Drought affects the growth and development of plants and can cause crop failure. As an important edible and medicinal plant, okra (Abelmoschus esculentus L. Moench) is very popular in China and shows strong resistance to drought. In this study, gene expression profiles of okra leaves were investigated under water-limited conditions at the seedling stage. A total of 94,769 unigenes with an average length of 1921 bp and an N90 of 981 bp were obtained through next-generation sequencing. Furthermore, 38.18% of total unigenes were annotated in NT, NR, COG, KEGG, and SwissProt databases. A total of 2276, 5626, 11,719, 14,892, 855, 4593, and 5170 differentially expressed genes (DEGs) in seven pairwise comparisons (A5 vs. A0; A7 vs. A0; A15 vs. A0; A20 vs. A0; A7 vs. A5; A15 vs. A7, and A20 vs. A15) were identified. Among these, 22,751 DEGs were up-regulated, and the number was slightly more than that of the down-regulated DEGs. The number of up-regulated DEGs among different samples increased with increasing drought stress. We identified that the majority of DEGs were related to ''integral component of membrane'', ''oxidation-reduction process'', and ''metal ion binding'' categories. Pathway analysis revealed that most DEGs were enriched in ''Biosynthesis of secondary metabolites'', ''Carbon metabolism'', and ''Glycolysis/Gluconeogenesis pathways''. Additionally, a total of 17,456 simple sequence repeat motifs, 47,9831 single nucleotide polymorphisms, and 3746 transcription factors were identified in this study. RNA-Seq data were also verified by RT-qPCR. Our findings engender a further understanding of molecular mechanisms in response to drought stress. Keywords Okra (Abelmoschus esculentus L.) Á Transcriptome sequencing Á Drought stress Á Differential expression Abbreviations RNA-Seq Ribonucleic acid-sequencing NGS Next generation sequencing cDNA Complementary deoxyribonucleic acid PCR Polymerase chain reaction EB Ethambutol GO Gene ontology KEGG Kyoto encyclopedia of genes and genomes CDSs Coding sequences SSR Simple sequence repeat Jiyue Wang and Yu Bai: co-first author.

In recent years, due to its medicinal properties and reputation as a healthy vegetable, consumption of okra (Abelmoschus esculentus L.) has considerably increased in China. In this study, texture parameters (hardness, springiness, cohesiveness, gumminess, chewiness, and resilience) of okra fruit subjected to chitosan (CTS) treatment and control were determined during storage. The changing pattern of texture properties and the differences between three different cultivars (Kariba, ACF, and Xianzhi) were observed at three testing stages (0, 15, and 30 days of storage), which indicated a significant cultivar-dependent pattern. The hardness, cohesiveness, gummi-ness, chewiness, and resilience of the fruit, both in the 1% CTS treatment group and the control group, declined along with storage time. The small fruits (length < 10 cm) scored relatively low in most of the texture parameters and rate of intact when compared with large (length ? 15 cm) and medium-sized fruits (10 ? length < 15 cm). There was a significant, positive correlation between firmness, cohesiveness, gumminess, chewiness, and resilience. Our results revealed that a 1% N, O-carboxymethyl CTS solution can effectively delay softening and maintain the texture profile of the okra fruit. In the case of Kariba (A) and Xianzhi (C), the medium-sized fruits showed better storage resistance, while the large fruit of ACF (B) showed the best storage resistance.

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