Metal stress is among the important environmental stresses, which influences the growth and development of plants and crops in many areas in the biosphere. Root is an important gate for the absorption of water and mineral nutrition which in many types of lands is also accompanied by a higher concentration of metal elements, either essential (such as Fe, Mn, and Cu) or non-essential metal elements or heavy metals (such as Al, Pb, Hg, Cd, and Ag). In response to metal stress, plant roots sometimes develop a cellular structure to prevent excessive concentration of metal components to avoid toxic effects and cellular damage. Physiological and biochemical responses at the cellular level, which result in ultrastructure changes may occur due to or to avoid the negative effect of metal toxicity. In many cases it was followed by the reduction of root growth followed by discontinuing entirely plant growth. On the other hand, the structural changes are an important part of root mechanism to sustain the plant from metal toxicity. In this chapter, different changes in the cellular ultrastructure resulting from toxic damage or indicating tolerance response to metal stress will be elucidated.

Gold mine wastewater treatment caused all the plants to undergo stress characterized by the increase of malondialdehyde and the decrease of chlorophyll content and leaf growth of R. trisperma, even though there was variation among the varieties. KM2 and KD2 had the best performance among all varieties in response to gold-mine wastewater.

This study aimed to find out the lead tolerance of sengon (Paraserianthes falcataria) seedling based on growth performance, tolerance index, and secretion and accumulation of organic acids content. Seedlings were exposed to lead (Pb) with the concentration of 0, 0.5, 1, 1.5, 5, and 10 mM in liquid nutrient culture for 4 days in order to investigate secretion and accumulation of oxalic, malic, and citric content, and for 15 days to examine growth performance and tolerance index. The result showed that tolerance index and growth performance of sengon seedling were insignificant to the rising of Pb concentration up to 1.5 mM with tolerance index at least 95%, and even caused an increase of fresh weight. However, the tolerance index and growth of sengon decreased significantly due to Pb exposure of 5 and 10 mM. Among the three organic acids, citrate was most dominant as compared to malate and oxalate. Secretion of citrate increased significantly with the rising concentration-1 of Pb 0.5, 1 and 1.5 mM, reaching to 0.464, 0.540, and 0.587 µg m , respectively, or rising according linear line (r = 0.9, p < 0.5). Citrate accumulation showed inconsistent pattern with the rising Pb exposure. The result suggested that sengon seedling have a slightly tolerance to lead by secretion of organic acid especially citric acid.

Setyaningsih L, Wulandari AS, Hamim H. 2018. Growth of typha grass (Typha angustifolia) on gold-mine tailings with application of arbuscular mycorrhiza fungi. Biodiversitas 19: 454-459. Gold mine tailings contain extreme physical and chemical properties, which inhibit plant growth due to lower nutrition and higher heavy metal contaminants. Typha (Typha angustifolia) is type of grass growing well on waterlogged area including tailing dam. The objective of this study was to investigate the effect of arbuscular mycorrhizal fungi (AMF) in combination with compost and soil on the typha growth in gold mine tailings. The study was conducted in greenhouse by inoculating two AMF isolates (Glomus etunicatum and G. manihotis) to typha seedlings grown in pure tailing media, mixed tailing-compost media, and mixed tailing-compost-soil media. The compatibility and growth of typha grass were analysed after 1 month. Results showed that G. etunicatum and G. manihotis application significantly increased AMF colonization of typha roots up to 16.6% and 21.8% respectively. The length, number of leaves and biomass of typha also increased up to 90%, 50% and 97% respectively compared to those without AMF inoculation. G. etunicatum contributed the best growth of typha grown in mixed compost-soil-tailings, resulting in double increase of its length and biomass. The application of G. manihotis did not significantly increase the growth of typha in mixed media; however, under pure tailing, this mycorrhiza had the best induction for typha biomass and leaf number. In general, AMF application increased growth of typha grass in tailings media.

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