RNA-Sequencing Analysis Revealed Genes Associated with Sweet Potato (Ipomoea batatas (L.) Lam.) Responses to Stem Rot during Different Infection Stages.

The sweet potato, which is an important tuber crop in China, is susceptible to a variety of pathogens and insect pests during cultivation and production. Stem rot is a common sweet potato disease that seriously affects tuber yield and quality. Unfortunately, there have been relatively few studies on the mechanism mediating the stem rot resistance of sweet potatoes. In this study, a transcriptome sequencing analysis was completed using Xushu 48 samples at different stages (T1, T2, and T3) of the stem rot infection. The T1 vs. T2, T1 vs. T3, and T2 vs. T3 comparisons detected 44,839, 81,436, and 61,932 differentially expressed genes (DEGs), respectively. The DEGs encoded proteins primarily involved in alanine, aspartate, and glutamate metabolism (ko00250), carbon fixation in photosynthetic organisms (ko00710), and amino sugar and nucleotide sugar metabolism (ko00520). Furthermore, some candidate genes induced by phytopathogen infections were identified, including gene-encoding receptor-like protein kinases (RLK5 and RLK7), an LRR receptor-like serine/threonine protein kinase (SERK1), and transcription factors (bHLH137, ERF9, MYB73, and NAC053). The results of this study provide genetic insights that are relevant to future explorations of sweet potato stem rot resistance, while also providing the theoretical basis for breeding sweet potato varieties that are resistant to stem rot and other diseases.

Comparative studies on physicochemical properties of three potato varieties different in RS2 and RS3 contents.

BACKGROUND: At present, increasing importance has been attracted to healthy food enriched in resistant starch (RS), which has great benefits in health-promoting. Raw potato has rich RS2, whereas most RS2 may become digestible after gelatinization, resulting in few RS being left in processed potato. Breeding potatoes with high RS2 or RS3 or both can meet the demand for various healthy potato products. RESULTS: There were apparent discrepancies among three potatoes with contrast RS2 and RS3 content in thermal properties, viscosity and digestibility. ZS-5 had the highest RS2 with 50.17% but the lowest RS3 with 3.31%. Meanwhile, ZS-5 had the largest starch granule, the highest proportion of B3, viscosity and hardness, and the highest digestibility. DN303 with the highest content of RS3 (5.08%) had the lowest hardness and fracturability. MG56-42 with both higher RS2 and RS3 content showed the highest resistance to digestion and moderate hardness and fracturability. CONCLUSION: The present study enriches the potential resources and provides a reliable scientific basis for high RS potatoes breeding. The various features of different potatoes make it possible to screen potatoes according to different demands. © 2023 Society of Chemical Industry.

Retaining a large amount of resistant starch in cooked potato through microwave heating after freeze-drying.

Resistant starch (RS) is beneficial for humans, especially for the diabetes. Raw potato had a great deal of RS, while most of which become digestible after gelatinization. Thus, few RS will be retained in potatoes after regular cooking. To preserve RS in cooked potatoes as much as possible, microwave heating before (MFD) and after freeze-drying (FDM) were conducted with three different potatoes. After MFD, the RS content in potatoes was lower than 7% and the RDS content was higher than 45% for three potatoes. However, RS in potatoes treated with FDM was still as high as 40%, similar to that in the raw potatoes. Meantime, FDM caused less browning, produced a certain level of pyrazines, benzeneacetaldehyde and other flavor compounds, endowing cooked potatoes special baked flavor. Freeze-drying before microwave heating is a valuable way to reserve RS in cooked potatoes, which could also be used to reserve high RS content in crisp, chips, and other processed potatoes.

Differential Impacts on Bacterial Composition and Abundance in Rhizosphere Compartments between Al-Tolerant and Al-Sensitive Soybean Genotypes in Acidic Soil.

In this study, two soybean genotypes i.e. aluminum-tolerant Baxi 10 (BX10) and aluminum-sensitive Bendi 2 (BD2) were used as plant materials and the acidic red soil was used as growth medium. The soil layers from the inside to the outside of the root are: rhizospheric soil after washing (WRH), rhizospheric soil after brushing (BRH) and rhizospheric soil at two sides (SRH), respectively. The rhizosphere bacterial communities were analyzed by high-throughput sequencing of V4 hypervariable regions of 16S rRNA gene (16S rDNA) amplicons via Illumina MiSeq. The results of alpha diversity showed that the BRH and SRH of BX10 were significantly lower on community richness than that of BD2, while the WRH existed no significant difference between BX10 and BD2. Among the three sampling compartments of the same soybean genotype, WRH had the lowest community richness and diversity while existed the highest coverage. Beta diversity analysis results displayed no significant difference for any compartment between the two genotypes, or among the three different sampling compartments for any same soybean genotype. However, the relative abundance of major bacterial taxa specifically nitrogen-fixating and/or aluminum-tolerant bacteria was significantly different in the compartments of the BRH and/or SRH at phylum and genus levels depicting genotype dependent variations in rhizosphere bacterial community. Strikingly, as compared with BRH and SRH, the WRH within the same genotype (BX10 or BD2) always had an enrichment effect on rhizosphere bacteria associated with nitrogen-fixation.

Detection of disease in Cucurbita maxima Duch. ex Lam. caused by a mixed infection of Zucchini yellow mosaic virus, Watermelon mosaic virus, and Cucumber mosaic virus in Southeast China using a novel small RNA sequencing method.

The genus Cucurbita comprises many popular vegetable and ornamental plants, including pumpkins, squashes, and gourds, that are highly valued in China as well as in many other countries. During a survey conducted in Zhejiang province, Southeast China in 2016, severe symptoms of viral infection were observed on Cucurbita maxima Duch. ex Lam. Diseased plants showed symptoms such as stunting, mosaicking, Shoe string, blistering, yellowing, leaf deformation, and fruit distortion. Approximately, 50% of Cucurbita crops produced in Jinhua were diseased, causing an estimated yield loss of 35%. In this study, we developed a method using all known virus genomes from the NCBI database as a reference to map small RNAs to develop a diagnostic tool that could be used to diagnose virus diseases of C. maxima. 25 leaf samples from different symptomatic plants and 25 leaf samples from non-symptomatic plants were collected from the experimental field of Jihua National Agricultural Technology Garden for pathogen identification. Small RNAs from each set of three symptomatic and non-symptomatic samples were extracted and sequenced by Illumina sequencing. Twenty-four different viruses were detected in total. However, the majority of the small RNAs were from Zucchini yellow mosaic virus (ZYMV), Watermelon mosaic virus (WMV), and Cucumber mosaic virus (CMV). Mixed infections of these three viruses were diagnosed in leaf samples from diseased plants and confirmed by reverse transcription PCR (RT-PCR) using primers specific to these three viruses. Crude sap extract from symptomatic leaf samples was mechanically inoculated back into healthy C. maxima plants growing under greenhouse conditions. Inoculated plants developed the same disease symptoms as those observed in the diseased plants and a mixed infection of ZYMV, WMV, and CMV was detected again by RT-PCR, thus fulfilling Koch's postulates. The diagnostic method developed in this study involves fewer bioinformatics processes than other diagnostic methods, does not require complex settings for bioinformatics parameters, provides a high level of sensitivity to rapidly diagnose plant samples with symptoms of virus diseases and can be performed cheaply. This method therefore has the potential to be widely applied as a diagnostic tool for viruses that have genome information in the NCBI database.

Genetic diversity and stability in starch physicochemical property traits of potato breeding lines.

Cross breeding may create wider genetic variation than two parents used in hybridization, but breeding efforts towards starch quality improvement are less reported in potato. A cross was made between Zhongshu-3 and Favorita to select desired starch properties in progenies. Among 206 F1 clones with potential high yield, starch qualities such as apparent amylose content (AAC), pasting viscosity, and thermal properties were further evaluated. A wide variation was observed in different starch physicochemical indices for 206 potato accessions. Twenty clones with high/low AAC, peak viscosity and peak gelatinization temperature were selected and then grown at another location to evaluate the stability of the traits. Similar wide range of variation in the starch properties was observed. Cluster analysis based on starch properties of the 20 selected clones indicating relative stability of the starch property traits across different locations. New breeding lines identified have potential for application in food and other industries.