Interspecific Inbred Line Research Articles

Photosynthetic characteristics in wild, cultivated species and interspecific inbred lines of safflower

Safflower (Carthamus tinctorius L.), a multipurpose oilseed crop is the only cultivated species in the Carthamus genus. Carthamus spp. have been explored for resistance to biotic and abiotic stresses but not for physiological efficiency. Photosynthetic traits of ten wild and ten cultivated species and six interspecific inbred lines were studied to understand the expression of the photosynthetic traits among them, and for trait introgression from wild species in interspecific derivatives. Relations among some physiological traits in interspecific inbred lines differed from those observed in wild and cultivated species. The high photosynthesis (Pn), low transpiration (E) and high intrinsic water use efficiency (iWUE) could be introgressed from the wild species, C. lanatus and C. turkesthanicusinto safflower cultivars. Inheritance of photosynthetic traitsfrom wild to cultivated speciesindicated that wild species are exploitable for safflower improvement. This study suggests the utilization of wild species for their high Pn, low E and iWUE characteristics for developing abiotic stress-tolerant safflower cultivars.

Antioxidant enzymatic activities and gene expression associated with heat tolerance in the stems and roots of two cucurbit species ("Cucurbita maxima" and "Cucurbita moschata") and their interspecific inbred line "Maxchata".

The elucidation of heat tolerance mechanisms is required to combat the challenges of global warming. This study aimed to determine the antioxidant enzyme responses to heat stress, at the enzymatic activity and gene expression levels, and to investigate the antioxidative alterations associated with heat tolerance in the stems and roots of squashes using three genotypes differing in heat tolerance. Plants of heat-tolerant “C. moschata”, thermolabile “C. maxima” and moderately heat-tolerant interspecific inbred line “Maxchata” genotypes were exposed to moderate (37 °C) and severe (42 °C) heat shocks. “C. moschata” exhibited comparatively little oxidative damage, with the lowest hydrogen peroxide (H2O2), superoxide (O2−) and malondialdehyde (MDA) contents in the roots compared to stems, followed by “Maxchata”. The enzyme activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT) and peroxidase (POD) were found to be increased with heat stress in tolerant genotypes. The significant inductions of FeSOD, MnSOD, APX2, CAT1 and CAT3 isoforms in tolerant genotypes suggested their participation in heat tolerance. The differential isoform patterns of SOD, APX and CAT between stems and roots also indicated their tissue specificity. Furthermore, despite the sequence similarity of the studied antioxidant genes among “C. maxima” and “Maxchata”, most of these genes were highly induced under heat stress in “Maxchata”, which contributed to its heat tolerance. This phenomenon also indicated the involvement of other unknown genetic and/or epigenetic factors in controlling the expression of these antioxidant genes in squashes, which demands further exploration.

Determination of heat tolerance of interspecific (Cucurbita maxima x Cucurbita moschata) inbred line of squash ‘Maxchata’ and its parents through photosynthetic response

Development of heat tolerant cultivars is the need of hour to combat the challenges of global warming and food supply to increasing population. This study was conducted to determine the extent of heat tolerance of newly developed interspecific inbred line of squash named as ‘ Maxchata ’ through comparing its photosynthetic attributes with its parents C. maxima and C. moschata . Plants of these three cultivars were subjected to three different temperatures i.e 30 ° C day/ 25 ° C night as control, 37 ° C day/ 32 ° C night as moderate heat stress and 42 ° C day/ 37 ° C night as severe heat stress, for seven days. Results showed that various gas exchange attributes like photosynthetic rate ( P N ), stomatal conductance (g s ) and transpiration rate (E) as well as chlorophyll florescence (F v /F m ) all dropped significantly in the studied cultivars with increasing temperature, while intercellular CO 2 concentration ( Ci ) increased pointing to the nonstomatal limitations. Further, chlorophyll pigments also degraded with heat shocks resulting in more Chl a to b ratio and decreased chlorophyll carotenoids ratio. However, these trends were more abrupt in C. maxima , chased by ‘ Maxchata’ and then C. moschata . Hence, C. moschata had the best photosynthetic machinery to sustain the heat regimes, followed by ‘ Maxchata ’, while, C. maxima was the most susceptible. So, ‘ Maxchata ’ with some degree of heat tolerance has the ability to cope with the climate change.

Carotenoid Accumulation and Carotenogenic Gene Expression during Fruit Development in Novel Interspecific Inbred Squash Lines and Their Parents

Carotenoid levels and composition during squash fruit development were compared in Cucurbita moschata , Cucurbita maxima , and two lines of their interspecific inbred lines, namely, Maxchata1 and Maxchata2. Eight genes associated with carotenoid biosynthesis were analyzed by quantitative RT-PCR. The two squash species and their interspecific inbred lines exhibited different qualitative and quantitative carotenoid profiles and regulatory mechanisms. C. moschata had the lowest total carotenoid content and mainly accumulated α-carotene and β-carotene, as expected in a fruit with pale-orange flesh. Low carotenoid content in this species was probably due to the comparatively low expression of all genes investigated, especially PSY1 gene, compared to the other squashes. The predominant carotenoids in C. maxima were violaxanthin and lutein, which produced a corresponding yellow flesh color in mature fruit. The relationship between the expression of the CHYB and ZEP genes may result in almost equal concentrations of violaxanthin and lutein in C. maxima at fruit ripening. In contrast, their interspecific inbred lines principally accumulated lutein and β-carotene, leading to orange flesh color. The PSY1 gene exhibited higher expression levels at earlier stages of fruit development in the Maxchata lines, potentially triggering the increased carotenoid accumulation seen in these fruits. Likewise, the higher transcription level of CHYB gene observed in the two interspecific inbred lines might be correlated with high lutein in these hybrids. However, this study could not explain the observed β-carotene accumulation on the basis of gene expression.

Starch accumulation and starch related genes expression in novel inter-specific inbred squash line and their parents during fruit development

Dry matter and starch composition during squash fruit development were observed in Cucurbita maxima (Indian squash), Cucurbita moschata (Chinese squash) and their inter-specific inbred line, namely Maxchata. Five genes associated with starch biosynthesis were isolated and analyzed for their expression patterns using quantitative RT-PCR to elucidate the molecular mechanism of starch biosynthesis in squash fruit. The two squash species and their inter-specific inbred line exhibited difference in starch composition and corresponding regulatory mechanisms. C. moschata had the lowest total starch content that can be correlated with the lower transcript levels of AGPaseL gene as compared to the other squashes. Starch content in C. maxima and Maxchata was not significantly different in mature fruit. The higher expression of the AGPaseL genes resulted in more starch accumulation in these squashes. However, AGPaseL gene in Maxchata was highly expressed at early fruit development that led to rapid increase in starch accumulation at early stage of fruit development. Likewise, high GBSSI gene expression in C. maxima and Maxchata triggered more amylose accumulation. In contrast, SSII, SBEII, and ISAI genes, responsible for amylopectin synthesis, were expressed late during fruit development with no significant difference in their transcript levels.

Registration of TAM SIUP 98 and TAM SIUP 162 Germplasm Lines of Cotton

TAM SIUP 98 (Reg. No. GP‐938, PI 662042) and TAM SIUP 162 (Reg. No. GP‐939, PI 662043) are Sea Island (Gossypium barbadense L.)/Upland (G. hirsutum L.) (SIUP) germplasm lines that were developed by the Cotton Improvement Laboratory in the Department of Soil and Crop Sciences at Texas A&M University and were released in 2008 by Texas AgriLife Research. These interspecific inbred lines are the result of the hybridization of improved Upland germplasm and a Sea Island breeding line, NMSI 1331. TAM SIUP 98 and TAM SIUP 162 demonstrated fiber traits that exceeded those of commercial cultivars as measured by high‐volume instrumentation. Lint yields were lower than those of commercial cultivars, but plant morphology and fruiting habit were typical of Upland cotton.

Genetics of Morpho-Physiological Traits in Segregating Populations of Interspecific Hybrid Rice Under Stress and Non-Stress Conditions

Drought is one of the major constraints for rice (Oryza sativa L.) production in the rainfed ecologies in Sub-Saharan Africa. The objectives of this study were to investigate the genetic effects of morpho-physiological traits controlling drought-stress tolerance. Five Oryza glaberrima genotypes, four interspecific inbred lines, two interspecific hybrids, and two O. sativa lines and their progenies from a North Carolina II mating design were evaluated at ICRISAT in Mali under drought and fully irrigated conditions in 8 × 8 lattice designs. Data were collected on morpho-physiological traits, such as plant height, leaf rolling and stress recovery ability. General combining ability (GCA) effects for females and males were significant for all traits. Female GCA and specific combining ability (SCA) effects were significant for tiller number, plant height, and specific leaf dry weight. Heritability estimates based on variance ratios ranged from 47% to 67% for plant height, leaf area, specific leaf dry weight, and SPAD (chlorophyll); these were not significant for tiller number, which was controlled by overdominance. Heritability estimates based on regression were significant and ranged from 22% to 72% for drought-tolerance scores and leaf rolling scores. Highly significant positive relationships were observed between F3 and F4 generations for drought tolerance and leaf-rolling scores in all the populations examined. Both additive and non-additive genetic affects were important in controlling morpho-physiological traits; hence breeding procedures that exploit both GCA and SCA should be considered to improve drought tolerance in this rice germplasm.

Performance of Diverse Rice Genotypes Based on Seed-Set in Interspecific Hybrid Production: Implications for Plant Breeders

ABSTRACT Interspecific hybridization is an important technique used in improving rice populations by combining desired traits from different species. However, this could be difficult due to barriers to interspecific hybridization. The objective of this study was to determine the performance of different rice species based on seed set in an interspecific hybridization program. Five Oryza glaberrima genotypes and four interspecific inbred lines were used as female (seed) parents and two improved O. sativa and two interspecific inbred lines (NERICA 2 and NERICA 3) as male (pollen) parents to generate 36 cross combinations representing the North Carolina Design II mating scheme. Four groups of crosses were made: group A (O. glaberrima × O. sativa), group B (O. glaberrima × Interspecific), group C (Interspecific × O. sativa) and group D (Interspecific × Interspecific). Groups A and B had seed-set levels of about 10%. Group D had the highest seed-set level, with a mean of 19%. The least seed-set was for group C...

Wild helianthus species used for broadening the genetic base of cultivated sunflower in India

SUMMARY The present investigation has been undertaken to introgress desirable traits from wild sunflowers to cultivated sunflower. Using conventional methods of crossing, backcrossing and selection, several pre-bred lines with altered plant architecture, high yield and oil content, maturity duration and inbuilt tolerance to major biotic stresses have been developed from crosses involving diploid annuals. These recombinant interspecific inbred lines are being utilized in the national sunflower network program for development of inbred lines and heterosis breeding. The pre-bred lines were characterized through cytological and molecular techniques using sunflower specific SSRs. Diploid perennial and hexaploid species have been utilized in the program aimed at introgression of resistance to A. helianthi through various ploidy manipulation procedures. The utility of the prebreeding material in the sunflower network program in India is presented. RESUMEN Esta investigación fue emprendida con el fin de realizar el traspaso de las características favorables de las especies silvestres en el girasol cultivado. Utilizando los métodos de cruzamiento estándares, el cruzamiento reversible y la selección, varias líneas de preselección con la arquitectura alterada y período de vegetación de la planta, el alto rendimiento contenido de aceite y la tolerancia hacia los estreses bióticos principales agregada, han sido engendradas por cruzamientos, que incluían las especies diploides anuales. Esas líneas interespecies consanguíneas recombinantes se utilizan en la red nacional para la investigación de girasol para la formación de las líneas consanguíneas y selección heterotrófica. Las líneas de preselección se caracterizan por las técnicas citológicas y moleculares sobre la base de los marcadores específicos SSRs. Las especies diploides y hexaploides perennes son utilizadas en el programa de introducción de la resistencia hacia A. helianthi mediante diferentes métodos de manipulación con los niveles de ploidía. En el trabajo se demuestra el grado de utilización del material de preselección en los programas de selección de girasol en India. RÉSUMÉ Cette recherche a été entreprise dans le but d’intégrer des caractéristiques du tournesol sauvage au tournesol de culture. En utilisant les méthodes courantes de croisement, de rétrocroisement et de sélection, on a développé plusieurs lignées présélectionnées avec architecture végétale et durée de végétation altérées, rendement et contenu d’huile élevés et tolérance au principaux stress biotiques à partir de croisements incluant des espèces diploïdes annuelles. On utilise ces lignées autogames interspécifiques recombinantes dans le programme du tournesol du réseau national pour développer des lignes autogames et pour la sélection hétérosis. Les lignées présélectionnées ont été caractérisées par les techniques cytologiques et moléculaires utilisant des marqueurs spécifiques SSRs. Les vivaces diploïdes et hexaploïdes ont été utilisées dans un programme destiné à l’intégration d’une résistance à l’ A. helianthi par différents procédés de manipulation au niveau de la ploïdie. L’article présente l’utilité du matériel présélectionné dans le programme de sélection du tournesol en Inde.

Differential reaction of recombinant interspecific inbred lines of sunflower to red Rust incited by Puccinia helianthi

SUMMARY Thirty wild Helianthus species, several interspecific hybrids and 380 recombinant interspecific inbred lines (RIILs) derived from interspecific crosses between the cultivated sunflower and four diploid annuals (wild H. annuus, H. argophyllus, H. petiolaris and H. debilis) and three diploid perennials (H. occidentalis, H. maximiliani and H. divaricatus) were studied for reaction to rust caused by Puccinia helianthi under severe natural epiphytotic condition. The disease incidence ranged from 0 to 100% in the stable interspecific derivatives while none of the wild sunflowers and their F1 hybrids revealed susceptibility to rust. The disease severity in the RIILs varied between 0 and 40%. The mean disease severity was low in lines derived from diploid annuals (6.0-10.4%) as compared with those derived from diploid perennials (23.131.1%). One line (PS 1089) derived from H. argophyllus ×c ultivated sunflower and two lines (PS 2011 and PS 2032) derived from H. petiolaris × cultivar crosses were found to be immune. Disease severity and disease incidence were correlated with various physiological traits.