Comprehensive Transcriptome Reveals an Opposite Regulatory Effect of Plant Growth Retardants in Controlling Seedling Overgrowth between Roots and Shoots

Abstract

Seedling overgrowth always develops in undernourished plants due to biotic or abiotic stresses, which significantly decrease the yield of crops and vegetables. It is known that the plant growth retardants paclobutrazol (PBZ) and chlormequat chloride (CCC) are the most commonly used chemicals in controlling seedling height in plants by regulating the gibberellin (GA) biosynthesis pathway. However, the exact molecular regulation mechanism remains largely unknown. This study performed a comprehensive transcriptome profile to identify significantly differentially expressed genes after adding CCC and PBZ to the water culture seedling raising system for the first time. According to the obviously restrained shoots and roots, the GA biosynthesis genes were significantly decreased, as well as the endogenous GA content being reduced. Intriguingly, the GA signaling pathway genes were affected in opposite ways, increasing in roots but decreasing in shoots, especially regarding the phytochrome interacting factor SlPIF1 and the downstream genes expansins (SlEXPs), which promote cell wall remodeling. Further study found that the most down-regulated genes SlEXPA5 and SlEXPA15 were expressed specifically in shoot tissue, performing the function of repressing elongation, while the up-regulated genes SlEXPB2 and SlEXPB8 were proven to be root-specific expressed genes, which may promote horizontal elongation in roots. This research reported the comprehensive transcriptome profiling of plant growth retardants in controlling seedling overgrowth and restraining GA biosynthesis through the regulation of the GA signaling-related genes SlPIF1 and SlEXPs, with an opposite expression pattern between roots and shoots.

Light Deficiency Inhibits Growth by Affecting Photosynthesis Efficiency as well as JA and Ethylene Signaling in Endangered Plant Magnolia sinostellata

“…When grown under weak light, elongated hypocotyls and shoots of Lycopersicon esculentum [77], Arabidopsis [78,79] and C. sativus [80] were observed. Excessive growth and elongated phenotypes were also observed in tomato, cucumber, eggplant, and lemon [16,17].…”

“…The R package (edgeR v3. 16) was employed to analyze the normalized gene expression level data in order to identify the differentially expressed genes (DEGs) under shading treatments. Genes that fulfilled the criteria of Log2fold change > 2 and q value < 0.05 were identified as DEGs, with a false discovery rate (FDR) < 0.05.…”

“…Leaf expansion in Glycine max and Zea mays grown under shade was inhibited, which ultimately affected their seed yield [14,15]. Vegetable seedlings of tomato, cucumber, and eggplant often grow excessively under weak light conditions, leading to decreased yield in cultivation [16].…”

Effect of Supplementary Lighting Duration on Growth and Activity of Antioxidant Enzymes in Grafted Watermelon Seedlings

“…However, it is also a bad phenomenon if the scion is only greater in length with slow accumulation of biomass. During the seedling cultivation period, stretchy growth of seedlings caused by insufficient light is very common [46][47][48]. Many seedling growers use the plant growth regulators (PGRs) such as chlormequat chloride, paclobutrazol, uniconazole, etc.…”