Additional insights into the adaptation of cotton plants under abiotic stresses by in silico analysis of conserved miRNAs in cotton expressed sequence tag database (dbEST)

Abiotic stress is the primary cause of crop losses worldwide. In addition to protein coding genes, microRNAs (miRNAs) have emerged as important players in plant stress responses. Though miRNAs are key in regulating many aspects of plant developmental plasticity under abiotic stresses, very few information are available in cotton. Hence, this study was conducted to identify the phylogenetically conserved miRNAs in cotton, using computational approaches. In this paper, we reported a set of miRNAs such as miR159, miR165, miR170, miR319, miR529, miR828, miR869, miR1030, miR1884, and miR2118 that are likely to be involved in abiotic stress response. Although, few of them have been described in literature for their specific role in fiber development, literature survey have shown that they may also be involved in abiotic stress response. Interestingly, miRNAs reported in this study were found to have several targets that are involved in abiotic stress resistance. Considering all together, it was concluded that these newly identified conserved microRNAs in cotton have great potential in future efforts to improve abiotic stress tolerance in cotton.Key words: miRNA, cotton, abiotic stress resistance, in silico analysis

Evaluation of oryzalin-induced putative polyploids of Jasminum sambac cv. Ramanathapuram Gundumalli

The aim of the research was to create genetic variations in Jasminum sambac using oryzalin as a polyploidizing agent. Rooted stem cuttings of J. sambac were treated with oryzalin (0.005, 0.01 and 0.05%) and their vegetative and flowering parameters were recorded on 150 days after treatment. The study revealed that the higher concentration of oryzalin (0.05%) caused reduction in plant height, internodal length, number of flowering cymes per plant and number of flower buds per cyme. However, the same treatment significantly enhanced certain vegetative parameters viz., number of secondary branches, stem girth, number of leaves and leaf area, and flowering parameters namely flower bud length, corolla tube length, flower bud girth, diameter of open flower and hundred flower bud weight. High GCV was recorded in major yield attributing traits, i.e. number of flowering cymes per plant and hundred flower bud weight. High heritability and genetic advance registered for the traits viz., plant height, number of secondary branches, internodal length, number of flowering cymes, flower bud girth and hundred flower bud weight per plant indicates least influence by environment and selection such characters may be useful

Exploring the genetic variability, heritability, gene action for yield related traits and ToLCNDV resistance on F3 and F4 generations in cucumber [Cucumis sativus L.]

Cucumber is traditionally cultivated in India and is recognized as a primary centre of origin, belonging to the gourd family, Cucurbitaceae. The study focused on assessing genetic variability in F3 and F4 cucumber populations and examining correlations among various characters including ToLCNDV resistance. In both F3 and F4 generations, per cent disease index, fruit weight and vine length exhibited high heritability and genetic advance as per cent of mean. In F4 generation, yield per plant, fruit girth, fruit length, number of branches and number of fruits per plant also showed high heritability and genetic advance as per cent of mean. Yield related traits viz., sex ratio, number of fruits per vine, yield per plant and vine length exhibited complementary gene action. Days to first harvest and crop duration demonstrated negatively skewed distribution suggesting duplicate gene action and rapid genetic gain under selection. Leptokurtic distribution in yield per plant and associated traits implied the involvement of few genes for genetic inheritance of the above traits. Significant positive associations were found between yield per plant and number of fruits per plant, fruit weight and number of branches per plant suggesting potential early selection for these characters to enhance overall yield

Marker-Assisted Breeding as Next-Generation Strategy for Genetic Improvement of Productivity and Quality: Can It Be Realized in Cotton?

The dawdling development in genetic improvement of cotton with conventional breeding program is chiefly due to lack of complete knowledge on and precise manipulation of fiber productivity and quality. Naturally available cotton continues to be a resource for the upcoming breeding program, and contemporary technologies to exploit the available natural variation are outlined in this paper for further improvement of fiber. Particularly emphasis is given to application, obstacles, and perspectives of marker-assisted breeding since it appears to be more promising in manipulating novel genes that are available in the cotton germplasm. Deployment of system quantitative genetics in marker-assisted breeding program would be essential to realize its role in cotton. At the same time, role of genetic engineering and in vitro mutagenesis cannot be ruled out in genetic improvement of cotton

Phenotypic and genotype analysis of drought-resistance traits for developement of rice cultivars adapted to rainfed environments

Many of the world's rice-growing regions lack adequate irrigation facilities, and drought frequently reduces yield. This paper reviews drought-resistance traits in rice and their quantitative trait loci (QTLs), with emphasis on CT9993/IR62266, one of the most widely studied mapping populations, and suggests ways to develop cultivars that will perform well in drought-prone environments. Information about the type of drought faced in the target region - particularly the timing of the drought (late season terminal drought, early stage vegetative drought, and intermittent drought) and the intensity of the drought - are important in determining the specific plant traits required to improve drought resistance in rice. Most of these traits are related to drought avoidance strategy, so that the drought-resistant genotypes are able to maintain better internal water status, either by taking up more water through a better root system or by reducing the rate of plant water use. We identified and listed a number of QTLs for many drought-resistance traits, such as deep roots. We identified four key genomic regions on chromosomes 1, 4, 8, and 9 on which are co-located a number of QTLs for traits considered to be directly or indirectly responsible for grain yield under stress. These regions, once they have been more finely mapped, appear promising for eventual use in marker-assisted selection for development of drought-resistant rice varieties. In addition to selecting for specific traits or specific genomic regions, screening under managed drought conditions on the basis of yield itself or on spikelet fertility adjusted for flowering time appears useful, because of the relatively high degrees of heritability of these characters, for the development of drought-resistant rice cultivars, and it is currently practiced in some breeding programs

Study on In vitro Seed Germination and Seedling Development of Tuberose (Agave amica Medik.)

Agave amica (Medik.) (Syn. Polianthes tuberosa L.) is commercially propagated asexually. For the diversification of the crop, seed propagation is essential hence there is a necessity to study the seed germination for hybrid development.  A protocol for in vitro germination of tuberose seeds was formulated. Two types of seed were utilized for germination in which the decoated seeds showed early and higher germination percentage than the intact seeds. Seeds inoculated on the basal media composition of half MS with gibberellic acid (1 mg/l) and benzylaminopurine (1 mg/l) recorded minimum time for germination (8 days), higher germination percentage (89.33%) and minimum mean germination time (8.88 days). Seedlings growth were studied under different composition of shoot and root proliferation media. The MS media with naphthaleneacetic acid (2 mg/l) and benzylaminopurine (2 mg/l) increased root length (12.33 cm), shoot length (14.80 cm), number of roots (13.23) and number of leaves (6.25). Under in vivo condition, the seedling developed from the basal media composition of half MS with gibberellic acid (1 mg/l) and benzylaminopurine (1 mg/l) which sub cultured on MS media with naphthaleneacetic acid (2 mg/l) and benzylaminopurine (2 mg/l) showed higher survival percentage of 91.53%

Identification of Contrasting Parents and Development of Mapping Population for Sucking Pest Resistance in Cotton

The current study was conducted to identify the best parents with good agronomical features and contrasting characteristics for sucking pest resistance to develop a population that can be used for Quantitative Trait Loci mapping of resistance component traits. Initial attempts at this university have enabled to identify of five potential parents (viz., KC3, NDLH 1938, CO18, K12, and RG8) with improved sucking pest resistance and yield characters and they were crossed with the recently released high-yielding variety CO-17, which is also suitable for high-density planting.  All these six parents were evaluated for fiber yield and quality traits besides anatomical characters such as trichomes density, length, width, and sharpness that confers sucking pest resistance and genotyped with 200 Simple Sequence Repeats markers that span the entire genome. Efforts have been dedicated to the careful selection of optimal parents, namely CO17 and KC3, each possessing distinct traits related to resistance against sucking pests and also fiber quality characters in addition. This strategic approach aims to combine their contrasting genetic components for sucking pest resistance, to develop a new generation of plants that exhibit heightened resilience to these types of pests. CIR139, a polymorphic SSR marker of these two parents was used to fix the true hybrids which were advanced to generate an F2 mapping population.  This population is believed to be useful for QTL mapping of anatomical features that confer sucking pest resistance such as trichome length, density, breadth, and sharpness besides fiber yield and quality traits

Evaluation of Interspecific Hybrids for Yield and Quality Characteristics in Bitter Gourd (Momordica charantia L.)

Bitter gourd (Momordica charantia ) is one of the most nutritional and commercially important vegetable crops of the family cucurbitaceae. In the present study, hybrids and parents of bitter gourd were assessed to study the per se performance for yield and quality attributes. A wide range of significant variation was observed among all parents and hybrids under study. Among the parents assessed, Preethi and CO-1 was found highly significant with regard to yield attributing characters viz., fruit weight, fruit yield per plant, fruit yield ha-1 and MCM-1, MCM-2 with regard to number of fruits per plant. The hybrids CO-1 x MCM-2 followed by Preethi x MCM-1 and MCM-1 x Preethi were recorded to be the top performing hybrids for all the quantitative characters like node of first female flower appearance, days taken to first flower appearance, days to 50% flowering, fruit length(cm), fruit girth(cm), fruit weight(g),  internodal length(cm), vine length(cm), sex ratio, No of seeds per fruit, No. of fruits per plant, No. of harvest and yield per plant.  High ascorbic acid and iron content was recorded in parents MCM-2 and Preethi while it was found maximum in hybrids, Preethi x MCM-1, CO-1 x MCM-2 and MCM-1 X Preethi. Hence based on performance of yield and quality, the hybrids, CO-1 x MCM-2, Preethi x MCM-1 and MCM-1 x Preethi were found to be superior and can be exploited for further studies