Regulation of Flowering Time by Improving Leaf Health Markers and Expansion by Salicylic Acid Treatment: A New Approach to Induce Flowering in Malus domestica.

Kamran Shah,Peng Jia,Chenguang Zhang,Mingyu Han,Lijuan Chen,Muhammad Mobeen Tahir,Svetlana Kamanova,Na An,Xiaolin Ren,Libo Xing,Yuduan Ding

doi:10.3389/fpls.2021.655974

Kamran Shah, Peng Jia + Show 9 more

Open Access

https://doi.org/10.3389/fpls.2021.655974

Copy DOI

Abstract

In the external coincidence model, internal and external molecular signals, provided by the circadian clock and sunlight, respectively, are required to induce flowering. Salicylic acid (SA) applications during floral induction have multiple effects. In the current study, Malus × domestica plants were exposed to SA during the flower-induction stage to analyze the effect on various health markers and flowering. A total of 56 equal-sized Fuji/M9 trees that were about 7 years old were randomly divided into two groups. The first group (SA-treated) was sprayed with 4 mM SA solution, while the second group was sprayed with distilled water which served as control (CK). The SA applications increased various leaf pigments. Abiotic stress markers were increased in CK during the flower-induction stage. In the SA-treated group, non-enzymatic antioxidants increased, whereas in the control group, enzymatic antioxidants increased during the flower-induction stage. Histo-morphometric properties of leaves were significantly improved in the SA-treated group. The relative expression of the mRNA levels of MdMED80, −81, −3, and −41 were significantly increased in SA-treated leaves, leading to an early and increased flowering phenotype. Thus, SA increased leaf expansion and health-related marker levels, which lead to early induction of flowering in M. domestica. Overall, our work established a role for leaf health assessments in the regulation of flowering in M. domestica.

Highlights

Salicylic acid (SA) is a natural phenolic plant hormone that is a leading candidate for improving salinity tolerance (Nazar et al, 2015)
At 0–20 days after full bloom (DAF), we observed no significant difference in leaf weight (Figure 1A), width (Figure 1B), dry matter content (Figure 1D), and area (Figure 1E) between CK and SA treated groups, while these parameters were significantly increased at 30–70 DAF in SA treated group
Leaf length was not influenced by SA at 0–10 DAF, while at 20–70 DAF the leaf length was significantly increased in SA treated group (Figure 1C)

Summary

Introduction

Salicylic acid (SA) is a natural phenolic plant hormone that is a leading candidate for improving salinity tolerance (Nazar et al, 2015). It plays vital physiological roles in nutrient uptake, growth, development, thermogenesis, ion absorption, flower induction, transport, stomatal movement, photosynthesis, and transpiration, which affect plant performance (Vlot et al, 2009; Hayat et al, 2010). Foliage Health Triggers Flowering plant resistance to NaCl-related toxicity (He and Zhu, 2008). It is important to understand the roles of exogenous SA applications during the flower-induction stage (FIS) in Malus × domestica

Methods

Results

Discussion

Conclusion