Regulation of Aegilops tauschii Coss Tiller Bud Growth by Plant Density: Transcriptomic, Physiological and Phytohormonal Responses

Haiyan Yu,Jingchao Chen,Hailan Cui,Xiangju Li

doi:10.3389/fpls.2020.01166

Haiyan Yu, Jingchao Chen + Show 2 more

Open Access

https://doi.org/10.3389/fpls.2020.01166

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Abstract

Aegilops tauschii Coss is one of the most hazardous weeds that severely infests wheat fields in China. The tillering ability of Ae. tauschii strongly affects the occurrence and spread by influencing its seed output. In this study, Ae. tauschii was sown at low plant density (LPD) and high plant density (HPD) to investigate the effect of plant density on tiller bud outgrowth and its potential regulators using RNA-Seq. Additionally, the chlorophyll content and photosynthesis, soluble sugar and phytohormone levels were also determined at different plant densities. The results showed that an increased plant density significantly inhibited the elongation of tiller buds in the axil of the first leaf at 15 days after planting, with 7.69 mm at LPD and 1.69 mm at HPD. A total of seven putative tiller-related genes were selected and validated using quantitative real-time PCR. Furthermore, chlorophyll levels, photosynthetic efficiency, and soluble sugar contents were distinctly inhibited by HPD in Ae. tauschii, which may be responsible for the restriction of tiller bud growth. In addition, differentially expressed genes (DEGs) were markedly enriched in indole-3-acetic acid (IAA), abscisic acid (ABA), and gibberellin metabolism and signaling. Accordingly, the levels of ABA and gibberellin A3 in Ae. tauschii were strikingly higher at HPD compared with those at LPD, yet the reverse tendency was observed for IAA. Undoubtedly, such results will be highly beneficial for illuminating the underlying regulators of the Ae. tauschii tillering response to plant density and may provide new ideas for the control of this weed in the future.

Highlights

Aegilops tauschii Coss, which belongs to the Poaceae family, is a notorious annual weed that greatly affects wheat yield and quality (Zhang et al, 2007)
The objectives of this study were to (i) evaluate the effect of plant density on the tiller bud growth; (ii) identify putative tiller-related genes from transcriptome analysis, and validate them using quantitative real-time PCR; (iii) ascertain metabolism and signaling pathways involved in the tillering response to plant density and (iv) assay some relevant physiological indices
The width and length of the first leaf were obviously inhibited by high plant density (HPD), at DAP13 and DAP15, indicating that Ae. tauschii leaves were bigger at low plant density (LPD) relative to HPD; at DAP15, plant density had significant effects on the plant height (P < 0.05) (Figure 1D)

Summary

Introduction

Aegilops tauschii Coss, which belongs to the Poaceae family, is a notorious annual weed that greatly affects wheat yield and quality (Zhang et al, 2007). The weed spreads in the main wheat production areas of China and competes with wheat for light, water, and resources (Yu and Li, 2017). Effective control methods of Ae. tauschii are lacking due to its close genetic relationship with wheat Ae. tauschii completely relies on its seed for reproduction and to expand to new habitats. For Poaceae, the seed output is largely dependent on the number of tillers (Lecarpentier et al, 2019). The accelerated infection and spread of Ae. tauschii greatly attributed to its high reproductivity are closely associated with its strong tillering ability

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