Hirsutum Lines Research Articles

Overexpression of ghr-miR166b generates resistance against Bemisia tabaci infestation in Gossypium hirsutum plants.

In silico identified Gossypium hirsutum ghr-miR166b shows multi-compatible targets in mitochondrial ATP synthase of Bemisia tabaci. Its overexpression in planta has the potential to act as a biopesticide in reducing B. tabaci population, and consequently the spread of whitefly-transmitted plant viruses. Whiteflies (B. tabaci) are hemipterous insects that act as a vector to transmit plant viruses causing enormous losses to the plants. In the present study, G. hirsutum-encoded miRNAs targeting expressed sequence tags (ESTs) of B. tabaci, based on sequence complimentarity and miRNA-target mRNA thermodynamics, were in silico identified. Out of 108 G. hirsutum miRNAs, 55 targeted the protein encoding ESTs. Among them, ghr-miR166b was selected owing to its intrinsic affinity for ATP synthase. Its functional role was validated following expression of ghr-MIR166b (precursor) sequence in G. hirsutum cv. HS6 plants through Agrobacterium-mediated transformation. Total of seven independent transformed (T0) G. hirsutum lines were obtained. The transcript level of ghr-MIR166b in the transgenic lines was observed to be 2.0- to 17-fold higher as compared to non-transformed plants. Northern-blot analysis of small RNAs isolated from the transgenic plants confirmed the presence of the ghr-miR166b. After feeding on the leaves of transgenic line (HS6-166-30) having highest level of ghr-miR166b expression, B. tabaci population was reduced up to 91% as compared to non-transformed leaves. Further, in the whole plant assay, a maximum of 78% B. tabaci mortality was observed in the same line, while there was an increase in B. tabaci population on the non-transformed plants. Our results revealed that ghr-miR166b supposedly targeting ATP synthase gene of B. tabaci, and subsequently its overexpression in planta has potential to act as biopesticide for reducing B. tabaci population and consequently spread of whitefly transmitted viruses.

Combining ability analysis for yield and yield attributing traits in interspecific (G. hirsutum L. X G. barabdense L.) hybrids of cotton

Combining ability studies were carried out in interspecific (G. hirsutum L. X G. barabdense L.) hybrids of cotton for plant height, number of monopodia, number of sympodia, number of bolls per plant, boll weight, lint index, seed index, ginning out turn and seed cotton yield by following the line x tester analysis, involving 17 hirsutum lines and three barbadense testers with their 51 hybrids. The analysis revealed predominance of non-additive gene action for most of the characters except for number of monopodia and number of sympodia. This suggests the possibility of exploiting heterosis in the present material. Superior parents HBS-1, FQT-37 and HBS-146 in lines while BCS-23 in testers are having high gca effects for yield and its components and can be used to develop multiple crosses leading to further selection. Top five cross combinations viz., FQT-37 X SB-YF-425, 543403A03N106 X BCS-23, CSHH-243M X BCS-23, HBS-1 X Suvin and HAG-1055 X SB-YF-425 exhibited high mean value with high sca effects for seed cotton yield. These crosses were found to involve at least one parent with high gca effect and the other parent having either high or low gca effect indicating the involvement of additive as well as non-additive gene action operating in these crosses except one cross where both the parents having high sca effects indicating the involvement of additive gene action.

Identification of hydrated and dehydrated lipids and protein secondary structures in seeds of cotton (Gossypium hirsutum) lines Diwas Kumar Silwal

Identification of hydrated and dehydrated lipids and protein secondary structures in seeds of cotton (Gossypium hirsutum) lines Diwas Kumar Silwal

Identification of resistance to Aspergillus flavus infection in cotton germplasm

ABSTRACTNatural resistance in cottonseed to Aspergillus flavus infection has not been explored to date. A green fluorescent protein (GFP) expressing A. flavus strain was used to assess the resistance of seed from 35 cotton varieties from Gossypium arboreum, G. barbadense, and G. hirsutum. Mature cotyledons devoid of seed coat were wounded, inoculated, and assessed for innate resistance to A. flavus infection. Of the initial 35 varieties tested, we observed a range of resistance to infection in representatives of all three species. A subset of 15 representatives was further analyzed. Within this group, G. arboreum cultivar A2 186 and G. hirsutum cultivar SA 1582 were most resistant to fungal infection. The most susceptible cultivar in this group was G. hirsutum SA 1595. The remaining 12 representatives tested in the secondary screen (3 G. arboreum, 3 G. barbadense, and 6 G. hirsutum lines) exhibited intermediate resistance. We did not observe any relationship between species and resistance. Within each species, there was a range of responses to fungal infection. Future studies using this methodology to screen additional diploid and tetraploid cotton lines may enable us to identify naturally resistant germplasm that can be used to develop cotton with enhanced resistance to fungal infection.

Registration of CA 4005 and CA 4006 Cotton Germplasm Lines with Partial Resistance to Feeding Injury from Thrips

Thrips (Thysanoptera: Thripidae) are common pests of cotton (Gossypium spp.) worldwide, typically causing economic damage within the first few weeks after planting of a cotton crop. With the loss of granular aldicarbs and resistance development to other insecticides in recent years, host plant resistance could play an important role in the integrated management of thrips. Two breeding lines originally developed for cold tolerance in the Texas A&M AgriLife Research cotton improvement program at Lubbock, TX, exhibited characteristics associated with thrips tolerance. These G. hirsutum lines, CA 4005 (Reg. No. GP‐1023, PI 681593) and CA 4006 (Reg. No. GP‐1024, PI 681594), are germplasm lines that were subsequently evaluated for potential resistance to thrips feeding injury. Both lines were evaluated in field and greenhouse tests from 2012 to 2014. CA 4005 and CA 4006 consistently displayed greater resistance to thrips feeding injury than the commercial and susceptible checks at the field level. Greenhouse evaluations, however, revealed that these lines are only partially resistant and can be overcome at high thrips densities. Yield potential, high‐volume instrument (HVI) fiber quality, and other agronomic characteristics of CA 4005 and CA 4006 were comparable to the evaluated commercial checks. These germplasm lines exhibited improved thrips resistance and competitive agronomic potential for the Texas High Plains and would be valuable sources of partial thrips resistance in adapted G. hirsutum germplasm.

Development of a 63K SNP Array for Cotton and High-Density Mapping of Intraspecific and Interspecific Populations of Gossypium spp.

High-throughput genotyping arrays provide a standardized resource for plant breeding communities that are useful for a breadth of applications including high-density genetic mapping, genome-wide association studies (GWAS), genomic selection (GS), complex trait dissection, and studying patterns of genomic diversity among cultivars and wild accessions. We have developed the CottonSNP63K, an Illumina Infinium array containing assays for 45,104 putative intraspecific single nucleotide polymorphism (SNP) markers for use within the cultivated cotton species Gossypium hirsutum L. and 17,954 putative interspecific SNP markers for use with crosses of other cotton species with G. hirsutum. The SNPs on the array were developed from 13 different discovery sets that represent a diverse range of G. hirsutum germplasm and five other species: G. barbadense L., G. tomentosum Nuttal × Seemann, G. mustelinum Miers × Watt, G. armourianum Kearny, and G. longicalyx J.B. Hutchinson and Lee. The array was validated with 1,156 samples to generate cluster positions to facilitate automated analysis of 38,822 polymorphic markers. Two high-density genetic maps containing a total of 22,829 SNPs were generated for two F2 mapping populations, one intraspecific and one interspecific, and 3,533 SNP markers were co-occurring in both maps. The produced intraspecific genetic map is the first saturated map that associates into 26 linkage groups corresponding to the number of cotton chromosomes for a cross between two G. hirsutum lines. The linkage maps were shown to have high levels of collinearity to the JGI G. raimondii Ulbrich reference genome sequence. The CottonSNP63K array, cluster file and associated marker sequences constitute a major new resource for the global cotton research community.

English

Ovule culture is one of the techniques currently used to introgress desirable traits from Gossypium arboreum germplasm into G. hirsutum cultivars. Twenty-six (26) G. hirsutum breeding lines were used as female parents in crosses with five G. arboreum accessions to determine if the G. hirsutum parent influenced the germination and recovery of plants from ovule culture. Variation in boll weight and the number of ovules per boll was observed for crosses with the G. hirsutum lines, but heavier bolls and a greater number of ovules per boll were not associated with a higher germination rate. Ovules derived from crosses with 16 G. hirsutum lines showed germination. Plants were recovered for seven of these lines (Acala GLS, DES 56, DES 119, Deltapine 50, Stoneville 132, Stoneville 506 and Stoneville 825) with vigorous growing plants derived from four crosses (DES 119 x PI 408763, Stoneville 506 x PI 408763, Acala GLS x PI 529779, and DES 119 x PI 615699). The breeding line DES 119 showed a better success rate and typically produced smaller bolls with fewer ovules. However, results would suggest the G. arboreum accessions had a greater influence on the success rate compared to the G. hirsutum lines.   Key words: Cotton, germplasm, immature embryo, tissue culture, wide-hybridization.

Gossypium Lines Resistant to Rotylenchulus reniformis Vary in Sensitivity to the Herbicide Fluometuron

Reniform nematode (Rotylenchulus reniformis) resistance is being transferred to Gossypium hirsutum from its distant relatives. Reports of fluometuron damage to LONREN lines with nematode resistance from G. longicalyx raised concerns about introducing herbicide sensitivity from other nematode resistance sources. The research objective was to evaluate 15 sources of reniform nematode resistance for their reaction to fluometuron three weeks after planting in a replicated greenhouse trial: two G. herbaceum accessions, four G. arboreum accessions, three G. barbadense accessions, three G. hirsutum accessions, and three G. hirsutum lines with resistance introgressed from G. barbadense (FR-05) or G. longicalyx (LONREN-1 and LONREN-2). The control genotype was G. hirsutum cultivar Deltapine 161 B2RF. Across all herbicide rates tested, mean herbicide injury ratings for G. arboreum accessions were greater than the control, whereas G. barbadense GB 713 and TX 110 were less. Regression analysis of herbicide rates indicated that injury increased linearly with increasing herbicide rate for all accessions, although G. arboreum A2-083 had more injury than the control. Regression analysis of herbicide rates indicated that biomass decreased linearly with increasing herbicide rate for all accessions, although G. barbadense GB 713 and Pima PHY 800 exhibited greater biomass reduction than the control. Across all herbicide rates tested, mean electron transport rates of all G. herbaceum and G. arboreum accessions and G. barbadense Pima PHY 800 were lower than the control. The relationship between herbicide rate and electron transport rate was curvilinear, with similar decreases in electron transport rate in response to increasing herbicide concentration for all lines. Increased sensitivity to fluometuron could be introduced into G. hirsutum through crosses with distantly related species, but with the exception of G. arboreum A2-083, the lines did not respond to the herbicide differently from the control.

Development of Heterotic Groups (<i>G.hirsutum</i> vs <i>G.barbadense</i>) Based on Combining Ability and Interspecific Hybrids Performance for Yield and Fiber Quality Traits

Utilization of heterosis depends on genetic diversity existing between the parents, magnitude of dominance at the yield influencing loci and the genetic distance between the chosen parental genotypes. It is possible to maximize heterosis by enhancing genetic distance between two chosen parental populations. The main objective of the Line Normal 0 7.8 pt 0 2 false false false EN-US ZH-CN AR-SA × /* Style Definitions */ table.MsoNormalTable {mso-style-name:Table Normal; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:Calibri,sans-serif; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-fareast-language:EN-US;} Tester study was to determine the combining ability status of the barbadense and hirsutum lines included in the heterotic box. These lines were compared with other barbadense and hirsutum lines. For the pattern of combining ability and the potentiality of the interspecific hybrids developed based on them. The efforts on creating recombinational variability have begun with two barbadense lines. However to compare the potentiality of the 8 hybrids with other potential hybrids developed over years at Dharwad centre and best commercial hybrids ( Bt and non Bt ), a separate evaluation of these hybrids was taken up. Realizing the need for developing potential interspecific ( G. hirsutum Normal 0 7.8 pt 0 2 false false false EN-US ZH-CN AR-SA × /* Style Definitions */ table.MsoNormalTable {mso-style-name:Table Normal; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:Calibri,sans-serif; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-fareast-language:EN-US;} G. barbadense ) hybrids, a detailed study was initiated at UAS Dharwad to identify hirsutum and barbadense genotypes capable of giving potential interspecific hybrids. Based on this study done during earlier years in 2009-2010 two barbadense DB 533 and DB 534 and four hirsutum DH 98-27 (T 1 ), ZCH 8 (T 2 ), 178-24 (T 3 ) and DH 18-31 (T 4 ) lines giving best hybrids (H Normal 0 7.8 pt 0 2 false false false EN-US ZH-CN AR-SA × /* Style Definitions */ table.MsoNormalTable {mso-style-name:Table Normal; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left

Development of Heterotic Groups (<i>G. hirsutum</i> vs <i>G. barbadense</i>) Based on Combining Ability and Inter Specific Hybrids Performance for Yield and Fiber Quality Traits

Utilization of heterosis depends on genetic diversity existing between the parents, magnitude of dominance at the yield influencing loci and the genetic distance between the chosen parental genotypes. It is possible to maximize heterosis by enhancing genetic distance between two chosen parental populations. The main objective of the Line x Tester study was to determine the combining ability status of the barbadense and hirsutum lines included in the heterotic box. These lines were compared with other barbadense and hirsutum lines. For the pattern of combining ability and the potentiality of the interspecific hybrids developed based on them. The efforts on creating recombinational variability have begun with two barbadense lines. However to compare the potentiality of the 8 hybrids with other potential hybrids developed over years at Dharwad centre and best commercial hybrids ( Bt and non Bt ), a separate evaluation of these hybrids was taken up. Realizing the need for developing potential interspecific ( G. hirsutum x G. barbadense ) hybrids, a detailed study was initiated at UAS Dharwad to identify hirsutum and barbadense genotypes capable of giving potential interspecific hybrids. Based on this study done during earlier years in 2009-2010 two barbadense DB 533 and DB 534 and four hirsutum DH 98-27 (T 1 ), ZCH 8 (T 2 ), 178-24 (T 3 ) and DH 18-31 (T 4 ) lines giving best hybrids (H x B) combinations between them were selected. Among four barbadense lines positive gca effects for seed cotton yield was recorded by DB 533 and DB 534 confiriming the potential of these barbadense lines in developing productive interspecific hybrids. Among 23 hirsutum testers, four testers DH 18-31, ZCH 8, DH 98-27 and 178-24 exhibited good positive values of gca effects for seed cotton yield and were located among top ten testers ranks 2, 8, 1 and 7 respectively when compared to other hirsutum testers. The potential of 8 bench mark crosses of heterotic box ZCH 8 x DB 533, DH 98-27 x DB 534, DH 18-31 x DB 533, ZCH 8 x DB 534, 178-24 x DB 533, DH 98-27 x DB 533, DH 18-31 x DB 534 and 178-24 x DB 534 recorded higher per se performance for seed cotton yield ranking 1, 2, 4, 6, 8, 10, 11 and 14 out of 49 crosses. These crosses also recorded superior value for yield attributing characters like number of bolls and mean boll weight. The mean performance of these crosses associated with this heterotic box was found to be 2174 kg/ha as compared to the overall mean of best HB interspecific hybrids which was 1921 kg/ha.

Combining Ability for Yield and Yield Attributing Characters in Line x Tester Inter Specific Hybrids (<i>G. hirsutum</i> × <i>G. barbadense</i>) for Confirmation of Heterotic Groups

The prime objective of cotton breeders is to develop new varieties with high yield and yield components. Present study aims to estimate general combining ability of the parents and specific combining ability of hybrids for yield and yield components. The term heterotic group refers to a group of related or unrelated genotypes from the same or different populations, which display similar combining ability and heterotic response when crossed with genotypes from other genetically distinct germplasm groups. If two lines A and B are found to give potential crosses with testers T 1 and T 2 , it is possible to increase the genetic distance between these opposite pairs A, B vs, T 1 and T 2 by following population improvement scheme for improving combining ability defined in cross pollinated crops by introducing suitable changes to match the crossing system seen in self pollinated crops. The Line x Tester study was planned to assess the relative potential of the barbadense and hirsutum in developing interspecific hybrid combinations. The objective of this study was to determine the relative the 4 barbadense and 23 hirsutum lines. Barbadense were used as lines and hirsutum were used as testers. The ongoing study at Agricultural Research Station, Dharwad on evaluation of interspecific hybrids led to formation of a heterotic box of two barbadense lines DB 533 and DB 534 and hirsutum testers DH 98-27 (T 1 ), ZCH 8 (T 2 ), 178-24 (T 3 ) and DH 18-31(T 4 ). Among four barbadense lines positive gca effects for seed cotton yield was recorded by DB 533 and DB 534 confiriming the potential of these barbadense lines in developing productive interspecific hybrids. Among 23 hirsutum testers, four testers DH 18-31, ZCH 8, DH 98-27 and 178-24 exhibited good positive values of gca effects for seed cotton yield and were located among top ten testers ranks 2, 8, 1 and 7 respectively when compared to other hirsutum testers.

Combining Ability for Yield and Yield Attributing Characters in Line×Tester Interspecific Hybrids (<i>G. hirsutum</i>×<i>G. barbadense</i>) for Confirmation of Heterotic Groups

The prime objective of cotton breeders is to develop new varieties with high yield and yield components. Present study aims to estimate general combining ability of the parents and specific combining ability of hybrids for yield and yield components. The term heterotic group refers to a group of related or unrelated genotypes from the same or different populations, which display similar combining ability and heterotic response when crossed with genotypes from other genetically distinct germplasm groups. If two lines A and B are found to give potential crosses with testers T 1 and T 2 , it is possible to increase the genetic distance between these opposite pairs A, B vs, T 1 and T 2 by following population improvement scheme for improving combining ability defined in cross pollinated crops by introducing suitable changes to match the crossing system seen in self pollinated crops. The Line Normal 0 7.8 pt 0 2 false false false EN-US ZH-CN X-NONE × /* Style Definitions */ table.MsoNormalTable {mso-style-name:Table Normal; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:none; font-size:11.0pt; font-family:Calibri,sans-serif; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-fareast-language:EN-US;} Tester study was planned to assess the relative potential of the barbadense and hirsutum in developing interspecific hybrid combinations. The objective of this study was to determine the relative the 4 barbadense and 23 hirsutum lines. Barbadense were used as lines and hirsutum were used as testers. The ongoing study at Agricultural Research Station, Dharwad on evaluation of interspecific hybrids led to formation of a heterotic box of two barbadense lines DB 533 and DB 534 and hirsutum testers DH 98-27 (T 1 ), ZCH 8 (T 2 ), 178-24 (T 3 ) and DH 18-31(T 4 ). Among four barbadense lines positive gca effects for seed cotton yield was recorded by DB 533 and DB 534 confiriming the potential of these barbadense lines in developing productive interspecific hybrids. Among 23 hirsutum testers, four testers DH 18-31, ZCH 8, DH 98-27 and 178-24 exhibited good positive values of gca effects for seed cotton yield and were located among top ten testers ranks 2, 8, 1 and 7 respectively when compared to other hirsutum testers.

INVESTIGATION ON GENETICS OF NEPPINESS AND STICKINESS OF FIBRES IN TETRAPLOID COTTON FIBRES

The results on neppiness and stickiness of cotton fibres in two groups f... 28 intra- hirsutum L. and 35 interspecific (G. hirsutum L. x G. barbadense L.) hybrids have been reported. Neps are small entangled cluster of fibres and one of the major causes for neppinss was high in G. barbadense parents compared to G. hirsutum lines. It was very high in interspecific hybrids than the intra-hirsutum hybrids. Seventeen intra-hirsutum and 18 interspecific crosses exhibited a desirable negative seu effect for this trait. Few hybrids displayed negative heterosis in both groups. The parents and hybrids of the both groups showed either a little or no stickiness in their fibres.

Evaluation of flavonoids inGossypium arboreum (L.) cottons as potential source of resistance to tobacco budworm

Asiatic cottons [Gossypium arboreum (L.)] have been investigated as a source of resistance to the tobacco budworm [Heliothis virescens (Fab.)] because their diversely colored petals have been presumed to contain various allelochemicals. However, we found that larvae fedG. arboreum squares (buds) grew about equally compared with those fed squares from commercialG. hirsutum lines. The best source of resistance was found in severalG. hirsutum double-haploid (DH) lines. In our investigation of allelochemicals, G.arboreum lines were found to contain much less gossypol in leaves, squares (buds), and petals thanG. hirsutum L. lines. Flavonoids were significantly higher inG. arboreum lines only in petals. Of 22G. arboreum lines from which squares were gathered and fed to tobacco budworm (TBW) larvae in the laboratory, larval growth was not significantly decreased on any, but larval survival was decreased on six. When the square flavonoids were isolated and incorporated in laboratory diets for the TBW, moderate toxicity was observed. However, the estimated toxicities were not greater than those of the same flavonoid isolates fromG. hirsutum lines. The most prevalent flavonoids, all previously found in G.arboreum plant tissues, were gossypetin 8-0-glucoside and gossypetin 8-0-rhamnoside, neither of which were present inG. hirsutum tissue. Quercetin 3-0-glucoside, quercetin-3'-0-glucoside, and quercetin 7-0-glucoside were also present in significant amounts in both species. Gossypetin 8-0-rhamnoside and gossypetin 8-0-glucoside were the most toxic flavonoids tested (the ED50% was estimated to be 0.007 and 0.024) and therefore may prove to be contributing factors of resistance to TBW feeding.

Genetic Variability for Cottonseed Germination at Favorable and Low Temperatures1

Many plant breeders are concerned with developing cotton (Gossypium hirsutum L. and G. barbadense L.) lines that are adapted for germination and seedling emergence when soil temperatures are low. Seedlings, however, should emerge rapidly over a range of soil temperatures. Little information is available about the association between rapid seedling emergence at favorable and low temperatures. To evaluate this relationship for a broad base of genetic lines, seeds of 18 G. barbadense and 12 G. hirsutum lines of diverse genetic background were germinated in six experiments at 15 and 25 C. Significant differences in germination properties were found among the genotypes and the temperature ✕ genotype interaction was generally significant. Correlation coefficients for germination parameters of the genotypes at the two temperatures were generally positive but small in magnitude. Germination properties of the cotton lines were associated with geographical area where developed. Generally lines developed for low elevations had better germination properties at both 15 and 25 C than did lines developed for high elevations. The results of this study suggest that potential exists for developing cotton lines with improved germination at low temperatures. Because of the poor correlation between germination at low and favorable temperatures, cotton lines should be evaluated under both conditions.

A Bioassay Differentiates Resistance to the Colorado Potato Beetle on Tomatoes1

Abstract Leaf disks of tomato, Lycopersicon esculentum Mill, and L. hirsutum C. H. Mull, subjected to feeding by the Colorado potato beetle, Leptinotarsa decemlineata (Say), were altered by insect age, sex, moisture level, and plant age. Feeding response was altered by temperatures of 21.1°C or 26.7° in young adult beetles, but not in larvae or older adults. Resistance to feeding by the insect was found with L. hirsutum lines PI 134417 and PI 134418.

Genetics of Flowering Response in Cotton. VI. Flowering Behavior of Gossypium hirsutum L. and G. barbadense L. Hybrids1

The center‐of‐origin cottons (Gossypium spp.) are isolated from cultivated American cottons by their shortday flowering response, and an understandng of the inheritance of flowering response is important hi attempting to transfer genes from these primitive cottons. The genetic systems controlling flowering response in Gossypium hirsutum and G. barbadense cottons were studied in diallel crosses involving short‐day anl day‐neutral lines of each species. The G. hirsutum lines were Texas Marker‐1 and M‐ll (day‐neutral) and Texas 220 and Texas 371 (short‐day). The G. barbadense lines were ‘Pima S‐l’ and 3‐79 (day‐neutral) and ‘Lengupa’ (shortday). These lines were crossed in all possible combinations, and the F1, F2, backcrosses to both parents, and a testcross to Texas Marker‐1 were grown for each combination. Flowering response was recorded as percentage of flowering plants and the mean date of flowering for each line in the field at College Station, Texas. A failure to meet the preanalysis tests of assumptions prevented the analysis of these data by the Hayman‐Jinks diallel analysis. The data were analyzed by comparison of mean, performance. We concluded that G. hirsutum and G. barbadense, represented in this study, have nonhomologous systems controlling flowering response. Within G. barbadense, flowering response is recessive to nonflowering and under single‐gene control. In G. hirsutum, however, flowering response is under multigenic control, which is partially dominant or additive to nonflowering. In interspecific cross combinations, the segregation for flowering response follows a multigenic pattern.