Drought-Tolerant Rice at Molecular Breeding Eras:An Emerging Reality

Rice(Oryza sativa L.)stands as the most significantly influential food crop in the developing world,with its total production and yield stability affected by environmental stress.Drought stress impacts about 45%of the world’s rice area,affecting plants at molecular,biochemical,physiological,and phenotypic levels.The conventional breeding method,predominantly employing single pedigree selection,has been widely utilized in breeding numerous drought-tolerant rice varieties since the Green Revolution.With rapid progress in plant molecular biology,hundreds of drought-tolerant QTLs/genes have been identified and tested in rice crops under both indoor and field conditions.Several genes have been introgressed into elite germplasm to develop commercially accepted drought-tolerant varieties,resulting in the development of several drought-tolerant rice varieties through marker-assisted selection and genetically engineered approaches.This review provides up-to-date information on proof-of-concept genes and breeding methods in the molecular breeding era,offering guidance for rice breeders to develop drought-tolerant rice varieties.

Progress and perspective on cotton breeding in Pakistan

Cotton is the prime natural fiber with economic significance globally.Cotton farming and breeding have a long his-tory in Pakistan.The development of high yielding upland cotton(Gossypium hirsutum)varieties gradually replaced the cultivation of diploid Gossypium species.Climate change along with emergence of new epidemic diseases caused yield loss in recent years.The biotic stress considerably reduced the performance and yield potential of cotton.Suit-able breeding strategies are essential to generate useful genetic variations and to identify desired traits.Conventional breeding has remarkably increased cotton yield and fiber quality,which has cultivated the NIAB-78,S-12,MNH‐786,and FH‐Lalazar like cultivars.However,this phenotypic selection based breeding method has low efficiency to pro-duce stress resilient cotton.The efficiency of traditional breeding has significantly improved by the marker assisted selection technology.Breakthroughs in molecular genetics,bioinformatics analysis,genetic engineering,and genome sequencing have opened new technique routes for cotton breeding.In addition,genetic improvement through quantitative trait loci,transcriptome,and CRISPR/Cas9 mediated genomic editing can provide suitable platform to improve the resistance to stresses induced by bollworms,cotton leaf curl virus,heat,drought,and salt.The approval of transgenic lines harboring triple gene Cry1Ac+Cry2A+GTG are critical for cotton crop.This review has critically discussed the progress and limitations of cotton breeding in Pakistan,and reviewed the utilization of novel genetic variations and selection tools for sustainable cotton production.

Advances in Breeding of Festuca arundinacea Schreb.

In this paper, domestic and foreign advances in breeding situation and conventional breeding methods of Festuca arundinacea Schreb. and the applica- tion of modem biological techniques （ somaclonal variation, somatic cell hybridization, genetic map construction, genetic diversity, gene cloning and expression, ge- netic engineering） in breeding of new varieties of F. arundinacea were summarized, which proposed new ideas for the development of F. arundinacea breeding and provided reference for breeding of new varieties of F. arundinacea.

Genetic Improvement of Betula platyphylla Suk.in China:A Review

Birch(Betula platyphylla Suk.),distributed in Eurasia,North America,and Australia,is a kind of cold-resistant,fast-growing,and vital pulpwood tree species.It is also one of the most important ecological restoration tree species with high values of economic benefits in Northeast China.To improve the genetic gain and expand the economic benefit of B.platyphylla,many genetic improvements have been carried out.In China,B.platyphylla is widely distributed and varied,and there are many varieties with excellent genetic characteristics.In this paper,the genetic improvement of B.platyphylla was reviewed,and the previous research results were discussed from two aspects:conventional breeding and molecular breeding.Some problems and corresponding solutions in the genetic improvement were put forward to provide ideas for B.platyphylla breeding in the future.