Wang Li, Zhou Tao, Cheng Bin, Du Yongli, Qin Sisi, Gao Yang, Xu Mei, Lu Junji, Liu Ting, Li Shuxian, Liu Weiguo, Yang Wenyu
College of Agronomy, Sichuan Agricultural University, Chengdu 611130, Sichuan, China.
College of pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, Sichuan, China.
Plants (Basel). 2020 Sep 15;9(9):1204. doi: 10.3390/plants9091204.
In this study, soybean root distribution in an inter-cropping system was influenced by various environmental and biotic cues. However, it is still unknown how root development and distribution in inter-cropping responds to aboveground light conditions. Herein, soybeans were inter- and monocropped with P (phosphorus) treatments of 0 and 20 kg P ha yr (P0 and P20, respectively) in field experiment over 4 years. In 2019, a pot experiment was conducted as the supplement to the field experiment. Shade from sowing to V5 (Five trifoliolates unroll) and light (SL) was used to imitate the light condition of soybeans in a relay trip inter-cropping system, while light then shade from V5 to maturity (LS) was used to imitate the light condition of soybeans when monocropped. Compared to monocropping, P uptake and root distribution in the upper 0-15 cm soil layer increased when inter-cropped. Inter-cropped soybeans suffered serious shade by maize during a common-growth period, which resulted in the inhibition of primary root growth and a modified auxin synthesis center and response. During the solo-existing period, plant photosynthetic capacity and sucrose accumulation increased under ameliorated light in SL (shade-light). Increased light during the reproductive stage significantly decreased leaf P concentration in SL under both P-sufficient and P-deficient conditions. Transcripts of a P starvation response gene () in leaves and genes () involved in root growth were upregulated by ameliorated light during the reproductive stage. Furthermore, during the reproductive stage, more light interception increased the auxin concentration and expression of (encoding the auxin synthesis) and (auxin receptor) in roots. Across the field and pot experiments, increased lateral root growth and shallower root distribution were associated with inhibited primary root growth during the seedling stage and ameliorated light conditions in the reproductive stage. Consequently, this improved topsoil foraging and P uptake of inter-cropped soybeans. It is suggested that the various light conditions (shade-light) mediating leaf P status and sucrose transport can regulate auxin synthesis and respond to root formation and distribution.
在本研究中，间作系统中大豆根系分布受多种环境和生物因素影响。然而，间作中根系发育和分布如何响应地上光照条件仍不清楚。在此，在为期4年的田间试验中，大豆进行了间作和单作，并设置了0和20 kg P ha yr的磷处理（分别为P0和P20）。2019年，进行了盆栽试验作为田间试验的补充。从播种到V5（五片三出复叶展开）遮荫然后光照（SL）用于模拟接力套种系统中大豆的光照条件，而从V5到成熟阶段先光照后遮荫（LS）用于模拟单作时大豆的光照条件。与单作相比，间作时0 - 15 cm上层土壤中磷吸收和根系分布增加。间作大豆在共生期受到玉米严重遮荫，导致主根生长受抑制以及生长素合成中心和响应发生改变。在单生期，SL（遮荫 - 光照）条件下改善的光照使植株光合能力和蔗糖积累增加。在生殖阶段增加光照显著降低了磷充足和磷缺乏条件下SL处理叶片中的磷浓度。生殖阶段改善的光照上调了叶片中磷饥饿响应基因（）和参与根系生长的基因（）的转录本。此外，在生殖阶段，更多的光截获增加了根系中生长素浓度以及（编码生长素合成）和（生长素受体）的表达。通过田间和盆栽试验，侧根生长增加和根系分布变浅与苗期主根生长受抑制以及生殖阶段改善的光照条件有关。因此，这改善了间作大豆的表土觅食和磷吸收。研究表明，介导叶片磷状态和蔗糖运输的各种光照条件（遮荫 - 光照）可调节生长素合成并影响根系形成和分布。
