Comparative physiochemical and transcriptomic analysis reveals the influences of cross-pollination on ovary and fruit development in pummelo (Citrus maxima).

'Shuijingmiyou' pummelo (SJ), one of the most popular fruits in Yunnan province of China, is of relatively low fruit shape (FS) quality. In this study, we compared the FS promoting effects of cross pollinations using pollens from seven pummelo varieties, and found that 'Guanximiyou' pummelo (GX) cross-pollination showed the best FS promoting effects on SJ fruits by shortening its fruit neck. To explore the underlying mechanism, physiochemical and transcriptomic differences between self- and cross-pollinated SJ ovaries (SJO and GXO) were investigated. Higher salicylic acid, gibberellin and indole acetic acid contents and superoxide dismutase, peroxidase and catalase activities, and lower polyphenol oxidase activity were determined in GXO compared with SJO. Enrichment analysis of the identified 578 differentially expressed genes (123 up-regulated and 455 down-regulated) in GXO showed that genes involved in solute transport, RNA biosynthesis, phytohormone action and cell wall organization were significantly enriched. The results obtained in this study will be helpful in understanding the influences of cross-pollination on pummelo ovary and fruit development, and can provide the basis for clarifying the underlying mechanism of cross-pollination improved fruit quality.

Characterization of the complete chloroplast genome of Yuanjiang wild Ichang papeda (Citrus cavaleriei) in China.

Ichang papeda (Citrus cavaleriei) is an endemic perennial plant in China. In this study, we assembled and annotated the complete chloroplast genome of Yuanjiang wild Ichang papeda using Illumina Hiseq-2500 sequencing data. The chloroplast genome is constituted of 160,996 bp, containing a 87,634 bp large single-copy region, a 18,762 bp small single-copy region, and a pair of 27,300 bp inverted repeat regions. The chloroplast genome contains 114 unique genes, including 80 protein-coding genes, 30 tRNAs and 4 rRNAs. Phylogenetic analysis showed that the relationship between the chloroplast gennomes of C. cavaleriei and C. reticulata is the closest, which consistently support their chloroplast relationships.