Water Stress and Foliar Boron Application Altered Cell Wall Boron and Seed Nutrition in Near-Isogenic Cotton Lines Expressing Fuzzy and Fuzzless Seed Phenotypes

RESEARCH ARTICLE Water Stress and Foliar Boron Application Altered Cell Wall Boron and Seed Nutrition in Near-Isogenic Cotton Lines Expressing Fuzzy and Fuzzless Seed Phenotypes Nacer Bellaloui*☯, Rickie B. Turley☯, Salliana R. Stetina☯ Crop Genetics Research Unit, United States Department of Agriculture, Agricultural Research Service, Stoneville, Mississippi, United States of America a11111 ☯ These authors contributed equally to this work. * Abstract OPEN ACCESS Citation: Bellaloui N, Turley RB, Stetina SR (2015) Water Stress and Foliar Boron Application Altered Cell Wall Boron and Seed Nutrition in Near-Isogenic Cotton Lines Expressing Fuzzy and Fuzzless Seed Phenotypes. PLoS ONE 10(6): e0130759. doi:10.1371/journal.pone.0130759 Editor: Jinfa Zhang, New Mexico State University, UNITED STATES Received: January 14, 2015 Accepted: May 22, 2015 Published: June 22, 2015 Copyright: This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication. Data Availability Statement: All required and relevant data for the current research are submitted herein and included within the manuscript. Our previous research, conducted under well-watered conditions without fertilizer application, showed that fuzziness cottonseed trait resulted in cottonseed nutrition differences between fuzzy (F) and fuzzless (N) cottonseed. Under water stress conditions, B mobility is further limited, inhibiting B movement within the plant, affecting seed nutrition (quality). Therefore, we hypothesized that both foliar B and water stress can affect B mobility, altering cottonseed protein, oil, and mineral nutrition. The objective of the current research was to evaluate the effects of the fuzziness seed trait on boron (B) and seed nutrition under water stress and foliar B application using near-isogenic cotton lines (NILs) grown in a repeated greenhouse experiment. Plants were grown under-well watered conditions (The soil water potential was kept between -15 to -20 kPa, considered field capacity) and water stress conditions (soil water potential between -100 and -150 kPa, stressed conditions). Foliar B was applied at a rate of 1.8 kg B ha-1 as H3BO3. Under well-watered conditions without B the concentrations of seed oil in N lines were higher than in F lines, and seed K and N levels were lower in N lines than in Flines. Concentrations of K, N, and B in leaves were higher in Nlines than in Flines, opposing the trend in seeds. Water-stress resulted in higher seed protein concentrations, and the contribution of cell wall (structural) B to the total B exceeded 90%, supporting the structural role of B in plants. Foliar B application under well-watered conditions resulted in higher seed protein, oil, C, N, and B in only some lines. This research showed that cottonseed nutrition differences can occur due to seed fuzziness trait, and water stress and foliar B application can alter cottonseed nutrition. Funding: Funding for this research was provided by USDA, Agricultural Research Service projects 606621220-012-00D and 6066-21000-051-00D (http:// www.ars.usda.gov/pandp/people/projects.htm? personid=37050). Introduction Competing Interests: The authors have declared that no competing interests exist. Upland cotton (Gossypium hirsutum L.) is a major crop in the world because of its natural fiber and cottonseed composition (protein, oil, fatty acids, and mineral nutrition). Cottonseed is a PLOS ONE | DOI:10.1371/journal.pone.0130759 June 22, 2015 1 / 13 Water Stress and Boron Effects on Cottonseed Nutrition source of oil for human consumption [1– 3] and cottonseed meal for livestock [1, 4, 5]. Cottonseed oil production ranks third after soybean and rapeseed [6]. Protein in cottonseed ranges from 17–27% and oil from 12–30%, saturated fatty acids ~29%, and unsaturated fatty acids ~70% [2, 3, 5, 7]. Cottonseed oil has a desirable trait in that it contains enough saturated fatty acids (~ 22% palmitic, ~3% stearic, ~ 1% myristic acid) to prevent partial hydrogenation, making it relatively stable. Also, it contains sufficient unsaturated fatty acid, making it beneficial for human health (22% oleic acid, ~52% linoleic acid, and <1% linolenic acid). Although seed composition constituents are genetically controlled, they are also found to be influenced by environmental factors such growing seasons, locations, and years [4, 8], temperature [9], and agricultural practices [10–12]. Therefore, maintaining high quality of cottonseed nutrition under different environments is essential. The genetic basis controlling protein and oil in fuzzless cottonseed has received little attention [5], and understanding the genotypic and environmental factors influencing cottonseed composition may result in a better product [2, 3]. Protein, oil, and fatty acids were investigated in several conventional cotton genotypes in 2006 and 2007 in a total of nine environments in six locations, and found that the level of most fatty acids was influenced by environment and genotype, but the interaction between environment and genotype was relatively small [2]. A comparative study was conducted on fatty acids among G. hirsutum genotypes and hybrids and concluded that the fatty acids in cottonseed lines significantly differ and the degree of variability of fatty acids was influenced by the conditions during the period of the formation and ripening of the seeds, and these researchers were able to recommend lines as donors to improve the food-value indices of cottonseed oil [13]. They also observed that higher levels of saturated fatty acids occurred in the second year, with lower average humidity and higher temperature compared with the conditions of the first year [13]. This observation was in agreement with those found by others [2] in that the higher temperatures and drier growing conditions reduced linoleic acid and increased saturated fatty acids, and this response of fatty acids was dependent on genotype. It was also found that there was a significant effect of genotype × environment interactions, which did not agree with the findings of some other researchers [2]. The effects of planting dates on seed nutrition (protein, oil, fatty acids, carbohydrates, and gossypol) were investigated using six conventional cotton cultivars planted late April and late May under irrigated and non-irrigated field conditions near Stoneville, MS, USA in 2005 through 2008 [3]. They found that irrigation resulted in higher oil and total soluble carbohydrates in seeds, and lower protein and saturated fatty acids content. Also, they found that the effect of late April planting on the fatty acid distribution was similar to that observed under dryland conditions. They concluded that, depending on the desirable benefits, growers can adopt production strategies to prod (...truncated)