eChapters

ABSTRACT

Though the genetic control of sex determination is being explored in several animal systems, no much information is available on the genetic basis for sex specificities in dioecious or sexually polymorphic plant species. Date palm is a unique member of the family Palmaceae which exhibits dioecy. Here we report the sex-specific variation in the genomic DNA of male and female date palms as revealed from an extensive study conducted with palms representing different date palm growing regions of the Kingdom of Saudi Arabia. The genomic DNA content in females was less than 60 per cent compared to those of the male genotypes. Polymerase chain reactions carried out to amplify different segments of the alcohol dehydrogenase (AdhA) gene from the date palm genomic DNA yielded two DNA fragments each in the female genotypes where as the same primers amplified a single fragment in male plants. Genomic Southern analysis of Eco R1 restriction digests showed RFLP between the male and female genotypes with the male plants showing a single hybridization signal of approximately 14 kb size and the females showing six additional bands of varying molecular weights. The results of our investigations reveal the potential of molecular biology in differentiating the sex in date palm at DNA level. Further research is needed to develop DNA markers that will help to unequivocally identify the sex of dioecious plants at the seedling stage.

Green revolution technologies such as greater use of synthetic agrochemicals like fertilizers and pesticides, adoption of nutrient-responsive, high-yielding varieties of crops, greater exploitation of irrigation potentials etc. has boosted the production output in most cases. However, continuous use of these high energy inputs indiscriminately now leads to decline in production and productivity of various crops as well as deterioration of soil health and environments.

ABSTRACT

Piper colubrinum is a wild relative of the cultivated species of black pepper, Piper nigrum. The enzyme hydroxy methyl glutaryl Co A reductase which catalyses mevalonate synthesis, is the key enzyme in isoprenoid biosynthesis.This is the rate limiting step in the pathway which leads to the formation of sesquiterpene phytoalecins, a group of plant defense metabolites. Piper colubrinum is known to be tolerant to the dreaded disease called foot rot, incited by Phytophthora capsici. The hmgr gene is reported to confer resistance to fungal pathogens. Hence we made an attempt to isolate gene encoding this enzyme. cDNA was synthesised by reverse transcription from total RNA of P.colubrinum using oligo dt primers. Specific degenerate primers designed based on the conserved boxes among various plant species were used for amplifying hmgr gene from the cDNA. The 700 bp amplicon was cloned in pGEMT vector and sequenced with T7 primer. Multiple sequence alignment using clustal W 1.8 revealed homology of the cDNA fragment with hmgr genes in several other plant species. Maximum similarity was observed among P. colubrinum, Solanum xanthocarpum and Nicotiana tabacum. The cDNA library of P. colubrinum constructed in lTriplEx2 when screened with radiolabelled hmgr amplicon, yielded positive signals. Attempts are being made to isolate full length gene from these clones, which could be later used for imparting biotic stress tolerance to cultivated crop species.

Recurrent selection is a method of breeding applicable to cross-pollinated crops, designed to concentrate favourable genes scattered among a number of individuals by selecting in each generation among the progeny produced by mating inter se of the selected individuals (or their selfed progeny) of the previous generation. The concept of recurrent selection grew out of need to increase the number of superior genotypes that could be obtained from breeding stock of corn. This could have been possible by increasing the frequency of superior genes in the gene pool and by increasing the chances for genetic recombination to occur. The original idea behind recurrent selection was proposed first by Hayes and Gerber in 1919 and independently by East and Jones in 1920. Jenkins (1940) was the first to describe the method in detail and Hull (1945) proposed the name ‘recurrent selection’. Each cycle of recurrent selection requires:

Cropping system is defined as the cropping pattern followed on a farm and its interactions with farm resources, other farm enterprises and production technology. The yearly sequence and spatial arrangement of crops and fallow on a given area is termed as cropping pattern.

India has over 17% of world’s population living on 2.4% of the world’s geographical area. Per capita agricultural land has reduced by 67% from 0.48 ha in 1951 to 0.16 ha in 2008 due to explosive increase in population. In this situation, it is very difficult to get horizontal expansion in vegetable cultivation. Hence, total production per unit area can be increased by increasing the productivity per unit area through (a) growing improved high yielding varieties and hybrids, (b) adequate and scientific crop management practices and (c) increasing cropping intensities following different cropping patterns.

Any organism with other than two basic sets of chromosomes, that is, monoploid, triploid, tetraploid, and various aneuploids is termed as polyploid. There are several economically important crops which are natural polyploids emphasizing the economic importance of polyploids in agriculture. These are:

Triploid-Banana

Autotetraploid-Alfalfa, potato, coffee, peanut or groundnut Autohexaploid- Sweet potato

Amphidiploid/allopolyploid-Wheat, cotton, oats, Brassica species (B. carinata- Ethiopian mustard, B. juncea-Indian mustard, B. napus--rapeseed), sugarcane

Man-made commercially successful allopolyploid- Triticale

1. Stem rot / Foot rot/Collar rot
Diagnostic Symptoms
• The appearance of water-soaked spots on the stem close to ground level is what characterizes it.
• The tissues degrade as a result of the fast enlargement of these patches, girdling the stem and turning it dark brown or black.
• Strong winds cause these afflicted plants to topple over and eventually die.
• If the disease attack is not too severe, the plants will still be stunted and only one side of the stem will decay.
• If fruit develops, it is deformed and withered.
• The plant eventually dies (Fig.1).
Etiology
• Pathogen: Pythium aphanidermatum.
• Mycelium is colorless, slender, coenocytic, profusely branching and rapidly growing mostly intracellularly.
• Sporangia terminal or intercalary produce a vesicle at the end of hyphal branch.
• Zoospores biflagellate and reniform.

ABSTRACT

Basic understanding of plant cell proliferation and differentiation is essential for applying modern techniques of genetic transformation. The lack of understanding about the physiological and molecular mechanisms underlying in vitro morphogenesis, together with the non-availability of reliable morphogenetic markers, is one of the most serious constraints for application of gene transfer technology to plant improvement. Plant tissue culture has therefore remained an empirical science. In recent years, concerted efforts are being made to understand the molecular control of cell differentiation. In light of this, present work was carried out to study the role of CKI1 (cytokinin independent 1) gene, one of the genes implicated in shoot regeneration, by transforming the tomato cotyledons through Agrobacterium mediated transformation with two different gene constructs one with CKI 1 gene and another without CKI1 gene. In both the constructs, nptII gene was used as a selectable marker. Transformation of tomato cotyledon explants with CKI 1 gene resulted in higher regeneration of putative transformant s (8.0%) as compared to transformation of explants without CKI1 gene (2.1%). The results show that CKI1 gene has a role in increasing the regeneration frequency in tomato.

ABSTRACT

Astudy was undertaken with the main objective to standardise the Agrobacterium mediated genetic transformation technique in Dendrobium Sonia 17. Protocorms and protocorm like bodies (PLBs) of Dendrobium orchid were transformed by Agrobacterium tumefaciens strains LBA4404 and EHA105 harbouring the plasmids pCAMBIA2301, pCAMBIA1301 and PBI121. The PLBs were generated in vitro by culturing the shoot apices in half strength MS medium. The protocorms were obtained by culturing the seeds in vitro. The sensitivity of orchid tissues to various antibiotics viz., ampicilin, rifampicin, cefotaxime, carbenicillin, kanamycin and hygromycin was evaluated to use the antibiotics as selection agents. The sensitivity was studied in detail by scoring the tissues, based on the morphological changes as those remaining fully green, partially discoloured, bleached, completely turning brown and dead. The various requirements for transformation viz., the type and size of explant, infection time, wounding, co-cultivation and incubation period, concentration of acetosyringone required, elimination of bacteria, and the selection of transformants were optimised to establish a successful transformation system. The pre- cultured explants were mixed thoroughly by gentle swirling with the bacterial cells obtained by centrifuging the bacterial suspension, and also with the bacterial suspension diluted to 1/5 with fresh medium. Then the explants were cocultivated with the bacteria for 2 days at 28°C. The transformation was performed through two consecutive stages of cultivation, the first stage on half strength MS medium containing cefotaxime and subsequent stage on selection medium containing kanamycin. Initially recovered PLBs following co-cultivation, were allowed for further selection with kanamycin. New PLBs and leaves were formed from the transformed PLBs when they were regenerated under kanamycin selection. Successful transformants were obtained with a maximum transformation efficiency of 3.0 per cent with the addition of acetosyringone 100 mM. Out of the kanamycin resistant PLBs 69.23 per cent were GUS positives. The newly formed PLBs and leaves when subjected to histochemical GUS assay indicated successful transformation and it was detected as distinct blue spots on the PLBs after 24’ hours. The PLBs which were not co-cultivated with Agrobacterium were green in colour. The transformation were further confirmed by PCR analysis.

1. SEED STORAGE

Is the maintenance of high seed germination and vigour from harvest until planting.

1.1. Importance of seed storage

Seed storage is important to get adequate plant stands in addition to healthy and vigorous plants.

ABSTRACT

Cassava has developed importance mainly as an industrial crop due to its ability to store large quantities of starch (74% to 85% of dry weight) within secondary root structures. Cassava starch is exploited as a source of human food, feed for livestock and as raw material for the food processing and chemical industries. Research accomplishments during the last four decades helped India to have the top position among cassava growing countries with an average yield of 24 t ha-1. However several traits like starch quality, high protein , post harvest deterioration etc can be altered only through the development of transgenics. The present study summarizes the results of the experiments undertaken to optimize the protocol for the development of transgenic cassava through Agrobacterium mediated gene transfer. Friable Embryogenic Callus (FEC) was developed in the cassava var. TMS 60444 us ing Murashige and Skoog (MS) media with picloram (50μM). Experiments were conducted to study the efficiency of different Agrobacterium stains viz, AGL 8, GV3101, C58C1, LBA 4404 and EH105 in transforming FEC. The strains differed in their growth rate. The strains EH105 and AGL were slower in growth as compared to other strains and the protocol was modified accordingly. Among all the strains, EH105 resulted in maximum recovery of transgenic tissues. The paper also summarizes the present status of development of transgenic cassava along with future thrusts.

1) Bud Rot
Diagnostic Symptoms
• Severe on young palms.
• Yellowish green discoloration of the heart leaf or crown leaf.
• The basal tissues of the leaf rot quickly and can be easily separated from the crown.
• Spindle withers and droop down.
• Older leaves develop irregular, water soaked spots which are sunken in nature.
• The leaves and sheath in the central spindle fall off leaving an outer whorl of green leaves.
• The withered central shoot can be pulled out very easily from the crown.
• The central crown may rot and in few months the tree may wilt.
• Young nuts fail to mature and fall (Fig.1).

ABSTRACT

An efficient in vitro micro propagation protocol was developed for direct shoot produc tion of Contoloupe (Cucumis melo variety (NS Abhijit) using cotyledons as explant. The excised cotyledons were cultured on Murashige and Skoog’s medium (MS) contain- ing plant growth regulator, 6 Benzyl adenine with various concentrations for the study of shoot production. The best condition for the shoot production was with 1.2mg/l Benzyl adenine (BA) in MS medium. The shooting frequency was 65% and three shoots were obtained from each explant after 14 days of culture. The shoots (~1.5 cm length) were rooted most effectively on 0.1mg/l of α Naphthalene acetic acid (NAA) supplemented MS medium. We have also standardized the transformation protocol for GUS gene in the muskmelon variety Eden Gem to see test the feasibility of this variety for Agrobacterium mediated transformation. The transformed explants were confirmed through Indigogenic GUS assay.

1. SEED INDUSTRY BEFORE INDEPENDENCE

The Royal Commission on Agriculture (RCA) constituted in 1925 suggested the following for seed improvement

There should be a separate organization within agriculture departments to deal with seed distribution and seed testing.

The seed distribution enterprise should be self-sustaining.

Seed distribution should be organized through co-operatives, other associations, seed merchants (whenever they are available), through seed agents, as well as through agricultural department staff and any other agency which could be considered suitable.

Seed merchants of proven enterprise should be given every encouragement.

ABSTRACT

Biofertilizers can supplement the chemical nutrients and helps in reducing the production expenditure in agriculture. Crop biofertilization with microbial consortia is an important strategy to improve the physical, chemical and biological conditions of the soil. The facultative methylotrophs are capable of fixing atmospheric nitrogen, besides it produces phytohormones viz; IAA, GA and cytokinin, vitamin B₁₂, polysaccharides, PHB, and siderophores. The essential nutrients are considered as the most important, among the factors limiting growth and yield of the tomato crop. The application of adequate amount of fertilizers is a pre-requisite for exploiting the genetic potential of tomato variety. Therefore, efficient and economic use of the fertilizer with microbial consortia would help in decreasing the input costs for raising bumper crop.

More number of studies carried out on the effect of facultative methylotrophs in different parts of the world and in India. The results confirmed that the facultative methylotrophs have a greater importance in increasing the growth and yield of various crop plants. Keeping this in view an experiment was conducted to find out the interaction effect of facultative methylotrophs with other bioinoculants viz., Azospirillum, Azotobacter, PSB and VAM (by seedling dip method followed by PPFM phyllosphere spray) on yield of tomato var Ruchi. The results showed that the treatment with above microbial consortia (50.71 t/ha) was found to increase the yield of the tomato crop by 62.73 percent over uninoculated control (18.90 t/ha) and individual treatments.

1. DEFINITION

Seed marketing is the one of the most vital components of seed technology. On it depends the size and scope of the seed industry. Broadly it includes such activities as production, processing, storage, quality control and marketing of seeds.

Seed marketing refers to the actual acquisition and selling of packed seeds, intermediate storage, delivery and sales promotional activities.

ABSTRACT

Phytophthora rot is the most destructive disease of black pepper nursery inflicting heavy crop losses. Considering the seriousness of the disease, the present study was undertaken to isolate and select the efficient antagonists from pepper nurseries raised in Government farms at Chelakkara, Pazhayannur, Mannuthy and Pananchery of Thrissur district. A quantitative estimation of the rhizosphere microflora from different nurseries revealed more abundance of soil bacteria followed by fungi and actinomycetes. Based on cultural characters of the rhizosphere microflora, 22 fungi, 20 bacteria and five actinomycetes were selected for further studies. Antagonistic action of soil microflora against Phytophthora capsici was studied by dual culture method in comparison with that of standard culture of T. harzianum. The study revealed that all fungal isolates and five bacterial isolates were antagonistic towards the pathogen with varying degrees. Among the fungal isolates, 13 isolates including T.harzianum recorded cent per cent inhibition of P.capsici. From among the fungal isolates that showed antagonistic reaction in dual culture, further selection of efficient ones was carried out based on the antagonistic index (AI). The isolate 22 F₂ (Trichoderma sp.) showed the maximum AI of 3000 followed by isolate 34 F₂ (Trichoderma sp.) and T. harzianum with an AI of 1500 each. The cultural and morphological characters of the efficient native isolates (22 F₂ and 34 F) were studied and were identified as Trichoderma longibrachiatum Rifai aggr. and Trichoderma viride Pers. ex S.F. Gray aggr. The three antagonists were found parasitic on P.capsici as evidenced by excessive coiling, penetration and disintegration of the hyphae and thereby these Trichoderma spp. used in the study is found to have effective parasitic effect on the pathogen in addition to some degree of antibiosis and these fungi could be utilised for the management of Phytophthora rot in black pepper nursery.

ABSTRACT

Studies on the impact of bio-fertilizers with levels of NPK on bulb yield, dry matter production, nutrient uptake and cost: benefit ratio in onion (cv. Bellary Red) were conducted in medium black soils during kharif and rabi seasons of 1999 and 2000 both under irrigated and rainfed conditions at the Agricultural Research Station, Hiriyur located under Central Dry Zone of Karnataka. The treatments were; T₁-Control, T₂-Azotobacter, T₃-Azotobacter+75% N+PK, T₄-Azotobacter +100%N+PK, T₅-Azospirillum, T₆-Azospirillum+75% N+PK, T₇-Azospirillum+100%N+PK, T₈-VAM, T₉-VAM 75% P+NK, T₁₀- VAM+100%P+NK, T₁₁ ? recommended NPK(125:50:125 kgha-1) and T₁₂-75% recommended NPK. The experiments were laid out in RBD in three replications.

The bio-fertilizers Azospirillum brasilence (500g ha-1) and Azotobacter vinelandii(500g ha-1) were applied to seedlings at transplanting separately by dipping the roots in the slurry for 15 minutes. The VAM fungi - Glomus mossae was applied to soil @ 1 kilogram per square meter area of nursery bed. The recommended dose of FYM @ 25 t ha-1 was applied to all the treatments as basal dose.

The results of the investigations revealed that the plants provided with Azospirillum + 100% N+PK (T₇) produced highest bulb yield (250.29;339.02;232.98 q/ha), highest total dry matter production (7053.96;8992.78;6287.03 kg/ha), maximum uptake of N, P a nd K ( 1 5 7 . 8 8 : 7 3 . 5 6 ; 7 0 . 4 6 N PK k g / ha ) , ( 2 0 6 . 8 6 : 9 6 . 2 5 : 9 1 . 1 0 N PK k g / ha ) , (131.81:50.25:71.24 NPK kg/ha) and also the maximum cost:benefit ratio of 4.00 (1:400), 5.42 (1:5.42), 3.94 (1:3.94) under irrigated condition during kharif and rabi seasons and under rainfed situation during kharif season respectively.

Thus, among all the treatments, application of Azospirillum + 100% N + PK (Azospirillum + 125:50:125 NPK kg/ha) was found to be most remunerative considering the nutrient uptake, bulb yield and total dry matter production and cost:benefit ratio, which gave the highest returns. This level can be followed for Bellary Red onion irrespective of seasons both under irrigated and rainfed conditions in the Central Dry Zone of Karnataka.

1) Anthracnose
Diagnostic Symptoms
• All the above ground parts are affected. However, the characteristic symptoms appear on pods.
• On cotyledons, spots are sunken dark brown or black with pink spore mass.
• Seedling infection results in collapse of seedling.
• Spots on leaves appear on lower side and are black. Later these may also appear on upper surface. When the infection is severe, the affected plants wither off.
• Black, sunken, circular spots of varying sizes appear on pods with bright red, yellow or orange margins. The centre of these spots later turns grey or pink due to sporulation of the pathogen. The border of these spots appear raised (Fig.1).

1) Leaf Spot
Diagnostic Symptoms
• Initially oblong brown spots having about 4-5 cm in length and 2-3 cm in width with grey centres surrounded with yellow hallo are found on the leaves.
• Large number of spots may be found on a single leaf and as the disease advances, spots enlarge and cover a major portion of leaf blade.
• Severly affected plants dry and wilt.
• Black dots acervuli formed in concentric rings on spot.The grey centres become thin and get teared(Fig-1).
Etiology
Scientific Classification
Kingdom : Fungi
Division : Eumycota
Sub- division : Deuteromycotina