The early responsive to dehydration-like (ERDL or ERD) subfamily, subclade within the monosaccharide transporter (MST) superfamily, is crucial in the regulation of growth and seed yield in Arabidopsis. Here, we identified OsERD5 as an AtERDL6 homologue and explored the function of OsERD5. We found that OsERD5 overexpression significantly enhanced the tiller number and grain yield of rice. OsERD5 was widely expressed in aboveground tissues, encoded a tonoplast-localized protein, and exhibited transport activities for fructose, glucose and mannose when expressed in yeast. Expression character assay revealed that OsERD5 mediated hexose efflux across tonoplasts and participated in maintaining the diurnal rhythm-regulated intracellular hexose homeostasis. Additional physiological and molecular evidence showed that OsERD5 overexpression promoted vacuolar glucose efflux, enhanced sucrose synthesis and transport, increased sugar content in the shoot base, and promoted rice tillering by activating the synthesis of cytokinin simultaneously repressing strigolactone and gibberellin signaling. This study elucidates the function of OsERD5 and the mechanism underlying the overexpression of OsERD5 increasing rice tillering and yield.

Elucidating crops’ physiological and molecular mechanisms to adapt to low nitrogen environment and promoting nitrogen transfer from senescent leaves to new leaves is crucial in improving Brassica’s nitrogen use efficiency (NUE). Glutamine synthetase gene (GS) plays a vital role in helping plants reassimilate ammonium released from protein degradation in leaves, and it was the focus of our research on this topic. In this study, we identified high (H141) and low (L65) NUE genotypes of Brassica juncea with different responses to low-nitrogen stress. We found that H141 has a lower nitrate content but higher ammonium and free amino acid contents as well as higher nitrate reductase and GS activities in the shoots. These physiological indicators are responsible for the high NUE of H141. Whole-genome resequencing data revealed that 5,880 genes associated with NUE are polymorphic between H141 and L65. These genes participate in various amino acid, carbohydrate, and energy metabolic pathways. Haplotype analysis revealed two haplotypes for BjuB05.GS1.4, Hap1 and Hap2, which have multiple single nucleotide polymorphisms or insertions/deletions in the regulatory regions of the 5´ and 3´ untranslated regions and introns. Furthermore, the shoot NUE of Hap1 is significantly lower than that of Hap2. These two haplotypes of BjuB05.GS1.4 lead to differences in the shoot NUEs of different genetic populations of mustard and are associated with the local soil nitrogen content, suggesting that they might help mustard to adapt to different geographic localities. In conclusion, the results of our study shed light on the physiological and molecular mechanisms underlying different mustard NUE genotypes and demonstrate the enormous potential of NUE breeding in B. juncea.

Nitrogen (N) is an essential plant growth nutrient whose coordinated distribution from source to sink organs is crucial for seed development and overall crop yield. We compared high and low N use efficiency (NUE) Brassica napus (rapeseed) genotypes. Metabonomics and transcriptomics revealed that leaf senescence induced by N deficiency promoted amino acid allocation from older to younger leaves in the high-NUE genotype at the vegetative growth stage. Efficient source to sink remobilization of amino acids elevated the numbers of branches and pods per plant under a N-deficiency treatment during the reproductive stage. A ¹⁵N tracer experiment confirmed that more amino acids were partitioned into seeds from the silique wall during the pod stage in the high-NUE genotype, owing mainly to variation in genes involved in organic N transport and metabolism. We suggest that the greater amino acid source-to-sink allocation efficiency during various growth stages in the high-NUE genotype resulted in higher yield and NUE under N deficiency. These findings support the hypothesis that strong amino acid remobilization in rapeseed leads to high yield, NUE, and harvest index.

As a consequence of industrial development, soil Cd pollution leads to crop contamination by Cd, posing a threat to food safety and human health. Excessive accumulation of Cd in plants also inhibits their growth via oxidative stress damage to their photosynthetic systems. Through evolutionary selection, plants have developed a set of efficient strategies to respond to Cd in their environments. These include the accumulation and detoxification of heavy metals. Cd is absorbed by plant roots through the apoplastic and symplastic pathways and then translocated to plant shoots via xylem loading, long-distance transport, and phloem redistribution. Simultaneously, plants initiate a series of mechanisms to reduce Cd toxicity, including cell wall adsorption, cytoplasmic chelation, and vacuolar sequestration. This review summarizes current knowledge of Cd accumulation and detoxification in plants.