Dynamic allocation and transfer of non-structural carbohydrates, a possible mechanism for the explosive growth of Moso bamboo (Phyllostachys heterocycla).

Xinzhang Song,Guomo Zhou,Honghao Gu,Changhui Peng,Chao Zhang,Quan Li

doi:10.1038/srep25908

Abstract

Moso bamboo can rapidly complete its growth in both height and diameter within only 35–40 days after shoot emergence. However, the underlying mechanism for this “explosive growth” remains poorly understood. We investigated the dynamics of non-structural carbohydrates (NSCs) in shoots and attached mature bamboos over a 20-month period. The results showed that Moso bamboos rapidly completed their height and diameter growth within 38 days. At the same time, attached mature bamboos transferred almost all the NSCs of their leaves, branches, and especially trunks and rhizomes to the “explosively growing” shoots via underground rhizomes for the structural growth and metabolism of shoots. Approximately 4 months after shoot emergence, this transfer stopped when the leaves of the young bamboos could independently provide enough photoassimilates to meet the carbon demands of the young bamboos. During this period, the NSC content of the leaves, branches, trunks and rhizomes of mature bamboos declined by 1.5, 23, 28 and 5 fold, respectively. The trunk contributed the most NSCs to the shoots. Our findings provide new insight and a possible rational mechanism explaining the “explosive growth” of Moso bamboo and shed new light on understanding the role of NSCs in the rapid growth of Moso bamboo.

Highlights

The high carbon demand during bud break may exceed the carbon supplied by current photosynthesis in evergreen species[25] and depend partly on the non-structural carbohydrates (NSCs) pool
As a woody rhizomatous plant, Moso bamboo is a monopodial giant bamboo with a mean height of 10–20 m and diameter at breast height (DBH) of 8–16 cm, and it is well-known for its fast growth rate[28,29]
We present a series of observations and experiments that examine the NSC changes in Moso bamboo shoots and attached mature bamboos during fast growth of bamboo shoots to test the hypothesis that the carbohydrates needed for the construction and metabolism of bamboo shoots during EGP are provided by attached mature bamboos via underground rhizomes

Summary

Introduction

Bud break[16,17,18]. The lack of photosynthetically active tissues at bud break results in broad-leaved trees that are dependent on last season’s carbon reserves for flushing[24]. It was speculated that the carbohydrates and nutrients needed for the construction of new bamboo are provided by other attached mature bamboos via underground rhizomes[29,32] (Fig. 1). This hypothesis lacked support from direct evidence and needed to be tested by field observations. We present a series of observations and experiments that examine the NSC changes in Moso bamboo shoots and attached mature bamboos during fast growth of bamboo shoots to test the hypothesis that the carbohydrates (in the form of NSCs) needed for the construction and metabolism of bamboo shoots during EGP are provided by attached mature bamboos via underground rhizomes

Methods

Results

Discussion

Conclusion