The PTI1-like kinase ZmPti1a from maize (Zea mays L.) co-localizes with callose at the plasma membrane of pollen and facilitates a competitive advantage to the male gametophyte

BACKGROUND: The tomato kinase Pto confers resistance to bacterial speck disease caused by Pseudomonas syringae pv. tomato in a gene for gene manner. Upon recognition of specific avirulence factors the Pto kinase activates multiple signal transduction pathways culminating in induction of pathogen defense. The soluble cytoplasmic serine/threonine kinase Pti1 is one target of Pto phosphorylation and is involved in the hypersensitive response (HR) reaction. However, a clear role of Pti1 in plant pathogen resistance is uncertain. So far, no Pti1 homologues from monocotyledonous species have been studied. RESULTS: Here we report the identification and molecular analysis of four Pti1-like kinases from maize (ZmPti1a, -b, -c, -d). These kinase genes showed tissue-specific expression and their corresponding proteins were targeted to different cellular compartments. Sequence similarity, expression pattern and cellular localization of ZmPti1b suggested that this gene is a putative orthologue of Pti1 from tomato. In contrast, ZmPti1a was specifically expressed in pollen and sequestered to the plasma membrane, evidently owing to N-terminal modification by myristoylation and/or S-acylation. The ZmPti1a:GFP fusion protein was not evenly distributed at the pollen plasma membrane but accumulated as an annulus-like structure which co-localized with callose (1,3-β-glucan) deposition. In addition, co-localization of ZmPti1a and callose was observed during stages of pollen mitosis I and pollen tube germination. Maize plants in which ZmPti1a expression was silenced by RNA interference (RNAi) produced pollen with decreased competitive ability. Hence, our data provide evidence that ZmPti1a plays an important part in a signalling pathway that accelerates pollen performance and male fitness. CONCLUSION: ZmPti1a from maize is involved in pollen-specific processes during the progamic phase of reproduction, probably in crucial signalling processes associated with regions of callose deposition. Pollen-sporophyte interactions and pathogen induced HR show certain similarities. For example, HR has been shown to be associated with cell wall reinforcement through callose deposition. Hence, it is hypothesized that Pti1 kinases from maize act as general components in evolutionary conserved signalling processes associated with callose, however during different developmental programs and in different tissue types

The maize (Zea mays L.) roothairless3 gene encodes a putative GPI-anchored, monocot-specific, COBRA-like protein that significantly affects grain yield

The rth3 (roothairless 3) mutant is specifically affected in root hair elongation. We report here the cloning of the rth3 gene via a PCR-based strategy (amplification of insertion mutagenized sites) and demonstrate that it encodes a COBRA-like protein that displays all the structural features of a glycosylphosphatidylinositol anchor. Genes of the COBRA family are involved in various types of cell expansion and cell wall biosynthesis. The rth3 gene belongs to a monocot-specific clade of the COBRA gene family comprising two maize and two rice genes. While the rice (Oryza sativa) gene OsBC1L1 appears to be orthologous to rth3 based on sequence similarity (86% identity at the protein level) and maize/rice synteny, the maize (Zea mays L.) rth3-like gene does not appear to be a functional homolog of rth3based on their distinct expression profiles. Massively parallel signature sequencing analysis detected rth3 expression in all analyzed tissues, but at relatively low levels, with the most abundant expression in primary roots where the root hair phenotype is manifested.In situ hybridization experiments confine rth3 expression to root hair-forming epidermal cells and lateral root primordia. Remarkably, in replicated field trials involving near-isogenic lines, the rth3 mutant conferred significant losses in grain yield

Показатели токсичности промышленных отходов

Безотходное производство - новая тенденция в промышленности всего мира. Продукция, получаемая из вторсырья, считается экологичной. Данное направление приветствуется в обществе. Но прежде чем приступить к переработке любой отход проходит оценку на пригодность для дальнейшего использования и токсичность. В зависимости от класса отхода применяется инструментальные методы (химические, физические и физико-химические) или биологические (биоиндикация, биотетирование).Wasteless production is a new trend in the industry of the whole world. Products derived from recyclables are considered environmentally friendly. This direction is becoming popular. Before recycling wastes pass the toxicity assessment. Permission or renouncemen will be issued after verification. Depending on the class of waste, instrumental methods (chemical, physical and physico-chemical), biological methods (bioindication, biotesting) are used

Novel transgenic rice overexpressing anthocyanidin synthase accumulates a mixture of flavonoids leading to an increased antioxidant potential

In addition to their plant-associated functions, flavonoids act as antioxidants against harmful free radicals in animals. Genetic engineering of food crops for a mix of antioxidant flavonoids is highly beneficial in promoting human health. Anthocyanidin synthase (ANS) is one of the four dioxygenases (DOX) of the flavonoid biosynthetic pathway that catalyzes the formation of anthocyanidins from leucoanthocyanidins. To investigate whether ANS mediates different DOX reactions of the pathway and produces a mix of flavonoids, the rice ANS cDNA was cloned and overexpressed in a rice mutant Nootripathu (NP). This mutant accumulates proanthocyanidins exclusively in pericarp and absolutely no anthocyanins in any tissue. In silico sequence analysis revealed that ANS contains a double-stranded beta helix and shows high sequence similarity with other DOXs of the pathway including flavonol synthase, flavonone 3β-hydroxylase and flavone synthase I. Bacterially expressed ANS protein converted dihydroquercetin to quercetin and Pro35S:ANS complemented the maize a2 mutant in producing anthocyanins in aleurone, suggesting that ANS functions as a DOX with different flavonoid substrates. Similarly, transgenic NP plants overexpressing ProMAS:ANS channeled the proanthocaynidin precursors to the production of anthocyanins in pericarp. Transgenics showed approximately ten and four-fold increase in the ANS transcripts and enzyme activity, respectively. As a result, these plants showed an increased accumulation of a mixture of flavonoids and anthocyanins, with a concomitant decrease in proanthocyanidins, suggesting that ANS may act directly on different flavonoid substrates of DOX reactions. Thus, overexpression of ANS in a rice mutant resulted in novel transgenic rice with a mixture of flavonoids and an enhanced antioxidant potential

The maize (Zea mays L.) roothairless3 gene encodes a putative GPI-anchored, monocot-specific, COBRA-like protein that significantly affects grain yield

The rth3 (roothairless 3) mutant is specifically affected in root hair elongation. We report here the cloning of the rth3 gene via a PCR-based strategy (amplification of insertion mutagenized sites) and demonstrate that it encodes a COBRA-like protein that displays all the structural features of a glycosylphosphatidylinositol anchor. Genes of the COBRA family are involved in various types of cell expansion and cell wall biosynthesis. The rth3 gene belongs to a monocot-specific clade of the COBRA gene family comprising two maize and two rice genes. While the rice (Oryza sativa) gene OsBC1L1 appears to be orthologous to rth3 based on sequence similarity (86% identity at the protein level) and maize/rice synteny, the maize (Zea mays L.) rth3-like gene does not appear to be a functional homolog of rth3based on their distinct expression profiles. Massively parallel signature sequencing analysis detected rth3 expression in all analyzed tissues, but at relatively low levels, with the most abundant expression in primary roots where the root hair phenotype is manifested.In situ hybridization experiments confine rth3 expression to root hair-forming epidermal cells and lateral root primordia. Remarkably, in replicated field trials involving near-isogenic lines, the rth3 mutant conferred significant losses in grain yield.This article is from The Plant Journal 54 (2008): 888–898, doi:10.1111/j.1365-313X.2008.03459.x. Posted with permission.</p