Alien chromosome transmission and somatic elimination in monosomic addition lines of Gossypium australe F. Muell in G. hirsutum L.

The efficiency of using monosomic alien addition lines (MAALs) to introgress agronomical traits of interest carried by wild diploid Gossypium species into the main cultivated cotton species G. hirsutum depends on the opportunities of confronting the alien chromosome with the recipient background genome at each generation and on the occurrence of translocations and homoeologous recombinations. The selfed-progeny of five MAALs of G. australe in G. hirsutum was screened with SSR markers to determine the transmission frequency of the alien chromosome and monitor its integrity. Three MAALs revealed a transmission frequency significantly lower than the expected ratio and one MAAL presented an exclusive transmission of the additional chromosome. In these four MAAL the alien chromosome was transmitted almost unaltered. With the fifth MAAL the alien chromosome was normally transmitted but was altered in half of the plants carrying it. In one MAAL, normally carrying brown fiber, the emergence of some plants carrying white and brown fiber revealed the somatic elimination of the additional chromosome. The loss of this chromosome seems to be triggered by its deletion.     

Effects of partial dietary substitution of groundnut meal by defatted,Aspergillus niger–fermented and heated Jatropha curcas kernel meal on feed intake and growth performance of broiler chicks

Tropical Animal Health and Production - This study was conducted to determine intake and growth performance of broiler chicks fed with Jatropha curcas kernel meal physico-chemically and...     

Cytogenetics of a new trispecies hybrid in cotton: [(Gossypium hirsutum L. × G. thurberi Tod.)2 × G. longicalyx Hutch. & Lee]

A three‐species hybrid named HTL including Gossypium hirsutum L. [2n = 4 x = 52, (AD)₁ genome] was created using the pseudophyletic introgression method with G. longicalyx Hutch. & Lee (2n = 2x = 26, F₁ genome) as donor parent and G. thurberi Tod. (2n = 2x = 26, D₁ genome) as bridge species. The new hybrid was totally self‐sterile and its interspecific status was confirmed using simple sequence repeat markers and cytogenetic analysis. Cytogenetic studies showed that its chromosome configuration was 2n = 52 = 14.13 I + 15.10 II + 1.03 III + 0.9 IV + 0.03 V + 0.13 VI (where I, II, III, IV, V and VI are univalents, bivalents, trivalents, tetravalents, pentavalents and hexavalents, respectively). Prospects for successfully exploiting the HTL hybrid in breeding programmes are discussed.     

Development of high-gossypol cotton plants with low-gossypol seeds using trispecies bridge crosses and in vitro culture of seed embryos

The objective of this work is to develop an upland cotton, Gossypium hirsutum L. [2n = 4x =52, 2(AD)h], having a reduced level of gossypol in the seeds for food and feed uses, and a high level of gossypol in the remaining organs to limit pest incidence. Using G. sturtianum Willis (2n = 2x = 26, 2C1) as donor and G. thurberi Torado (2n = 2x = 26, 2D1) or G. raimondii Ulbrich (2n = 2x = 26, 2D5) as bridge species, two trispecies hybrids G. thurberi– G. sturtianum– G. hirsutum and G. hirsutum– G. raimondii– G. sturtianum were synthesized. Both trispecies hybrids were male sterile. Recurrent backcrossing to G. hirsutum as pollinator and selfing of the second backcross (BC) progenies resulted in seeds which were rescued by in vitro culture. In total, 1208 flowers of the trispecies hybrids and their BC progenies yielded 192 seed embryos from which 62 plants were obtained. Cytogenetic analyses indicated a relatively high frequency of chromosome pairing and chiasmata. The gland levels in backcross seeds ranged from glandless seeds to normally glanded seeds. All vegetative parts of those hybrids were glanded, but a wide range of variability for gland density was observed on leaf, stem, bract and calyx. Plants derived from seeds having a reduced level of gossypol constitute very interesting germplasm to develop a cultivated glanded cotton with low-gossypol seeds. This revised version was published online in July 2006 with corrections to the Cover Date.     

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.     

Cultural Characteristics, Pathogenicity and Vegetative Compatibility of Fusarium udum Isolates from Pigeonpea (Cajanus cajan (L.) Millsp.) in Kenya

Seventy-nine single-spore isolates of Fusarium udum, the causal agent of wilt disease of pigeonpea, from Kenya, India and Malawi were characterized according to their cultural characteristics, pathogenicity and vegetative compatibility group (VCG). The isolates exhibited high variation in pathogenicity on a wilt-susceptible pigeonpea variety, and in mycelial growth and sporulation on potato dextrose agar medium. The 79 isolates were categorized into two virulence groups, two groups of radial mycelial growth and four groups of sporulation. Radial mycelial growth showed a moderate negative correlation (r = –0.40; P = 0.01) with sporulation. However, mycelial growth and sporulation had no correlation with virulence. Pairings between complementary nitrate non-utilizing (nit) mutants of F. udum generated on chlorate containing minimal medium revealed that all the isolates belonged to a single VCG (VCG 1) with two subgroups, VCG 1 I and VCG 1 II. Vegetative compatibility was independent of cultural characteristics and pathogenicity. This is the first report of vegetative compatibility in F. udum.     

Expression of the “<Emphasis Type="Italic">glanded-plant</Emphasis> and <Emphasis Type="Italic">glandless-seed</Emphasis>” trait of Australian diploid cottons in different genetic backgrounds

The expression of the “glanded-plant and glandless-seed” trait was assessed using High Performance Liquid Chromatography (HPLC) analysis methods in different Gossypium hybrids obtained by crossing Australian diploid cottons and various diploid and tetraploid species. Significant variation in the gossypol content in the seed was observed among the analyzed genotypes. HPLC data demonstrated that the gossypol synthesis repression mechanism in the Australian diploid species belonging to C and G genomes was dominant but did not confirm its preferential functioning against A genome species bearing GL₂ locus. About 10% of the produced seeds had total gossypol content lower than the limit imposed by the World Health Organisation (600 ppm) for the use of cotton flour in food and feed. HPLC analysis of the terpenoids aldehyde (TA) contents in the aerial parts of the hybrids showed important qualitative and quantitative variability. This result could indicate a certain separation between pigment gland morphogenesis and terpenoid synthesis mechanisms in cotton.     

Improved RAPD amplification of recalcitrant plant DNA by the use of activated charcoal during DNA extraction

An efficient procedure has been developed for DNA extraction from cotton by modifying the original CTAB method. The major improvement concerns the use of activated charcoal to bind resinous and coloured compounds which copurify with the DNA. The efficiency of amplification by RAPD was used as a criterion to evaluate the action of activated charcoal. Twenty-five random decamers from Operon Technologies were used to compare DNA samples extracted in the presence or absence of activated charcoal. The results in terms of amplification suggest that the use of activated charcoal in DNA extraction enhances RAPD amplification. This technique was initially developed for cotton but it has been applied successfully to other recalcitrant plants such as coffee, rubber tree, cassava and banana.