New promising high yielding cotton Bt-Variety RH-647 adapted for specific agro-climatic zone

The Bt-cotton RH-647 was developed by Cotton Research Institute CRI, Khanpur has been acknowledged for its possesses superior plant characteristics and potential to yield out under harsh agro-climatic conditions of cotton productive district of Rahimyar Khan in Bahawalpur Division and southern Punjab in 2016. RH- 647 for its novel plant structure and improved fiber quality heat and drought tolerant to withstand successfully sustain yield out in harsh, highly variable hot and dry climatic conditions of and harsh seasoned. RH-647 was developed through one-way hybridization of elite parental genotypes accompanied by pedigree selection method through gene pyramiding technique for incorporation of excellent combinations of fiber traits and CLCuV disease tolerance with higher yield potential right from F1 population. The superior plant combinations were selected in F2-F6 generations were entirely based on phenotypic plant traits and progeny yield potential in field, plant shape, number of bolls per plant, average boll weight (g) and fiber quality traits over standard varieties. The single plant progenies were selected 56 sister lines were tested for Bt-gene (Cry1 Ac) were evaluated for high yielding performance for this superior cross and finally RH-647 as superior breeding line was bulked in year 2010. The strain was evaluated in Randomized Complete Block Design in preliminary yield trials (PYT) and two years in Advance Yield Trials (AYT) trials and Zonal Varietal trials for two years. The superior line 647/10 was ensued for performance in variety attestation tests as RH-647. RH-647 performed best in two years varietal trials (NCVT and PCCT and DUS) conducted for two successive growing seasons (2014–2015 and 2015–2016). RH-647 yielded out significantly compared with standard varieties MNH-886, FH-142 and CIM 602. After completion of mandatory trials in year 2016, RH-647 was approved as new Bt. cotton variety “RH-647”. RH-647 is early in maturity with high yield potential and best suited for wheat-cotton cropping pattern. It has fluffy opening and is easy to pick, strongly tolerant to CLCuV disease, high Ginning out turn GOT% (40.2%) with improved fiber traits; staple length (28.3 mm), fiber strength (4.2ug/inch) is duly capable to fulfill all industrial requisitions.     

不同抗虫遗传背景对棉花经济性状的影响

为培育高产、优质、抗病虫的棉花新品种,本实验以一组转基因抗虫棉为材料,对不同类型抗虫棉的经济性状,农艺性状,早熟性,抗红铃虫和抗黄萎病进行了研究。结果表明,转(Bt CpTI)基因抗虫杂交棉新组合667表现为高产,纤维品质优良,高抗红铃虫、耐黄萎病,综合性状好。在参试材料中,双价抗虫棉优于单价(Bt)抗虫棉;杂交抗虫棉优于常规抗虫棉。利用外源抗虫基因转导的棉花新材料为杂交亲本,可以培育出丰产优质的高抗虫的棉花新品种。     

Anthocyanin accumulation enhanced in <Emphasis Type="Italic">Lc</Emphasis>-transgenic cotton under light and increased resistance to bollworm

Breeding of naturally colored cotton fiber has been hampered by the limited germplasm, an alternative way is to use transgenic approach to create more germplasm for breeding. Here, we report our effort to engineer anthocyanin production in cotton. The maize Lc gene, under the control of the constitutive 35S promoter, was introduced into cotton through genetic transformation. Our data showed that the expression of the Lc gene alone is sufficient to trigger the accumulation of anthocyanin in a variety of cell types including fiber cells in cotton. However, the accumulation of colored anthocyanin in cotton fibers requires the participation of light signaling. These data indicate that it is feasible to engineer colored fibers through transgenic approach in cotton. Furthermore, we showed that the Lc-transgenic cotton plants are resistant to cotton bollworm. These transgenic plants are, therefore, potentially useful for cotton breeding against cotton bollworm.     

Genetic mapping and quantitative trait locus analysis of fiber quality traits using a three-parent composite population in upland cotton (Gossypium hirsutum L.)

Composite cross populations (CP) developed from three or more cultivars/lines are frequently used to improve agronomic and economic traits in crop cultivar development programs. Employing CP in linkage map construction and quantitative trait locus (QTL) mapping may increase the marker density of upland cotton (Gossypium hirsutum L.) genetic maps, exploit more adequate gene resources and facilitate marker-assisted selection (MAS). To construct a relatively high-density map and identify QTL associated with fiber quality traits in upland cotton, three elite upland cultivars/lines, Yumian 1, CRI 35 and 7,235, were used to obtain the segregating population, Yumian 1/CRI 35//Yumian 1/7,235. A genetic map containing 978 simple sequence repeat (SSR) loci and 69 linkage groups was constructed; the map spanned 4,184.4 cM, covering approximately 94.1% of the entire tetraploid cotton genome. A total of 63 QTL were detected, explaining 8.1–55.8% of the total phenotypic variance: 11 QTL for fiber elongation, 16 QTL for fiber length, 9 QTL for fiber micronaire reading, 10 QTL for fiber strength and 17 QTL for fiber length uniformity. The genetic map and QTL detected for fiber quality traits are promising for further breeding programs of upland cotton with improved fiber quality.     

Developing Fiber Specific Promoter-Reporter Transgenic Lines to Study the Effect of Abiotic Stresses on Fiber Development in Cotton

Cotton is one of the most important cash crops in US agricultural industry. Environmental stresses, such as drought, high temperature and combination of both, not only reduce the overall growth of cotton plants, but also greatly decrease cotton lint yield and fiber quality. The impact of environmental stresses on fiber development is poorly understood due to technical difficulties associated with the study of developing fiber tissues and lack of genetic materials to study fiber development. To address this important question and provide the need for scientific community, we have generated transgenic cotton lines harboring cotton fiber specific promoter (CFSP)-reporter constructs from six cotton fiber specific genes (Expansin, E6, Rac13, CelA1, LTP, and Fb late), representing genes that are expressed at different stages of fiber development. Individual CFSP::GUS or CFSP::GFP construct was introduced into Coker 312 via Agrobacterium mediated transformation. Transgenic cotton lines were evaluated phenotypically and screened for the presence of selectable marker, reporter gene expression, and insertion numbers. Quantitative analysis showed that the patterns of GUS reporter gene activity during fiber development in transgenic cotton lines were similar to those of the native genes. Greenhouse drought and heat stress study showed a correlation between the decrease in promoter activities and decrease in fiber length, increase in micronaire and changes in other fiber quality traits in transgenic lines grown under stressed condition. These newly developed materials provide new molecular tools for studying the effects of abiotic stresses on fiber development and may be used in study of cotton fiber development genes and eventually in the genetic manipulation of fiber quality.     

Expression of an Arabidopsis vacuolar sodium/proton antiporter gene in cotton improves photosynthetic performance under salt conditions and increases fiber yield in the field

Drought and salinity are two major limiting factors in crop productivity. One way to reduce crop loss caused by drought and salinity is to increase the solute concentration in the vacuoles of plant cells. The accumulation of sodium ions inside the vacuoles provides a 2-fold advantage: (i) reducing the toxic levels of sodium in cytosol; and (ii) increasing the vacuolar osmotic potential with the concomitant generation of a more negative water potential that favors water uptake by the cell and better tissue water retention under high soil salinity. The success of this approach was demonstrated in several plants, where the overexpression of the Arabidopsis gene AtNHX1 that encodes a vacuolar sodium/proton antiporter resulted in higher plant salt tolerance. Overexpression of AtNHX1 increases sodium uptake in vacuoles, which leads to increased vacuolar solute concentration and therefore higher salt tolerance in transgenic plants. In an effort to engineer cotton for higher drought and salt tolerance, we created transgenic cotton plants expressing AtNHX1. These AtNHX1-expressing cotton plants generated more biomass and produced more fibers when grown in the presence of 200 mM NaCl in greenhouse conditions. The increased fiber yield was probably due to better photosynthetic performance and higher nitrogen assimilation rates observed in the AtNHX1-expressing cotton plants as compared with wild-type cotton plants under saline conditions. Furthermore, the field-grown AtNHX1-expressing cotton plants produced more fibers with better quality, indicating that AtNHX1 can indeed be used for improving salt stress tolerance in cotton.     

Genetic and DNA Methylation Changes in Cotton (Gossypium) Genotypes and Tissues

In plants, epigenetic regulation is important in normal development and in modulating some agronomic traits. The potential contribution of DNA methylation mediated gene regulation to phenotypic diversity and development in cotton was investigated between cotton genotypes and various tissues. DNA methylation diversity, genetic diversity, and changes in methylation context were investigated using methylation-sensitive amplified polymorphism (MSAP) assays including a methylation insensitive enzyme (BsiSI), and the total DNA methylation level was measured by high-performance liquid chromatography (HPLC). DNA methylation diversity was greater than the genetic diversity in the selected cotton genotypes and significantly different levels of DNA methylation were identified between tissues, including fibre. The higher DNA methylation diversity (CHG methylation being more diverse than CG methylation) in cotton genotypes suggest epigenetic regulation may be important for cotton, and the change in DNA methylation between fibre and other tissues hints that some genes may be epigenetically regulated for fibre development. The novel approach using BsiSI allowed direct comparison between genetic and epigenetic diversity, and also measured CC methylation level that cannot be detected by conventional MSAP.     

陆地棉纤维优势表达基因GhRACK1的克隆与序列分析

纤维品质改良是我国棉花育种的主要目标之一,纤维特异或优势表达基因的挖掘是利用基因工程手段改良纤维品质的关键。根据苏棉12纤维中优势表达的GhRACK1 EST序列设计引物,通过RACE技术克隆了GhRACK1基因的全长cDNA。推导的氨基酸序列含有4个串联的WD基序,属于WD40重复家族,与已知的RACK1蛋白同源性达70％以上,PDB模拟的蛋白三维结构也与已知的RACK1蛋白结构相似。荧光定量PCR分析表明GhRACK1在纤维中的表达量比叶片中高20倍以上。研究结果为棉花纤维品质改良基因工程提供了新的基因资源。     

Cotton annexin proteins participate in the establishment of fiber cell elongation scaffold

Cotton plant is one of the most important economic crops in the world which supplies natural fiber for textile industry. The crucial traits of cotton fiber quality are fiber length and strength, which are mostly determined by the fiber elongation stage. Annexins are assumed to be involved in regulating fiber elongation, but direct evidences remain elusive. Recently, we have investigated the activities of fiber-specific expressed annexins AnGb5/6 and their interacted proteins in cotton. AnGb5 and 6 can interact reciprocally to generate a protein macro-raft in cell membrane. This macro-raft is probably a stabilized scaffold for Actin1 organization. The actin assembling direction and density are correlated with AnGb6 gene expression and fiber expanding rate among three fiber length genotypes. These results suggest that annexins may act as the adaptor that linked fiber cell membrane to actin assembling. Due to the strong Ca²⁺ and lipid binding ability of annexins, these results also indicate that annexins complex may function as an intermediate to receive Ca²⁺ or lipid signals during fiber elongation.     

Genotypic and developmental evidence for the role of plasmodesmatal regulation in cotton fiber elongation mediated by callose turnover

Cotton fibers are single-celled hairs that elongate to several centimeters long from the seed coat epidermis of the tetraploid species (Gossypium hirsutum and Gossypium barbadense). Thus, cotton fiber is a unique system to study the mechanisms of rapid cell expansion. Previous work has shown a transient closure of plasmodesmata during fiber elongation (Y.-L. Ruan, D.J. Llewellyn, R.T. Furbank [2001] Plant Cell 13: 47-60). To examine the importance of this closure in fiber elongation, we compared the duration of the plasmodesmata closure among different cotton genotypes differing in fiber length. Confocal imaging of the membrane-impermeant fluorescent molecule carboxyfluorescein revealed a genotypic difference in the duration of the plasmodesmata closure that positively correlates with fiber length among three tetraploid genotypes and two diploid progenitors. In all cases, the closure occurred at the rapid phase of elongation. Aniline blue staining and immunolocalization studies showed that callose deposition and degradation at the fiber base correlates with the timing of plasmodesmata closure and reopening, respectively. Northern analyses showed that the expression of a fiber-specific beta-1,3-glucanase gene, GhGluc1, was undetectable when callose was deposited at the fiber base but became evident at the time of callose degradation. Genotypically, the level of GhGluc1 expression was high in the short fiber genotype and weak in the intermediate and long fiber genotypes. The data provide genotypic and developmental evidence that (1) plasmodesmata closure appears to play an important role in elongating cotton fibers, (2) callose deposition and degradation may be involved in the plasmodesmata closure and reopening, respectively, and (3) the expression of GhGluc1 could play a role in this process by degrading callose, thus opening the plasmodesmata.     

Isolation and characterization of a cotton <Emphasis Type="Italic">cdh</Emphasis>-like gene

Cotton fiber cells elongate without dividing to form economically valuable spinnable fiber. Reports of the ploidy level of fiber cells are variable. Early reports indicated an increase in nuclear DNA content in young fibers; however, subsequent reports failed to observe such a significant increase in ploidy level. Evaluation and analysis of genes involved in regulation of DNA synthesis and other aspects of cell cycle regulation identified relevant genes that were present in fiber cells though usually at low levels. We report the isolation and characterization of another gene likely to be involved in cell cycle/DNA synthesis control. This gene was similar to a gene from Medicago species that controls entry into anaphase by regulating the activity of the anaphase promoting complex ability to ubiquinate selected proteins. The cotton gene was composed of nine exons and the deduced translational sequences have motifs similar to a Medicago gene expressed in highly polyploid cells. Based on this similarity the cotton gene was designated Ghcdh. Ghcdh is highly expressed in meristems and leaves but is present at much lower levels in fiber cells. These data are consistent with the lower levels of polyploidy reported for cotton fiber. A simple sequence repeat was identified in the gene that may be exploited as a marker to map this gene and associate it with important traits in cotton.     

棉纤维发育响应高温胁迫的关键时间窗口

以温度弱敏感性棉花品种(科棉1号)和温度敏感性棉花品种(苏棉15)为材料,在人工气候室模拟自然温周期设置高温(34 ℃\[38/30 ℃\],HT)和对照(26 ℃\[30/22 ℃\],CK)2个温度处理,研究了花铃期不同时段进行高温胁迫后纤维发育重要相关物质的变化及其与纤维品质的关系.结果表明： 在花后不同时间开始高温胁迫持续处理5 d,苏棉15纤维长度、纤维比强度、马克隆值响应高温胁迫的关键时间窗口分别为花后0～18.3 d,花后10.9～26.1 d和花后10.5～34.0 d.因此,花后11～18 d左右是棉花综合纤维品质形成响应高温胁迫的关键时间窗口.在关键时间窗口对棉花进行高温处理5 d后,苏棉15纤维中的蔗糖含量相对常温条件下呈先降低后增加的变化趋势,胼胝质含量上升,纤维素含量下降4.2%,纤维长度变短(最大变幅为23.3%),纤维比强度上升(最大变幅为4.3%),马克隆值下降(最大变幅为10.5%)并偏离最适范围,纤维品质变差.科棉1号的上述纤维发育主要相关物质含量及纤维品质与苏棉15变化趋势一致、最敏感时间相近,仅变化幅度相对较小.