β-Amylase Is Predominantly Localized to Plastids in the Developing Tuberous Root of Sweet Potato

Starch degradation in cells is closely associated with cereal seed germination, photosynthesis in leaves, carbohydrate storage in tuber and tuberous roots, and fleshy fruit development. Based on previously reported in vitro assays, β amylase is considered as one of the key enzymes catalyzing starch breakdown, but up to date its role in starch breakdown in living cells remains unclear because the enzyme was shown often extrachloroplastic in living cells. Recently we have shown for the first time that β_amylase is predominantly immuno_localized to plastids in living cells of developing apple fruit. But it remains to know whether this model of β_amylase compartmentation is more widespread in plant living cells. The present experiment, conducted in tuberous root of sweet potato ( Ipomea batatas Lam. cv. Xushu 18) and via immunogold electron_microscopy technique, showed that β amylase visualized by gold particles was predominantly localized in plastids especially at periphery of starch granules, but the gold particles were scarcely found in other subcellular compartments, indicating that the enzyme is subcellularly compartmented in the same zone as its starch substrates. The density of gold particles (β amylase) in plastids was increasing during growing season, but the predominantly plastid_distributed pattern of β amylase in cells was shown unchanged throughout the tuberous root development. These data prove that the enzyme is compartmented in its functional sites, and so provide evidence to support the possible widespread biological function of the enzyme in catalyzing starch breakdown in plant living cells or at least in living cells of plant storage organs.

Screening and Breeding of Sweetpotato Varieties Suitable for Mechanical Harvesting

The lower degree of mechanical harvesting is a bottleneck hindering the healthy development of sweetpotato industry in China, while the mismatching be- tween agricultural machinery and agronomy is one of the main factors for poor me- chani.cal harvesting. In this study, total five sweetpotato varieties were selected, and the effects of different shapes and sizes on mechanical harvesting of sweetpotato were investigated. The results showed that the breakage rate of Xuzishu 5 was lowest, so it is more suitable for mechanical harvesting in field. At the same time, the correlations between sweetpotato shape, breakage rate and exposure rate were analyzed. It was found that there was a significant linear correlation between sweet- potato shape and breakage rate （P〈0.01）; the higher the flat rate is, the higher the breakage rate is; and sweetpotato shape had no significant effect on exposure rate. Therefore, tuberous root with lower flat rate, as well as better agronomic characters should be selected in the breeding process of new sweetpotato varieties.

Effects of Soil Aeration on Sweet Potato Yield and Its Physiological Mechanism

The effects of soil aeration on physiological characters and root tuber yield of Ipomoea batatas (L.) Lam. CV Lushu7 and Xushu18 were studied. The results showed that soil aeration improvement could increase ATP content and ATPase activity in functional leaves and root tubers and ABA content in root tubers. It also accelerated the transportation of 14C-photosynthate from leaves to root tubers and enhanced dry matter distribution in root tubers and thus root tuber yield was significantly raised. The role of ATP, ATPase and ABA in accelerating the transportation of 14C-photosynthate was discussed based on the changes of soluble carbonhydrate content in sweet potato plant.

A Preliminary Study on the Infrared Spectra Characteristics of Radix Chuanmingshinis Violacei

[Objectives] To carry out infrared spectroscopic study of different growth years and different parts of the traditional Chinese medicine Radix Chuanmingshinis Violacei. [Methods]Using potassium bromide squash method and Fourier transform infrared spectroscopy on the different growth years and different parts of Radix Chuanmingshinis Violacei for infrared spectrum and second derivative spectrum. [Results]With the increasing growth time,Radix Chuanmingshinis Violacei accumulated in the secondary metabolism substances gradually increased,the characteristic absorption peak appeared in the position such as 3 366,2 927,1 634,1 416,1 516,1 080,1 020,and 928 cm^(-1),the main chemicals as polysaccharide,coumarin,saponins and steroids. The difference of chemical position between root tuber and cauline leaf is obvious. [Conclusions]Infrared spectroscopy was applied in studying different growing periods and different parts of Radix Chuanmingshinis Violacei,of obvious characteristics,identification and quality evaluation method,is simple and suitable for Radix Chuanmingshinis Violacei.

Influence of biochar on growth performances,yield of root and tuber crops and controlling plant-parasitic nematodes

Root and tuber crops are important sources of food and provide income for millions of people worldwide besides an observed high demand for organically produced harvests.Hence,recent attention has been given to utilizing biochar,a carbon-rich material produced from the pyrolysis of organic materials,which improves soil structure,water-holding capacity,and nutrient availability,as an amendment to produce organic root and tuber crops.These effects are caused by the formation of organic coatings on the surface of biochar,which decreases hydrophobicity and increases the ability to retain nutrients,acting as a slow-release mechanism delivering nutrients dependent on plant physiological requirements.However,comprehensive studies on the impact of biochar application on root and tuber crop growth,productivity,and effectiveness in eliminating soil parasites have not been extensively studied.Thus,the purpose of this review is to explore the use of biochar and biochar-based soil amendments and their potential applications for improving the growth,yield,and efficacy of controlling parasitic nematodes in a wide range of root crops.Most of the studies have investigated the effects of biochar on cassava,sweet potatoes,and minor root crops such as ginger and turmeric.It has been observed that biochar application rates(5-20 t ha^(−1))increase the vine length and the number of leaves,tubers,and tuber weight.The addition of biochar demonstrates the ability to control plant-parasitic nematodes in a rate-dependent manner.While biochar has shown promising results in improving crop growth and yield of limited root and tuber crops based on a few biochar types,ample opportunities are around to evaluate the influence of biochar produced in different temperatures,feedstock,modifications and controlling parasitic nematodes.