Effects Of Nutrient Elements On The Growth Of Phytophthora Nicotianae And Gene Differential Transcription In The Sporangiogenesis Of P.Nicotianae By Boron

Tobacco is one of the important economical crops. Tobacco black shank, which is caused by Phytophthora nicotianae, is one of the important soil-borne diseases of tobacco. The pathogen can produce sprorangia or zoo spores which invade to the host plant. The disease can be effectively controlled if the sporangia of P. nicotianae can be controlled or reduced. Recent research shows that soil mineral nutrients not only affect the normal growth of plants, but also have significant effects on the fungal, bacterial, viral and other infectious diseases.Previous studies in our laboratory have indicated that5mg/L of boron can significantly inhibit the production of P. nicotianae sporangia. Thus, it is a new way to control the disease by regulating mineral nutrients in the soil. The effects of the nutrient elements on the mycelial growth and sporangia of P. nicotianae were studied in this paper. The differentially gene transcription in the sporangio gene sis of P. nicotianae by5mg/L of boron was analyzed using SSH. The mechanism of nutrient elements on the mycelial growth and sporangia of P. nicotianae and the inhibition of boron against production of P. nicotianae sporangia was also studied, which can help understanding the relationship between the minaeral nutrients and the pathogen P. nicotianae. The results are as follows. 1The effects of the moderate and trace mineral nutrients on the mycelial growth of P. nicotianaeThe results showed that among moderate element,200～1500mg/L of Ca2+can significantly promote the mycelial growth of P. nicotianae, while800mg/L of Mg2+inhibit the growth. Among the trace elements,0.25～20mg/L of B4O72-and0.5～5.64mg/L of Cu2+have no significant effects on the growth of the pathogen.150mg/L of Fe3+can promote significantly, while2.5mg/L,7mg/L and300mg/L of Fe3+can highly inhibit the mycelial growth.5mg/L of Mn2+affects the growth obviously, while10mg/L,150mg/L and300mg/L of Mn2+have significantly promote or no significant effects on the gro wth of the mycelial27mg/L of Zn2+and300mg/L of Mo7O246-highly inhibit the growth of the pathogen.2The effects of the moderate and trace mineral nutrients on the production of sporangia of P. nicotianaeThe results showed that1～1000mg/L of Ca2+and Mg2+can significantly promote the production of sporangia,1mg/L,10mg/L of Ca2+and Mg2+can increase the size of the sporangia, while100mg/L of SO42-can significantly promote the production of sporangia,10mg/L、1000mg/L of SO422-can dramatically inhibit the production of the sporangia. Among the trace elements, only0.1mg/L of Mn2+can dramatically inhibit the production of the sporangia. The number of sporangia decreases with the increasing concentration of Mn2+. The inhibitory effects of Fe3+is less than Mn2+.0.1mg/L and100mg/L Fe3+highly inhibit the production. More than0.1mg/L ofCu2+and Mo7O246-can dramatically inhibit the production of the sporangia. Only1mg/L Zn2+can increase the production, while0.1mg/L、10mg/L、100mg/L of Zn2+inhibit it significantly. The previous results showed5mg/L of B4O72-can dramatically inhibit the production of the sporangia.3The effects of gene transcription to P. nicotianae during sporulation by boronComparing the previous results, B4O72-has no significant effects on the mycelial growth, while it can highly inhibit the production of sporangia. Therefore, the effects of gene transcription to P. nicotianae during sporulation by boron were studied using SSH. The function of the obtained sequence was analyzed.COG database analysis showed that seventy and fifty-four unigenes are annotated in the pros and cons subtracted library respectively. In the "cell processing and signal", respectively, six and four genes are related to "post-processing, protein folding, molecular chaperones". Twenty-six and thirteen genes are related to metabolism, in the pros subtractive library, nine genes are related to "carbohydrate transport and metabolism", five genes are related to "energy production and conversion". In the cons subtractive library, six genes are related to "carbohydrate transport and metabolism", four genes are related to "energy production and conversion", three genes are related to "amino acid transport and metabolism". Twenty-nine and twenty-eight genes belong to the "Information Storage and Processing" classes respectively, both twenty-seven genes are related to "Translation, ribosomal structure and bio transformation" in the two libraries.KEGG database analysis showed that two hundred and one and one hundred and forty-two unigenes are annotated respectively, in which one hundred and two and eighty-four unigenes belong to genetic information processing category, ranking first. Translation are82.1%and72.5%, respectively, the majority are related to "ribosome "(ko03010and ko03011) translation. In the cons subtractive library, a high quality420bp fragment (COPS4signaling complexes CSN4subunit) was obtained by further sequence analysis. It is homologized with COP9complex CSN4which is derived by the genome sequencing of P. infestans. Respectively seventy and thirty-three unigenes belong to metabolism, in the pros subtractive library,30%and15.7%are carbohydrate and amino acid metabolism respectively. In the cons subtractive library, amino acid metabolism account for36.36%, while carbohydrate metabolism account for30.3%.GO database analysis showed that four hundred and thirty-four and three hundred and thirty-six unigenes are annotated in the pros and cons subtracted library respectively. In the class of CC, two subclasses called "cells and part" and "polymer mixture and organelles" are the majority in pros subtractive library, which account for51.9%,41.1%and38.3%,43.0%respectively. In the class of MF, most of them participate in "connection","catalytic activity" and "structural molecule activity", which account for39.5%,28.9%,25.4%and43.3%,24.4%,30.0%. In BP,"cellular processes" and "metabolic process" are36.4%,40.1%and43.3%,46.2%.The results of COG,KEGG and GO databases analysis showed that the main reason of inhibiting the production of sporangia of P.nicotianae by boron is probably related to the translation of ribosome and structural formation and metabolism of organelle. A gene segment of420bp was obtained by further sequence analysis. It is homologized with COP9complex CSN4which is derived by the genome sequencing of P. infestans. This gene would be presumably related to the production of the sporangia of P.nicotianae, while its function should be studied further.