Waqas Malik

GhABF2, a bZIP transcription factor, confers drought and salinity tolerance in cotton ( Gossypium hirsutum L.)

The bZIP transcription factor (TF) act as an important regulator for the abscisic acid (ABA) mediated abiotic stresses signaling pathways in plants. Here, we reported the cloning and characterization of GhABF2, encoding for typical cotton bZIP TF. Overexpression of GhABF2 significantly improved drought and salt stress tolerance both in Arabidopsis and cotton. However, silencing of GhABF2 made transgenic cotton sensitive to PEG osmotic and salt stress. Expression of GhABF2 was induced by drought and ABA treatments but repressed by high salinity. Transcriptome analysis indicated that GhABF2 increases drought and salt tolerance by regulating genes related to ABA, drought and salt response. The proline contents, activity of superoxide dismutase (SOD) and catalase (CAT) were also significantly increased in GhABF2-overexpression cottons in comparison to wild type after drought and salt treatment. Further, an increase in fiber yield under drought and saline-alkali wetland exhibited the important role of GhABF2 in enhancing the drought and salt tolerance in transgenic lines. In conclusion, manipulation of GhABF2 by biotechnological tools could be a sustainable strategy to deploy drought and salt tolerance in cotton.

Molecular Markers and Cotton Genetic Improvement: Current Status and Future Prospects

Narrow genetic base and complex allotetraploid genome of cotton (Gossypium hirsutum L.) is stimulating efforts to avail required polymorphism for marker based breeding. The availability of draft genome sequence of G. raimondii and G. arboreum and next generation sequencing (NGS) technologies facilitated the development of high-throughput marker technologies in cotton. The concepts of genetic diversity, QTL mapping, and marker assisted selection (MAS) are evolving into more efficient concepts of linkage disequilibrium, association mapping, and genomic selection, respectively. The objective of the current review is to analyze the pace of evolution in the molecular marker technologies in cotton during the last ten years into the following four areas: (i) comparative analysis of low- and high-throughput marker technologies available in cotton, (ii) genetic diversity in the available wild and improved gene pools of cotton, (iii) identification of the genomic regions within cotton genome underlying economic traits, and (iv) marker based selection methodologies. Moreover, the applications of marker technologies to enhance the breeding efficiency in cotton are also summarized. Aforementioned genomic technologies and the integration of several other omics resources are expected to enhance the cotton productivity and meet the global fiber quantity and quality demands.

Estimation of genetic diversity using SSR markers in sunflower.

Microsatellites or simple sequence repeats (SSRs) were used for the estimation of genetic diversity among a group of 40 sunflower lines developed at the research area of Department of Plant Breeding and Genetics, University of Agriculture, Faisalabad. Total numbers of alleles amplified by 22 polymorphic primers were 135 with an average of 6.13 alleles per locus, suggesting that SSR is a powerful technique for assessment of genetic diversity at molecular level. The expected heterozygosity (PIC) ranged from 0.17 to 0.89. The highest PIC value was observed at the locus C1779. The genetic distances ranged from 9% to 37%. The highest genetic distance was observed between the lines L50 and V3. Genetic distances were low showing lesser amount of genetic diversity among the sunflower lines.

Co‐expression of GR79 EPSPS and GAT yields herbicide‐resistant cotton with low glyphosate residues

Summary Glyphosate‐resistant (GR) crops have been adopted on a massive scale by North and South American farmers. Currently, about 80% of the 120 million hectares of the global genetically modified (GM) crops are GR crop varieties. However, the adoption of GR plants in China has not occurred at the same pace, owing to several factors including, among other things, labour markets and the residual effects of glyphosate in transgenic plants. Here, we report the co‐expression of codon‐optimized forms of GR79 EPSPS and N‐acetyltransferase (GAT) genes in cotton. We found five times more resistance to glyphosate with 10‐fold reduction in glyphosate residues in two pGR79 EPSPS‐pGAT co‐expression cotton lines, GGCO2 and GGCO5. The GGCO2 line was used in a hybridization programme to develop new GR cottons. Field trials at five locations during three growing seasons showed that pGR79‐pGAT transgenic cotton lines have the same agronomic performance as conventional varieties, but were USD 390‐495 cheaper to produce per hectare because of the high cost of conventional weed management practices. Our strategy to pyramid these genes clearly worked and thus offers attractive promise for the engineering and breeding of highly resistant low‐glyphosate‐residue cotton varieties.

Activation of ABA Receptors Gene GhPYL9-11A Is Positively Correlated with Cotton Drought Tolerance in Transgenic Arabidopsis

The sensitivity to abscisic acid (ABA) by its receptors, pyrabactin resistance-like proteins (PYLs), is considered a most important factor in activating the ABA signal pathway in response to abiotic stress. However, it is still unknown which PYL is the crucial ABA receptor mediating response to drought stress in cotton (Gossypium hirsutum L.). Here, we reported the identification and characterization of highly induced ABA receptor GhPYL9-11A in response to drought in cotton. It is observed that GhPYL9-11A was highly induced by ABA treatment. GhPYL9-11A binds to protein phosphatase 2Cs (PP2Cs) in an ABA-independent manner. Moreover, the GhPYL-11A-PP2C interactions are partially disrupted by mutations, proline (P84) and histidine (H111), in the gate-latch region. Transgenic Arabidopsis overexpressing GhPYL9-11A plants were hypersensitive to ABA during seed germination and early seedling stage. Further, the increased in root growth and up regulation of drought stress-related genes in transgenic Arabidopsis as compared to wild type confirmed the potential role of GhPYL9-11A in abiotic stress tolerance. Consistently, the expression level of GhPYL9-11A is on average higher in drought-tolerant cotton cultivars than in drought-sensitive cottons under drought treatment. In conclusion, the manipulation of GhPYL9-11A expression could be a useful strategy for developing drought-tolerant cotton cultivars.

Recent insights into cotton functional genomics: progress and future perspectives

Summary Functional genomics has transformed from futuristic concept to well‐established scientific discipline during the last decade. Cotton functional genomics promise to enhance the understanding of fundamental plant biology to systematically exploit genetic resources for the improvement of cotton fibre quality and yield, as well as utilization of genetic information for germplasm improvement. However, determining the cotton gene functions is a much more challenging task, which has not progressed at a rapid pace. This article presents a comprehensive overview of the recent tools and resources available with the major advances in cotton functional genomics to develop elite cotton genotypes. This effort ultimately helps to filter a subset of genes that can be used to assemble a final list of candidate genes that could be employed in future novel cotton breeding programme. We argue that next stage of cotton functional genomics requires the draft genomes refinement, re‐sequencing broad diversity panels with the development of high‐throughput functional genomics tools and integrating multidisciplinary approaches in upcoming cotton improvement programmes.

Mode of inheritance for biochemical traits in genetically engineered cotton under water stress.

The optimal level of Bt toxin in Bt cotton is imperative for sustainability and adoption of Bt cotton under water stressed and non-stressed environments. We investigated the mode of inheritance and association of various drought tolerance biochemicals traits with Bt toxin under normal and water stressed conditions. We observed non-additive gene action coupled with low heritability estimates for all studied biochemical traits. The different kinds of association between Bt toxin and biochemical traits proved to be a simple innovative strategy. Furthermore, it is concluded that different biochemical traits can serve as a potential biochemical markers in future for breeding drought tolerant Bt cotton.

Cascades of Ionic and Molecular Networks Involved in Expression of Genes Underpin Salinity Tolerance in Cotton

Salt stress is a severe threat to agricultural productivity in many parts of the world. Cotton (Gossypium hirsutum) is an economically important fiber crop globally, and is regarded as a model crop for salinity tolerance research. Although cotton is a relatively salt-tolerant plant, its growth and development, as well as fiber yield and quality, are greatly reduced by severe salt conditions. Salinity tolerance studies in cotton have focused on finding the key molecular genetic processes activated in response to salt stress, for breeding salt-tolerant cotton genotypes. In response to salt stress, cotton exhibits a variety of changes at the molecular, biochemical, and physiological levels. Photosynthetic pathways and metabolism play pivotal roles in redox balance and ion homeostasis. Several stress signaling pathways, for example, abscisic acid, salt overly sensitive (SOS), mitogen-activated protein kinase (MAPK), reactive oxygen species (ROS), and membrane-bound Na+/H+ antiporters, all participate in salinity tolerance. The activation and regulation of specific genes drive this physiological and biochemical plasticity. In cotton, the roles of several transcription factors (for example, WRKY, ZFP, NAC, DREB, bZIP, and ERF) in salt stress tolerance have been well documented. We also highlight the potential areas for future investigation to elucidate the key pathways for effective breeding of salt-tolerant cotton genotypes.

Morphological, Growth and Yield Response of Cotton to Exogenous Application of Natural Growth Promoter and Synthetic Growth Retardant

Azra Yasmeen, Muhammad Arif, Nazim Hussain, Waqas Malik and Ihsan Qadir Department of Agronomy, Faculty of Agricultural Sciences and Technology, Bahauddin Zakariya University Multan, Pakistan Department of Plant Breeding and Genetics, Faculty of Agricultural Sciences and Technology, Bahauddin Zakariya University, Multan, Pakistan Department of Forestry, Faculty of Agricultural Sciences and Technology, Bahauddin Zakariya University, Multan, Pakistan For correspondence: azra.yasmeen@bzu.edu.pk