Optimal protocol for in vitro polyploid induction of Cymbidium aloifolium (L.) Sw.

BACKGROUND: Cymbidium aloifolium is a popular ornamental flower in Thailand with both economic and medical values. Polyploid induction techniques are used to improve plant quality. This study identified polyploidy levels of C. aloifolium induction by colchicine. Protocorms of C. aloifolium were treated on solid New Dogashima Medium (NDM) with various concentrations of colchicine (0, 0.01, 0.02, 0.03, 0.04 and 0.05% w/v) for 2, 4 and 8 weeks. RESULTS: Colchicine effectively induced plant polyploidy. Tetraploid plants were found after treatment with 0.03% and 0.04% colchicine for 8 weeks, while at increased concentration and duration, survival, response and growth performance decreased. Tetraploid plants showed the lowest growth performance but highest size of stomatal and epidermal cells. Growth performance and leaf surface anatomy data were analyzed by Pearson's correlation and PCA. Results showed that stomatal and epidermal cell sizes had strongly negative correlations with other variables, while HCA revealed that stomatal and epidermal cell sizes of tetraploid plantlets were larger but stomatal and epidermal cell densities decreased when compared with the diploids. CONCLUSION: Colchicine at suitable concentrations and duration produced polyploid plants with alteration of morphological and anatomical traits. This study provides potential information to support orchid quality production as ornamental plants and a source of pharmaceutical raw materials.

Exploring airborne fungal contaminations and air quality pollution in nine ancient stone temples, Surin, Thailand.

This study provided crucial insights into the concentrations of airborne fungi, environmental parameters, and atmospheric pollution in Thailand's ancient stone temples. Airborne fungi were identified based on morphological characteristics. Airborne fungi, meteorological parameters, and atmospheric pollutants concurrently assessed during each sampling event, evaluating indoor/outdoor ratio. Prevalent genera included Penicillium (14.36%), Aspergillus (10.94%), Cladosporium (10.74%), Rhizopus (6.31%), and Fusarium (5.90%), with an average fungi concentration of 4884.46 ± 724.79 CFU/m3. Eighteen fungal species out of the 64 airborne fungi identified were well-known serious pathogenic agents, contributing not only to structural deterioration but also to human health. Significant variations were observed between indoor and outdoor environments and across diverse landscapes, particularly for PM10 (ranging from 43.47 to 121.31 µg/m3) and PM2.5 (ranging from 29.59 to 89.60 µg/m3), with intensive incense burning identified as a prominent source of indoor atmospheric pollution. Historical temples, particularly situated in urban areas, were identified as significant reservoirs of airborne fungi. Correlations between meteorological parameters and pollutants revealed strong associations. Furthermore, principal component analysis (PCA) and cluster analysis elucidated distinct patterns in airborne fungal concentrations and contaminations. This study analyzed environmental factors, pollutants, airborne fungi, and geographical variations from July 2020 to March 2021. Understanding prevalent genera, airborne fungi concentrations, pathogenic species, biodeterioration, and environmental dynamics provided strategies for improving indoor air quality and mitigating airborne fungal contamination in archaeological buildings worldwide.

Salinity Stress Response of Rice (Oryza sativa L. cv. Luem Pua) Calli and Seedlings.

Soil salinity limits plant growth and production. This research investigated a suitable medium for callus induction and plantlet regeneration in the Luem Pua rice cultivar. The effect of salt stress on seedling growth was determined using in vitro culture and soil conditions. An efficient protocol for callus induction has been developed by culture sterilized seeds on the Murashige and Skoog (MS, 1962) medium containing 0.5 mg/l benzyladenine (BA) with 1 mg/l 2,4-dichlorophenoxyacetic acid (2,4-D) that resulted in a 100% callus induction. Plantlet regeneration percentage of 49% was recorded on the MS medium containing 4 mg/l BA with 0.5 mg/l 1-naphthaleneacetic acid (NAA) after 4 weeks. For salt stress investigation, the calli were treated on an induction medium containing various concentrations of NaCl (0, 50, 100, 150, and 200 mM), while two-week-old rice seedlings were planted in soil and treated with the same concentration of NaCl for 4 weeks. In vitro culture revealed that callus survival percentage decreased when NaCl concentration increased, similar to soil culture. Seedling growth under salinity treatment also decreased when NaCl concentration increased, while other physiological parameters such as total chlorophyll, chlorophyll a, chlorophyll b, green intensity, and chlorophyll fluorescence under light conditions increased under salinity stress. These changes define the growth and physiological salinity tolerance characteristics of Luem Pua rice calli and seedlings. They can be utilized as a baseline for demand-driven in vitro rice propagation, providing useful information that can be combined with other agronomic features in rice development or breeding programs to improve the flexibility of abiotic stress-tolerant cultivars.

Effect of Heat Stress on Some Physiological and Anatomical Characteristics of Rice (Oryza sativa L.) cv. KDML105 Callus and Seedling.

Global warming is a serious problem, with significant negative impacts on agricultural productivity. To better understand plant anatomical adaptation mechanisms as responses to heat stress, improved basic knowledge is required. This research studied the physiological and anatomical responses of Khao Dawk Mali 105 (KDML105) to artificial heat stress. Dehusked seeds were sterilized and cultured on Murashige and Skoog (MS) medium, supplemented with 3 mg/L 2,4-Dichlorophenoxyacetic acid (2,4-D) for callus induction. The cultures were maintained at 25 °C and 35 °C for 4 weeks, while the other culture was treated with heat shock at 42 °C for 1 week before further incubation at 25 °C for 3 weeks. Results revealed that elevated temperatures (35 °C and 42 °C) adversely impacted seedling growth. Plant height, root length, leaf number per plant, fresh and dry weight, chlorophyll a, chlorophyll b and total chlorophyll content decreased after heat stress treatment, while malondialdehyde (MDA) and electrolyte leakage percentage significantly increased, compared to the control. Heat stress induced ROS accumulation, leading to lipid peroxidation and membrane instability. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) results also confirmed negative correlations between MDA, electrolyte leakage and other parameters. MDA content and electrolyte leakage are effective indicators of heat stress in rice. Surface anatomical responses of rice seedlings to heat stress were studied but significant alterations were not observed, and heat stress had no significant negative effects on KDML105 calli. Size and mass of calli increased because heat stress stimulated gene expression that induced thermotolerance. Our results provide useful information for rice breeding and heat stress tolerance programs to benefit long-term global food security.

Effect of stress on the leaf anatomy of sugarcane cultivars with different drought tolerance(Saccharum officinarum, Poaceae) / Efecto del estrés sobre la anatomía foliar de cultivares de caña de azúcar con diferente tolerancia a la sequía (Saccharum officinarum, Poaceae)

Introduction: Drought is an important stress factor for sugarcane production in many areas of the world. Water proportion and moisture indices are applicable information for agronomic planning to forecast water excess or deficit during the crop cycle. Objective: Leaf anatomical features of two different sugarcane Saccharum 'UT12' (drought susceptible cultivar) and Saccharum 'UT13' (drought tolerant cultivar) were compared under early drought stress situation between 30 and 90 days after planting. Methods: Forty leaf anatomical features were investigated using peeling and free hand sectioning technique. Results: Some anatomical characteristics showed response to drought stress. Saccharum 'UT12' demonstrated higher sensitivity toward anatomical characteristics than Saccharum 'UT13'. A total of 23 and 15 out of the 40 anatomical characteristics showed significance in Saccharum 'UT12' and Saccharum 'UT13', respectively. Some anatomical features such as cell wall and cuticle thickness, vascular bundle size, stomatal size and density can be used as important markers for drought stress assessment in sugarcane leaf. Conclusions: This is the first report describing comparative leaf anatomy of sugarcane Saccharum 'UT12' and Saccharum 'UT13' in Thailand under drought stress. Results will provide important information to improve adaptation mechanisms of tolerant sugarcane cultivars under initial drought stress situations.

Introducción: La sequía es un factor de estrés importante para la producción de caña de azúcar en muchas áreas del mundo. La proporción de agua y los índices de humedad son información aplicable en la planificación agronómica para pronosticar el exceso o el déficit de agua durante el ciclo del cultivo. Objetivo: Se compararon las características anatómicas de las hojas de dos cañas de azúcar diferentes Saccharum 'UT12' (cultivar susceptible a la sequía) y Saccharum 'UT13' (cultivar tolerante a la sequía) bajo una situación de estrés por sequía temprana entre 30 y 90 días después de la siembra. Métodos: Se investigaron las características anatómicas de cuarenta hojas utilizando la técnica de seccionamiento de pelado y manos libres. Resultados: Algunas características anatómicas mostraron respuesta a estrés por sequía. Saccharum "UT12" demostró una mayor sensibilidad hacia las características anatómicas que Saccharum 'UT13'. Un total de 23 y 15 de las 40 características anatómicas mostraron significancia en Saccharum 'UT12' y Saccharum 'UT13', respectivamente. Algunas características anatómicas como la pared celular y el grosor de la cutícula, el tamaño del haz vascular, el tamaño y la densidad de los estomas se pueden utilizar como marcadores importantes para evaluar el estrés por sequía en la hoja de caña de azúcar. Conclusiones: Este es el primer reporte que describe la anatomía comparada de la hoja de la caña de azúcar Saccharum 'UT12' y Saccharum 'UT13' en Tailandia bajo estrés por sequía. Los resultados proporcionarán información importante para mejorar los mecanismos de adaptación de cultivares tolerantes de caña de azúcar bajo situaciones iniciales de estrés por sequía.