Effect of Waterlogging on Carbohydrate Metabolism and the Quality of Fiber in Cotton (Gossypium hirsutum L.).

Jie Kuai,Wenqing Zhao,Zhiguo Zhou,Yinglong Chen,Binglin Chen,Youhua Wang,Yali Meng

doi:10.3389/fpls.2016.00877

Abstract

Transient waterlogging occurs frequently in the Yangtze River and adversely affects cotton fiber quality. However, the carbohydrate metabolic mechanism that affects fiber quality after waterlogging remains undescribed. Here, the effects of five waterlogging levels (0, 3, 6, 9, and 12 days) were assessed during flowering and boll formation to characterize the carbohydrates, enzymes and genes that affect the fiber quality of cotton after waterlogging. The cellulose and sucrose contents of cotton fibers were significantly decreased after waterlogging for 6 (WL6), 9 (WL9), and 12 d (WL12), although these properties were unaffected after 3 (WL3) and 6 days at the fruiting branch 14–15 (FB14–15). Sucrose phosphate synthase (SPS) was the most sensitive to waterlogging among the enzymes tested. SPS activity was decreased by waterlogging at FB6–7, whereas it was significantly enhanced under WL3–6 at FB10–15. Waterlogging down-regulated the expression of fiber invertase at 10 days post anthesis (DPA), whereas that of expansin, β-1,4-glucanase and endoxyloglucan transferase (XET) was up-regulated with increasing waterlogging time. Increased mRNA levels and activities of fiber SuSy at each fruiting branch indicated that SuSy was the main enzyme responsible for sucrose degradation because it was markedly induced by waterlogging and was active even when waterlogging was discontinued. We therefore concluded that the reduction in fiber sucrose and down-regulation of invertase at 10 DPA led to a markedly shorter fiber length under conditions WL6–12. Significantly decreased fiber strength at FB6–11 for WL6–12 was the result of the inhibition of cellulose synthesis and the up-regulation of expansin, β-1,4-glucanase and XET, whereas fiber strength increased under WL3–6 at FB14–15 due to the increased cellulose content of the fibers. Most of the indictors tested revealed that WL6 resulted in the best compensatory performance, whereas exposure to waterlogged conditions for more than 6 days led to an irreversible limitation in fiber development.

Highlights

Cotton (Gossypium hirsutum L.) is known to be poorly adapted to waterlogging
Our results show that the activities of fiber acid invertase and alkaline invertase were restricted after waterlogging, whereas fiber sucrose synthase activity was higher at FB6−7, with the maximum level observed under waterlogging for 6 (WL6) (Figure 2)
The sucrose and cellulose contents of fibers at FB6–7 were significantly reduced by a reduction in the activities of Sucrose phosphate synthase (SPS) and invertase after waterlogging, whereas significant compensation was observed in fibers at FB10–15 for WL3–6

Summary

Introduction

Cotton (Gossypium hirsutum L.) is known to be poorly adapted to waterlogging. Waterlogging adversely affects cotton yield and fiber quality (Hearn, 1995; Bange et al, 2004) and is considered to be a major problem in global cotton production (Gillham et al, 1995). Many of the textile properties of cotton fibers (e.g., fiber wall thickness or maturity, strength, dye-ability, and extensibility) are directly dependent on the cellulose content (Triplett, 1993). The amount of another structural carbohydrate, β-1,3-glucan, rapidly increases with the onset of secondary cell wall synthesis. This carbohydrate can be broken down in the later period of fiber development to provide UDPG for cellulose synthesis (Tucker et al, 2001). The major product of photosynthesis, can either be utilized directly via glycolysis or translocated within the plant as a soluble carbohydrate through the phloem. Following import into sink tissues, sucrose is used for the maintenance of cellular metabolism, cell wall biosynthesis, and respiration or is converted to starch for storage and used at a later time (Wind et al, 2010)

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