A simple method for the extension of shelf life of cultures of Phytophthora species causing black pod disease of cacao (Theobroma cacao L.)

Black pod disease of cacao caused by Phytophthora palmivora and Phytophthora megakarya in Ghana take heavy toll of cacao production in the field. Intensive research has been carried out worldwide on these pathogens. However, viability of the cultures during prolonged storage has remained a major challenge in the research. This paper reports findings of assessment of six storage media viz sterilised distilled water (SDW), sterilised and unsterilized soil suspension (SSS and USS), vegetable 8 juice broth (V8JB), Oat Meal Agar slant under mineral oil (at 4°C) and empty tube. Viability of the cultures was assessed on V8JA and in tetrazolium chloride test. Ability of zoospores of the cultures to infect cacao leaf discs was used to assess growth vigour and pathogenicity. Phytophthora cultures stored in SDW (26 ± 2°C; alternating day light and night) were preserved for 60 days (5 years). Both P. palmivora and P. megakarya performed better on SDW and SSS than on USS due to removal of staling substances in the soil medium by the sterilisation. Vigour of growth and pathogenicity of the stored cultures required re-inoculation of host tissue (cacao pod) in order to maintain potency to continually infect host.

Genome Wide Identification of Cotton C-Repeat Binding Factor (CBF) and Overexpression of Gthu17439 (GthCBF4) Gene Confer Cold Stress Tolerance in Arabidopsis Thaliana

Low temperature is a common biological abiotic stress in major cotton growing areas. Cold stress significantly affects the growth, yield and yield quality of cotton. Therefore, it is important to develop a more robust and cold stress tolerant cotton germplasms. Climate change and erratic climatic condition, plants have evolved various survival mechanisms, one of which induction of various stress responsive transcriptome factors, such as the C-repeat binding factor GthCBF4, which have been found to enhance cold tolerance in various plants. In this study detailed evaluation of the cotton C-repeat binding factor has been carried out. A total of29, 28, 25, 21, 30, 26 and 15 proteins encoded by the C-repeat binding factor were identified in G. herbaceum, G. arboreum, G. thurberi, G. raimondii, G. turneri, G. longicalyx and G. australe, respectively. Phylogeny evaluation revealed that the proteins were grouped into seven clades, with clade 1 and 6 being the largest. Moreover, majority of the proteins encoded by the genes were predicted to be located within. the nucleus, while some are distributed in other parts of the cell. Based on the transcriptome and RT-qPCR analysis, Gthu17439 (GthCBF4) was highly upregulated and was further validated through forward genetics. The Gthu17439 (GthCBF4) overexpressed plants showed a significantly tolerance to cold stress, with higher growth vigour compared to the wild types. The results showed that the Gthu17439 (GthCBF4) could be playing a significant role in enhancing cold stress tolerance in cotton and can be further exploited in developing a more cold stress tolerance cotton germplasm

Aspects influencing the rootstock – scion performance during long term evaluation in pear orchard

During 1999–2016, the performance of ‘Red Bartlett’, ‘Conference’ and ‘Beurré Alexander Lucas’ grafted on four pear (Pyrus) rootstocks OH × F 69, OH × F 87, OH × F 230, OH × F 333 and on quince (Cydonia) rootstock BA 29 was evaluated at the RBIP Holovousy Ltd. For each combination, trunk cross-section area, cumulative yield, yield efficiency and mean fruit weight were assessed. The growth vigour of the scion cultivars on OH × F rootstocks was similar or slightly higher comparing to the growth on BA 29. Throughout the years, the growth vigor and productivity of the rootstock combinations may change. Less vigorous combinations of rootstock/scion were linked with higher yields in young trees, but usually with just moderate yields in later seasons. By contrast, combinations with higher growth vigour had usually higher yields in the later seasons. This balance is genotype specific, where aside of rootstock an important role is played by the scion cultivar vigour. The bearing precocity may be influenced by the cultivar as well. The results can vary with different climatic conditions and orchard management.