Lowering seed gossypol content in glanded cotton (Gossypium hirsutum L.) lines

Cottonseed is a rich source of high quality protein, but its value as an animal feed is limited by gossypol, a toxic polyphenolic compound contained in glands located throughout the plant. This compound helps protect the plant from pests. Totally glandless varieties have been developed, but not adopted as these plants are left vulnerable to pests. This study describes a breeding strategy to decrease the levels of gossypol in the seed while maintaining a high enough concentration of toxin in vegetative plant parts to offer protection from pests. Preliminary studies indicated that crosses between varieties with different gland densities and distributions produced a range of glanding patterns. By selecting within the resulting progeny, we have identified F₇ generation progeny that have <0.30% total gossypol in the seed, while still possessing glands at critical locations on the vegetative plant parts. These new lines will be a valuable source of germplasm for developing low seed gossypol varieties. Seed from these varieties would provide a new source of inexpensive protein for animal feeding rations.     

低酚棉种仁含油量的母体效应和杂种优势分析

利用3个低酚棉品种配制的四个正、反交组合的F1、F2和回交世代对棉籽种仁含油量的母体效应和杂种优势进行了遗传分析。结果表明，棉籽的种仁含油量受母体基因型的控制，即存在母体效应，细胞质效应对种仁含油量无显著影响。用种仁含油量高的品种作母本配制的杂种一代（F1）棉籽，其种仁含油量有极显著的中亲和高亲优势，F2棉籽种仁含油量的自交衰退率虽较大，但其中亲优势仍较大，且优于用低种仁含油量品种作母本配制的杂种二代（F2）棉籽。利用杂种优势是提高棉籽种仁含油量的有效方法，其中的关键是亲本选配。此外，本文还讨论了棉籽含油量遗传研究的模型选择问题和提高棉籽含油量的育种方法问题。     

Genetic effects and heterosis of within-boll yield components in upland cotton (Gossypium hirsutum L.)

Within-boll yield components are the most basic contributors to lint and seed yield of cotton (Gossypium hirsutum L.), which is a major source of natural fiber and edible oil throughout the world. Little information is available on genetic effects and heterosis of these traits in cotton. Three cotton cultivars and six breeding lines differing in within-boll yield components were used for this study. Parents and their F₁ progeny with reciprocals from a 3×6 factorial mating design were grown at Jiangxi Agricultural University experimental farm in 2008 and 2009. Seven within-boll yield components and two boll bur characters were analyzed under an additive-dominance genetic model with genotype and environment interaction. Additive effects were significant for all traits and dominance effects were significant for all traits except seed mass per seed. Genetic variances for lint mass per seed, SM/S and boll bur weight were primarily additive variances ranging from 39.6 to 58.9 %. Lint mass per boll and seed number per boll variances were primarily due to dominance genetic effects ranging from 36.4 to 48.8 %. Dominance and additive effects were equally important for boll weight, seed mass per boll and boll bur percentage. Additive and additive × environment effects were more important than other effects for lint percentage. A802-1 had the best mean performance and additive effects increasing BW, SM/B, S/B and SM/S, but reduced LP and LM/S. A9-1 and Lu40534 had additive effects associated with increasing LP. The two crosses A9-1×Lu40534 and Tezsh×33B were detected with favorable heterozygous dominant effects and heterosis over best parent for BW, LP, LM/B, SM/B and S/B. Favorable genotypic and phenotypic correlations were identified between within-boll lint yield components (LM/B, LM/S) and within-boll seed yield components (SM/B, S/B, SM/S). These results indicate that simultaneous genetic improvement of multiple within-boll yield components can be expected in breeding populations derived from these cotton cultivars and breeding lines.     

Identification of resistance gene analogs in cotton (Gossypium hirsutum L.)

Sequence analyses of numerous plant disease resistance genes have revealed the presence of conserved motifs common to this class of genes, namely a nucleotide binding site (NBS) and leucine rich repeat region. In this study, thirty-three resistance gene analogs (RGAs) were cloned and sequenced from cotton (Gossypium hirsutum L.) following PCR with degenerate primers designed from the conserved NBS motif of plant resistance (R) genes. Phylogenetic analysis of the predicted amino acid sequences grouped the RGAs into four distinct classes from which several subgroups were delineated based on nucleic acid sequences. Gene database searches with the consensus protein sequences of each of the four classes and respective subgroups of cotton RGAs revealed their conserved NBS domains and homology to RGAs and known resistance genes from a variety of plant genera. Given the complete lack of knowledge regarding molecular organization of R genes in cotton, the cloned RGAs described here may be useful as probes to map, characterize, and manipulate R genes of the cotton genome. This revised version was published online in July 2006 with corrections to the Cover Date.     

QTL analysis for early-maturing traits in cotton using two upland cotton (Gossypium hirsutum L.) crosses

Making use of the markers linked closely to QTL for early-maturing traits for MAS (Marker-assisted selection) is an effective method for the simultaneous improvement of early maturity and other properties in cotton. In this study, two F₂ populations and their F_2:3 families were generated from the two upland cotton (Gossypium hirsutum L.) crosses, Baimian2 × TM-1 and Baimian2 × CIR12. QTL for early-maturing traits were analyzed using F_2:3 families. A total of 54 QTL (31 suggestive and 23 significant) were detected. Fourteen significant QTL had the LOD scores not only > 3 but also exceeding permutation threshold. At least four common QTL, qBP-17 for bud period (BP), qGP-17a/qGP-17b (qGP-17) for growth period (GP), qYPBF-17a/qYPBF-17b (qYPBF-17) for yield percentage before frost (YPBF) and qHFFBN-17 for height of first fruiting branch node (HFFBN), were found in both populations. These common QTL should be reliable and could be used for MAS to facilitate early maturity. The common QTL, qBP-17, had a LOD score not only > 3 but also exceeding permutation threshold, explaining 12.6% of the phenotypic variation. This QTL should be considered preferentially in MAS. Early-maturing traits of cotton are primarily controlled by dominant and over-dominant effects.     

陆地棉种质资源抗旱性状的关联分析

干旱是导致全世界棉花严重减产、纤维品质下降的重要因素,因此获得高产、优质、耐旱的棉花新品种一直是棉花的育种目标。本研究选取217份陆地棉栽培种组成的自然群体为研究对象,采用全生育期处理组灌水量为对照组50%的干旱胁迫处理,并在处理后期对217份材料的株高、衣分、单铃重等18个性状进行2年2点的表型鉴定,干旱胁迫后,群体间响应差异明显,多个表型性状在对照和处理间表现显著差异。通过BLUP分析表型数据并计算各性状的抗旱系数;全基因组范围选取的214对多态性SSR分子标记扫描群体,共检测到393个多态性位点,基因多样性系数平均值为0.402,范围为0.072～0.631, PIC值平均为0.329,范围为0.070～0.560;群体结构分析表明,该群体可分为2个亚群。用上述SSR标记分别对18个性状的抗旱系数进行关联分析,共关联到76个极显著位点(P<0.01),表型变异解释率为2.930%～7.218%,其中共有14个标记位点能同时被2种或以上性状检测到。研究结果可为后期棉花杂交育种亲本选择及抗旱分子标记辅助育种提供理论基础及参考依据。     

Inheritance of resistance to Verticillium wilt (Verticillium dahliae) in cotton (Gossypium hirsutum L.)

Verticillium wilt, caused by Verticillium dahliae Kleb., is a major constraint to cotton production in almost all countries where cotton is cultivated. Developing new cotton cultivars resistant to Verticillium wilt is the most effective and feasible way to combat the problem. Little is known about the inheritance of resistance to Verticillium wilt of cotton, especially that caused by the defoliating (D) and nondefoliating (ND) pathotypes of the soil‐borne fungus V. dahliae. The objective of this study was to determine the inheritance of resistance in cotton against both pathotypes of V. dahliae. Crosses were made between the susceptible parent ‘Cukurova 1518’ and each of four resistant parents PAUM 401, PAUM 403, PAUM 405 and PAUM 406 to produce F₂ generations in 2002 and F_2:3 families in 2003. Disease responses of parent and progeny populations to the D and ND pathotypes were scored based on a scale of 0‐4 (0, resistant; 4, susceptible). F₂ populations inoculated with the D pathotype showed a 3 : 1 (resistant : susceptible) plant segregation ratio. Tests of F_2:3 families confirmed that resistance was controlled by a single dominant gene. In contrast, analysis of data from F₂‐ and F₂‐derived F₃ families suggested that resistance to the ND pathotype is controlled by dominant alleles at two loci.     

陆地棉棕色纤维色泽的遗传效应

以2个棕色和3个白色纤维陆地棉做完全双列杂交,分析陆地棉棕色纤维的遗传效应、长绒与短绒的遗传相关及F1的色泽差异。用扫描仪获取长绒和短绒图像,利用Photoshop 9.0获取图像RGB信息、量化纤维色泽。按照QGAStation软件中的ADM和AD模型,采用MINQUE法分析,调整无偏预测法(AUP)预测各遗传效应值。结果表明,棕色棉的长绒和短绒的遗传规律一致,其加性和显性遗传方差均极显著,其中,长绒的加性遗传方差比率为0.8501,约为显性遗传方差比率的6倍,短绒的加性遗传方差比率为0.8726,约为显性遗传方差比率的8倍;相关分析显示长绒和短绒的基因型和表现型均达显著相关,基因型相关系数达0.9935;5个亲本加性效应均不相同,但均达极显著水平,其中,棕色棉为正效应,白色棉为负效应。说明棕色纤维陆地棉的长绒和短绒色泽的遗传变异主要来自加性和显性效应,其中加性效应起主导作用;长绒和短绒的色泽遗传存在连锁和互作;因不同品种(系)的加性效应大小不同,造成不同F1纤维色泽的表现差异。     

Genetic analysis of earliness in upland cotton ( Gossypium hirsutum L.). II. Yield and lint percentage

Inheritance and interrelationships of seed cotton and lint yields were evaluated in a diallel analysis involving seven early maturing parents of different origin and a commercial variety. Lint yield showed relatively little additive variance and low heritability, whereas lint percentage showed the opposite. Highest yields were shown by the least determinate and slowest-maturing genotypes; yields generally decreased as determinacy increased and rate of maturity accelerated. Except for date for first open boll, components of earliness showed no associated with yield.     

Drought‐induced osmotic adjustment and changes in carbohydrate distribution in leaves and flowers of cotton (Gossypium hirsutum L.)

Research has indicated osmotic adjustment as a mechanism by which leaves and roots of cotton plants overcome a drought period. However, the relevance of this mechanism in reproductive tissues of modern cultivars under drought has not been fully investigated. The objectives of this study were to measure osmoregulation and carbohydrate balance in reproductive tissues and their subtending leaves grown under water‐deficit conditions. Two cotton cultivars were grown under controlled environment and field conditions. Plants were exposed to water‐deficit stress at peak flowering, approximately 70 days after planting. Measurements included stomatal conductance, proline concentration, soluble carbohydrates and starch concentration, and water potential components. Stomatal conductance of drought‐stressed plants was significantly lower compared to control, while osmotic adjustment occurred in reproductive tissues and their subtending leaves by different primary mechanisms. Pistils accumulated higher sucrose levels, maintaining cell turgor in plants exposed to drought at similar levels to those in well‐watered plants. However, subtending leaves lowered osmotic potential and maintained cell turgor by accumulating more proline. Soluble carbohydrates and starch concentration in leaves were more affected by drought than those of floral tissues, with corresponding reduction in dry matter, suggesting that flowers are more buffered from water‐deficit conditions than the adjacent leaves.     

脱落酸对棉花体细胞胚胎发生的影响

【目的】研究脱落酸(Abscisic acid, ABA)对棉花体细胞胚胎发生过程中下胚轴脱分化和再分化的影响,优化体细胞胚胎发生体系和初步解析脱落酸调控棉花体细胞胚胎发生分子机制。【方法】以棉花品种中棉所24(CCRI 24)下胚轴为外植体,设置5个ABA浓度0、0.02、0.04、0.06、0.08μmol·L^-1,分别以A0、A1、A2、A3、A4表示,添加至MSB(MS培养基+B5维生素)培养基诱导愈伤和胚性愈伤,研究ABA对棉花下胚轴初始细胞脱分化、愈伤组织诱导和胚性愈伤组织诱导的影响。【结果】ABA促进下胚轴初始细胞脱分化;显著提高愈伤组织的脱分化率和增殖率;0.02μmol·L^-1ABA显著提高胚性愈伤分化率,0.04~0.08μmol·L^-1ABA显著降低胚性愈伤分化率。ABA处理后胚性愈伤和非胚性愈伤的增殖率均显著提高且质地受到影响。0.02~0.08μmol ABA处理下,LBD和LBD在愈伤起始期上调表达。0.02μmol·L^-1ABA处理下,在愈伤增殖早期和中期BBM、LEC1和AGL15上调表达,愈伤增殖后期FUS3、LEA、ABI3基因上调表达。【结论】脱落酸调控的棉花体细胞胚胎发生与相关标记基因的时空性表达密切相关,这些基因表达水平的增加是ABA调控愈伤和胚性愈伤分化的分子基础。     

陆地棉Li1纯合显性不致死重组体的遗传分析

极短纤维突变体Li₁自国外引入本实验室后,出现了纯合致死现象。而在杂交组合(Li₁×XZ142 FLM)的后代中意外发现了一些Li₁基因纯合的突变体株系,其自交后代均为极短纤维。这种Li₁基因显性纯合不致死突变体被命名为Li-R重组体。本实验利用Li-R重组体分别与TM-1、海7124及突变体Li₁新组配了3个F₂群体,对Li-R重组体进行遗传分析。组合Li-R×XZ142 FLM、Li-R×TM-1、Li-R×海7124及Li-R×Li₁的F₂后代的分离结果均表明, Li-R重组体的纯合显性不致死表型是由2对基因控制的,一个是显性基因Li₁,另一个是来自XZ142 FLM的隐性基因li_a。其中的li_a基因是本实验室新提出的一个基因。因而Li-R的基因型就是li_ali_aLi₁Li₁;并由此推断,Li₁纯合致死突变体的基因型是Li_aLi_aLi₁Li₁,XZ142 FLM的基因型为li_ali_ali₁li₁,1929年发现的Li₁显性杂合突变体的基因型为Li_aLi_aLi₁li₁。利用(Li-R×TM-1)F_2:3进一步分析Li-R中的新基因li_a的等位性,发现li_a与控制纤维起始发育的基因li₃、n₂均不等位。新基因li_a的提出,进一步丰富了纤维发育基因资源。     

Analysis of decision-making coefficients of the lint yield of upland cotton (Gossypium hirsutum L.)

Cold water irrigation and growth in low temperature phytotron are two commonly used methods to evaluate cold tolerance of rice at the seedling stage and the cold sensitive seedlings exhibit different injury symptoms, respectively. However, so far no one has systematically dissected the differences of cold tolerance at seedling stage in rice under the two cold environments. We used a recombinant inbred line (RIL) population derived from a cross of a cold-tolerant japonica cultivar, Lijiangxintuanheigu and a cold sensitive indica cultivar, Sanhuangzhan-2 for this study. The cold sensitive seedlings exhibited leaf yellowing after cold water irrigation and leaf rolling during growth in the low temperature phytotron. Leaf yellowing and leaf rolling in RILs was significantly correlated, but the correlation coefficient was low. A total of four quantitative trait locus (QTLs) on chromosomes 1, 6, 9 and 12 were detected using leaf yellowing and percent seedling survival as indicators of cold tolerance after cold water irrigation, while five QTLs on chromosomes 7, 8, 9, 11 and 12 were detected using leaf rolling and percent seedling survival as indicators of cold tolerance during growth in the low temperature phytotron. The two QTLs, qCTS-9 and qCTS-12 were detected using different evaluation indicators under the two cold environments. Our results suggest that rice cold tolerance mechanisms at the seedling stage differ between the two environments, but the detection of common QTL implies the existence of overlap in the metabolic pathways for cold tolerance. The two common QTLs have potential value in rice breeding.     

Genetic variability of heat tolerance, and its effect on yield and fibre quality traits in upland cotton (Gossypium hirsutum L.)

Global temperature is rising because of increasing concentrations of CO₂ and other greenhouse gases (e.g. methane, nitrous oxide, etc.) in the atmosphere because of the excessive use of fossil fuels. High temperature causes heat stress which reduces crop productivity. The development of heat-tolerant varieties is feasible and will help mitigate the effects of climate change. Fifty-one cotton accessions were screened in heat-stressed and non-stressed conditions in the glasshouse and field. Relative cell injury percentage (RCI %), a measure of cell membrane thermostability (CMT), was used to assess heat tolerance. Heat-tolerant accessions had more stable yield and yielded more seed cotton with better quality fibre than the heat-intolerant accessions across four environments. The responses of the 51 accessions to all four environments for the measured traits were strongly associated. RCI % of the accessions and hybrids was strongly and negatively associated with yield and fibre traits. CMT was concluded to be a useful technique for identification of heat-tolerant cotton.     

Cytogenetics of the 'glandless-seed and glanded-plant' trait from Gossypium sturtianum Willis introgressed into upland cotton (Gossypium hirsutum L.)

In order to introgress the ‘glandless-seed and glanded-plant’ trait from Gossypium sturtianum Willis (2n= 2x= 26, C₁ genome) into the cultivated upland cotton Gossypium hirsutum L. (2n= Ax= 52 (AD), genome), two trispecific hybrids have been created using either Gossypium thurberi Torado (2n= 2x= 26, D₁ genome) or Gossypium raimondii Ulbrich (2n= 2x= 26, D₅ genome) as bridge species. The cross of both trispecific hybrids by G. hirsutum produced the first backcross progenies (BCl). Cytogenetic analysis showed that the trispecific hybrids had 52 chromosomes, their chromosome configurations at metaphase I (Ml) being 15.071 + 15.3411 + 0.93III + 0.69IV + 0.26VI in G. thurberi×G. sturtianum×G. hirsutum (TSH) and 14.421 + 17.0311 + 0.82III + 0.15IV + 0.07VI in G. hirsutum × G. raimondii ×. G. sturtianum (HRS), respectively. Among six BCl plants analysed, the only plant expressing the ‘glandless-seed and glanded-plant’ trait had 52 chromosomes and a meiotic configuration of 5.261 + 20.61II + 0.69III + 0.77IV at MI. Pollen fertility was 2.90% in TSH, 8.97% in HRS, and ranged from 0% to 40.28% in the BCl progenies. The introgressed BCl plant is perennial in growth habit. It can be used in breeding programmes aiming at the introgression of the ‘glandless-seed and glanded-plant’ trait into a cultivar of upland cotton.     

Genetic analysis of earliness in upland cotton Gossypium hirsutum L. I. Morphological and phenological variables

Inheritance and interrelationships of morphological and phenological components of earliness were evaluated in a diallel analysis involving seven early-maturing parents and a standard cultivar. This study was initiated in 1993 by making all possible crosses, without reciprocals, among the eight parents. Field evaluation of the eight parental genotypes and the 28 F1 was made in 1994 in a randomized complete block design with four replications. Of 13 earliness components studied, all but days to first square, vertical flowering interval, boll maturation period, and production rate index showed significant additive genetic variance. Heritability estimates ranged from 0.02 for production rate index to 0.39 for days to first open boll. Correlation analysis showed generally that the lower the node to the first fruiting branch and the shorter the plant, the earlier was the onset of squaring, flowering, and boll opening.     

低酚棉棉子品质性状的遗传分析

利用ＡＤＭ模型对棉子品质性状的遗传分析结果表明，壳指、仁指、仁壳比、种仁率和种仁蛋白质指数存在母体效应，其中蛋白质指数的母体效应还大于加性和显性效应。子指主要受显性效应控制，且不存在母体效应，其它四个棉子物理品质性状的显性效应大于加性效应，但年度间存在差异。蛋白质含量、油分含量和油分指数不存在母体效应。所有棉子品质性状的狭义遗传率均较低。仁指可作为棉子物理品质性状改良的选择指标；棉子营养品质的选择在很大程度上取决于快速、可靠的检验方法的建立和完善。ＩＳＡＢＣ４ｇｌ可用于棉子物理品质性状的改良，浙棉９号可用于棉子营养品质性状的改良。这两个品种的杂种后代，棉子品质有较强的杂种优势。     

陆地棉钾转运体基因GhHAK5启动子的克隆与功能分析

KUP/HAK/KT钾转运体基因的转录调控是植物响应低钾胁迫的一项重要机制。克隆和分析棉花钾转运体基因的启动子,不仅有助于了解其表达模式及调控机制,对于改良棉花的钾吸收特性也具有重要意义。陆地棉钾转运体基因GhHAK5是一个在根中特异性高表达的基因,其表达受低钾胁迫诱导,目前关于该基因启动子的功能还不清楚。本研究以陆地棉品种百棉1号为材料,通过PCR方法对GhHAK5上游2000bp启动子片段(pGhHAK5)进行克隆,并通过转化拟南芥、GUS组织定位和低钾诱导表达特性分析来研究其功能。结果表明, pGhHAK5除具有TATA-box和CAAT-box等基本顺式作用元件外,还含有多个响应于光、逆境胁迫、植物激素和生物钟等的顺式作用元件。pGhHAK5与雷蒙德氏棉pGrHAK5在重要调控元件的数量和位置分布上具有较高的一致性,均具有5个参与根特异性表达调控的元件(ATAAAAT)和1个参与低钾条件下转录调控的ARF转录因子结合位点(TGTCNN)。GUS组织化学染色结果显示,转基因拟南芥幼苗的叶脉和胚轴维管束组织染色较深,根系染色较浅;成熟期转基因拟南芥植株的根、叶脉和花萼维管束组织染色...