Genetics of biochemical attributes regulating morpho-physiology of upland cotton under high temperature conditions

Background Cotton is a strategically important fibre crop for global textile industry.It profoundly impacts several countries’industrial and agricultural sectors.Sustainable cotton production is continuously threatened by the unpre-dictable changes in climate,specifically high temperatures.Breeding heat-tolerant,high-yielding cotton cultivars with wide adaptability to be grown in the regions with rising temperatures is one of the primary objectives of modern cotton breeding programmes.Therefore,the main objective of the current study is to figure out the effective breed-ing approach to imparting heat tolerance as well as the judicious utilization of commercially significant and stress-tolerant attributes in cotton breeding.Initially,the two most notable heat-susceptible(FH-115 and NIAB Kiran)and tolerant(IUB-13 and GH-Mubarak)cotton cultivars were spotted to develop filial and backcross populations to accom-plish the preceding study objectives.The heat tolerant cultivars were screened on the basis of various morphological(seed cotton yield per plant,ginning turnout percentage),physiological(pollen viability,cell membrane thermostabil-ity)and biochemical(peroxidase activity,proline content,hydrogen peroxide content)parameters.Results The results clearly exhibited that heat stress consequently had a detrimental impact on every studied plant trait,as revealed by the ability of crossing and their backcross populations to tolerate high temperatures.However,when considering overall yield,biochemical,and physiological traits,the IUB-13×FH-115 cross went over particularly well at both normal and high temperature conditions.Moreover,overall seed cotton yield per plant exhibited a posi-tive correlation with both pollen viability and antioxidant levels(POD activity and proline content).Conclusions Selection from segregation population and criteria involving pollen viability and antioxidant levels concluded to be an effective strategy for the screening of heat-tolerant cotton germplasms.Therefore,understanding acquired from this study can assist breeders identifying traits that should be prioritized in order to develop climate resilient cotton cultivars.

Enhancing cotton resilience to challenging climates through genetic modifications

Cotton is one of the most important fiber crops that plays a vital role in the textile industry.Its production has been unstable over the years due to climate change induced biotic stresses such as insects,diseases,and weeds,as well as abiotic stresses including drought,salinity,heat,and cold.Traditional breeding methods have been used to breed climate resilient cotton,but it requires a considerable amount of time to enhance crop tolerance to insect pests and changing climatic conditions.A promising strategy for improving tolerance against these stresses is genetic engineering.This review article discusses the role of genetic engineering in cotton improvement.The essential concepts and techniques include genome editing via clustered regularly interspaced short palindromic repeats(CRISPR)/CRISPR-associated protein 9(CRISPR-Cas9),overexpression of target genes,downregulation using RNA interference(RNAi),and virus-induced gene silencing(VIGS).Notably,the Agrobacterium-mediated transformation has made significant contributions to using these techniques for obtaining stable transgenic plants.

Comparative analysis of SIMILAR to RCD ONE(SRO)family from tetraploid cotton species and their diploid progenitors depict their significance in cotton growth and development

Background SRO(Similar to RCD1)genes family is largely recognized for their importance in the growth,develop-ment,and in responding to environmental stresses.However,genome-wide identification and functional characteri-zation of SRO genes from cotton species have not been reported so far.Results A total of 36 SRO genes were identified from four cotton species.Phylogenetic analysis divided these genes into three groups with distinct structure.Syntenic and chromosomal distribution analysis indicated uneven distribu-tion of GaSRO,GrSRO,GhSRO,and GbSRO genes on A2,D5 genomes,Gh-At,Gh-Dt,Gb-At,and Gb-Dt subgenomes,respectively.Gene duplication analysis revealed the presence of six duplicated gene pairs among GhSRO genes.In promoter analysis,several elements responsive to the growth,development and hormones were found in GhSRO genes,implying gene induction during cotton growth and development.Several miRNAs responsive to plant growth and abiotic stress were predicted to target 12 GhSRO genes.Organ-specific expression profiling demonstrated the roles of GhSRO genes in one or more tissues.In addition,specific expression pattern of some GhSRO genes dur-ing ovule development depicted their involvement in these developmental processes.Conclusion The data presented in this report laid a foundation for understanding the classification and functions of SRO genes in cotton.

Genome editing in cotton:challenges and opportunities

Cotton has enormous economic potential providing high-quality protein,oil,and fibre.A large increase in cotton output is necessary due to the world’s changing climate and constantly expanding human population.In the past,conventional breeding techniques were used to introduce genes into superior cotton cultivars to increase production and to improve quality.The disadvantages of traditional breeding techniques are their time-consuming,reliance on genetic differences that are already present,and considerable backcrossing.To accomplish goals in a short amount of time,contemporary plant breeding techniques,in particular modern genome editing technologies(GETs),can be used.Numerous crop improvement initiatives have made use of GETs,such as zinc-finger nucleases,transcription-activator-like effector nucleases,clustered regularly interspaced palindromic repeats(CRISPR),and CRISPR-associated proteins systems(CRISPR/Cas)-based technologies.The CRISPR/Cas system has a lot of potential because it combines three qualities that other GETs lack:simplicity,competence,and adaptability.The CRISPR/Cas mechanism can be used to improve cotton tolerance to biotic and abiotic stresses,alter gene expression,and stack genes for critical features with little possibility of segregation.The transgene clean strategy improves CRISPR acceptability addressing regulatory issues associated with the genetically modified organisms(GMOs).The research opportunities for using the CRISPR/Cas system to address biotic and abiotic stresses,fibre quality,plant architecture and blooming,epigenetic changes,and gene stacking for commercially significant traits are highlighted in this article.Furthermore,challenges to use of CRISPR technology in cotton and its potential for the future are covered in detail.

Growth, yield and fiber quality characteristics of Bt and non-Bt cotton cultivars in response to boron nutrition

Background Boron(B)deficiency is an important factor for poor seed cotton yield and fiber quality.However,it is often missing in the plant nutrition program,particularly in developing countries.The current study investigated B’s effect on growth,yield,and fiber quality of Bt(CIM-663)and non-Bt(Cyto-124)cotton cultivars.The experimental plan consisted of twelve treatments:Control(CK);B at 1 mg·kg^(−1) soil application(SB1);2 mg·kg^(−1) B(SB2);3 mg·kg^(−1) B(SB3);0.2%B foliar spray(FB1);0.4%B foliar spray(FB2);1 mg·kg^(−1) B+0.2%B foliar spray(SB1+FB1);1 mg·kg^(−1) B+0.4%B foliar spray(SB1+FB2);2 mg·kg^(−1) B+0.2%B foliar spray(SB2+FB1);2 mg·kg^(−1) B+0.4%B foliar spray(SB2+FB2);3 mg·kg^(−1) B+0.2%B foliar spray(SB3+FB1);3 mg·kg^(−1) B+0.4%B foliar spray(SB3+FB2).Each treat-ment has three replications,one pot having two plants per replication.Results B nutrition at all levels and methods of application significantly(P≤0.05)affected the growth,physiological,yield,and fiber quality characteristics of both cotton cultivars.However,SB2 either alone or in combination with foliar spray showed superiority over others,particularly in the non-Bt cultivar which responded better to B nutrition.Maxi-mum improvement in monopodial branches(345%),sympodial branches(143%),chlorophyll-a(177%),chlorophyll-b(194%),photosynthesis(169%),and ginning out turn(579%)in the non-Bt cultivar was found with SB2 compared with CK.In Bt cultivar,although no consistent trend was found but integrated use of SB3 with foliar spray performed relatively better for improving cotton growth compared with other treatments.Fiber quality characteristics in both cultivars were improved markedly but variably with different B treatments.Conclusion B nutrition with SB2 either alone or in combination with foliar spray was found optimum for improving cotton’s growth and yield characteristics.

Heritability and correlation analysis of morphological and yield traits in genetically modified cotton

Background:Cotton is known for fiber extraction and it is grown in tropical and sub-tropical areas of the world due to having hot weather.Cotton crop has a significant role in GDP of Pakistan.Therefore,the two-years research was conducted to estimate heritability and association among various yield contributing parameters of cotton,i.e.,plant height,number of bolls per plant,number of sympodial branches per plant,seed cotton yield,boll weight,seed index,ginning outturn(GOT),fiber length,fiber strength,and fiber fineness.Results:Association analysis revealed that seed cotton yield had a significant positive correlation with plant height,number of bolls per plant,number of sympodial branches per plant,GOT,staple length and fiber strength.Staple length and fiber strength were negatively linked with each other.Estimates of heritability were high for all of the traits except the number of sympodial branches per plant and boll weight.Conclusion:The parent IUB-222 was found to be the best for plant height,the number of bolls per plant,boll weight,GOT,seed cotton yield,and seed index.The genotypes namely,NIAB-414 and VH-367 were identified as the best parents for fiber length,strength,and fineness.Among the crosses NIAB-414×IUB-222 was the best for the number of bolls per plant,seed index,seed cotton yield and fiber fineness,whereas,the cross of NIAB-414×CIM-632 was good for plant height.The combination of A555×CIM-632 was the best for the number of sympodial branches per plant,boll weight,fiber length,and strength,and VH-367×CIM-632 proved the best for GOT.

Genetic effects conferring heat tolerance in upland cotton(Gossypium hirsutum L.)

Background:Climate change and particularly global warming has emerged as an alarming threat to the crop productivity of field crops and exerted drastic effects on the cropping patterns.Production of cotton has been dropped down to one million bales from 1.4 million bales since 2015 in Pakistan due to the increase in temperature at critical growth stages,i.e.,flowering and boll formation.Keeping in view the importance of cotton in the country,this study was conducted to investigate the genetic effects conferring heat tolerance in six populations(P1,P2,F1,F2,BC1 and BC2)developed from cross-1 and cross-2,i.e.,VH-282×FH-142 and DNH-40×VH-259.Results:The results revealed that cross-1 performed better in heat stress as compared with cross-2 for majority of the traits recorded.Boll weight and ginning outturn(GO-T)were highly effected under heat stress and had negative correlation with Relative cell injury(RCI).Boll weight,fiber length,fiber strength and fiber fineness were under the control of non-additive gene action,whereas RCI was controlled by additive gene effects.Lower values of genetic advance coupled with higher values of broad sense heritability for these traits except RCI confirmed the role of non-additive genetic effects.Duplicate types of epistasis were recorded for fiber strength in cross-1 in normal condition.However,complementary type of non-allelic interaction was recorded for fiber strength under normal condition,fiber fineness and RCI under heat stressed condition in cross-1.Likewise,boll weight,GOT and fiber length in populations derived from cross-2 in normal condition were also under the influence of complementary type of non-allelic interaction.Significant differences among values of mid parent and better parent heterosis for boll weight in both normal and heat stress condition provided the opportunity to cotton breeders for utilization of this germplasm for improvement of this trait through exploitation of heterosis breeding.Conclusion:Cross-1 performed better in heat stress and could be utilized for development of heat tolerant cultivar.RCI was under the influence of additive gene action,so one can rely on this trait for screening of large number of accessions of cotton for heat stress.While other traits were predominantly controlled by non-additive gene action and selection based on these should be delayed in later generations.

Role of SNPs in determining QTLs for major traits in cotton

A single nucleotide polymorphism is the simplest form of genetic variation among individuals and can induce minor changes in phenotypic,physiological and biochemical characteristics.This polymorphism induces various mutations that alter the sequence of a gene which can lead to observed changes in amino acids.Several assays have been developed for identification and validation of these markers.Each method has its own advantages and disadvantages but genotyping by sequencing is the most common and most widely used assay.These markers are also associated with several desirable traits like yield,fibre quality,boll size and genes respond to biotic and abiotic stresses in cotton.Changes in yield related traits are of interest to plant breeders.Numerous quantitative trait loci with novel functions have been identified in cotton by using these markers.This information can be used for crop improvement through molecular breeding approaches.In this review,we discuss the identification of these markers and their effects on gene function of economically important traits in cotton.

A discussion on cotton transformation during the last decade (2010–2021);an update on present trends and future prospects

The introduction of genetically modified(GM)cotton in 1996 in the US and its worldwide spread later rejuvenated cotton production in many parts of the world.The evolution is continued since then and currently,the 3rd and fourth generation of same GM cotton is grown in many parts of the world.The GM cotton introduced in 1996 was simple Bt cotton that expressed a single Cry1Ac gene,the later generation carried multiple Cry genes along with the genes controlling herbicide tolerance.Current day GM cotton does not only give stable resistance against lepidopteran insects but also facilitates the farmers to spray broad-spectrum herbicides without harming the crop.The evolution of GM cotton is continued both on the basic and applied side and interventions have been introduced during the last decade.Earlier the cotton transformation was limited to Cocker strains which are getting possible in many other varieties,too.It is successful with both gene gun,and Agrobacterium and inplanta transformation has made it a routine activity.Apart from overexpression studies for various purposes including biotic,abiotic,and quality traits,RNAi and genome editing are explored vigorously.Through this review,we have tried to explore and discuss various interventions for improving transformation protocols,the applications of cotton transformation,and future strategies being developed to get maximum benefits from this technology during the last decade.