Characterization of the Molecular Events Underlying the Establishment of Axillary Meristem Region in Pepper

Haoran Wang; Sujun Liu; Shijie Ma; Yun Wang; Hanyu Yang; Jiankun Liu; Mingxuan Li; Xiangyun Cui; Sun Liang; Qing Cheng; Huolin Shen

doi:10.3390/ijms241612718

Characterization of the Molecular Events Underlying the Establishment of Axillary Meristem Region in Pepper

Int J Mol Sci. 2023 Aug 12;24(16):12718. doi: 10.3390/ijms241612718.

Authors

Haoran Wang^{1

2}, Sujun Liu^{1

2}, Shijie Ma^{1

2}, Yun Wang^{1

2}, Hanyu Yang^{1

2}, Jiankun Liu^{1

2}, Mingxuan Li^{1

2}, Xiangyun Cui^{1

2}, Sun Liang^{1

2

3}, Qing Cheng^{1

2

3}, Huolin Shen^{1

2

3}

Affiliations

¹ Department of Vegetable Science, College of Horticulture, China Agricultural University, Beijing 100193, China.
² Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, China Agricultural University, Beijing 100193, China.
³ Sanya Institute, China Agricultural University, Sanya 572025, China.

Abstract

Plant architecture is a major motif of plant diversity, and shoot branching patterns primarily determine the aerial architecture of plants. In this study, we identified an inbred pepper line with fewer lateral branches, 20C1734, which was free of lateral branches at the middle and upper nodes of the main stem with smooth and flat leaf axils. Successive leaf axil sections confirmed that in normal pepper plants, for either node n, P_n (Primordium n) < 1 cm and P_n+1 < 1 cm were the critical periods between the identification of axillary meristems and the establishment of the region, whereas P_n+3 < 1 cm was fully developed and formed a completely new organ. In 20C1734, the normal axillary meristematic tissue region establishment and meristematic cell identity confirmation could not be performed on the axils without axillary buds. Comparative transcriptome analysis revealed that "auxin-activated signaling pathway", "response to auxin", "response to abscisic acid", "auxin biosynthetic process", and the biosynthesis of the terms/pathways, such as "secondary metabolites", were differentially enriched in different types of leaf axils at critical periods of axillary meristem development. The accuracy of RNA-seq was verified using RT-PCR for some genes in the pathway. Several differentially expressed genes (DEGs) related to endogenous phytohormones were targeted, including several genes of the PINs family. The endogenous hormone assay showed extremely high levels of IAA and ABA in leaf axils without axillary buds. ABA content in particular was unusually high. At the same time, there is no regular change in IAA level in this type of leaf axils (normal leaf axils will be accompanied by AM formation and IAA content will be low). Based on this, we speculated that the contents of endogenous hormones IAA and ABA in 20C1734 plant increased sharply, which led to the abnormal expression of genes in related pathways, which affected the formation of Ams in leaf axils in the middle and late vegetative growth period, and finally, nodes without axillary buds and side branches appeared.

Keywords: ABA; IAA; auxin transport; axillary meristem; comparative transcriptome; lateral branch; pepper.

MeSH terms

Abscisic Acid
Bone Nails
Food*
Indoleacetic Acids
Meristem* / genetics

Substances

Abscisic Acid
Indoleacetic Acids

Abstract

MeSH terms

Substances

Grants and funding