Effects of irrigation and planting geometry on cotton (Gossypium hirsutum L.) fiber quality and seed composition

[Background] Cotton fiber quality and seed composition play vital roles in the economics of cotton production systems and the cottonseed meal industry. This research aimed to examine the effects of different irrigation levels and planting geometries on fiber quality and seed composition of cotton (Gossypium hirsutum L.). We conducted a 2-year study in 2018 and 2019 in a warm, humid area in the Southeast United States on Dundee silt loam soil. There were three irrigation treatments in the study. The treatments included irrigating every furrow, or full irrigation (FI), every alternate furrow, or half irrigation (HI), and no irrigation, or rain-fed (RF). Planting geometries were on ridges spaced 102 cm apart and either a single-row (SR) or twin-rows (TR).

[Results] The results of high-volume instrument (HVI), advanced fiber information systems (AFIS) and near-infrared reflectance spectroscopy (NIRS) showed that irrigation and planting treatments played a significant role in fiber quality and seed composition. Across irrigation treatments, significant differences were seen in fiber properties, including fineness, maturity ratio, micronaire, neps, short fiber, strength, uniformity, upper half mean length (UHML), upper quartile length by weight (UQLw), and yellowness (+b). Irrigation and planting geometry (PG) had a significant effect on micronaire, strength, and UHML while their interaction was significant only for micronaire. The micronaire was negatively affected by irrigation as FI-SR, FI-TR, HI-SR, and HI-TR recorded 11% ~ 12% lower over the RF-SR and TR treatments. The PG played a minor role in determining fiber quality traits like micronaire and nep count. Irrigation treatments produced significantly lower (3% ~ 4%) protein content than rain-fed, while oil content increased significantly (6% ~ 10%).

[Conclusion] The study results indicate a potential for improving cotton fiber and seed qualities by managing irrigation and planting geometries in cotton production systems in the Mississippi (MS) Delta region. The HI-TR system appears promising for lint and seed quality.

[Title] Effects of irrigation and planting geometry on cotton (Gossypium hirsutum L.) fiber quality and seed composition

[Authors]  PINNAMANENI Srinivasa R., ANAPALLI Saseendran S., SUI Ruixiu, BELLALOUI Nacer & REDDY Krishna N. 

Journal of Cotton Research 2021, 42


Cotton germplasm improvement and progress in Pakistan

[Abstract] Cotton (Gossypium spp.) contributes significantly to the economy of cotton-producing countries. Pakistan is the fourth-largest producer of cotton after China, the USA and India. The average yield of cotton is about 570.99 kg.hm− 2 in Pakistan. Climate change and different biotic stresses are causing reduction in cotton production. Transgenic approaches have unique advantage to tackle all these problems. However, how to confer permanent resistance in cotton against insects through genetic modification, is still a big challenge to address. Development of transgenic cotton has been proven to be effective. But its effectiveness depends upon several factors, including heterogeneity, seed purity, diffusion of varieties, backcrossing and ethical concerns. Cotton biotechnology was initiated in Pakistan in 1992–1993 with a focus on acquiring cotton leaf curl virus (CLCuV)-resistant insect-resistant, and improving fiber quality. This review summarizes the use of molecular markers, QTLs, GWAS, and gene cloning for cotton germplasm improvement, particularly in Pakistan.
[Title] Cotton germplasm improvement and progress in Pakistan

[Authors] RAZZAQ Abdul, ZAFAR Muhammad Mubashar, ALI Arfan, HAFEEZ Abdul, BATOOL Wajeeha, SHI Yuzhen,  GONG Wankui & YUAN Youlu

Journal of Cotton Research 2021, 41


Identification of candidate genes controlling fiber quality traits in upland cotton through integration of meta-QTL, significant SNP and transcriptomic data

[Background] Meta-analysis of quantitative trait locus (QTL) is a computational technique to identify consensus QTL and refine QTL positions on the consensus map from multiple mapping studies. The combination of meta-QTL intervals, significant SNPs and transcriptome analysis has been widely used to identify candidate genes in various plants.

[Results] In our study, 884 QTLs associated with cotton fiber quality traits from 12 studies were used for meta-QTL analysis based on reference genome TM-1, as a result, 74 meta-QTLs were identified, including 19 meta-QTLs for fiber length; 18 meta-QTLs for fiber strength; 11 meta-QTLs for fiber uniformity; 11 meta-QTLs for fiber elongation; and 15 meta-QTLs for micronaire. Combined with 8 589 significant single nucleotide polymorphisms associated with fiber quality traits collected from 15 studies, 297 candidate genes were identified in the meta-QTL intervals, 20 of which showed high expression levels specifically in the developing fibers. According to the function annotations, some of the 20 key candidate genes are associated with the fiber development.

[Conclusion] This study provides not only stable QTLs used for marker-assisted selection, but also candidate genes to uncover the molecular mechanisms for cotton fiber development.

[Title] Identification of candidate genes controlling fiber quality traits in upland cotton through integration of meta-QTL, significant SNP and transcriptomic data
[Authors] XU Shudi, PAN Zhenyuan, YIN Feifan, YANG Qingyong, LIN Zhongxu, WEN Tianwang, ZHU Longfu, ZHANG Dawei and NIE Xinhui

Journal of Cotton Research 2020, 334


Insect resistance management in Bacillus thuringiensis cotton by MGPS (multiple genes pyramiding and silencing)

[Abstract] The introduction of Bacillus thuringiensis (Bt) cotton has reduced the burden of pests without harming the environment and human health. However, the efficacy of Bt cotton has decreased due to field-evolved resistance in insect pests over time. In this review, we have discussed various factors that facilitate the evolution of resistance in cotton pests. Currently, different strategies like pyramided cotton expressing two or more distinct Bt toxin genes, refuge strategy, releasing of sterile insects, and gene silencing by RNAi are being used to control insect pests. Pyramided cotton has shown resistance against different cotton pests. The multiple genes pyramiding and silencing (MGPS) approach has been proposed for the management of cotton pests. The genome information of cotton pests is necessary for the development of MGPS-based cotton. The expression cassettes against various essential genes involved in defense, detoxification, digestion, and development of cotton pests will successfully obtain favorable agronomic characters for crop protection and production. The MGPS involves the construction of transformable artificial chromosomes, that can express multiple distinct Bt toxins and RNAi to knockdown various essential target genes to control pests. The evolution of resistance in cotton pests will be delayed or blocked by the synergistic action of high dose of Bt toxins and RNAi as well as compliance of refuge requirement.

[Title]Insect resistance management in Bacillus thuringiensis cotton by MGPS (multiple genes pyramiding and silencing)

[Authors] ZAFAR Muhammad Mubashar, RAZZAQ Abdul, FAROOQ Muhammad Awais, REHMAN Abdul, FIRDOUS Hina, SHAKEEL Amir, MO Huijuan and REN Maozhi

Journal of Cotton Research 2020, 333


Genetic map construction and functional characterization of genes within the segregation distortion regions (SDRs) in the F2:3 populations derived from wild cotton species of the D genome

[Background] Segregation distortion (SD) is a common phenomenon among stable or segregating populations, and the principle behind it still puzzles many researchers. The F2:3 progenies developed from the wild cotton species of the D genomes were used to investigate the possible plant transcription factors within the segregation distortion regions (SDRs). A consensus map was developed between two maps from the four D genomes, map A derived from F2:3 progenies of Gossypium klotzschianum and G. davidsonii while Map B from G. thurberi and G. trilobumF2:3 generations. In each map, 188 individual plants were used.

[Results] The consensus linkage map had 1 492 markers across the 13 linkage groups with a map size of 1 467.445 cM and an average marker distance of 1.037 0 cM. Chromosome D502 had the highest percentage of SD with 58.6%, followed by Chromosome D507 with 47.9%. Six thousand and thirty-eight genes were mined within the SDRs on chromosome D502 and D507 of the consensus map. Within chromosome D502 and D507, 2 308 and 3 730 genes were mined, respectively, and were found to belong to 1 117 gourp out of which 622 groups were common across the two chromosomes. Moreover, genes within the top 9 groups related to plant resistance genes (R genes), whereas 188 genes encoding protein kinase domain (PF00069) comprised the largest group. Further analysis of the dominant gene group revealed that 287 miRNAs were found to target various genes, such as the gra-miR398, gra-miR5207, miR164a, miR164b, miR164c among others, which have been found to target top-ranked stress-responsive transcription factors such as NAC genes. Moreover, some of the stress- responsive cis-regulatory elements were also detected. Furthermore, RNA profiling of the genes from the dominant family showed that higher numbers of genes were highly upregulated under salt and osmotic stress conditions, and also they were highly expressed at different stages of fiber development.

[Conclusion] The results indicated the critical role of the SDRs in the evolution of the key regulatory genes in plants.

[Title]Genetic map construction and functional characterization of genes within the segregation distortion regions (SDRs) in the F2:3 populations derived from wild cotton species of the D genome

[Authors] KIRUNGU Joy Nyangasi, MAGWANGA Richard Odongo, SHIRAKU Margaret Linyerera, LU Pu, MEHARI Teame Gereziher, XU Yuanchao, HOU Yuqing, AGONG Stephen Gaya, ZHOU Yun, CAI Xiaoyan,  ZHOU Zhongli, WANG Kunbo & LIU Fang 

Journal of Cotton Research 2020, 332


Calibration of HVI cotton elongation measurements

[Background] The strength of cotton fiber has been extensively studied and significant improvements in fiber strength have been made, but fiber elongation has largely been ignored, despite it contributing to the energy needed to break fibers, which affects fiber handling and processing. High Volume Instruments (HVI) measure fiber elongation but have not been calibrated for this property, making the measurement unavailable for comparative work among instruments. In prior work, a set of elongation calibration materials had been developed based on Stelometer results. A round trial of ten Australian and U.S. instruments was conducted on six cotton samples representing a range of 4.9% to 8.1% elongation.

[Results] By scaling the HVI elongation values of each instrument to the values of the two calibration samples, the coefficient of variation in instrument measurements was reduced from an average of 34% for the uncalibrated measurements to 5% for the calibrated measurements. The reduction in variance allows for the direct comparison of results among instruments. A single-point elongation calibration was also assessed but found to be less effective than the proposed two-point calibration.

[Conclusion] The use of an effective calibration routine on HVI measurement of cotton significantly reduces the coefficient of variation of the elongation measurement within and between instruments. The implementation of the elongation calibration will allow testing and breeding programs to implement high-speed elongation testing which makes the use of elongation values possible in breeding programs.

[Title] Calibration of HVI cotton elongation measurements

[Authors] DELHOM Christopher D., HEQUET Eric F., KELLY Brendan, ABIDI Noureddine and MARTIN Vikki B.

Journal of Cotton Research 2020, 331


Bt cotton seed purity in Burkina Faso: status and lessons learnt

[BackgroundSince the commercial release of Bt cotton in Burkina Faso in 2009, the issue of seed purity in producers’ fields has rarely been addressed in an unbiased and objective manner. The potential for contamination of conventional seed varieties with Bt traits and the consequent threat to the continuation of organic cotton production has been documented. However, studies are rare on the varietal purity of Bt cotton seeds, despite the implications for the effectiveness and sustainability of their use.

This paper compensates for the lack of research on the varietal purity of cotton seeds in Burkina Faso by reporting the results of Enzyme linked immunosorbent assay tests collected in 2015 on samples of both conventional and Bt varieties from 646 fields.

[Results] According to the conservative criteria used to declare the presence of a Bt gene in a given variety (more than 10% of seeds of conventional variety exhibit Bt traits, and at least 90% of seeds of Bt variety exhibit Bt traits), seed purity was very questionable for both types of variety. For the supposedly conventional variety, the Cry1Ac gene was observed in 63.6% of samples, the Cry2Ab gene was observed in 59.3% of samples, and both genes were detected in 52.2% of the seed samples. Only 29.3% of the seeds that were supposed to be of conventional type contained no Bt genes. Conversely, for the labeled Bt variety, the Cry1Ac gene was found in only 59.6% of samples, the Cry2Ab gene was found in 53.6% of the samples, and both genes were found in 40.4% of the samples. Finally, for the seeds that were supposed to contain both genes (Bollguard 2), both Cry1Ac and Cry2Ab genes were found in only 40.4% of the samples, only one of the genes was found in 32.4% of the samples, and 27.2% of the seeds in the samples contained neither.

Two factors are responsible for the severe lack of seed purity. First, conventional varieties are being contaminated with Bt traits because of a failure to revise the seed production scheme in Burkina Faso to prevent cross-pollination. Second, the original Bt seeds provided to Burkina Faso lacked varietal purity.

The organic sector plays a very minor role in the cotton sector of Burkina Faso (production of organic cotton totaled 453 t in 2018/2019, out of national cotton production of 183 000 t). Nevertheless, the lack of purity in conventional seed varieties is a threat to efforts to expand certified organic cotton production. The poor presence of Bt proteins in supposed Bt varieties undermines their effectiveness in controlling pests and increases the likelihood of the development of resistance among pest populations.

[Conclusion] Our results show the extent of purity loss when inadequate attention is paid to the preservation of seed purity. Pure conventional seeds could vanish in Burkina Faso, while Bt seeds do not carry the combination of the expected Bt traits. Any country wishing to embark on the use of Bt cotton, or to resume its use, as in the case of Burkina Faso, must first adjust its national seed production scheme to ensure that procedures to preserve varietal purity are enforced. The preservation of varietal purity is necessary to enable the launch or the continuation of identity-cotton production. In addition, the preservation of varietal purity is necessary to ensure the sustainable effectiveness of Bt cotton. In order to ensure that procedures to preserve varietal purity are observed, seed purity must be tested regularly, and test results must be published.

[Title] Bt cotton seed purity in Burkina Faso: status and lessons learnt

[Authors] BOURGOU Larbouga, KARGOUGOU Ester, SAWADOGO Mahamadou and FOK Michel

Journal of Cotton Research 2020, 330


Apprehending the potential of BABY BOOM transcription factors to mitigate cotton regeneration and transformation

[Abstract] Since the advent of transgenic technology, the incorporation of gene(s) encoding traits of economic importance in cotton is being practiced worldwide. However, factors like recalcitrant nature of cotton cultivars, in vitro regeneration via tissue culture (especially via somatic embryogenesis), genotype dependency, long and toilsome protocols impede the pace of development of transgenic cotton. Besides that, types and age of explants, media composition, plant growth regulators and other environmental factors affect in vitro cotton regeneration significantly. The studies of genetic control of in vitro regeneration in plants have elucidated the role of certain transcription factor genes that are induced and expressed during somatic embryogenesis. Among these transcription factors, BABY BOOM (BBM) plays a very important role in signal transduction pathway, leading to cell differentiation and somatic embryos formation. The role of BBM has been established in plant cell proliferation, growth and development even without exogenous growth regulators. This review intends to provide an informative summary of regeneration and transformation problems in cotton and the latest developments in utilization of BBM transcription factors in cotton. We believe that the use of BBM will not only ease cotton genetic improvement but will also accelerate cotton breeding programmes.

[Title] Apprehending the potential of BABY BOOM transcription factors to mitigate cotton regeneration and transformation

[Authors] YAVUZ Caner, TILLABOEVA Shakhnozakhan & BAKHSH Allah

Journal of Cotton Research 2020, 329


Cotton N rate could be reduced further under the planting model of late sowing and high-density in the Yangtze River valley

[Background] An optimal N rate is one of the basic determinants for high cotton yield. The purpose of this study was to determine the optimal N rate on a new cotton cropping pattern with late-sowing, high density and one-time fertilization at the first flower period in Yangtze River Valley, China. A 2-year experiment was conducted in 2015 and 2016 with a randomized complete block design. The cotton growth process, yield, and biomass accumulation were examined.

[Result] The results showed that N rates had no effect on cotton growing progress or periods. Cotton yield was increased with N rates increasing from 120 to 180 kg·hm−2, while the yield was not increased when the N rate was beyond 180 kg·hm−2, or even decreased (929%). Cotton had the highest biomass at the N rate of 180 kg·hm−2 is due to its highest accumulation speed during the fast accumulation period.

[Conclusion] The result suggests that the N rate for cotton could be reduced further to be 180 kg·hm− 2 under the new cropping pattern in the Yangtze River Valley, China.

[Title] Cotton N rate could be reduced further under the planting model of late sowing and high-density in the Yangtze River valley

[Authors] SONG Xinghu, HUANG Ying, YUAN Yuan, SHAHBAZ Atta Tung, BIANGKHAM Souliyanonh & YANG Guozheng

Journal of Cotton Research 2020, 328


Phenylpropanoid metabolism and pigmentation show divergent patterns between brown color and green color cottons as revealed by metabolic and gene expression analyses

[Background] Naturally-colored cotton has become increasingly popular because of their natural properties of coloration, UV protection, flame retardant, antibacterial activity and mildew resistance. But poor fiber quality and limited color choices are two key issues that have restricted the cultivation of naturally-colored cotton. To identify the possible pathways participating in fiber pigmentation in naturally-colored cottons, five colored cotton accessions in three different color types (with green, brown and white fiber) were chosen for a comprehensive analysis of phenylpropanoid metabolism during fiber development.

[Result] The expression levels of flavonoid biosynthesis pathway genes in brown cotton fibers were significantly higher than those in white and green cotton fibers. Total flavonoids and proanthocyanidin were higher in brown cotton fibers relative to those in white and green cotton fibers, which suggested that the flavonoid biosynthesis pathway might not participate in the pigmentation of green cotton fibers. Further expression analysis indicated that the genes encoding enzymes for the synthesis of caffeic acid derivatives, lignin and lignan were activated in the developing fibers of the green cotton at 10 and 15 days post-anthesis.

[Conclusion] Our results strengthen the understanding of phenylpropanoid metabolism and pigmentation in green and brown cotton fibers, and may improve the breeding of naturally-colored cottons.

[Title] Phenylpropanoid metabolism and pigmentation show divergent patterns between brown color and green color cottons as revealed by metabolic and gene expression analyses

[Authors] LI Zhonghua, SU Qian, XU Mingqi, YOU Jiaqi, KHAN Anam Qadir, LI Junyi, ZHANG Xianlong, TU Lili & YOU Chunyuan

Journal of Cotton Research 2020, 327