Comparative Analysis of Phytohormone Biosynthesis Genes Responses to Long-Term High Light in Tolerant and Sensitive Wheat Cultivars.

Phytohormones are vital for developmental processes, from organ initiation to senescence, and are key regulators of growth, development, and photosynthesis. In natural environments, plants often experience high light (HL) intensities coupled with elevated temperatures, which pose significant threats to agricultural production. However, the response of phytohormone-related genes to long-term HL exposure remains unclear. Here, we examined the expression levels of genes involved in the biosynthesis of ten phytohormones, including gibberellins, cytokinins, salicylic acid, jasmonic acid, abscisic acid, brassinosteroids, indole-3-acetic acid, strigolactones, nitric oxide, and ethylene, in two winter wheat cultivars, Xiaoyan 54 (XY54, HL tolerant) and Jing 411 (J411, HL sensitive), when transferred from low light to HL for 2-8 days. Under HL, most genes were markedly inhibited, while a few, such as TaGA2ox, TaAAO3, TaLOG1, and TaPAL2, were induced in both varieties. Interestingly, TaGA2ox2 and TaAAO3 expression positively correlated with sugar content but negatively with chlorophyll content and TaAGP expression. In addition, we observed that both varieties experienced a sharp decline in chlorophyll content and photosynthesis performance after prolonged HL exposure, with J411 showing significantly more sensitivity than XY54. Hierarchical clustering analysis classified the phytohormone genes into the following three groups: Group 1 included six genes highly expressed in J411; Group 2 contained 25 genes drastically suppressed by HL in both varieties; and Group 3 contained three genes highly expressed in XY54. Notably, abscisic acid (ABA), and jasmonic acid (JA) biosynthesis genes and their content were significantly higher, while gibberellins (GA) content was lower in XY54 than J411. Together, these results suggest that the differential expression and content of GA, ABA, and JA play crucial roles in the contrasting responses of tolerant and sensitive wheat cultivars to leaf senescence induced by long-term HL. This study enhances our understanding of the mechanisms underlying HL tolerance in wheat and can guide the development of more resilient wheat varieties.

[Studies on the dynamic trends of diosgenin content in vegetative organs of Dioscorea zingiberensis].

Diosgenin was determined by HPLC to study dynamic trend of diosgenin content in vegetative organs especially the rhizome, and the differences of diosgenin content between strains and between male and female rhizomes of Dioscorea zingiberensis C. H. Wright. The results are as follows: Diosgenin content of biennial seedling rhizome is higher than that of annual seedling rhizome; Diosgenin content of biennial rhizome derived from vegetative propagation is higher than that of annual rhizome derived from vegetative propagation; In piebald leaf strain is higher than in green leaf strain; In male is higher than in female. Diosgenin was not detected in twining stem nor in leaf. Diosgenin content of annual rhizome from vegetative propagation increased slowly at early stage, and it increased comparatively quickly at later stage; Diosgenin content of biennial rhizome at the stage of blossom is the highest, and it is the lowest at the later stage of bloom, afterwards it increases gradually. So cultivated variety of higher output and higher fastness should be chosen from the piebald leaf strain. The right time to collect rhizome should be at the stage of twining stem withering.

[Development of aloin cells and accumulation of anthraquinone in aloe leaf].

The development of aloin cells and its relationship with the accumulation of anthraquinone in aloe leaf were investigated with the methods of paraffin section, semi-thin section, histochemistry and fluorescent microscopy. The results showed: cells rounded the procambium bundle differentiated into bundle sheath at the initial stage of procambium bundle developing into vascular bundle. When the sieve tube members appeared in protophloem, there were a lay of procambium bundle cells reserved between the sieve tube members and bundle sheath. These cells began to devise, then developed into aloin cells through enlargement of volume and vacuolization with the differentiation of metaphloem and metaxylem. So the aloin cells were special phloem parenchyma cells because they shared the same origin with the other phloem cells. The investigation of histochemistry reflected that there were aloin precipitate in the central vacuole of aloin cells after the material was soaked in the liquid of 1% lead acetate [Pb (CH3COO)2]. In addition, the yellow fluorescence was observed in aloin cells when the section of fresh material was investigated under the fluorescent microscope with blue light, which suggested the aloin cells of vascular bundles were the mainly storage site of anthraquinone.