Role of sucrose synthase and invertases during petal senescence in rose (Rosa hybrida L.)

Summary

The roles of sucrose synthase and invertases were explored in relation to petal senescence in rose (Rosa hybrida L.). A developmental shift in the activities of these enzymes was observed. Higher sucrose synthase activity (0.52 – 0.95 µmol sucrose min^–1 mg^–1 protein) was observed during the initial stages (S1 and S2) of flower bud development, in contrast to invertases. However, the lower activity (0.56 µmol sucrose min^–1 mg^–1 protein) of sucrose synthase at a later stage (S6) of senescence could help the mobilisation of vacuolar sucrose. The different isoforms of invertase exhibited variable levels of activity. Insoluble acid invertases (IAI) were the most active (11.01 µmol glucose min^–1 mg^–1 protein), followed by soluble acid invertases (SAI; 8.02 µmol glucose min^–1 mg^–1 protein), and soluble neutral invertases (SNI; 0.74 µmol glucose min^–1 mg^–1 protein) at Stage-4. A significant decline in invertase activities (IAI, 0.98; SAI, 1.25; SNI, 0.32 µmol glucose min^–1 mg^–1 protein) coincided with higher levels of ethylene production at the later stages (S5 and S6) of flower bud development and senescence. We propose that developmental as well as ethylene-mediated pathways account for petal senescence in rose.     

Soil test-based nutrient balancing improved crop productivity and rural livelihoods: case study from rainfed semi-arid tropics in Andhra Pradesh,India

Widespread multinutrient deficiencies in the semi-arid tropics (SAT) are among major factors for large gaps between farmers’ current crop yields and potential yields. In this study, we adopted a stratified soil sampling method to assess soil fertility-related constraints in farmers’ fields in eight districts of Andhra Pradesh in the semi-arid tropics of India. Most of the fields across all eight districts were critical in sulfur (61%–98% deficient fields); and up to six districts each in boron (83%–98% deficient fields), zinc (50–85% deficient fields), and soil organic carbon (55–97% deficient fields). Low soil organic carbon specifically indicates nitrogen deficiency. Phosphorus deficiency was critical in three districts (60–84%) while potassium in general was adequate. Soil test-based nutrient balancing through the application of sulfur, boron, and zinc in addition to farmers’ practice of adding only nitrogen, phosphorus, and potassium increased crop productivity by 8%–102%. Benefit–cost ratio (1.60–28.5) proved favourable to scale-up balanced nutrition. Better post-harvest soil health and residual benefits of sulfur, boron, and zinc up to four succeeding seasons indicated sustainability of the practice. Results showed that balanced nutrition is a way forward for sustainably improving farm productivity and livelihoods.     

The potential of entomopathogens in biological control of white grubs

Abstract

White grubs are highly polyphagous and most destructive soil pests inflicting damage to a wide variety of crops. In India, more than 1000 species of white grubs are known of which over 40 species attack wide range of plants. White grubs are naturally infected by various entomopathogens which include fungi, bacteria and nematodes. Entomopathogenic fungi offer great potential and members of genera Beauveria and Metarhizium are widely used against white grubs. Several commercial products of entomopathogenic fungi like Bio Green, ORY-X, Grub X 10G, Betel, Biotrol FMA and Meta-Guard have been developed for the control of white grubs. In India, good control of white grubs in paddy, ginger and sugarcane has been achieved with different entomofungi. Among EPNs, Heterorhabditis bacteriophora is moderately effective against Popillia japonica and Rhizotrogus majalis. H. indica and H. bacteriophora are effective against potato white grubs in India. Paenibacillus popilliae cause milky disease in P. japonica grubs. The bacterium is pathogenic to Holotrichia consanguinea, H. serrata and Leucopholis lepidophora. In north-western Himalaya, B. cereus is highly toxic to the grubs of H. seticollis and Anomala dimidiata.     

EST‐SSR analysis provides insights about genetic relatedness,population structure and gene flow in grass pea (Lathyrus sativus)

Grass pea (Lathyrus sativus) is an important food‐legume crop for resource‐poor farmers in the developing world. However, given its cultivation in the most underprivileged regions, the crop has not received appropriate scientific attention particularly from the genomic perspective, thereby giving it a status of genomic orphan. Nevertheless, some recent studies have attempted to develop modern molecular tools to strengthen the genetic and genomic research. In the present investigation, a comprehensive collection comprising 176 accessions was analysed using EST‐simple sequence repeats (SSRs). The SSR analysis revealed existence of a total of 51 alleles with an average polymorphic information content value of 0.35. A moderate level of gene diversity was noticed that ranged from 0.04 to 0.73 with an average of 0.43. Noticeably, two distinct subpopulations were recovered using cluster analysis. In addition, the presence of admixtures in population reflected the strong possibilities of gene flow between the accessions across the geographical boundary. In summary, we provide additional insights about the informativeness of available EST‐SSR markers along with an extended understanding of relatedness, genetic structure and gene flow in an under‐researched legume crop.     

Demographics and functional response of Blaptostethus pallescens preying on Tuta absoluta

Phytoparasitica - In order to enhance the ecofriendly management of Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), we studied the demographics and functional response of Blaptostethus...     

Brassica coenospecies: a rich reservoir for genetic resistance to leaf spot caused by Alternaria brassicae

Development of leaf spot resistant mustard cultivars is a relevant objective in view of heavy crop losses caused by this pathogen. Thirty-eight species belonging to 9 genera, including cultivated and wild allies, of the genus Brassica were evaluated under epiphytotic conditions for two years. Inoculations were done on whole plants (in vivo) and on detached leaves (in vitro). Data on incubation period, number of lesions per leaf, lesion size and leaf area covered by lesions were recorded. Species which never produced disease symptoms throughout the growing period in pots and until 72 hours after inoculation in detached leaf assays during both years were treated as resistant, while those that produced symptoms were classified as moderately resistant, susceptible or highly susceptible depending upon incubation period, size of lesions and leaf area covered by disease symptoms. Eight species (Brassica desnottesii, Camelina sativa, Coincya pseuderucastrum, Diplotaxis berthautii, D. catholica, D. cretacea, D. erucoides, and Erucastrum gallicum) were found completely resistant, whereas others were classified as moderately resistant (12), susceptible (11) or highly susceptible (9). Since resistance is unavailable within the cultivated species, these 8 resistant wild species could be used as donor parents for introgressing resistance to leaf spot disease in Indian mustard. This revised version was published online in August 2006 with corrections to the Cover Date.     

Optimizing seed quality during germplasm regeneration inpearl millet

The effect of water stress during flowering and grain filling on seed longevity was studied in three pearl millet genotypes,ICTP-8202, ICTP-8203 and MBH-110. The seeds were produced by three pollination methods; open pollination, selfing(individual panicles enclosed in paper bags), and cluster bagging (panicles from 3–4 adjacent plants enclosed in a paper bag), stored in air-tight plastic bottles underambient conditions (20–40°C,30–80%RH) and germination was tested at 12-month'sintervals. The seeds lost germination completely after six years ofstorage in all treatments. Analysis of variance of the estimates of potential seed longevity (i.e. the seed lot constantK _i of the seed viabilityequation) showed significant effects of water stress andpollination method (P < 0.01). The interaction between irrigation treatment and method of pollination control was also significant (P < 0.05). Averaged over genotypes and pollination methods,potential longevity was greatest(K _i = 2.8) in theirrigated control, and averaged over genotypes and irrigationtreatments, it was greatest (K _i= 3.1) in seeds produced by open pollination. Theimplications of these results were discussed in relation to germplasmseed production.     

Analysis of association between various fertility indicators and production traits in Mehsana buffaloes

Tropical Animal Health and Production - Female fertility in domestic animals in India has exhaustively suffered owing to indiscriminate breeding with single objective of increasing milk production....     

Antioxidant Capacity and Phenolics Content of Apricot (<Emphasis Type="Italic">Prunus armeniaca</Emphasis> L.) Kernel as a Function of Genotype

Fourteen apricot genotypes grown under similar cultural practices in Trans-Himalayan Ladakh region were studied to find out the influence of genotype on antioxidant capacity and total phenolic content (TPC) of apricot kernel. The kernels were found to be rich in TPC ranging from 92.2 to 162.1 mg gallic acid equivalent/100 g. The free radical-scavenging activity in terms of inhibitory concentration (IC₅₀) ranged from 43.8 to 123.4 mg/ml and ferric reducing antioxidant potential (FRAP) from 154.1 to 243.6 FeSO₄.7H₂O μg/ml. A variation of 1–1.7 fold in total phenolic content, 1–2.8 fold in IC₅₀ by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and 1–1.6 fold in ferric reducing antioxidant potential among the examined kernels underlines the important role played by genetic background for determining the phenolic content and antioxidant potential of apricot kernel. A positive significant correlation between TPC and FRAP (r = 0.671) was found. No significant correlation was found between TPC and IC₅₀; FRAP and IC₅₀; TPC and physical properties of kernel. Principal component analysis demonstrated that genotypic effect is more pronounced towards TPC and total antioxidant capacity (TAC) content in apricot kernel while the contribution of seed and kernel physical properties are not highly significant.     

Breeding Potential of Potato Somatic Hybrids: Evaluations for Adaptability,Tuber Traits,Late Blight Resistance,Keeping Quality and Backcross (BC<Subscript>1</Subscript>) Progenies

Ten tetraploid interspecific potato somatic hybrids developed earlier through protoplast fusion between the dihaploid Solanum tuberosum L. ‘C-13’ and the diploid wild species Solanum pinnatisectum Dun. were used in this study. Somatic hybrids and standard control cultivars were evaluated for adaptability, tuber traits, late blight resistance and keeping quality attributes (dormancy, sprouting, weight loss and appearance after 75 days of storage) during two successive winter crop seasons (short-days) in the sub-tropical plains of India, where nearly 90% of India’s potatoes are grown. Somatic hybrids showed medium to good plant vigour and late to very late plant maturity. Though none of the somatic hybrids produced equal or higher tuber yield than the control cultivars, except clone P7, all other somatic hybrids produced significantly higher marketable and total tuber yield after a 90-day growth than the parent C-13. Most of the somatic hybrids possessed higher tuber dry matter concentration, resistance to late blight and better keeping quality attributes than the control cultivars. Notably, the tubers of somatic hybrids showed a tendency for colour change from white to purple on exposure to sunlight. Breeding potential of somatic hybrids was further assessed by crossing them with commonly grown local potato cultivars for the development of backcross (BC₁) progenies. In the hybridization programme, berries were formed while somatic hybrids were used either as male or female parents with common cultivars. Our results revealed that the use of bulk pollen of somatic hybrids not only resulted in higher pollination success but also helped to achieve higher numbers of true potato seeds (TPS) per berry. Despite the formation of berries, TPS was absent in 22 crosses using somatic hybrids as a female or male parent which may be due to ovule or embryo abortions. Segregating BC₁ generations were evaluated under the same sub-tropical conditions for further exploitation in potato breeding. Based on our study, the somatic hybrids P4, P8 and P10 can be utilized for the introgression of important characters such as high tuber dry matter concontration, resistance to late blight and excellent keeping quality attributes into the cultivated potato via conventional breeding methods for cultivar development in the sub-tropical plains of India.