Comprehensive Analysis of Five Phyllostachys edulisSQUA-like Genes and Their Potential Functions in Flower Development.

Yuting Zhang,Minyan Song,Xinchun Lin,Mingquan Ding,Zaikang Tong,Junhong Zhang

doi:10.3390/ijms221910868

Yuting Zhang, Minyan Song + Show 4 more

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https://doi.org/10.3390/ijms221910868

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Abstract

Bamboo is one of the most important non-timber forest resources worldwide. It has considerable economic value and unique flowering characteristics. The long juvenile phase in bamboo and unpredictable flowering time limit breeding and genetic improvement and seriously affect the productivity and application of bamboo forests. Members of SQUA-like subfamily genes play an essential role in controlling flowering time and floral organ identity. A comprehensive study was conducted to explain the functions of five SQUA-like subfamily genes in Phyllostachys edulis. Expression analysis revealed that all PeSQUAs have higher transcript levels in the reproductive period than in the juvenile phase. However, PeSQUAs showed divergent expression patterns during inflorescence development. The protein–protein interaction (PPI) patterns among PeSQUAs and other MADS-box members were analyzed by yeast two-hybrid (Y2H) experiments. Consistent with amino acid sequence similarity and phylogenetic analysis, the PPI patterns clustered into two groups. PeMADS2, 13, and 41 interacted with multiple PeMADS proteins, whereas PeMADS3 and 28 hardly interacted with other proteins. Based on our results, PeSQUA might possess different functions by forming protein complexes with other MADS-box proteins at different flowering stages. Furthermore, we chose PeMADS2 for functional analysis. Ectopic expression of PeMADS2 in Arabidopsis and rice caused early flowering, and abnormal phenotype was observed in transgenic Arabidopsis lines. RNA-seq analysis indicated that PeMADS2 integrated multiple pathways regulating floral transition to trigger early flowering time in rice. This function might be due to the interaction between PeMADS2 and homologous in rice. Therefore, we concluded that the five SQUA-like genes showed functional conservation and divergence based on sequence differences and were involved in floral transitions by forming protein complexes in P. edulis. The MADS-box protein complex model obtained in the current study will provide crucial insights into the molecular mechanisms of bamboo’s unique flowering characteristics.

Highlights

Licensee MDPI, Basel, Switzerland.Bamboos are important members of the subfamily Bambusoideae and the family Poaceae, which are important timber, fiber, and food products worldwide [1]
The phylogenetic tree of SQUA-like proteins showed that these five P. edulis SQUA-like genes are clustered within monocot species (Oryza sativa, Brachypodium distachyon, Setaria italica, and D. latiflorus) and are separate from Arabidopsis (Figure 1A)
PeMADS2 and PeMADS13 were clustered in one branch with rice OsMADS18, whereas PeMADS3 and PeMADS28 were gathered in the other branch with rice OsMADS14

Summary

Introduction

Bamboos are important members of the subfamily Bambusoideae and the family Poaceae, which are important timber, fiber, and food products worldwide [1]. Unlike other members of Poaceae, bamboo has unique flowering features and an unpredictable juvenile phase [2]. Wood bamboo retains vegetative growth for a very long time (13–120 years) and usually dies after seed production [1]. The flowering incidence may be restricted to a few plants of a population, i.e., so-called sporadic flowering, whereas. Synchronous flowering may happen across populations in a community in which all plants flower and die within the same year [3]. The long juvenile phase in bamboo and unpredictable flowering time possibly limit breeding and genetic improvement and cause economic losses. Many research groups tried to uncover the cause of bamboo flowering by genomes and transcriptomes [4,5,6], the molecular aspects of bamboo flowering remain unclear

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