Genomic Characterization and Expressional Profiles of Autophagy-Related Genes (ATGs) in Oilseed Crop Castor Bean (Ricinus communis L.)

Abstract

Cellular autophagy is a widely-occurring conserved process for turning over damaged organelles or recycling cytoplasmic contents in cells. Although autophagy-related genes (ATGs) have been broadly identified from many plants, little is known about the potential function of autophagy in mediating plant growth and development, particularly in recycling cytoplasmic contents during seed development and germination. Castor bean (Ricinus communis) is one of the most important inedible oilseed crops. Its mature seed has a persistent and large endosperm with a hard and lignified seed coat, and is considered a model system for studying seed biology. Here, a total of 34 RcATG genes were identified in the castor bean genome and their sequence structures were characterized. The expressional profiles of these RcATGs were examined using RNA-seq and real-time PCR in a variety of tissues. In particular, we found that most RcATGs were significantly up-regulated in the later stage of seed coat development, tightly associated with the lignification of cell wall tissues. During seed germination, the expression patterns of most RcATGs were associated with the decomposition of storage oils. Furthermore, we observed by electron microscopy that the lipid droplets were directly swallowed by the vacuoles, suggesting that autophagy directly participates in mediating the decomposition of lipid droplets via the microlipophagy pathway in germinating castor bean seeds. This study provides novel insights into understanding the potential function of autophagy in mediating seed development and germination.

Transcriptome analysis of developing castor bean seeds and identification of ricinoleic acid biosynthesis genes

“…As displayed in Fig. 1, the castor oil and ricinoleic acid accumulation in R. communis seeds at three developmental stages (15,30, and 45 DAP) were analyzed. The seed oil content quickly increased from stage 1 (15 DAP, S1) to stage 2 (30 DAP, S2) (53.8%), and then gradually increased to 61.7% at stage 3 (45 DAP, S3).…”

“…Results In order to better understand the regulation mechanism of ricinoleic acid biosynthesis, immature seeds at three developmental stages (15,30, and 45 days after pollination) were collected. The results indicated that the accumulation of castor oil and ricinoleic acid increased gradually during seed development, and reached the maximum value at the late stages of seed development (45 days after pollination).…”

“…Chandrasekaran et al (2014) [29] identi ed ABA mediated regulatory changes in the process of oil accumulation in developing castor seeds through transcriptome pro ling. Han et al (2020) [30] found autophagy-related genes in castor bean by RNA-sEq. Tian et al (2019) revealed a series of genes related to biosynthesis via transcriptome analysis in Hiptage benghalensis [31].…”

“…In this study, we aimed to better understate the regulation mechanism of ricinoleic acid biosynthesis and castor oil accumulation by transcriptional pro ling. A high oil-content variety of castor bean was chosen and seeds were harvested at three developmental stages [15,30, and 45 days after pollination (DAP)] for ricinoleic acid analysis. Additionally, the developing castor seeds transcriptome pro les of developing seeds and candidate key enzyme genes of were summarized by second-generation sequencing (SGS).…”

In Silico Analyses of Autophagy-Related Genes in Rapeseed (Brassica napus L.) under Different Abiotic Stresses and in Various Tissues

“…Identifying the abiotic stress-responsive genes in B. napus can increase our knowledge to improve commercial B. napus cultivars and increase its tolerance to abiotic stresses such as cold and salinity. Although the genome of many plants is known, ATGs were studied in a few plants, including Arabidopsis [ 34 ], O. sativa [ 35 ], Nicotiana tabacum [ 36 ], Z. mays [ 29 ], Capsicum annuum [ 37 ], Setaria italica [ 38 ], Musa acuminate [ 39 ], Vitis vinifera [ 12 ], Citrus sinensis [ 40 ], and Ricinus communis [ 41 ]. Further investigations are necessary to characterize these genes in the various plant species to increase our knowledge about ATGs in plants.…”