Low soil available phosphorus level reduces cotton fiber length via osmoregulation

Miao Sun; Cangsong Zheng; Weina Feng; Jingjing Shao; Chaoyou Pang; Pengcheng Li; Helin Dong

doi:10.3389/fpls.2023.1254103

Low soil available phosphorus level reduces cotton fiber length via osmoregulation

Front Plant Sci. 2023 Aug 18:14:1254103. doi: 10.3389/fpls.2023.1254103. eCollection 2023.

Authors

Miao Sun¹, Cangsong Zheng¹, Weina Feng¹, Jingjing Shao¹, Chaoyou Pang¹, Pengcheng Li¹, Helin Dong^{1

2}

Affiliations

¹ State Key Laboratory of Cotton Bio-breeding and Integrated Utilization, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang, China.
² Western Agricultural Research Center, Chinese Academy of Agricultural Sciences, Changji, China.

Abstract

Introduction: Phosphorus (P) deficiency hinders cotton (Gossypium hirustum L.) growth and development, seriously affecting lint yield and fiber quality. However, it is still unclear how P fertilizer affects fiber length.

Methods: Therefore, a two-year (2019-2020) pool-culture experiment was conducted using the split-plot design, with two cotton cultivars (CCRI-79; low-P tolerant and SCRC-28; low-P sensitive) as the main plot. Three soil available phosphorus (AP) contents (P₀: 3 ± 0.5, P₁: 6 ± 0.5, and P₂ (control) with 15 ± 0.5 mg kg^-1) were applied to the plots, as the subplot, to investigate the impact of soil AP content on cotton fiber elongation and length.

Results: Low soil AP (P₀ and P₁) decreased the contents of the osmotically active solutes in the cotton fibers, including potassium ions (K⁺), malate, soluble sugar, and sucrose, by 2.2-10.2%, 14.4-47.3%, 8.7-24.5%, and 10.1-23.4%, respectively, inhibiting the vacuoles from facilitating fiber elongation through osmoregulation. Moreover, soil AP deficiency also reduced the activities of enzymes participated in fiber elongation (plasma membrane H⁺-ATPase (PM-H⁺-ATPase), vacuole membrane H⁺-ATPase (V-H⁺-ATPase), vacuole membrane H⁺-translocating inorganic pyrophosphatase (V-H⁺-PPase), and phosphoenolpyruvate carboxylase (PEPC)). The PM-H⁺-ATPase, V-H⁺-ATPase, V-H⁺-PPase, and PEPC were reduced by 8.4-33.0%, 7.0-33.8%, 14.1-38.4%, and 16.9-40.2%, respectively, inhibiting the transmembrane transport of the osmotically active solutes and acidified conditions for fiber cell wall, thus limiting the fiber elongation. Similarly, soil AP deficiency reduced the fiber length by 0.6-3.0 mm, mainly due to the 3.8-16.3% reduction of the maximum velocity of fiber elongation (V_Lmax). Additionally, the upper fruiting branch positions (FB_10-11) had higher V_Lmax and longer fiber lengths under low soil AP.

Discussion: Cotton fibers with higher malate content and V-H⁺-ATPase and V-H⁺-PPase activities yielded longer fibers. And the malate and soluble sugar contents and V-H⁺-ATPase and PEPC activities in the SCRC-28's fiber were more sensitive to soil AP deficiency in contrast to those of CCRI-79, possibly explaining the SCRC-28 fiber length sensitivity to low soil AP.

Keywords: cotton; fiber length; low-phosphorus tolerant ability; osmoregulation; soil available phosphorus.

Grants and funding

This research was funded by the National Key Research and Development Program of China (2017YFD0201906), the Central Research Institutes of Basic Research and the Public Service Special Foundation (1610162022044), the China Agriculture Research System (CARS-15-11), and the Agricultural Science and Technology Innovation Program of Chinese Academy of Agricultural Sciences.