Light Intensity Affects the Coloration and Structure of Chimeric Leaves of Ananas comosus var. bracteatus

Wei Yang,Hao Hu,Yuke Lin,Jiawen Liu,Huiling Zhang,Meiqin Mao,Jiaheng Luo,Xuzixing Zhou,Lijun Feng,Jun Ma,Yanbin Xue

doi:10.32604/phyton.2022.016862

Abstract

Ananas comosus var. bracteatus is an important ornamental plant because of its green/white chimeric leaves. The accumulation of anthocyanin makes the leaf turn to red especially in the marginal part. However, the red fades away in summer and winter. Light intensity is one of the most important factors affecting leaf color along the seasons. In order to understand the effects of light intensity on the growth and coloration of the chimeric leaves, Ananas comosus var. bracteatus was grown under full sunlight, 50% shade and 75% shade for 75 days to evaluate the concentration of pigments, the color parameters (values L*, a*, b*) and the morpho-anatomical variations of chimeric leaves. The results showed that a high irradiance was beneficial to keep the chimeric leaves red. However, prolonged exposure to high irradiance caused a damage, some of the leaves wrinkled and even burned. Shading instead decreased the concentration of anthocyanin and increased the concentration of chlorophyll, especially in the white marginal part of the leaves. Numerous chloroplasts were observed in the mesophyll cells of the white marginal part of the chimeric leaves under shading for 75 days. The increase in chlorophyll concentration resulted in a better growth of plants. In order to balance the growth and coloration of the leaves, approximately 50% shade is suggested to be the optimum light irradiance condition for Ananas comosus var. bracteatus in summer.

Highlights

Variegated leaf chimeric plants are important ornamental plants because of their unique colorful characteristics
The marginal parts of the chimeric leaves under 75% shade firstly lost the red color and became white, turned to green
We showed that light intensity affects the leaf color; color parameters; pigment accumulation, distribution and ratio; mesophyll cells, and chloroplast occurrence in the marginal and central parts of chimeric leaves of A. comosus var. bracteatus. 75% shading boosted the decrease in anthocyanin concentration, the increase in chlorophyll concentration, and the number of chloroplasts in the mesophyll cells, and the leaves changed their color from red to green reducing their plant ornamental value

Summary

Introduction

Variegated leaf chimeric plants are important ornamental plants because of their unique colorful characteristics. The high diversity of color in chimeric plants is due to the changes of spatial distribution of pigment types, concentrations and proportions in the leaves. These changes are the result of the interaction between genetic and environmental factors [1,2,3]. Soil nutrients, and water have long been understood to be primary factors influencing plant growth, and the light intensity is an important environmental factor [4,5]. Light intensity can affect the concentration of chlorophyll, carotenoid, and anthocyanin in the leaves, leading to variation in leaf color [6]. Photinia × fiaseri grown under full light was more densely foliated than shaded plants [7]

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