Abstract
Plant hormones play important roles in regulating the occurrence of crop tillers. However, little is known about the relationships and the underlying mechanisms between endogenous hormones and the occurrence of wheat tillers induced by exogenous hormones. In this study, two winter wheat cultivars, Xinong 979 and Xiaoyan 22, were used to investigate the effects of the exogenous application of indole-3-acetic acid (IAA) and zeatin (Z) on the occurrence of wheat tillers and investigate underlying mechanisms regulating the occurrence of tillers. The results showed that the application of IAA inhibited the occurrence of tillers, and external Z application promoted the occurrence rate of tillers under low nitrogen conditions. Further analysis of the results showed that exogenous IAA completely inhibited the growth of tiller buds, while exogenous Z significantly promoted the growth rate of tiller buds in low nitrogen conditions. Endogenous hormones exhibit important functions in regulating the growth of tiller buds, which contents were affected by exogenous hormones. Furthermore, according to the principal component analysis and correlation analysis, the growth of tiller buds was significantly positively correlated with the content of endogenous Z, whereas it was significantly negatively correlated with the ratios of endogenous IAA to endogenous Z (IAA:Z) and endogenous abscisic acid (ABA) to endogenous Z (ABA:Z). Moreover, no significant correlation was observed between the growth of the tiller buds and the endogenous IAA, endogenous gibberellins (GAs), and endogenous ABA content. These results suggested that Z played key roles in regulating the tiller occurrence, and exogenous hormones regulated the growth of wheat tiller buds via affecting the Z contents, thus regulating the occurrence of wheat tiller.
Highlights
Wheat (Triticum aestivum L.) is one of the most essential crops worldwide (Yang et al, 2018)
In order to address these limitations of previous research (Currently, there is no effective technical approach for the direct control of wheat tiller occurrence at present; there is limited information available about hormones and the occurrence of wheat tillers; there are different opinions on the role of endogenous hormones such as indole-3-acetic acid (IAA), CTKs, GAs, abscisic acid (ABA) in the growth of tiller buds.), the objectives of the present study were to investigate the effect of exogenous IAA and Z on the occurrence of tillers in wheat and analyze the relationship between endogenous hormones and the growth of wheat tiller buds
We found that after the application of exogenous IAA, the endogenous Z content decreased during the growth of tiller buds and was lower than that of plants grown under normal conditions
Summary
Wheat (Triticum aestivum L.) is one of the most essential crops worldwide (Yang et al, 2018). The yield potential of wheat can be dissected into four major components: Regulation of Tillering in Wheat plant number per unit area, spike number per plant, grain number per spike, and grain weight (Yu, 2013). The number of tillers is dynamic and adjustable (Cai et al, 2014). Tiller development is greatly inhibited by abiotic stressors, such as drought, low nitrogen, and low temperature, resulting in lower crop yields due to a smaller population (Mitchell et al, 2012) (Figure 1A). Too many surviving tillers owing to better environmental factors leads to a larger population, which may cause lodging in the late growth stage because of deterioration of the stem quality (Zheng et al, 2017) (Figure 1B). It is essential to construct a rational population structure for wheat to enhance yield potential and avoid lodging
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