Efficient Rooting System for Apple “M.9” Rootstock Using Rice Seed Coat and Smocked Rice Seed Coat

“M.9” rootstock is considered as one of the most useful apple (Malus x domestica Borkh.) rootstocks; it produces dwarfing trees efficiently. As “M.9” rootstock shows a poor, brittle, and shallow roots system, we grafted “M.9” rootstocks onto “Marubakaidou” (M. prunifolia Borkh. var. ringo Asami Mo 84-A). We then propagated them by mound layering to establish a high-density root system. It was found that covering the roots with rice seed coat (RSC), RSC + smoked rice seed coat (SRSC), and vermiculite during mound layering was effective for the initiation of rooting. Utilizing RSC and SRSC seemed especially effective for producing “M.9” roots efficiently

High-throughput analysis of anthocyanins in horticultural crops using probe electrospray ionization tandem mass spectrometry (PESI/MS/MS)

農作物に含まれる成分を簡便・迅速に分析する技術を確立 --煩雑な抽出や分離操作が不要、わずか3分間で81種類のアントシアニンを分析可能--. 京都大学プレスリリース. 2023-03-30.Plant secondary metabolites exhibit various horticultural traits. Simple and rapid analysis methods for evaluating these metabolites are in demand in breeding and consumer markets dealing with horticultural crops. We applied probe electrospray ionization (PESI) to evaluate secondary metabolite levels in horticultural crops. PESI does not require pre-treatment and separation of samples, which makes it suitable for high-throughput analysis. In this study, we targeted anthocyanins, one of the primary pigments in horticultural crops. Eighty-one anthocyanins were detected in approximately 3 minutes in the selected reaction-monitoring mode. Tandem mass spectrometry (MS/MS) could adequately distinguish between the fragments of anthocyanins and flavonols. Probe sampling, an intuitive method of sticking a probe directly to the sample, could detect anthocyanins qualitatively on a micro-area scale, such as achenes and receptacles in strawberry fruit. Our results suggest that PESI/MS/MS can be a powerful tool to characterize the profile of anthocyanins and compare their content among cultivars

Tomato ATP-binding cassette transporter SlABCB4 is involved in auxin transport in the developing fruit

Plant ATP binding cassette (ABC) transporters are membrane proteins that are important for transporting a wide range of compounds, including secondary metabolites and phytohormones. In Arabidopsis, some members of the ABCB subfamily of ABC transporter, also known as Multi-Drug Resistance proteins (MDRs), have been implicated in auxin transport. However, reports on the roles of the auxin-mediated ABCBs in fleshy fruit development are rare. Here, we present that SlABCB4, a member of the tomato ABCB subfamily, transports auxin in the developing fruit of tomato. Transient expression of SlABCB4-GFP fusion proteins in tobacco cells showed plasma membrane localization. The transport activity of SlABCB4, expressed in Nicotiana benthamiana protoplasts, revealed substrate specificity for indole-3-acetic acid export. Gene expression analysis of SlABCB4 revealed high expression levels at the early stages of fruit development. Therefore, SlABCB4 is considered to facilitate auxin distribution in tomato fruit, which is important for tomato fruit development

Enhancement of RNA-directed DNA methylation of a transgene by simultaneously downregulating a ROS1 ortholog using a virus vector in Nicotiana benthamiana

Cytosine methylation can be induced by double-stranded RNAs through the RNA-directed DNA methylation (RdDM) pathway. A DNA glycosylase REPRESSOR OF SILENCING 1 (ROS1) participates in DNA demethylation in Arabidopsis and may possibly counteract RdDM. Here, we isolated an orthologue of ROS1 (NbROS1) from Nicotiana benthamiana and examined the antagonistic activity of NbROS1 against virus-induced RdDM by simultaneously inducing RdDM and NbROS1 knockdown using a vector based on Cucumber mosaic virus. Plants were inoculated with a virus that contained a portion of the CaMV 35S promoter, which induced RdDM of the promoter integrated in the plant genome and transcriptional silencing of the green fluorescent protein gene driven by the promoter. Plants were also inoculated with a virus that contained a portion of NbROS1, which induced downregulation of NbROS1. Simultaneous induction of RdDM and NbROS1 knockdown resulted in an increase in the level of cytosine methylation of the target promoter. These results provide evidence for the presence of antagonistic activity of NbROS1 against virus-induced RdDM and suggest that the simultaneous induction of promoter-targeting RdDM and NbROS1 knockdown by a virus vector is useful as a tool to enhance targeted DNA methylation

Genome-Wide Analysis of Aquaporins in Japanese Morning Glory (<i>Ipomoea nil</i>)

The aquaporin (AQP) family, also called water channels or major intrinsic proteins, facilitate water transport. AQPs also transport low-molecular-weight solutes, including boric acid, glycerol, urea, and ammonia. Since plants are sessile, water homeostasis is crucial. Therefore, plants have developed diverse AQP variants at higher expression levels than animals. For example, 35 and 33 AQPs have been identified in Arabidopsis and rice, respectively. In the present study, we identified AQPs in morning glory (Ipomoea nil), which has been widely used as a model plant in research on flowering and floral morphology. The importance of AQPs in the opening of morning glory flowers has been reported. In the morning glory genome, 44 AQPs were identified, and their characteristics were analyzed. A phylogenetic analysis revealed five AQP subfamilies in morning glory: plasma membrane-intrinsic proteins (PIPs), tonoplast-intrinsic proteins (TIPs), nodulin 26-like intrinsic proteins (NIPs), small basic intrinsic proteins (SIPs), and X-intrinsic proteins (XIPs). Further, transport substrates of morning glory AQPs were estimated based on their homology to the known AQPs in other plant species and their corresponding amino acid motifs that possess permeability pores. It was expected that PIPs are likely to transport water, carbon dioxide, and hydrogen peroxide; TIPs are likely transport water, hydrogen peroxide, ammonia, urea, and boric acid; NIPs are likely transport water, boric acid, ammonia, glycerol, and formamide; and XIPs are likely to transport water, hydrogen peroxide, and glycerol. Overall, these results suggest that AQPs are involved in water and nutrient transport in Japanese morning glory. An in silico gene expression analysis suggested the importance of AQPs in flower opening, water or nutrient uptakes from the soil to roots, and photosynthesis in morning glory. Our findings provide fundamental information that enables further study into the importance of AQPs in morning glory, including their roles in flower opening and other physiological events

Efficient Breeding and Cultivation of Type 2 Red-fleshed Apple Cultivars Using a Search System for Suitable Apple Cultivar Combination

As apple possesses self-incompatibility, knowledge of the S-genotypes is very important for apple breeding and cultivation. We investigated the S-RNase genotypes of 13 type 2 red-fleshed apple cultivars and 8 lineages. All of the investigated type 2 red-fleshed apples contained the S3-RNase allele closely linked to the red-fleshed trait. We made a search system for ovule parents to efficiently produce new type 2 red-fleshed cultivars based on the S-RNase allele information (http://www.agr.nagoya-u.ac.jp/∼hort/apple/red/). More than 90% of progenies from crossing a selected white-fleshed ovule parent with a type 2 red-fleshed pollen parent are expected to show the red-fleshed phenotype. We also compiled a database of the S-RNase genotypes of more than 1 000 apple cultivars, including a survey system of cultivar combinations showing those that were fully incompatible, semicompatible and fully compatible, written in Chinese (http://www.agr.nagoya-u.ac.jp/∼hort/apple/ch/) and Japanese (http://www.agr.nagoya-u.ac.jp/∼hort/apple/ja/). Keywords: Malus × domestica, type 2 red-fleshed, S-RNase, genotype, cultivar combination, self-incompatibilit