Drought stress is a significant abiotic stress factor that affects wheat yield and quality. MicroRNA (miRNA) plays an important role in regulating caryopsis development in response to drought stress. However, little is known about the expression characteristics of miRNAs and how they regulate protein accumulation in wheat caryopsis under drought stress. To address this, two small RNA libraries of wheat caryopsis under control and drought stress conditions were constructed and sequenced. A total of 125 miRNAs were identified in the two samples, of which 110 were known and 15 were novel. A total of 1,981 miRNA target genes were predicted and functional annotations were obtained from various databases for 1,641 of them. Four miRNAs were identified as differential expression under drought stress, and the expression patterns of three of them were consistent with results obtained by reverse transcription polymerase chain reaction (RT-PCR) and reverse transcription quantitative polymerase chain reaction (RT-qPCR). Moreover, three miRNA-target pairs showed negative regulation tendency, as revealed by RT-qPCR. Functional enrichment and pathway analysis revealed that four pathways might be involved in storage protein biosynthesis. Furthermore, drought stress significantly increased the accumulation of protein bodies and protein content in wheat endosperm. In summary, our findings suggest that drought stress may enhance storage protein by regulating the expression of miRNAs and their target genes.

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Taro [Colocasia esculenta (L.) Schott] is an edible underground bulb crop belonging to the family Araceae, and its main component is starch. We systematically studied and compared the morphological and physicochemical characteristics of the starches isolated from bulbs of three taro varieties with high output and quality. Viscosity analysis showed that the starches from Xiangsha and Longxiang displayed the highest and lowest peak, trough, breakdown, and final viscosity, respectively. Xiangsha presented the highest proportion of crystalline region and V-type single helical components, whereas the opposite was observed in Longxiang. When hydrolyzed by porcine pancreatic a-amylase, amyloglucosidase, and hydrochloric acid, Longxiang and Xiangsha ultimately presented the highest and lowest hydrolysis degrees, respectively. The results indicate that starches from the three taro bulbs significantly differed in morphological and physicochemical characteristics, and these results may provide valuable information for the exploitation and utilization of taro starch in food and non-food industries.

Background Taro is an important potato crop, which can be used as food, vegetable, feed, and industrial raw material. The yield and quality of taro are primarily determined by the expansion degree of taro bulb and the filling condition of starch, whereas the expansion of taro bulb is a complex biological process. However, little information is reviewed on the research progress of bulb expansion and starch enrichment in taro. Methodology PubMed, Web of Science, and the China National Knowledge Infrastructure databases were searched for relevant articles. After removing duplicate articles and articles with little relevance, 73 articles were selected for review. Results This article introduces the formation and development of taro bulb for workers engaged in taro research. The content includes the process of amyloplast formation at the cytological level and changes in bulb expansion and starch enrichment at physiological levels, which involve endogenous hormones and key enzyme genes for starch synthesis. The effects of environment and cultivation methods on taro bulb expansion were also reviewed. Conclusions Future research directions and research focus about the development of taro bulb were proposed. Limited research has been conducted on the physiological mechanism and hormone regulatory pathway of taro growth and development, taro bulb expansion, key gene expression, and starch enrichment. Therefore, the abovementioned research will become the key research direction in the future.

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