Protein Cross-Interactions for Efficient Photosynthesis in the Cassava Cultivar SC205 Relative to Its Wild Species

Deciphering the impact of nitrogen morphologies distribution on nitrogen and biomass accumulation in tobacco plants

Background and aims

Nitrogen (N) distribution in plants is intricately linked to key physiological functions, including respiration, photosynthesis, structural development, and nitrogen storage. However, the specific effects of different N morphologies on N accumulation and plant growth are poorly understood. Our research specifically focused on determining how different N morphologies affect N absorption and biomass accumulation.

Methods

This study elucidated the impact of different application rates (CK: 0 g N/plant; T1: 4 g N/plant; T2: 8 g N/plant) of N fertilizer on N and biomass accumulation in tobacco cultivars Hongda and K326 at different growth stages.

Results

Our findings emphasize the critical role of N distribution in various plant parts, including leaves, stems, and roots, in determining the complex mechanisms of N and biomass accumulation in tobacco. We found that in relation to total N, a greater ratio of water-soluble N (N w) in leaves facilitated N accumulation in leaves. In contrast, an increased ratio of SDS (detergent)-insoluble N (N in-SDS) in leaves and non-protein N (N np) in roots hindered this increase. Additionally, our results indicate that a greater proportion of N np in leaves has a negative impact on biomass accumulation in leaves. Furthermore, elevated levels of N in-SDS, N w, and N np in roots, and N np in leaves adversely affected biomass accumulation in tobacco leaves. The Hongda cultivar exhibited greater biomass and N accumulation abilities as compared to K326.

Conclusions

Our findings highlight the significant role of distribution of N morphologies on plant growth, as well as N and biomass accumulation in tobacco plants. Understanding N distribution allows farmers to optimize N application, minimizing environmental losses and maximizing yield for specific cultivars. These insights advance sustainable agriculture by promoting efficient resource use and reducing environmental impact.

Genome-wide identification and characterization of 14-3-3 gene family related to negative regulation of starch accumulation in storage root of Manihot esculenta

The 14-3-3 protein family is a highly conservative member of the acid protein family and plays an important role in regulating a series of important biological activities and various signal transduction pathways. The role of 14-3-3 proteins in regulating starch accumulation still remains largely unknown. To investigate the properties of 14-3-3 proteins, the structures and functions involved in starch accumulation in storage roots were analyzed, and consequently, 16 Me14-3-3 genes were identified. Phylogenetic analysis revealed that Me14-3-3 family proteins are split into two groups (ε and non-ε). All Me14-3-3 proteins contain nine antiparallel α-helices. Me14-3-3s-GFP fusion protein was targeted exclusively to the nuclei and cytoplasm. In the early stage of starch accumulation in the storage root, Me14-3-3 genes were highly expressed in high-starch cultivars, while in the late stage of starch accumulation, Me14-3-3 genes were highly expressed in low-starch cultivars. Me14-3-3 I, II, V, and XVI had relatively high expression levels in the storage roots. The transgenic evidence from Me14-3-3II overexpression in Arabidopsis thaliana and the virus-induced gene silencing (VIGS) in cassava leaves and storage roots suggest that Me14-3-3II is involved in the negative regulation of starch accumulation. This study provides a new insight to understand the molecular mechanisms of starch accumulation linked with Me14-3-3 genes during cassava storage root development.

Integrated Metabolomic and Transcriptomic Analyses Reveals Sugar Transport and Starch Accumulation in Two Specific Germplasms of Manihot esculenta Crantz

As a starchy and edible tropical plant, cassava (Manihot esculenta Crantz) has been widely used as an industrial raw material and a dietary source. However, the metabolomic and genetic differences in specific germplasms of cassava storage root were unclear. In this study, two specific germplasms, M. esculenta Crantz cv. sugar cassava GPMS0991L and M. esculenta Crantz cv. pink cassava BRA117315, were used as research materials. Results showed that sugar cassava GPMS0991L was rich in glucose and fructose, whereas pink cassava BRA117315 was rich in starch and sucrose. Metabolomic and transcriptomic analysis indicated that sucrose and starch metabolism had significantly changing metabolites enrichment and the highest degree of differential expression genes, respectively. Sugar transport in storage roots may contribute to the activities of sugar, which will eventually be exported to transporters (SWEETs), such as (MeSWEET1a, MeSWEET2b, MeSWEET4, MeSWEET5, MeSWEET10b, and MeSWEET17c), which transport hexose to plant cells. The expression level of genes involved in starch biosynthesis and metabolism were altered, which may result in starch accumulation. These results provide a theoretical basis for sugar transport and starch accumulation and may be useful in improving the quality of tuberous crops and increasing yield.

Systematic Analysis of bHLH Transcription Factors in Cassava Uncovers Their Roles in Postharvest Physiological Deterioration and Cyanogenic Glycosides Biosynthesis

The basic helix-loop-helix (bHLH) proteins are a large superfamily of transcription factors, and play a central role in a wide range of metabolic, physiological, and developmental processes in higher organisms. However, systematic investigation of bHLH gene family in cassava (Manihot esculenta Crantz) has not been reported. In the present study, we performed a genome-wide survey and identified 148 MebHLHs genes were unevenly harbored in 18 chromosomes. Through phylogenetic analyses along with Arabidopsis counterparts, these MebHLHs genes were divided into 19 groups, and each gene contains a similar structure and conserved motifs. Moreover, many cis-acting regulatory elements related to various defense and stress responses showed in MebHLH genes. Interestingly, transcriptome data analyses unveiled 117 MebHLH genes during postharvest physiological deterioration (PPD) process of cassava tuberous roots, while 65 MebHLH genes showed significantly change. Meanwhile, the relative quantitative analysis of 15 MebHLH genes demonstrated that they were sensitive to PPD, suggesting they may involve in PPD process regulation. Cyanogenic glucosides (CGs) biosynthesis during PPD process was increased, silencing of MebHLH72 and MebHLH114 showed that linamarin content was significantly decreased in the leaves. To summarize, the genome-wide identification and expression profiling of MebHLH candidates pave a new avenue for uderstanding their function in PPD and CGs biosynthesis, which will accelerate the improvement of PPD tolerance and decrease CGs content in cassava tuberous roots.