Abstract

   Uniconazole (UNZ) can alleviate a variety of abiotic stresses such as
   low temperature. With application of UNZ on Coix lachryma‐jobi L.
   (coix) under low‐temperature stress, growth and physiological
   parameters were investigated in seedlings. Meanwhile, transcriptome
   profile in coix seedlings was characterized as well. The results showed
   an increase of 11.90%, 13.59%, and 10.98% in stem diameter, the
   aboveground and belowground biomass in 5 mg/L uniconazole application
   group (U3), compared with control check low‐temperature group (CKL).
   Some anti‐oxidase activities also show significant difference between
   CKL and U3 (p < .05). Transcriptome results showed that 3,901 and 1,040
   genes had different expression level at control check (CK) and CKL, CKL
   and U3. A considerable number of different expressing genes (DEGs)
   related to the plant hormone signal transduction, photosynthesis,
   reactive oxygen species (ROS)‐related genes, and secondary metabolism
   in response to uniconazole application were identified in this study.
   The transcriptomic gene expression profiles present a valuable genomic
   tool to improve studying the molecular mechanisms underlying
   low‐temperature tolerance in coix. At the same time, it would provide a
   certain basis for the application of UNZ in the production of coix
   resistance under low temperature.

   Keywords: coix seedlings, growth and physiological parameters, low
   temperature, transcriptome, uniconazole (UNZ)
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   With application of S3307 on Coix lachryma‐jobi L (coix) under
   low‐temperature stress, growth and physiological parameters were
   investigated in seedlings. Meanwhile, using Illumina sequencing
   technology, transcriptome profile in coix seedlings was characterized
   as well.

   graphic file with name FSN3-8-534-g005.jpg

1. INTRODUCTION

   Coix, commonly known as Job's tears, is an annual crop that has long
   been consumed as both a herbal medicine and a nourishing food (Lin &
   Li, [36]2016). Coix is a nourishing food containing 16.2% proteins,
   4.65% lipids, and 79.17% carbohydrates (Kim et al., [37]2004). Modern
   scientific studies demonstrate that adlay seeds have exhibited
   antitumor (Lu, Zhang, Jia, Wu, & Lu, [38]2011), anti‐inflammatory
   (Chen, Chung, Chiang, & Lin, [39]2011), and anti‐allergic properties
   (Chen, Shih, Hsu, & Chiang, [40]2010). With the increasing value of
   coix, the research on coix has drawn more and more attention.

   Temperature greatly affects the growth and development of crops. When
   crops are exposed to low‐temperature stress, the growth and production
   may be suppressed in some crops (Li & Colin, [41]2011; Li et al.,
   [42]2017). At present, coixs mainly grow in south China including
   Hubei, Yunnan, Guizhou, Guangdong, and Guangxi in south China. There is
   fewer coix planting in north China including Liaoning, Jilin, and
   Heilongjiang, which are located on the Northeast plain and belong to
   the cold zone. The effective accumulated temperature is insufficient,
   and cold damage frequently occurs in Heilongjiang province (Chen, Tian,
   et al., [43]2014; Chen, Song, et al., [44]2014). The low temperature
   seriously affects the germination, emergence, growth, and yield of
   coix.

   It has been well documented that plant growth regulators (PGRs) play
   important roles in crop production and resisting environmental stresses
   (Prat, Botti, & Fichet, [45]2008). As a member of the triazole PGRs
   family, UNZ was increasingly applied in crops (Wu, Sun, Zhang, & Liu,
   [46]2013). This chemical could regulate numerous growth and development
   processes, such as flowering period (Cao, Zhang, Zhang, & Jiang,
   [47]2003), increasing output and quality (Liu et al., [48]2016), and
   enhancing plant resistance (Zhang et al., [49]2007). Some studies
   showed that UNZ exerted beneficial effects on alleviating adverse
   stresses (Gan, He, Yan, & Hu, [50]2012; Wu et al., [51]2013; Zhen et
   al., [52]2012). For example, UNZ could improve the anti‐oxidation
   system of the omega plant under low‐temperature stress, enhance the
   photosynthetic electron transfer efficiency in plants, and reduce the
   damage to leaf cells under low temperature (Zheng et al., [53]2016).
   When sorghum treated by uniconazole, the SOD, POD, and CAT activities
   showed a trend of earlier increasing and later decreasing with UNZ
   concentration increasing (Liang, Guo, Zhou, Zhang, & Yan, [54]2016).
   High‐throughput sequence analysis is an efficient and powerful method
   for transcriptome analysis, and over the past several years, the
   technology has increasingly been used to characterize transcriptomic in
   plants. It was particularly useful in nonmodel species, whose genomic
   sequences were often unavailable, such as black cottonwood, Prunus
   dulcis Mill, Beta vulgaris, Eucalyptus dunnii, and Chrysanthemum
   nankingense (Liu, Jiang, Lan, Zou, & Gao, [55]2014; Moliterni et al.,
   [56]2015; Mousavi et al., [57]2014; Ren et al., [58]2014; Tang et al.,
   [59]2015). Previous studies mainly focused on the effect of UNZ on the
   aspects of physiology and biochemistry under adverse stress. However,
   the effect of UNZ on the transcriptome under low‐temperature stress in
   coix has not been investigated yet.

   In this work, we studied the physiological parameters and relevant
   transcriptome of coix in response to UNZ under low‐temperature stress.
   The DEGs generated by de novo assembly were annotated and analyzed
   according to unigene's GO annotation and KEGG metabolic pathways. Thus,
   this study aimed to find the correlation between the physiological
   parameters and DEGs via the transcriptome analysis, which would be
   useful for the application of UNZ in the production of coix. At the
   same time, it provided some references for the coix cultivation in