The G-protein subunits FGA2 and FGB1 play distinct roles in development and pathogenicity in the banana fungal pathogen Fusarium oxysporum f. sp. cubense

The soil-borne fungus Fusarium oxysporum f. sp. cubense causes banana (Musa spp.) vascular wilt. Here, we examine the roles of G-protein α and β subunit genes fga2 and fgb1 in F. oxysporum development and pathogenicity. Deletion of either or both genes led to increased heat resistance, lower cAMP levels, and enhanced pigmentation, whereas phenotypic defects of colony morphology and reduced conidiation were seen in Δfgb1 and Δfga2/Δfgb1 deletion strains but not in Δfga2. Conversely, Δfgb1 retained greater virulence against banana, suggesting that FGA2 regulates fungal virulence whereas FGB1 modulates both development and virulence, potentially via the cAMP-dependent protein kinase A pathway.     

绿色产业链视角下的蔗糖产业发展探析

工业化推进带来了资源衰竭、环境污染、生态破坏等不良后果．从产业链的整合提升入手,介绍了绿色产业链的内涵、特征,在分析蔗糖产业发展状况及面临问题的基础上,提出构建甘蔗制糖绿色产业链的建议．     

甜高粱茎秆糖产量形成及其调控研究进展

甜高粱茎秆多汁,糖分含量高,是最具有发展前景的绿色能源作物之一。作为重要的生物质能源作物,种植甜高粱的直接目标是获得高的糖产量。     

干巴菌菌丝营养生理特性的初步研究

本文报道了不同碳源、氮源、微量元素及维生素培养基对干巴菌菌丝生长的影响。试验表明，干巴菌菌丝利用最好的的碳源是葡萄糖，其次是蔗糖。利用最好的氮源是硝酸钙，其次是硝酸铵和硫酸铵，对蛋白胨和尿素的利用效果差。缺少碳源或氮源时，菌丝生长细弱、稀少，不形成原基。微量元素和维生素均对干巴菌菌丝生长有促进作用，其中以锰、铜和维生素Ｂ２的作用尤为突出。     

Physiological Factors Limiting Grain Growth in Wheat Ears Cultured in Sucrose Solution

Detached wheat ears (15 days post-anthesis) were cultured in liquid nutrient medium containing different sucrose concentrations (2. 6 and 10%). The volume of solution taken up was highest from 2% sucrose solution and decreased with increasing sucrose concentration. Grain development in terms of grain weight, glumes and rachis weight, nitrogen and protein content showed a linear increase in these variables over 11 days. Dry weight per grain increased with the sucrose level in the medium and the reduced uptake of solution did not decrease the moisture percentage of the grain. The culture of ears decreased the solution pH more with 2% than with 10% sucrose. Addition of 0.5% chloramphenicol to the culture solution had no adverse effect on grain weight, rather it prevented contamination and maintained a higher pH of the solution.     

Solute Accumulation as a Cause for Quality Losses in Sugar Beet Submitted to Continuous and Temporary Drought Stress

Adaptation to low water availability in sugar beet includes the accumulation of solutes relevant for the technical quality of the beet. Two sugar beet genotypes were grown in pot experiments under drought stress of different severity to study effects on taproot composition and concentration of solutes relevant for technical quality, reversibility of drought effects after re‐watering and genotypic differences in drought response. Differences in stress sensitivity between the genotypes were not observed as reductions in taproot and leaf dry weight and white sugar yield were the same. Increasing dry matter concentration with decreasing water supply could, in part, be attributed to an increase in the concentration of cell wall components. The major solutes in the taproot were sucrose, potassium, amino N (the sum of amino acids) and betaine. Sucrose concentration decreased considerably under drought, indicating limited availability of assimilates. In contrast, all further solutes increased in concentration with increasing severity of stress. However, the response of individual solutes varied largely. Changes in amino N and nitrate were most pronounced and probably reflect accumulation of non‐utilized metabolites under limited growth. The drought‐induced accumulation of taproot solutes implicates a considerable decrease in the technical quality of the beet. It was only in part reversible by re‐watering. Genotypic variability for solute accumulation under water deficiency was observed but was not linked to drought tolerance.     

Plant Regeneration from in vitro Cultured Anthers of Black Mustard (Brassica nigra Koch)

Anthers of Brassica nigra, excised from fresh as well as cold-pretreated (3 days at 3 ± 2°C) buds cultivated on modified B₅ medium (Gamborg et al. 1968) containing sucrose level varying from 2 % to 10 %, along with 1O^?6M BAP (benzylaminopurine) and 9 × 10^?6M 2,4-D (2,4-dichlorophenoxyacetic acid), developed calli and/or embryos. The latter response was observed only in anthers reared on media containing 6 % or higher levels of sucrose. On media containing two or four per cent sucrose, the anthers produced calli, exclusively. The growth of embryos was inhibited or else they started callusing if left on the media containing higher levels of sucrose. However, on transfer to MS medium (Murashige and Skoog 1962), containing 2 % sucrose, embryos started callusing and subsequently a few secondary embryos differentiated. Such embryos were sub-cultured on MS + 5 × 10^?6M BAP + 2 % sucrose, wherein numerous shoots developed from embryos. The shoots were rooted by transferring to a medium containing 5 × 10^?6M NAA (naphthalene acetic acid). Within two months of culture, some of these plants started flowering in vitro.     

甘蔗增糖增产剂试验结果

１９９３年９月下旬至１０月中旬，采用广西农业大学研制、生产的甘蔗增糖增产剂在对旱地和水田蔗的５个品种进行试验，喷药后４０～９０ｄ测定１３个点的甘蔗蔗糖分，平均比对照提高１．３０％（绝对值），甘蔗产量增加５８５０ｋｇ／ｈｍ２；８月份和９月份追施氮肥的甘蔗增糖增产较显著，甘蔗蔗糖分提高１．６９％（绝对值），增产１０３５１．５ｋｇ／ｈｍ２；８月份和９月份不追肥的甘蔗．喷施增糖增产剂的效果相对较差。平均来说，糖厂增利２５８２．２５元／ｈｍ２，农民增收８１９元／ｈｍ２。     

Potato tuber sugars, starch and organic acids in relation to ozone exposure

Summary Data from two Swedish and one Finnish open-top chamber experiments were combined to investigate effects of ozone exposure on potato (Solanum tuberosum L.) tuber content of starch, sucrose, fructose, glucose, malic, citric and ascorbic acids. The glucose, fructose and malic acid concentrations showed strong negative correlations with ozone exposure, while citric acid, consistently increased with ozone exposure. No ozone effects could be demonstrated on starch, sucrose or ascorbic acid concentrations. It is discussed to what extent the changes found in potato tuber composition can be explained in terms of ozone effects on tuber maturity. Ozone exposure was expressed as the accumulated exposure over a cut-off concentration of 40 nmol mol⁻¹ (AOT40) and as the accumulated uptake of ozone over an ozone uptake rate threshold of 7 nmol m⁻² s⁻¹ (CUO 7). The difference in ability of the exposure indices to explain observed effects was small.