Anatomical Adaptation of Schumannianthus dichotomus (Roxb.) Gagnep.: Marantaceae in Dry and Wet Conditions

บทคัดย่อ คล้าน้ำ (Schumannianthus dichotomus (Roxb.) Gagnep.) เป็นพืชใบเลี้ยงเดี่ยวจัดอยู่ในวงศ์ Marantaceae ในธรรมชาติคล้าสามารถเจริญได้ทั้งในน้ำและที่แห้งแล้ง จึงได้ทำการศึกษาวิเคราะห์ลักษณะทางกายวิภาคศาสตร์และการปรับตัวให้เจริญเติบโตได้ในทั้งสองสภาพดังกล่าว โดยเก็บตัวอย่างราก ลำต้นใต้ดิน ลำต้นเหนือดิน และใบมาผลิตเป็นสไลด์ถาวรตามกรรมวิธีพาราฟฟิน การแช่ยุ่ยเนื้อเยื่อ และการฟอกใสตัวอย่าง จากการศึกษาพบกายวิภาคศาสตร์ของคล้าน้ำมีลักษณะที่ผสมผสานกันระหว่างพืชน้ำคือรากมีช่องอากาศใหญ่ ลำต้นใต้ดินมีชั้นเอนโดเดอร์มิส ลำต้นเหนือดินมีเนื้อเยื่อแอเรงคิมาจำนวนมาก ผิวใบมีชั้นคิวติเคิลบาง และลักษณะของพืชแล้งคือลำต้นเหนือดินมีคิวติเคิลหนา มีเซลล์ไฟเบอร์มาก ในใบมีเนื้อเยื่อไฮโปเดอร์มิสที่ทำหน้าที่เก็บน้ำ จากการที่มีลักษณะดังกล่าวจึงทำให้คล้าน้ำสามารถเจริญได้ทั้งในน้ำและบนบก ABSTRACT Schumannianthus dichotomus (Roxb.) Gagnep.is a monocotyledonous plant in the family Marantaceae.  According to the species can naturally grows in both wet and dry conditions, the anatomical character was investigated and analysed. Roots, rhizomes, aerial stems and leaves were prepared into permanent slides using a paraffin method, tissue maceration and tissue clearing techniques. The results revealed that the anatomical character of Schumannianthus dichotomusconsists of both hydrophytic and xerophytic characters. The hydrophytic characters are the presence of large lacunae in root, endodermis in rhizome, aerenchyma in aerial stem, and thin layer of cuticle on the leaf surface. The xerophytic characters are thick cuticular layer, abundant fiber cells in aerial stem, and the presence of hypodermis, a water storage tissue in leaf. Consequently, Schumannianthus dichotomus can normally grow in wet and dry conditions

Isolation and molecular identification of β-carotene producing strains of Dunaliella salina and Dunaliella bardawil from salt soil samples by using species-specific primers and internal transcribed spacer (ITS) primers

Dunaliella salina and Dunaliella bardawil are unique species of the genus Dunaliella that produce large amounts of â-carotene when cultivated under appropriate conditions. These include high light intensity, high sodium chloride concentration, nitrate deficiency and extreme temperatures. Under these conditions, only D. salina and D. bardawil can accumulate â-carotene to as much as 10% of the cellular dry weight. Because the morphological characterization is based on the environmental factors, the Dunaliella will change the shape, so identification and differentiation of Dunaliella species by morphology is very difficult. In this research study, we isolated, identified and discriminated the different Dunaliella β-carotene producing strains from salt soil samples, by using 18S rDNA and internal transcribed spacer (ITS) gene sequences. The soil samples were collected from four different provinces of the North Eastern part of Thailand.namely: UdonThani, BuriRam, AmnartCharoen and Chaiyaphum. Among the four isolates, only BuriRam KU01 and UdonThani KU01 were D. salina and D. bardawil, respectively whereas AmnartCharoen KU01 and Chaiyaphum KU01 were not these Dunaliella species. At 4 M NaCl, with deficiency of nitrate (KNO3) and phosphate (KH2PO4) in the medium, the D. salina strain BuriRam KU01 produced β-carotene at the level of 56.25 ± 0.97 pg·cell-1 and D. bardawil strain UdonThani KU01 produced β-carotene at the level of 52.91 ± 0.29 pg·cell-1 at the 25th day after inoculation. The 18S rDNA and ITS sequences of D. salina strain BuriRam KU01 and D. bardawil strain UdonThani KU01 were submitted to the National Center for Biotechnology Information (NCBI) database with accession numbers of JN052202, JN052203, JN034031 and JN052204, respectively. By using the species-specific primers and ITS primers the â-carotene producing strains of Dunaliella was identified.Key words: 18S rDNA, β-carotene, carotenoid, Dunaliella bardawil, Dunaliella salina, internal transcribed spacer (ITS), salinity

Short-term physiological responses to drought stress in seedling of tropical and temperate maize (Zea mays L.) cultivars

Understanding of the response of tropical and temperate maize (Zea mays L.) to drought is the first step for tolerant temperate maize improvement. Eight maize hybrids were used to investigate physiology responses under drought stress, four of them were tropical maize and the others were temperate maize. Results showed that there were different drought tolerances but similar trends in both tropical maize and temperate maize. Gas exchange parameters revealed different strategies of maize under the stress. In our study, most of the temperate hybrids maintained open stomata to keep a higher photosynthesis rate at the beginning of stress, while the other hybrids decreased stomatal conductance. Compared to temperate maize, the tropical maize had higher antioxidase activity and greater physiological parameter variation among hybrids. KS5731 and ZD309 had stronger drought resistance among tropical and temperate maize hybrids separately. Tolerant hybrids maintained active photosynthesis, have higher osmotic adjustment ability and antioxidase activities but lower malonaldehyde content than the sensitive ones. Our results led to a better understanding of the physiological responses of tropical and temperate maize plants to drought stress and may provide an insight of breeding for drought resistance in maize

Reproductive organ characteristics and phenology of a seagrass Thalassia hemprichii (Ehrenberg) Ascherson in the Andaman Sea, Thailand

Characteristics of the reproductive organs and phenology of Thalassia hemprichii using samples collected from the Andaman Sea, West coat of Thailand, are described. Permanent slides of specimens were prepared by the paraffin method. Preparations were observed under a stereo microscope and a light microscope. The occurrences of reproductive organs were recorded monthly for one year. Staminate and carpellate flowers are actinomorphic. They have three tepals and are unscented. Secretory cells were found in tepals, connective parenchyma of the anther and ovary wall. The pollen grains are spherical and 30-50 µm in diameter. Numerous long papillae were found on the stigmas. One to nine viviparous seeds were observed per fruit. The reproductive organs occurred in the greatest number during the lowest tides during the night time and when temperatures were 24 to 26 oC (December to March). The reproductive organs tend to change with water depth. They decrease when the water depth increases. The highest number of staminate flowers (168.67±47.05 m-2), carpellate flower (205.67±41.23 m-2) and fruit (161.17±31.16 m-2) were found at 1.5 m above lowest low water (LLW)

<span style="font-size:15.0pt;mso-bidi-font-family:"Times New Roman";mso-bidi-font-weight: bold" lang="EN-GB">Screening, phenotypic and genotypic identification of β-carotene producing strains of <i style="mso-bidi-font-style:normal">Dunaliella</i> <i style="mso-bidi-font-style:normal">salina</i> from Thailand </span>

2198-2216<i style="mso-bidi-font-style: normal">Dunaliella salina is a salt-loving microalga that accumulates high amounts of β-carotene when cultivated under unfavorable conditions. In this study we aimed to screen <span style="mso-bidi-font-weight:bold; mso-bidi-font-style:italic">β-carotene producing strains of D.salina <span style="mso-bidi-font-style: italic">from salt soil samples collected from 19 provinces in the northeastern part of Thailand. For preliminary screening 70 pure isolated strains were screened by using 18S rDNA conserved primers (MA1&MA2), only 15 isolates produced a band (~2100 bp) as that of <i style="mso-bidi-font-style: normal">D.salina.  For the o<span style="mso-bidi-font-style: italic">bservation of β-carotene production, these 15 isolates were grown on agar plate containing modified Ramaraj medium with 1.0 M NaCl under continuous illumination.  After a month only 3 isolates completely turned red. However, by using the banding pattern produced by 18S rDNA primers, the 15 isolates could not be differentiated between the β-carotene and non β-carotene producing strains. Comparing the above results we found that the <span style="mso-bidi-font-style: italic">observation of β-carotene production on agar plate is more easy and suitable method than molecular technique to screen β-carotene producing strains. Morphological characteristics of the 3 screened Thai isolates clearly delineated that it belongs to the genus Dunaliella. ITS-RFLP banding pattern, 18S rDNA, ITS and RuBisCo large subunit (rbcL) sequences were used to confirm at the species level. These results indicated that these 3 isolates are D.salina and were named <i style="mso-bidi-font-style: normal">D.salina strain KU07, D.salina strain KU11 and D.salina strain KU13. Under non-stress conditions these 3 strains had an ability to accumulate β-carotene up to 5.61±0.25, 7.58±0.19 and 6.73±0.32 pg/cell, respectively. </span