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Start Over Coverage 121-132

1. Maize F1 hybrid differs from its maternal parent in the development of chloroplasts in bundle sheath, but not in mesophyll cells: Quantitative analysis of chloroplast ultrastructure and dimensions in different parts of leaf blade at the beginning of its senescence

Creator:
Vičánková, A., Holá, D., and Kutík, J.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
chloroplast development, electron microscopy, genetic variability, granal thylakoids, leaf blade heterogeneity, peripheral reticulum, plastoglobuli, starch inclusions, and Zea mays
Language:
Multiple languages
Description:
The quantitative changes of chloroplast ultrastructure and dimensions in mesophyll (MC) and bundle sheath (BSC) cells, associated with the onset of leaf senescence, were followed along the developmental leaf blade gradient of the third leaf of maize (Zea mays L.). To ascertain whether the rapidity of structural changes associated with the transition of chloroplasts from mature to senescent state is a heritable trait, the parental and the first filial generations of plants were used. The heterogeneity of leaf blade, associated with the development of maize leaf (with the oldest regions at the apex and the youngest ones at the base) was clearly discernible in the ultrastructure and dimensions of chloroplasts; however, there were differences in the actual pattern of chloroplast development between both genotypes as well as between both cell types examined. While the course of MC chloroplasts' development at the onset of leaf senescence in maize hybrid followed that of its parent rather well, this did not apply for the BSC chloroplasts. In this case, each genotype was characterized by its own distinguishable developmental pattern, particularly as regards the accumulation of starch inclusions and the associated changes of the size and shape of BSC chloroplasts. and A. Vičánková, D. Holá, J. Kutík.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2. Sap flow in response to rainfall pulses for two shrub species in the semiarid Chinese Loess Plateau

Creator:
Jian, Shengqi, Wu, Zening, Hu, Caihong, and Zhang, Xueli
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
rainfall pulses, sap flow, meteorological factors, loess plateau, Caragana korshinskii, and Hippophae rhamnoides
Language:
Slovak
Description:
Rainfall pulses can significantly drive the evolution of the structure and function of semiarid ecosystems, and understanding the mechanisms that underlie the response of semiarid plants to rainfall is the key to understanding the responses of semi-arid ecosystems to global climatic change. We measured sap flow in the branches and stems of shrubs (Caragana korshinskii Kom. and Hippophae rhamnoides Linn.) using sap flow gauges, and studied the response of sap flow density to rainfall pulses using the ''threshold-delay'' model in the Chinese Loess Plateau. The results showed that the sap flow began about 1 h earlier, and increased twofold after rainfall, compared to its pre-rainfall value. The sap flow increased significantly with increasing rainfall classes, then gradually decreased. The response of sap flow was different among rainfall, species, position (branch and stem) during the pulse period, and the interactive effects also differed significantly (P < 0.0001). The response pattern followed the threshold-delay model, with lower rainfall thresholds of 5.2, 5.5 mm and 0.7, 0.8 mm of stem and branch for C. korshinskii and H. rhamnoides, demonstrating the importance of small rainfall events for plant growth and survival in semi-arid regions.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public