters were induced strongly upon Se exposure. Results revealed that exogenous Se treatment promotes the overaccumulation of GSLs and 4MSOB content in broccoli by activating the transcript levels of genes involved in sulfur absorption, GSLs biosynthesis, and translocation pathways.