Comparative Transcriptomic Analysis of Differentially Expressed Transcripts Associated with Flowering Time of Loquat (Eriobotya japonica Lindl.)

Haishan An,Shuang Jiang,Jiaying Zhang,Fangjie Xu,Xueying Zhang

doi:10.3390/horticulturae7070171

Haishan An, Shuang Jiang + Show 3 more

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https://doi.org/10.3390/horticulturae7070171

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Abstract

Flowering is an important phenophase of plant species, however, knowledge about the regulatory mechanism controlling flowering cues in loquat is limited. To identify candidate genes regulating flowering time in loquat, we used RNA-Seq technology to conduct a comparative transcriptome analysis of differentiating apical buds collected from the early-flowering variety ‘Baiyu’ and the late-flowering variety ‘Huoju’. A total of 28,842 differentially expressed transcripts (DETs) were identified. Of these, 42 DETs controlled flowering time while 17 other DETs were associated with the ABA signaling pathway. Compared with those in ‘Huoju’, EjFT, EjFY, EjFLK, and EjCAL1-like were significantly upregulated in ‘Baiyu’. Moreover, transcripts of the ABA 8′-hydroxylases (EjABH2, EjABH4, and EjABH4-like2), the ABA receptors (EjPYL4/8), and the bZIP transcription factor EjABI5-like were upregulated in ‘Baiyu’ compared with ‘Huoju’. Hence, they might regulate loquat flowering time. There was no significant difference between ‘Baiyu’ and ‘Huoju’ in terms of IAA content. However, the ABA content was about ten-fold higher in the apical buds of ‘Baiyu’ than in those of ‘Huoju’. The ABA:IAA ratio sharply rose and attained a peak during bud differentiation. Thus, ABA is vital in regulating floral bud formation in loquat. The results of the present study help clarify gene transcription during loquat flowering.

Highlights

IntroductionPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
Based on the Fragments per kilobase per million mapped reads (FPKM) values and the Gene ontology (GO) or Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses, we identified Differentially expressed transcripts (DETs) involved in abscisic acid (ABA) signaling
28,842 DETs involved in multiple regulatory pathways were significantly differentially regulated between early-flowering and late-flowering loquat cultivars

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Understanding the mechanisms that control flowering events is essential for efficient fruit reproduction [1]. It involves elegant mechanisms that integrate complex signals including photoperiod and temperature [2,3]. Several major pathways in Arabidopsis include floral integrator genes that govern flowering time. FT and FT-like play pivotal roles in the flowering of fruit trees in the Rosaceae family such as apple [10,11], pear [12], peach [13], and loquat [14,15,16]. Flowering time is affected by environmental conditions and phytohormones. ABA plays a positive role in flower bud Horticulturae 2021, 7, 171.

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